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Keith M Bagnall - One of the best experts on this subject based on the ideXlab platform.
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development of scoliosis following Pinealectomy in young chickens is not the result of an artifact of the surgical procedure
2001Co-Authors: M Beuerlein, Marc Moreau, J Mahood, X Wang, J Raso, Keith M BagnallAbstract:Pinealectomy in young chickens consistently results in scoliosis, which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of Pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity, or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different Pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The Pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the etiology of AIS and can lead to the development of novel treatment methods. Microsc. Res. Tech. 53:81–86, 2001. © 2001 Wiley-Liss, Inc.
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the critical stage of Pinealectomy surgery after which scoliosis is produced in young chickens
2001Co-Authors: M Beuerlein, Xiaoping Wang, Marc Moreau, V J Raso, J Wilson, J Mahood, B J Greenhill, Keith M BagnallAbstract:Study design Stages of the surgical procedure for Pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. Objectives To determine the critical stage of surgery for Pinealectomy after which scoliosis develops in young chickens. Summary of background data Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. Methods Five distinct stages in the Pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. Results Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. Conclusions Cutting the pineal stalk was identified as the critical stage of Pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.
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the effects of melatonin therapy on the development of scoliosis after Pinealectomy in the chicken
1999Co-Authors: Keith M Bagnall, Xiaoping Wang, Marc Moreau, J Mahood, James V Raso, Jie ZhaoAbstract:The mechanism underlying the development of scoliosis after Pinealectomy in young chickens is unknown. However, since the main product of the pineal gland is melatonin, melatonin remains an obvious focus in studies designed to discover this mechanism. One confounding factor is that serum melatonin levels are close to zero after Pinealectomy but scoliosis does not develop in all chickens that have had this procedure. Therefore, the role of melatonin in the development of scoliosis in chickens after Pinealectomy remains controversial. In the current investigation, two pilot studies demonstrated that a physiological therapeutic dose of melatonin (2.5 milligrams per kilogram of body weight) restored the circadian rhythm of melatonin, as measured by serum assay. In the main study, this dose was administered daily starting either immediately after the Pinealectomy or two weeks after it, when scoliosis had developed. Scoliosis was assessed on weekly radiographs, and the Cobb angle was determined for all chickens in which scoliosis developed. Overall, scoliosis developed in only 56 percent (fifty) of the eighty-nine chickens that had had a Pinealectomy; this rate was consistent throughout all experimental groups. Scoliosis did not develop in any of the control chickens, which did not have a Pinealectomy. On the basis of the average Cobb angles in the chickens in which scoliosis had developed, it was determined that neither the prevalence nor the pattern of the scoliosis was affected by the therapy in any of the experimental groups. It was thus concluded that melatonin therapy after Pinealectomy in young chickens has no effect on the development or progression of scoliosis. These results raise doubts regarding the role of melatonin in the development of scoliosis after Pinealectomy in the young chicken. CLINICAL RELEVANCE: Although scoliosis has been produced in some animal studies, none of these models has proved to be entirely satisfactory. Consequently, research regarding adolescent idiopathic scoliosis has been hampered. Recently, it was shown that scoliosis with many characteristics similar to those seen in patients who have adolescent idiopathic scoliosis can be produced consistently in chickens after Pinealectomy. This finding encourages the development of this model. An understanding of the mechanism involved in the development of scoliosis after Pinealectomy in chickens might provide new insights into adolescent idiopathic scoliosis and aid in the development of novel treatment methods.
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the production of scoliosis after Pinealectomy in young chickens rats and hamsters
1999Co-Authors: Cian Okelly, Xiaoping Wang, Marc Moreau, Jie Zhao, J Mahood, James Raso, Keith M BagnallAbstract:Study Design. This study involved weekly radiographic examination of pinealectomized rats, hamsters, and chickens to observe the development of scoliosis. Objectives. To determine whether Pinealectomy produces scoliosis in animals more closely related phylogenetically to humans than to chickens, namely rats and hamsters, which are representative of mammals. Summary of Background Data. Pinealectomy in 3-day-old chickens has consistently resulted in the development of scoliosis with many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. It has not been determined whether this phenomenon is restricted solely to chickens or is applicable to other animals, especially those more closely related to humans. Methods. The pineal gland was removed from young rats, hamsters, and chickens. All animals underwent radiography weekly to detect the development of any scoliosis. Weight and length measurements were also taken weekly, and serum melatonin levels were determined at the time the animals were killed. Results. Scoliosis was not observed in either the rats or the hamsters. In contrast, scoliosis developed in 10 of 21 chickens. Serum melatonin levels in all pinealectomized animals were zero. Conclusions. In contrast to the chickens, Pinealectomy does not seem to cause scoliosis in either young rats or hamsters. The reasons for this discrepancy may include differences in the physiology and spinal morphology of the rat and hamster in comparison with the chicken. In the pinealectomized chickens, the results also suggest that future scoliosis development might be indicated by a significant increase in size when they are compared with pinealectomized chickens that do not develop scoliosis. Such differences in growth rates also distinguish patients with adolescent idiopathic scoliosis.
