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Judith M Stern - One of the best experts on this subject based on the ideXlab platform.
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maternal aggression in rats effects of Olfactory Bulbectomy znso4 induced anosmia and vomeronasal organ removal
Hormones and Behavior, 1995Co-Authors: Jane M Kolunie, Judith M SternAbstract:Abstract Previous studies from our laboratory indicate that somatosensory inputs to the snout and ventral trunk, but not visual or auditory stimuli, play critical roles in the elicitation and maintenance of maternal aggression by lactating Norway rats toward a strange male intruder. There are conflicting reports on the influence of olfaction on maternal aggression. We explored the possible roles of central or peripheral anosmia on maternal aggression in Long–Evans rats during early lactation. In Experiment 1, responsiveness to both volatile and non-volatile odors was eliminated by bilateral Olfactory Bulbectomy (BOB), carried out during mid-gestation. BOB resulted in a reduced likelihood and intensity of maternal aggression on days 1 and 5 of lactation (L1 and L5), but also severe deficiencies in maternal behavior and litter growth and survival. In Experiment 2, anosmia to volatile odors was induced by spraying zinc sulfate intranasally on gestation day 21 and L1. This treatment had little or no effect on maternal aggression on L1 or L2 or on maternal behavior, especially if there was a 1-day recovery between the second treatment and testing. In Experiment 3, responsiveness to non-volatile odors was eliminated by vomeronasal-organ removal (VNX) carried out prior to mating. VNX did not disturb maternal behavior on L2–L8 or maternal aggression on L1 or L5. These results and others suggest that the expression of maternal aggression is affected by volatile odors, mediated possibly by accessory chemosensory systems such as the septal organ, or by neural changes that follow Olfactory deafferentation, or both.
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maternal aggression in rats effects of Olfactory Bulbectomy znso4 induced anosmia and vomeronasal organ removal
Hormones and Behavior, 1995Co-Authors: Jane M Kolunie, Judith M SternAbstract:Abstract Previous studies from our laboratory indicate that somatosensory inputs to the snout and ventral trunk, but not visual or auditory stimuli, play critical roles in the elicitation and maintenance of maternal aggression by lactating Norway rats toward a strange male intruder. There are conflicting reports on the influence of olfaction on maternal aggression. We explored the possible roles of central or peripheral anosmia on maternal aggression in Long–Evans rats during early lactation. In Experiment 1, responsiveness to both volatile and non-volatile odors was eliminated by bilateral Olfactory Bulbectomy (BOB), carried out during mid-gestation. BOB resulted in a reduced likelihood and intensity of maternal aggression on days 1 and 5 of lactation (L1 and L5), but also severe deficiencies in maternal behavior and litter growth and survival. In Experiment 2, anosmia to volatile odors was induced by spraying zinc sulfate intranasally on gestation day 21 and L1. This treatment had little or no effect on maternal aggression on L1 or L2 or on maternal behavior, especially if there was a 1-day recovery between the second treatment and testing. In Experiment 3, responsiveness to non-volatile odors was eliminated by vomeronasal-organ removal (VNX) carried out prior to mating. VNX did not disturb maternal behavior on L2–L8 or maternal aggression on L1 or L5. These results and others suggest that the expression of maternal aggression is affected by volatile odors, mediated possibly by accessory chemosensory systems such as the septal organ, or by neural changes that follow Olfactory deafferentation, or both.
Philip V Holmes - One of the best experts on this subject based on the ideXlab platform.
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a role for 2 arachidonoylglycerol and endocannabinoid signaling in the locomotor response to novelty induced by Olfactory Bulbectomy
Pharmacological Research, 2010Co-Authors: Sarah A Eisenstein, Philip V Holmes, Jason R Clapper, Daniele Piomelli, Andrea G HohmannAbstract:Bilateral Olfactory Bulbectomy (OBX) in rodents produces behavioral and neurochemical changes associated clinically with depression and schizophrenia. Most notably, OBX induces hyperlocomotion in response to the stress of exposure to a novel environment. We examined the role of the endocannabinoid system in regulating this locomotor response in OBX and sham-operated rats. In our study, OBX-induced hyperactivity was restricted to the first 3 min of the open field test, demonstrating the presence of novelty (0-3 min) and habituation (3-30 min) phases of the open field locomotor response. Levels of the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide were decreased in the ventral striatum, a brain region deafferented by OBX, whereas cannabinoid receptor densities were unaltered. In sham-operated rats, 2-AG levels in the ventral striatum were negatively correlated with distance traveled during the novelty phase. Thus, low levels of 2-AG are reflected in a hyperactive open field response. This correlation was not observed in OBX rats. Conversely, 2-AG levels in endocannabinoid-compromised OBX rats correlated with distance traveled during the habituation phase. In OBX rats, pharmacological blockade of cannabinoid CB(1) receptors with either AM251 (1 mg kg(-1) i.p.) or rimonabant (1 mg kg(-1) i.p.) increased distance traveled during the habituation phase. Thus, blockade of endocannabinoid signaling impairs habituation of the hyperlocomotor response in OBX, but not sham-operated, rats. By contrast, in sham-operated rats, effects of CB(1) antagonism were restricted to the novelty phase. These findings suggest that dysregulation in the endocannabinoid system, and 2-AG in particular, is implicated in the hyperactive locomotor response induced by OBX. Our studies suggest that drugs that enhance 2-AG signaling, such as 2-AG degradation inhibitors, might be useful in human brain disorders modeled by OBX.
