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Akihisa Urano - One of the best experts on this subject based on the ideXlab platform.
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differences in seasonal expression of Neurohypophysial Hormone genes in ordinary and precocious male masu salmon
General and Comparative Endocrinology, 1999Co-Authors: Yuki Ota, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:Our previous study showed the seasonal variations in expression of vasotocin (VT) and isotocin (IT) genes in preoptic magnocellular neurons of female masu salmon (Oncorhynchus masou). The changes in the level of VT mRNA were coincident with those in plasma testosterone and estradiol levels. In the present study, generality of this phenomenon in salmonid was verified in males. We examined changes in expression of VT and IT genes by an in situ hybridization technique and an immunohistochemical avidin–biotin complex method in the preoptic nuclei of ordinary and precocious male masu salmon. Plasma levels of testosterone and estradiol were measured by enzyme immunoassay. Fish were sampled in March, May, August, and November 1994 and January 1995. The intensities of hybridization signals for VT and IT mRNAs, as well as immunoreactivity of VT and IT, showed seasonal variations, although the profiles were different between the ordinary and precocious males. In the ordinary males, the intensities of hybridization signals for VT and IT mRNAs were high in January. These strong hybridization signals, representing elevation of VT and IT gene expression, were accompanied by increases in plasma levels of testosterone and estradiol. However, in precocious males, changes in VT and IT mRNA levels were not coincident with variation of plasma levels of sex steroid Hormones. The sensitivity to sex steroid Hormones of VT and IT gene expression may be different between the ordinary and precocious male masu salmon.
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changes in expression of Neurohypophysial Hormone genes during spawning migration in chum salmon oncorhynchus keta
Journal of Molecular Endocrinology, 1997Co-Authors: S Hiraoka, Masatoshi Ban, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:We analyzed changes in the hypothalamic levels of vasotocin (VT) and isotocin (IT) mRNA in chum salmon during spawning migration to the Ishikari river. The fish were caught at Atsuta, a fisherman's village facing the Ishikari bay, and at Chitose, an upstream branch of the Ishikari river. The former are referred to as sea water (SW) fish, and the latter as freshwater (FW) fish. The levels of VT and IT mRNA in the forebrains were determined by quantitative Northern blot analysis using single-stranded DNA with the same mRNA sequences as the standards. Levels of VT mRNA were higher in the FW males than the FW females, although no such difference was seen in the SW fish. Changes in the levels of VT mRNA were markedly different in males and females. In the males, no significant differences were seen in the levels of VT-I and VT-II mRNA between the SW and FW fish. However, in the females, the levels of VT mRNA in the FW fish were significantly lower than those in the SW fish. Changes in the levels of IT-I and IT-II mRNA were essentially similar in the males and females. These results suggest that the control of VT gene expression is different in males and females during spawning migration, although the neuroendocrine mechanism is not known.
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effects of osmotic stimulation on expression of Neurohypophysial Hormone genes in pre spawning chum salmon
Zoological Science, 1996Co-Authors: Hironori Ando, Susumu Hyodo, Shuichi Hiraoka, Kaoru Kubokawa, Akihisa UranoAbstract:Abstract Changes in expression of vasotocin (VT) and isotocin (IT) genes were analyzed in chum salmon during the last stages of spawning migration. Pre-spawning chum salmon were caught at following four locations in the Sanriku coast of the Pacific Ocean in Japan: 1) the off-coast area north to the Otsuchi Bay, 2) the mouth of the Otsuchi Bay, 3) inside of the Otsuchi Bay, and 4) the place 500 m upstream to the mouth of the Otsuchi River. In addition, effects of hypo-osmotic stimulation by transition from sea water (SW) to freshwater (FW) were examined in animals caught at the mouth of the Otsuchi Bay. The levels of VT and IT mRNAs in the forebrains were determined by Northern blot analysis. The plasma osmolality and the levels of Na+ and Cl− were also analyzed. Expression patterns of VT and IT genes were different between the males and the females. In the males, VT and IT gene expression were maintained essentially at the same levels from the off-coast area to the Otsuchi River. In contrast, in the femal...