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changes in serum melatonin levels in response to Pinealectomy in the chicken and its correlation with development of scoliosis
1998Co-Authors: Xiaoping Wang, Marc Moreau, V J Raso, Jie Zhao, Hongxing Jiang, J Mahood, Keith M BagnallAbstract:Study Design. Normal, sham, and groups of chickens subjected to Pinealectomy from which serum melatonin levels were measured and correlated with scoliosis development in a period of 5 weeks. Objectives. To measure serum melatonin levels in chickens subjected to Pinealectomy and control chickens and correlate findings with development of scoliosis. of Background Data. In a previous study by others, scoliosis developed in 100% of chickens subjected to Pinealectomy, and serum melatonin levels were found to be reduced. Previous results in a study by the authors showed scoliosis developing in only approximately 55% of chickens that underwent Pinealectomy. Methods. Young chickens were subjected to Pinealectomy. Control groups consisted of sham operation and normal groups. Radiographs and blood samples were taken at weekly intervals to monitor scoliosis development and measure serum melatonin levels using radioimmunoassay techniques. Results. Scoliosis developed in only 52% of chickens that underwent Pinealectomy, but all had low levels of serum melatonin and no circadian rhythm. The chickens in the two control groups maintained normal serum melatonin levels and rhythms. Conclusions. Pinealectomy in young chickens reduces serum melatonin levels and eliminates the melatonin circadian rhythm. It can also produce scoliosis, but low levels of serum melatonin are a poor predictor of development of scoliosis.
Francois Gauer - One of the best experts on this subject based on the ideXlab platform.
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endogenous melatonin provides an effective circadian message to both the suprachiasmatic nuclei and the pars tuberalis of the rat
2009Co-Authors: Laurence Agez, Mireille Massonpevet, Paul Pevet, Virginie Laurent, Hilda Y Guerrero, Francois GauerAbstract:The suprachiasmatic nuclei (SCN) distribute the circadian neural message to the pineal gland which transforms it into a humoral circadian message, the nocturnal melatonin synthesis, which in turn modulates tissues expressing melatonin receptors such as the SCN or the pars tuberalis (PT). Nuclear orphan receptors (NOR), including rorbeta and rev-erbalpha, have been presented as functional links between the positive and negative loops of the molecular clock. Recent findings suggest that these NOR could be the initial targets of melatonin's chronobiotic message within the SCN. We investigated the role of these NOR in the physiological effect of endogenous melatonin on these tissues. We monitored rorbeta and rev-erbalpha mRNA expression levels by quantitative in situ hybridization after Pinealectomy. Pinealectomy had no effect on NOR circadian expression rhythms in the SCN in 8-day pinealectomized (PX) animals. However in animals PX for 3 months, significant desynchronization between per1 and per2 transcription patterns appeared. These results suggest that endogenous melatonin could sustain the circadian rhythmicity and the phase relationship between the molecular partners of the SCN circadian system on a long-term basis. On the other hand, Pinealectomy decreased the level and abolished the rhythmicity of NOR mRNA expression in the PT. These effects were partially prevented by daily melatonin administration in the drinking water. These results show that NOR can be regulated by the melatonin circadian rhythm in the PT and could be the link between the physiological action of melatonin and the core of the molecular circadian clock in this tissue.