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effects of chronic activity wheel running and imipramine on masculine copulatory behavior after Olfactory Bulbectomy
Physiology & Behavior, 2004Co-Authors: Heather O Chambliss, Philip V Holmes, Jacqueline D Van Hoomissen, B N Bunnell, Rod K DishmanAbstract:Abstract We examined the effects of chronic activity wheel running and imipramine administration on appetitive behavior after Olfactory Bulbectomy (OBX). Male Long–Evans rats were randomly assigned to the following conditions using a 2×2×2 design: (1) bilateral OBX or sham surgery, (2) voluntary activity wheel running or sedentary home cage, and (3) daily imipramine or saline injections. After 21 days of treatment, animals underwent behavioral testing for copulatory activity and sucrose preference. Bulbectomized animals exhibited decrements in copulatory performance and reductions in sucrose intake compared to sham animals. Within the bulbectomized groups, imipramine-treated rats either did not copulate or had reduced ejaculation frequencies. However, activity wheel running attenuated the copulatory deficits induced by OBX. The findings encourage studies of physical activity and male sexual dysfunction among depressed men being treated by pharmacotherapy.
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effects of chronic exercise and imipramine on mrna for bdnf after Olfactory Bulbectomy in rat
Brain Research, 2003Co-Authors: Jacqueline D Van Hoomissen, Philip V Holmes, Heather O Chambliss, Rod K DishmanAbstract:Abstract We examined the effects of chronic activity wheel running and antidepressant treatment on brain-derived neurotrophic factor (BDNF) messenger RNA (mRNA) in multiple brain regions—hippocampal formation (HF), ventral tegmental area/substantia nigra (VTA/SN), nucleus accumbens (NAc), and piriform cortex (PFx)—after bilateral Olfactory Bulbectomy (OBX). Male, Long-Evans rats ( n =72) underwent either sham or OBX surgery and were randomly divided into eight experimental groups in a 2 (sham vs. OBX)×2 (sedentary vs. activity wheel)×2 (saline vs. imipramine) factorial design. Animals were killed after 21 days of treatment. Drug×exercise interaction effects were observed for HF ( P =0.006–0.023) and VTA/SN ( P =0.021); exercise increased BDNF mRNA in the saline treated animals but not in the imipramine treated animals. OBX did not affect BDNF mRNA in the HF or VTA/SN ( P >0.05). BDNF mRNA levels in the PFx were not altered by exercise, drug, or OBX ( P >0.05). These results suggest that the effect of exercise on BDNF mRNA extends beyond the HF to the mesolimbic ventral tegmental area and that the potentiation of BDNF mRNA by exercise and antidepressant pharmacotherapy, reported by other investigators, is time limited.
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Olfactory Bulbectomy increases met enkephalin and neuropeptide y like immunoreactivity in rat limbic structures
Pharmacology Biochemistry and Behavior, 2000Co-Authors: Stefany D Primeaux, Philip V HolmesAbstract:Bilateral Olfactory Bulbectomy (OBX) in rats produces a well-characterized syndrome of behavioral, physiological, and neurochemical changes identical to those seen in depression. Previous experiments using in situ hybridization histochemistry have demonstrated that OBX increases prepro-neuropeptide-Y (NPY) and prepro-enkephalin (ENK) mRNA levels in limbic structures. The present experiments determined whether increases in peptide immunoreactivity occur in conjunction with increases in mRNA levels following OBX. In situ hybridization analyses in Olfactory bulbectomized and sham-operated rats revealed increased prepro-ENK mRNA in the piriform cortex (PIR) and Olfactory tubercles (OTs) of bulbectomized rats. Prepro-NPY mRNA levels were significantly increased in the PIR of bulbectomized rats as comapred to controls. Radioimmunoassays (RIAs) revealed significant elevations in ENK-like immunoreactivity in the OTs following OBX. NPY-like immunoreactivity was significantly elevated in the PIR following OBX. These data reveal that OBX-induced increases in ENK-like immunoreactivity occur concomitantly with increases in prepro-ENK mRNA, and NPY-like immunoreactivity occur concomitantly with increases in prepro-NPY mRNA.
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role of aversively motivated behavior in the Olfactory Bulbectomy syndrome
Physiology & Behavior, 1999Co-Authors: Stefany D Primeaux, Philip V HolmesAbstract:Abstract The aim of the present studies was to determine the extent to which changes in defensive behaviors could account for some of the behavioral effects of bilateral Olfactory Bulbectomy (OBX) in rats. Four tests of aversively-motivated behavior were conducted in bulbectomized and sham-operated rats: activity in a dimly lit or brightly lit open field, passive avoidance, foot shock-induced freezing, and defensive withdrawal. OBX reduced the duration of immobility in the open field. Bulbectomized rats exhibited less freezing in response to foot shock than sham-operated rats. In the defensive-withdrawal test, bulbectomized rats made more transitions into and spent less time inside the covered enclosure than sham-operated rats. The experiments thus reveal two novel paradigms for assessing the behavioral effects of OBX. The results also suggest that deficits in aversively-motivated behavior, specifically defensive freezing, may comprehensively explain the putative “hyperactivity” and “passive-avoidance learning deficits” widely associated with the OBX behavioral syndrome.
Stefany D Primeaux - One of the best experts on this subject based on the ideXlab platform.
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Olfactory Bulbectomy impairs the feeding response to 2 deoxy d glucose in rats
Brain Research, 2011Co-Authors: Bruce M King, Stefany D Primeaux, Mohammad L Zadeh, John E De Gruiter, Joshua D Plant, Adam V Ferguson, George A BrayAbstract:An early study reported that, unlike sham-operated rats, rats made anosmic by Olfactory Bulbectomy (OBX) failed to compensate for the dilution of their diet with nonnutritive bulk by increasing their food intake. In the present study, the effects of a glucoprivic challenge, intraperitoneal-administered 350 mg/kg 2-deoxy-D-glucose (2-DG), on food intake were measured in OBX and sham-operated female rats. Sham-operated rats significantly increased their food intake, but in two separate experiments OBX rats displayed no increase in food intake during the first 2 h following administration. Blood glucose levels were nearly identical in both groups. Body weights and daily food intakes of OBX rats did not differ from the sham-operated controls throughout the studies. Bulbectomized rats also displayed a normal drinking response after an intraperitoneal injection of 1M hypertonic saline. Hypothalamic nuclei and the neural pathways mediating taste have been implicated in the feeding response to 2-DG. The present results suggest that Olfactory input and Olfactory neural pathways also mediate, at least in part, the feeding response to a glucoprivic challenge induced by intraperitoneal injection of 2-DG.
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Olfactory Bulbectomy increases food intake and hypothalamic neuropeptide y in obesity prone but not obesity resistant rats
Behavioural Brain Research, 2007Co-Authors: Stefany D Primeaux, Maria J Barnes, George A BrayAbstract:Obese individuals often suffer from depression. The Olfactory Bulbectomy (OBX) model is an animal model of depression that produces behavioral, physiological, and neurochemical alterations resembling clinical depression. The OBX model was employed to assess depression-related changes in food intake in obesity-prone, Osborne-Mendel (OM) rats and obesity-resistant, S5B/Pl rats. OBX increased food intake in OM rats beginning 7 days following surgery, however, OBX did not alter food intake in S5B/Pl rats at any time point. Fourteen days following surgery, OBX significantly increased locomotor activity (total lines crossed and rears) in the openfield test in OM and S5B/Pl rats. Fifteen days following surgery, prepro-neuropeptide Y (NPY) mRNA levels were significantly increased in the hypothalamus of bulbectomized OM rats and in the medial nucleus of the amygdala of bulbectomized OM and S5B/Pl rats. OBX decreased NPY Y2 receptor mRNA levels in the hypothalamus and medial nucleus of the amygdala in OM rats, while increasing NPY Y2 receptor mRNA levels in the medial nucleus of the amygdala of S5B/Pl rats. These data indicate that though both obesity-prone and obesity-resistant strains were susceptible to the locomotor effects of OBX, food intake and hypothalamic prepro-NPY mRNA were only increased in OM rats. Therefore, strain specific alterations in hypothalamic NPY may account for increased food intake in the obesity-prone rats following OBX, and suggests a potential mechanism to explain the comorbidity of obesity and depression.