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differential regulation of melatonin receptors by short versus long term Pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis
1994Co-Authors: Francois Gauer, Mireille Massonpevet, Paul PevetAbstract:Gauer F, Masson-Pevet M, Pevet P. Differential regulation of melatonin receptors by short- versus long-term Pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis. J. Pineal Res. 1994: 16: 73–76. Abstract We have investigated the effects of short- and long-term Pinealectomy on the density of melatonin receptors in both the suprachiasmatic nuclei (SCN) and pars tubercles (PT) of the rat. Short-term Pinealectomy (conducted 3-5 days before sacrifice) induced a significant increase in the density of melatonin receptors in both structures. This increase can be interpreted as an up-regulation of melatonin receptors following the absence of plasma melanoma. In contrast, 7 days after pinelectomy, the receptor density began to decrease, reaching a low point 1. 5 months after Pinealectomy. At this time, the decrease represents a 40-45% reduction in binding sites as compared with values measured 3–5 days after Pinealectomy. This slow decrease could be related to a slowdown of melatonin receptor synthesis. These results suggest that emblazoning has a stimulatory effect on its own receptor synthesis. However, at 1. 5 months after Pinealectomy a novel equilibrium between synthesis and hydrolysis seems to be reached. Melanoma does not appear to be indispensable for the synthesis of its receptors.
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effect of constant light Pinealectomy and guanosine triphosphate gamma s on the density of melatonin receptors in the rat suprachiasmatic nucleus a possible implication of melatonin action
1992Co-Authors: Francois Gauer, Mireille Massonpevet, Paul PevetAbstract:We report here the effects of Pinealectomy and exposition to constant light on the density of melatonin receptors in the suprachiasmatic nuclei of the rat using quantitative autoradiography. The B(max) values were significantly increased when the animals were maintained in constant light for 3 days (8.22 ± 0.95 fmol/mg protein versus 4.55±0.14 fmol/mg protein in control group, 12 h light/12 h dark cycle (12L/12D), n = 6). A similar increase was also observed in rats pinealectomized 3 days before sacrifice and then maintained either under 12L/12D (B(max) 7.56±0.80 fmol/mg protein) or in constant light (B(max) 7.85±1.02 fmol/mg protein), while K(d) values failed to show any variations after constant light and/or Pinealectomy. The effect of GTPγS on the density of rnelatonin binding sites was also investigated in control animals and after 3 days of constant light. In 12L/12D animals, the B(max) shifted from 5.94 ± 0.14 fmol/mg protein in the absence of GTPγS to 3.97±0.22 fmol/ mg protein in the presence of 50μiM GTPγS. In animals maintained for 3 days in constant light, a similar decrease in the B(max) value was observed (8.95 ± 0.25 fmol/mg protein in absence and 5.95 ± 0.22 fmol/mg protein in presence of 50 μ GTPγS). In both cases, K(d) values were not affected by GTPγS. Pinealectomy and constant light exposition are known to induce a suppression of the nocturnal peak of plasma rnelatonin and to keep plasma rnelatonin concentrations at a very low level. These results could suggest a regulatory effect of rnelatonin on the density of its own receptors which are shown here to be also coupled with a G-protein.
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Pinealectomy and constant illumination increase the density of melatonin binding sites in the pars tuberalis of rodents
1992Co-Authors: Francois Gauer, Massonpe M Vet, Pe P VetAbstract:Abstract We report here the effects of Pinealectomy and light exposure on the melatonin receptor density in the pars tuberalis of the rat and the European hamster using quantitative autoradiography. Scatchard analysis revealed that 24 and 72 h of constant light exposure (LL) before sacrifice did not modify the K d value of melatonin for its receptors in rats and European hamsters (about 70 pM). In contrast, the B max value was significantly increased in both species when the animals were kept in constant illumination for 72 h before sacrifice (50%–70% compared with the controls). A similar increase was also observed in rats pinealectomized 3 days before sacrifice and then kept in either constant illumination or in 12L/12D. Pinealectomy or constant light exposure are known to result in a clear decrease in the concentration of circulating melatonin. We demonstrate here that they also result in an increase in the density of melatonin receptors. This could suggest a direct effect of melatonin on its own receptors.
Paul Pevet - One of the best experts on this subject based on the ideXlab platform.
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endogenous melatonin provides an effective circadian message to both the suprachiasmatic nuclei and the pars tuberalis of the rat
2009Co-Authors: Laurence Agez, Mireille Massonpevet, Paul Pevet, Virginie Laurent, Hilda Y Guerrero, Francois GauerAbstract:The suprachiasmatic nuclei (SCN) distribute the circadian neural message to the pineal gland which transforms it into a humoral circadian message, the nocturnal melatonin synthesis, which in turn modulates tissues expressing melatonin receptors such as the SCN or the pars tuberalis (PT). Nuclear orphan receptors (NOR), including rorbeta and rev-erbalpha, have been presented as functional links between the positive and negative loops of the molecular clock. Recent findings suggest that these NOR could be the initial targets of melatonin's chronobiotic message within the SCN. We investigated the role of these NOR in the physiological effect of endogenous melatonin on these tissues. We monitored rorbeta and rev-erbalpha mRNA expression levels by quantitative in situ hybridization after Pinealectomy. Pinealectomy had no effect on NOR circadian expression rhythms in the SCN in 8-day pinealectomized (PX) animals. However in animals PX for 3 months, significant desynchronization between per1 and per2 transcription patterns appeared. These results suggest that endogenous melatonin could sustain the circadian rhythmicity and the phase relationship between the molecular partners of the SCN circadian system on a long-term basis. On the other hand, Pinealectomy decreased the level and abolished the rhythmicity of NOR mRNA expression in the PT. These effects were partially prevented by daily melatonin administration in the drinking water. These results show that NOR can be regulated by the melatonin circadian rhythm in the PT and could be the link between the physiological action of melatonin and the core of the molecular circadian clock in this tissue.
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impaired cognitive performance in rats after complete epithalamus lesions but not after Pinealectomy alone
2005Co-Authors: Christopher Kelly, Michel Saboureau, Paul Pevet, Lucas Lecourtier, Peter H KellyAbstract:In the midbrain, the epithalamus comprises the habenular nuclei and the pineal gland. Based on evidence including imaging studies in schizophrenia patients, several investigators have postulated that dysfunction of this structure is causally involved in symptoms of schizophrenia. Recently, we showed that bilateral habenula lesions in the rat induced some schizophrenia-like behavioural changes, namely memory and attention impairments, but unaltered social interaction in a brief encounter and prepulse inhibition (PPI) of the startle reflex. Here, the possible involvement of the pineal gland in the same behaviours was assessed, by examining them in two series of experiments. In the first, these behaviours were examined in pinealectomized rats compared to sham-operated controls. In the second, they were examined in rats with combined lesion of habenula plus Pinealectomy compared to sham-operated controls, to examine whether Pinealectomy induced further deficits when combined with habenula damage. Lesions of habenula were confirmed histologically and neurochemically by reduction of choline acetyltransferase in the interpeduncular nucleus. Pinealectomy was confirmed post mortem by careful visual inspection. Pinealectomy induced no deficits in any test, while combined lesions led to the same pattern of deficits as previously observed after habenula lesion, i.e. marked memory impairment in the Morris water maze without affecting the amount of social interaction or PPI of the startle reflex. Thus, loss of pineal function causes no deficits in these behaviours and does not alter the qualitative pattern of deficits resulting from habenula damage.
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differential regulation of melatonin receptors by short versus long term Pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis
1994Co-Authors: Francois Gauer, Mireille Massonpevet, Paul PevetAbstract:Gauer F, Masson-Pevet M, Pevet P. Differential regulation of melatonin receptors by short- versus long-term Pinealectomy in the rat suprachiasmatic nuclei and pars tuberalis. J. Pineal Res. 1994: 16: 73–76. Abstract We have investigated the effects of short- and long-term Pinealectomy on the density of melatonin receptors in both the suprachiasmatic nuclei (SCN) and pars tubercles (PT) of the rat. Short-term Pinealectomy (conducted 3-5 days before sacrifice) induced a significant increase in the density of melatonin receptors in both structures. This increase can be interpreted as an up-regulation of melatonin receptors following the absence of plasma melanoma. In contrast, 7 days after pinelectomy, the receptor density began to decrease, reaching a low point 1. 5 months after Pinealectomy. At this time, the decrease represents a 40-45% reduction in binding sites as compared with values measured 3–5 days after Pinealectomy. This slow decrease could be related to a slowdown of melatonin receptor synthesis. These results suggest that emblazoning has a stimulatory effect on its own receptor synthesis. However, at 1. 5 months after Pinealectomy a novel equilibrium between synthesis and hydrolysis seems to be reached. Melanoma does not appear to be indispensable for the synthesis of its receptors.