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Olfactory Bulbectomy increases met enkephalin and neuropeptide y like immunoreactivity in rat limbic structures
Pharmacology Biochemistry and Behavior, 2000Co-Authors: Stefany D Primeaux, Philip V HolmesAbstract:Bilateral Olfactory Bulbectomy (OBX) in rats produces a well-characterized syndrome of behavioral, physiological, and neurochemical changes identical to those seen in depression. Previous experiments using in situ hybridization histochemistry have demonstrated that OBX increases prepro-neuropeptide-Y (NPY) and prepro-enkephalin (ENK) mRNA levels in limbic structures. The present experiments determined whether increases in peptide immunoreactivity occur in conjunction with increases in mRNA levels following OBX. In situ hybridization analyses in Olfactory bulbectomized and sham-operated rats revealed increased prepro-ENK mRNA in the piriform cortex (PIR) and Olfactory tubercles (OTs) of bulbectomized rats. Prepro-NPY mRNA levels were significantly increased in the PIR of bulbectomized rats as comapred to controls. Radioimmunoassays (RIAs) revealed significant elevations in ENK-like immunoreactivity in the OTs following OBX. NPY-like immunoreactivity was significantly elevated in the PIR following OBX. These data reveal that OBX-induced increases in ENK-like immunoreactivity occur concomitantly with increases in prepro-ENK mRNA, and NPY-like immunoreactivity occur concomitantly with increases in prepro-NPY mRNA.
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role of aversively motivated behavior in the Olfactory Bulbectomy syndrome
Physiology & Behavior, 1999Co-Authors: Stefany D Primeaux, Philip V HolmesAbstract:Abstract The aim of the present studies was to determine the extent to which changes in defensive behaviors could account for some of the behavioral effects of bilateral Olfactory Bulbectomy (OBX) in rats. Four tests of aversively-motivated behavior were conducted in bulbectomized and sham-operated rats: activity in a dimly lit or brightly lit open field, passive avoidance, foot shock-induced freezing, and defensive withdrawal. OBX reduced the duration of immobility in the open field. Bulbectomized rats exhibited less freezing in response to foot shock than sham-operated rats. In the defensive-withdrawal test, bulbectomized rats made more transitions into and spent less time inside the covered enclosure than sham-operated rats. The experiments thus reveal two novel paradigms for assessing the behavioral effects of OBX. The results also suggest that deficits in aversively-motivated behavior, specifically defensive freezing, may comprehensively explain the putative “hyperactivity” and “passive-avoidance learning deficits” widely associated with the OBX behavioral syndrome.
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effects of Olfactory Bulbectomy on neuropeptide gene expression in the rat Olfactory limbic system
Neuroscience, 1998Co-Authors: Philip V Holmes, R C Davis, Cher V Masini, Stefany D PrimeauxAbstract:Abstract Bilateral Olfactory Bulbectomy in the rat produces a well-characterized syndrome that is independent of anosmia. This syndrome is reversed by chronic antidepressant administration, which provides the basis for the Olfactory Bulbectomy model of depression. The present experiments focused on neuropeptide plasticity in central Olfactory/limbic structures following Olfactory Bulbectomy in rats. Male Sprague–Dawley rats received bilateral surgical ablation of the Olfactory bulbs, sham surgery, or no surgery and were killed either three, seven, 14 or 28 days later. Relative levels of messenger RNA encoding neuropeptide Y, somatostatin, thyrotropin-releasing hormone, and corticotropin-releasing factor precursors in the forebrain were measured by quantitative in situ hybridization histochemistry using oligonucleotide probes. Prepro-neuropeptide Y messenger RNA levels in the piriform cortex and dentate gyrus were significantly elevated in bulbectomized rats 14 and 28 days after surgery compared to sham-operated and surgically naive rats. Prepro-somatostatin messenger RNA levels in the piriform cortex were marginally increased in bulbectomized rats at these time-points. Thyrotropin-releasing hormone and corticotropin-releasing factor precursor messenger RNA levels were not altered in the brain regions studied. The results indicate that Olfactory Bulbectomy causes long-term increases in the expression of the neuropeptide Y gene. These findings suggest that neuropeptide Y plasticity in the Olfactory/limbic system may contribute to the Olfactory Bulbectomy syndrome in rats, and they provide further evidence of a role for neuropeptide Y in the pathophysiology of depression.