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effect of constant light Pinealectomy and guanosine triphosphate gamma s on the density of melatonin receptors in the rat suprachiasmatic nucleus a possible implication of melatonin action
1992Co-Authors: Francois Gauer, Mireille Massonpevet, Paul PevetAbstract:We report here the effects of Pinealectomy and exposition to constant light on the density of melatonin receptors in the suprachiasmatic nuclei of the rat using quantitative autoradiography. The B(max) values were significantly increased when the animals were maintained in constant light for 3 days (8.22 ± 0.95 fmol/mg protein versus 4.55±0.14 fmol/mg protein in control group, 12 h light/12 h dark cycle (12L/12D), n = 6). A similar increase was also observed in rats pinealectomized 3 days before sacrifice and then maintained either under 12L/12D (B(max) 7.56±0.80 fmol/mg protein) or in constant light (B(max) 7.85±1.02 fmol/mg protein), while K(d) values failed to show any variations after constant light and/or Pinealectomy. The effect of GTPγS on the density of rnelatonin binding sites was also investigated in control animals and after 3 days of constant light. In 12L/12D animals, the B(max) shifted from 5.94 ± 0.14 fmol/mg protein in the absence of GTPγS to 3.97±0.22 fmol/ mg protein in the presence of 50μiM GTPγS. In animals maintained for 3 days in constant light, a similar decrease in the B(max) value was observed (8.95 ± 0.25 fmol/mg protein in absence and 5.95 ± 0.22 fmol/mg protein in presence of 50 μ GTPγS). In both cases, K(d) values were not affected by GTPγS. Pinealectomy and constant light exposition are known to induce a suppression of the nocturnal peak of plasma rnelatonin and to keep plasma rnelatonin concentrations at a very low level. These results could suggest a regulatory effect of rnelatonin on the density of its own receptors which are shown here to be also coupled with a G-protein.
Xiaoping Wang - One of the best experts on this subject based on the ideXlab platform.
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the critical stage of Pinealectomy surgery after which scoliosis is produced in young chickens
2001Co-Authors: M Beuerlein, Xiaoping Wang, Marc Moreau, V J Raso, J Wilson, J Mahood, B J Greenhill, Keith M BagnallAbstract:Study design Stages of the surgical procedure for Pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. Objectives To determine the critical stage of surgery for Pinealectomy after which scoliosis develops in young chickens. Summary of background data Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. Methods Five distinct stages in the Pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. Results Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. Conclusions Cutting the pineal stalk was identified as the critical stage of Pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.
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the effects of melatonin therapy on the development of scoliosis after Pinealectomy in the chicken
1999Co-Authors: Keith M Bagnall, Xiaoping Wang, Marc Moreau, J Mahood, James V Raso, Jie ZhaoAbstract:The mechanism underlying the development of scoliosis after Pinealectomy in young chickens is unknown. However, since the main product of the pineal gland is melatonin, melatonin remains an obvious focus in studies designed to discover this mechanism. One confounding factor is that serum melatonin levels are close to zero after Pinealectomy but scoliosis does not develop in all chickens that have had this procedure. Therefore, the role of melatonin in the development of scoliosis in chickens after Pinealectomy remains controversial. In the current investigation, two pilot studies demonstrated that a physiological therapeutic dose of melatonin (2.5 milligrams per kilogram of body weight) restored the circadian rhythm of melatonin, as measured by serum assay. In the main study, this dose was administered daily starting either immediately after the Pinealectomy or two weeks after it, when scoliosis had developed. Scoliosis was assessed on weekly radiographs, and the Cobb angle was determined for all chickens in which scoliosis developed. Overall, scoliosis developed in only 56 percent (fifty) of the eighty-nine chickens that had had a Pinealectomy; this rate was consistent throughout all experimental groups. Scoliosis did not develop in any of the control chickens, which did not have a Pinealectomy. On the basis of the average Cobb angles in the chickens in which scoliosis had developed, it was determined that neither the prevalence nor the pattern of the scoliosis was affected by the therapy in any of the experimental groups. It was thus concluded that melatonin therapy after Pinealectomy in young chickens has no effect on the development or progression of scoliosis. These results raise doubts regarding the role of melatonin in the development of scoliosis after Pinealectomy in the young chicken. CLINICAL RELEVANCE: Although scoliosis has been produced in some animal studies, none of these models has proved to be entirely satisfactory. Consequently, research regarding adolescent idiopathic scoliosis has been hampered. Recently, it was shown that scoliosis with many characteristics similar to those seen in patients who have adolescent idiopathic scoliosis can be produced consistently in chickens after Pinealectomy. This finding encourages the development of this model. An understanding of the mechanism involved in the development of scoliosis after Pinealectomy in chickens might provide new insights into adolescent idiopathic scoliosis and aid in the development of novel treatment methods.
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the production of scoliosis after Pinealectomy in young chickens rats and hamsters
1999Co-Authors: Cian Okelly, Xiaoping Wang, Marc Moreau, Jie Zhao, J Mahood, James Raso, Keith M BagnallAbstract:Study Design. This study involved weekly radiographic examination of pinealectomized rats, hamsters, and chickens to observe the development of scoliosis. Objectives. To determine whether Pinealectomy produces scoliosis in animals more closely related phylogenetically to humans than to chickens, namely rats and hamsters, which are representative of mammals. Summary of Background Data. Pinealectomy in 3-day-old chickens has consistently resulted in the development of scoliosis with many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. It has not been determined whether this phenomenon is restricted solely to chickens or is applicable to other animals, especially those more closely related to humans. Methods. The pineal gland was removed from young rats, hamsters, and chickens. All animals underwent radiography weekly to detect the development of any scoliosis. Weight and length measurements were also taken weekly, and serum melatonin levels were determined at the time the animals were killed. Results. Scoliosis was not observed in either the rats or the hamsters. In contrast, scoliosis developed in 10 of 21 chickens. Serum melatonin levels in all pinealectomized animals were zero. Conclusions. In contrast to the chickens, Pinealectomy does not seem to cause scoliosis in either young rats or hamsters. The reasons for this discrepancy may include differences in the physiology and spinal morphology of the rat and hamster in comparison with the chicken. In the pinealectomized chickens, the results also suggest that future scoliosis development might be indicated by a significant increase in size when they are compared with pinealectomized chickens that do not develop scoliosis. Such differences in growth rates also distinguish patients with adolescent idiopathic scoliosis.
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changes in serum melatonin levels in response to Pinealectomy in the chicken and its correlation with development of scoliosis
1998Co-Authors: Xiaoping Wang, Marc Moreau, V J Raso, Jie Zhao, Hongxing Jiang, J Mahood, Keith M BagnallAbstract:Study Design. Normal, sham, and groups of chickens subjected to Pinealectomy from which serum melatonin levels were measured and correlated with scoliosis development in a period of 5 weeks. Objectives. To measure serum melatonin levels in chickens subjected to Pinealectomy and control chickens and correlate findings with development of scoliosis. of Background Data. In a previous study by others, scoliosis developed in 100% of chickens subjected to Pinealectomy, and serum melatonin levels were found to be reduced. Previous results in a study by the authors showed scoliosis developing in only approximately 55% of chickens that underwent Pinealectomy. Methods. Young chickens were subjected to Pinealectomy. Control groups consisted of sham operation and normal groups. Radiographs and blood samples were taken at weekly intervals to monitor scoliosis development and measure serum melatonin levels using radioimmunoassay techniques. Results. Scoliosis developed in only 52% of chickens that underwent Pinealectomy, but all had low levels of serum melatonin and no circadian rhythm. The chickens in the two control groups maintained normal serum melatonin levels and rhythms. Conclusions. Pinealectomy in young chickens reduces serum melatonin levels and eliminates the melatonin circadian rhythm. It can also produce scoliosis, but low levels of serum melatonin are a poor predictor of development of scoliosis.
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characterization of the scoliosis that develops after Pinealectomy in the chicken and comparison with adolescent idiopathic scoliosis in humans
1997Co-Authors: Xiaoping Wang, Marc Moreau, Jie Zhao, Hongxing Jiang, J Mahood, James Raso, Keith M BagnallAbstract:STUDY DESIGN The characteristics of the scoliosis that develops after Pinealectomy in young chickens were determined from weekly posteroanterior radiographs. These data were compared with similar data collected from human patients with adolescent idiopathic scoliosis. OBJECTIVES To characterize the scoliosis produced in young chickens after Pinealectomy and to compare these characteristics with those seen in human patients with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA Although it has been recognized that Pinealectomy produces scoliosis in chickens, the characteristics of these curves have never been well described other than by simple visual descriptions. METHODS The characteristics of the scoliosis produced in chickens after Pinealectomy done 3 days after hatching were measured from radiographs taken at weekly intervals. These characteristics were compared with similar data collected from human patients with adolescent idiopathic scoliosis. RESULTS Similarities included development of single and double curves, degree of curvature, stability of the curve, numbers of vertebrae involved, direction of rotation, and progression characteristics. Differences included wedged vertebrae in the chickens, in conjunction with curve development and increased variability in vertebrae involved. CONCLUSIONS There are many similarities in the development of scoliosis in young chickens after Pinealectomy and in children with adolescent idiopathic scoliosis. The few differences might be related to the different biomechanical properties associated with the spine in the two species.