Jane M Kolunie - One of the best experts on this subject based on the ideXlab platform.
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maternal aggression in rats effects of Olfactory Bulbectomy znso4 induced anosmia and vomeronasal organ removal
Hormones and Behavior, 1995Co-Authors: Jane M Kolunie, Judith M SternAbstract:Abstract Previous studies from our laboratory indicate that somatosensory inputs to the snout and ventral trunk, but not visual or auditory stimuli, play critical roles in the elicitation and maintenance of maternal aggression by lactating Norway rats toward a strange male intruder. There are conflicting reports on the influence of olfaction on maternal aggression. We explored the possible roles of central or peripheral anosmia on maternal aggression in Long–Evans rats during early lactation. In Experiment 1, responsiveness to both volatile and non-volatile odors was eliminated by bilateral Olfactory Bulbectomy (BOB), carried out during mid-gestation. BOB resulted in a reduced likelihood and intensity of maternal aggression on days 1 and 5 of lactation (L1 and L5), but also severe deficiencies in maternal behavior and litter growth and survival. In Experiment 2, anosmia to volatile odors was induced by spraying zinc sulfate intranasally on gestation day 21 and L1. This treatment had little or no effect on maternal aggression on L1 or L2 or on maternal behavior, especially if there was a 1-day recovery between the second treatment and testing. In Experiment 3, responsiveness to non-volatile odors was eliminated by vomeronasal-organ removal (VNX) carried out prior to mating. VNX did not disturb maternal behavior on L2–L8 or maternal aggression on L1 or L5. These results and others suggest that the expression of maternal aggression is affected by volatile odors, mediated possibly by accessory chemosensory systems such as the septal organ, or by neural changes that follow Olfactory deafferentation, or both.
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maternal aggression in rats effects of Olfactory Bulbectomy znso4 induced anosmia and vomeronasal organ removal
Hormones and Behavior, 1995Co-Authors: Jane M Kolunie, Judith M SternAbstract:Abstract Previous studies from our laboratory indicate that somatosensory inputs to the snout and ventral trunk, but not visual or auditory stimuli, play critical roles in the elicitation and maintenance of maternal aggression by lactating Norway rats toward a strange male intruder. There are conflicting reports on the influence of olfaction on maternal aggression. We explored the possible roles of central or peripheral anosmia on maternal aggression in Long–Evans rats during early lactation. In Experiment 1, responsiveness to both volatile and non-volatile odors was eliminated by bilateral Olfactory Bulbectomy (BOB), carried out during mid-gestation. BOB resulted in a reduced likelihood and intensity of maternal aggression on days 1 and 5 of lactation (L1 and L5), but also severe deficiencies in maternal behavior and litter growth and survival. In Experiment 2, anosmia to volatile odors was induced by spraying zinc sulfate intranasally on gestation day 21 and L1. This treatment had little or no effect on maternal aggression on L1 or L2 or on maternal behavior, especially if there was a 1-day recovery between the second treatment and testing. In Experiment 3, responsiveness to non-volatile odors was eliminated by vomeronasal-organ removal (VNX) carried out prior to mating. VNX did not disturb maternal behavior on L2–L8 or maternal aggression on L1 or L5. These results and others suggest that the expression of maternal aggression is affected by volatile odors, mediated possibly by accessory chemosensory systems such as the septal organ, or by neural changes that follow Olfactory deafferentation, or both.
Isaac Tunez - One of the best experts on this subject based on the ideXlab platform.
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antioxidant like effects and protective action of transcranial magnetic stimulation in depression caused by Olfactory Bulbectomy
Neurochemical Research, 2010Co-Authors: Inmaculada Tasset, Francisco J Medina, Jose Pena, Ignacio Jimena, Pedro Montilla, Rene Druckercolin, Isaac TunezAbstract:We studied the effects of transcranial magnetic stimulation (TMS, 60 Hz and 0.7 mT for 4 h/day for 14 days) on oxidative and cell damage caused by Olfactory Bulbectomy (OBX) in Wistar rats. The levels of lipid peroxidation products and caspase-3 were enhanced by OBX, whereas it prompted a reduction in reduced glutathione (GSH) content and antioxidative enzymes activities. The treatment with TMS reverted towards normality the biomarkers indicative of oxidative stress and apoptosis. In conclusion, our data show that TMS induced a protection against cell and oxidative damage induced by OBX, as well as they support the hypothesis that oxidative stress may play an important role in depression.
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protective effect of nicotine on oxidative and cell damage in rats with depression induced by Olfactory Bulbectomy
European Journal of Pharmacology, 2010Co-Authors: Isaac Tunez, Francisco J Medina, Jose Pena, Ignacio Jimena, Pedro Montilla, Rene Druckercolin, Inmaculada TassetAbstract:We evaluated the effects of nicotine on cell and oxidative damage caused by Olfactory Bulbectomy (OBX). The rats were divided into seven groups as follows: i) control; ii) vehicle (6% ethanol); iii) treated with nicotine; iv) sham operated; v) Olfactory Bulbectomy (OBX); vi) OBX + vehicle; and vii) OBX + Nic. The OBX was performed using the trepanation of frontal bone. The Olfactory bulbs were cut and removed without damage to the frontal cortex. Two weeks after surgery nicotine was administered chronically once daily for 14 days, intraperitoneally (i.p.) in doses of 1.5 mg/kg, two weeks after surgery. OBX caused an increase in lipid peroxidation products and caspase-3 but prompted a reduction in reduced glutathione (GSH) content and antioxidative enzyme activity. All these changes were reverted by treatment of nicotine (14 days). In conclusions: i) OBX induces oxidative stress and cell death by apoptosis; and ii) nicotine presents antidepressant and antioxidant effect. All these findings suggest that nicotine would be a therapeutic tool for depression, although more studies are needed in this area to define the appropriate treatment regime.
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Olfactory Bulbectomy induced oxidative and cell damage in rat protective effect of melatonin
Physiological Research, 2010Co-Authors: Inmaculada Tasset, Francisco J Medina, Jose Pena, Ignacio Jimena, M Del Carmen Munoz, Manuel Salcedo, Concepcion Ruiz, Montserrat Feijoo, Pedro Montilla, Isaac TunezAbstract:Summary In this study we analyzed the effects of melatonin (Mel, 1 mg/kg ip) on behavioral changes as well as cell and oxidative damage prompted by bilaterally Olfactory Bulbectomy. Olfactory Bulbectomy caused an increase in lipid peroxidation products and caspase-3, whereas it prompted a decrease of reduced glutathione (GSH) content and antioxidative enzymes activities. Additionally, Olfactory Bulbectomy induced behavioral changes characterized by the enhancement of immobility time in the forced swim test and hyperactivity in the open field test. All these changes were normalized by treatment of Mel (14 days). Our data show that Mel has a beneficial neuropsychiatric action against oxidative stress, cell damage and behavior alterations.
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antidepressant like effects of nicotine and transcranial magnetic stimulation in the Olfactory Bulbectomy rat model of depression
Brain Research Bulletin, 2008Co-Authors: Patricia Vieyrareyes, Isaac Tunez, Yann S Mineur, Marina R Picciotto, Roman Vidaltamayo, Rene DruckercolinAbstract:In this study, we compared the depression-like symptoms induced by Olfactory Bulbectomy (OBX) in the two inbred Wistar and Long Evans rat strains. We also analyzed the self-regulated oral intake of nicotine in these strains and the effect of nicotine on the depression-like symptoms of Olfactory Bulbectomy. Furthermore, we compared the antidepressant-like effects of nicotine on Wistar rats to those of transcranial magnetic stimulation (TMS), which has emerged as a therapeutic alternative for depression management. Our results show that Wistar rats develop depression-like symptoms, demonstrated by the forced swim test (FST), 4 weeks after OBX. However, in bulbectomized Long Evans rats these symptoms cannot be assessed due to a higher degree of variability of the swimming behavior of this strain. These results suggest that there are some innate differences in susceptibility to stress between these two rat strains. In Wistar rats, voluntary oral nicotine intake (1.2 mg/(kg day) for 14 days) as well as nicotine administered as a single daily i.p. injection (1.5 mg/(kg day) for 14 days) decrease the depression-like symptoms of OBX. Daily transcranial magnetic stimulation (60 Hz and 0.7 mT for 2h/day for 14 days) also decreases depression-like symptoms but is less effective than nicotine. In conclusion, our results support the idea that there are possible innate differences for depression susceptibility and that nicotine and TMS may be useful in the treatment of this syndrome.