Mehmet Turgut - One of the best experts on this subject based on the ideXlab platform.
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Stereological analysis of sciatic nerve in chickens following neonatal Pinealectomy: an experimental study
2010Co-Authors: Mehmet Turgut, Suleyman Kaplan, Bunyamin şahin, Yigit Uyanikgil, Burçin Zeynep Ünal, Mehmet Bozkurt, Sinan Yürüker, Çigdem Yenisey, Meral BakaAbstract:Background Although the injury to the peripheral nervous system is a common clinical problem, understanding of the role of melatonin in nerve degeneration and regeneration is incomplete. Methods The current study investigated the effects of neonatal Pinealectomy on the sciatic nerve microarchitecture in the chicken. The chickens were divided into two equal groups: unpinealectomized controls and pinealectomized chickens. At the end of the study, biochemical examination of 10 sciatic nerve samples from both groups was performed and a quantitative stereological evaluation of 10 animals in each group was performed. The results were compared using Mann-Whitney test. Results In this study, the results of axon number and thickness of the myelin sheath of a nerve fiber in newly hatched Pinealectomy group were higher than those in control group. Similarly, surgical Pinealectomy group had significantly larger axonal cross-sectional area than the control group (p < 0.05). In addition, the average hydroxyproline content of the nerve tissue in neonatal Pinealectomy group was higher than those found in control group. Our results suggest that melatonin may play a role on the morphologic features of the peripheral nerve tissue and that melatonin deficiency might be a pathophysiological mechanism in some degenerative diseases of peripheral nerves. The changes demonstrated by quantitative morphometric methods and biochemical analysis has been interpreted as a reflection of the effects of melatonin upon nerve tissue. Conclusion In the light of these results from present animal study, changes in sciatic nerve morphometry may be indicative of neuroprotective feature of melatonin, but this suggestion need to be validated in the human setting.
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effects of Pinealectomy on morphological features of blood vessel in chicken an electron microscopic and stereological study
2009Co-Authors: Mehmet Turgut, Suleyman Kaplan, Zeynep Burcin Unal, Zuhal Altunkaynak, Deniz Unal, Bunyamin şahin, Mehmet Recep Bozkurt, Mine YurtsevenAbstract:Although the effects of melatonin on vascular smooth muscle and vascular reactivity are described in last decade, the effects of melatonin on vascular tissues are still vague. The current study investigated the effects of Pinealectomy on the blood vessel wall in the chicken. Fifteen chicks were divided into three groups, namely unoperated control, sham-operated and pinealectomized chicks. At the end of the experiment, a quantitative structural analysis of 15 sciatic artery samples from these groups was investigated. Effects of Pinealectomy were quantified using volume fraction approach of stereological method. In this study, total cross-sectional area of the artery in Pinealectomy group was significantly higher than those in unoperated control and sham-operated animals (p < 0.05). However, surgical Pinealectomy procedure resulted in a significantly decreased thickness of the tunica adventitia of the vessel wall, in contrast to those of tunica media (p < 0.01). The present results indicate that Pinealectomy had a vasodilator effect on the sciatic artery. In the light of current study, the structural changes in the vessel demonstrated by quantitative morphometric methods have been interpreted as a reflection of the role of melatonin on vessel wall and vascular reactivity, but this suggestion need to be validated in the human setting.
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inhibitory effect of Pinealectomy on the development of cerebellar granule cells in the chick a stereological study
2007Co-Authors: Ayten Turkkani Tunc, Mehmet Turgut, Huseyin Aslan, Fatih Ekici, Ersan Odaci, Suleyman KaplanAbstract:Melatonin has some effects upon morphological features of various structures in small animals and human being. However, there has been no investigation concerning its physiological role on development of cerebellar granule cells. In this study, the changes induced by Pinealectomy procedure on cerebellar development and their granule cell numbers in the chick were investigated using quantitative stereological methods. A total of 15 Hybro Broiler newly hatched chicks were randomly divided into three equal groups: Pinealectomy group (n = 5) and non-pinealectomized control group (n = 5) and sham-operated group (n = 5). Pinealectomy procedure and sham operation were done in 3-day-old chicks and all animals were sacrificed for histopathological evaluation and subsequent stereological analysis in the 8th week. Here, it was observed that Pinealectomy significantly reduces the granular cell number in cerebellar cortex of the chicks (P < 0.001). The present study is the first stereological study to evaluate the histomorphological effects of Pinealectomy on the cerebellar granule cells of the chick. We suggest that the granule cell loss in the cerebellar cortex is due to developmental retardation in early postnatal period, although its exact mechanism is not clear. Based on our findings, we intimate that pineal gland/melatonin might play an important role in the development of cerebellar granule cells in the chick.
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effect of Pinealectomy on the morphology of the chick cervical spinal cord a stereological and histopathological study
2007Co-Authors: Mehmet Turgut, Ayten Turkkani Tunc, Huseyin Aslan, Ayse Canan Yazici, Suleyman KaplanAbstract:Melatonin has some effects upon morphological features of various structures in small animals and human being. In this study, the changes induced by Pinealectomy procedure on morphological features of developing cervical spinal cord and their neurons in the gray matter (GM) and white matter (WM) of cervical spinal cord in the chicken were investigated. A total of 15 Hybro Broiler newly hatched chicks were randomly divided into three equal groups: unoperated control group (n=5), sham-operated group (n=5) and Pinealectomy group (n=5). Pinealectomy procedure and sham operation were done in 3-day-old chicks and all animals were sacrificed at the 8th week and the 6th cervical (C6) spinal cord segment was dissected out for histopathological evaluation and subsequent stereological analysis. The volume of spinal cord segment did not show a significant difference between unoperated and sham-operated controls, but the Pinealectomy group has a declined volume value compared with those of the control and sham operated groups (P<0.01). By contrast, there was no statistically significant difference between unoperated and sham-operated controls and the Pinealectomy group with regard to volume fraction of the GM and WM of the cervical spinal cord. Finally, it was observed that Pinealectomy procedure significantly reduces neuron number in the GM and the volume of WM of the C6 segment of cervical spinal cord in the chicken (P<0.001). The present study is the first study at all to evaluate the effects of Pinealectomy on quantitative feature of the spinal cord in the chicken. Based on our findings, we suggest that pineal gland/melatonin might play an important role in morphological features of the developing spinal cord in the chicken.
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Pinealectomy stimulates and exogenous melatonin inhibits harmful effects of epileptiform activity during pregnancy in the hippocampus of newborn rats an immunohistochemical study
2006Co-Authors: Mehmet Turgut, Yigit Uyanikgil, Utku Ates, Meral Baka, Mine YurtsevenAbstract:Epilepsy during the pregnancy is an important problem in clinical practice for newborn individuals. Recently, it has been demonstrated that mothers’ epileptic seizures have some harmful effects on newborns, but present data concerning the effects of epileptic phenomena in pregnant mothers on newborn pups are still limited. The current study was undertaken to investigate the morphological changes in the hippocampus of newborn pups of pinealectomized rats subjected to experimental epilepsy during pregnancy. In this study, rats were randomly divided into four groups (ten animals each): intact control group, epilepsy control group, surgical Pinealectomy + epilepsy group, and group with melatonin treatment following Pinealectomy procedure. The animals in surgical Pinealectomy + epilepsy and melatonin treatment groups underwent a surgical intervention consisting of pineal gland removal. At 1 month after surgical Pinealectomy, an acute grand mal epileptic seizure was induced by 400 IU penicillin G administration into their hippocampal CA3 region on the 13th day of their pregnancy in all animals except the intact control animals. On the first neonatal day, the hippocampi were removed and processed for microscopic examination. Nestin expression was analysed in the developing hippocampal tissue. Normal migration and hippocampal maturation were determined in the postnatal rat hippocampus in intact control group, but the morphological structure of the hippocampus in the epilepsy control group corresponded to the early embryonal period. It was found that experimental epilepsy and Pinealectomy enhanced nestin immunoreactivity, whereas exogenous melatonin treatment (30 μg/100 g body weight, intraperitoneal) inhibited Pinealectomy-stimulated nestin expression in CA1 region of the hippocampus. These findings suggest that epileptic seizures during pregnancy may cause an impaired hippocampal neurogenesis and neuronal maturation in the newborn, and the negative effects in the postnatal rat hippocampus are more dramatic after Pinealectomy of the mother; conversely, melatonin administration suppresses these negative changes. This is the first report investigating the effects of maternal epilepsy during pregnancy in pinealectomized rats on nestin immunoexpression in the newborn rat hippocampus.