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Sexually Different Expression of Neurohypophysial Hormone Genes in the Preoptic Nucleus of Pre-Spawning Chum Salmon
Zoological Science, 1996Co-Authors: Yuki Ota, Hironori Ando, Masatoshi Ban, Hiroshi Ueda, Akihisa UranoAbstract:Abstract Vasotocin (VT) and isotocin (IT) are teleost Neurohypophysial Hormones produced by neurosecretory neurons in the magnocellular part of preoptic nucleus (PM) of the hypothalamus. Several previous studies indicated that Neurohypophysial Hormones are involved in teleost reproductive behavior. The changes in the expression of VT and IT genes were thus studied by an in situ hybridization technique and an immunohistochemical avidin-biotin-complex method in pre-spawning chum salmon (Oncorhynchus keta). Male and female fish were caught at Atsuta, the mouth of the Ishikari Bay, and at Chitose, upstream to the Ishikari River in October, 1994. The former and the latter are referred to as bay fish and river fish, respectively. The intensity of autoradiographic hybridization signals were determined in individual neurosecretory neurons in the rostroventral, middle, and dorsocaudal parts of the PM. in the females, the levels of VT and IT mRNAs in the river fish were significantly lower than those in the bay fis...
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divergence of gene expression in Neurohypophysial Hormone precursors among salmonids
General and Comparative Endocrinology, 1993Co-Authors: Shuichi Hiraoka, M Suzuki, Tadashi Yanagisawa, Munehico Iwata, Akihisa UranoAbstract:Abstract Salmonid fish have pairs of genes for various hypothalamic and pituitary Hormones including Neurohypophysial Hormones, vasotocin, and isotocin, probably because they are tetraploid. The problem here is whether two genes for the same Hormone are expressed equally or differently. We therefore examined expression patterns of vasotocin and isotocin genes in four salmonid species using Northern blot analysis with chum salmon cDNAs as hybridization probes. The presence of two vasotocin and also two isotocin genes was confirmed by Southern blot analysis in rainbow trout and sockeye salmon which were not examined previously. Prior to Northern blot analysis, isotocin-I eDNA of sockeye salmon was determined and compared to those of chum salmon and masu salmon, since molecular probes are so specific that cross-species hybridization often leads misinterpretation in a quantitative study. The nucleotide sequence of sockeye salmon isotocin-I cDNA showed sufficiently high humology (>96.0%) to those of chum salmon and masu salmon for cross-species hybridization among salmonids. Northern blot analysis showed that both isotocin-I and isotocin-II genes were well expressed in all species examined. Expression of isotocin-I gene tended to be relatively higher than that of isotocin-II gene in all species. However, expression pattern of vasotocin-I and vasotocin-II genes did not coincide among species. Expression of vasotocin-II genes was very weak or scarce in masu salmon and rainbow trout, while that in sockeye salmon was stronger than vasotocin-I gene expression. The present result may reflect complicated molecular evolution of salmonid vasotocin genes probably both in regulatory and coding regions.
Hironori Ando - One of the best experts on this subject based on the ideXlab platform.
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differences in seasonal expression of Neurohypophysial Hormone genes in ordinary and precocious male masu salmon
General and Comparative Endocrinology, 1999Co-Authors: Yuki Ota, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:Our previous study showed the seasonal variations in expression of vasotocin (VT) and isotocin (IT) genes in preoptic magnocellular neurons of female masu salmon (Oncorhynchus masou). The changes in the level of VT mRNA were coincident with those in plasma testosterone and estradiol levels. In the present study, generality of this phenomenon in salmonid was verified in males. We examined changes in expression of VT and IT genes by an in situ hybridization technique and an immunohistochemical avidin–biotin complex method in the preoptic nuclei of ordinary and precocious male masu salmon. Plasma levels of testosterone and estradiol were measured by enzyme immunoassay. Fish were sampled in March, May, August, and November 1994 and January 1995. The intensities of hybridization signals for VT and IT mRNAs, as well as immunoreactivity of VT and IT, showed seasonal variations, although the profiles were different between the ordinary and precocious males. In the ordinary males, the intensities of hybridization signals for VT and IT mRNAs were high in January. These strong hybridization signals, representing elevation of VT and IT gene expression, were accompanied by increases in plasma levels of testosterone and estradiol. However, in precocious males, changes in VT and IT mRNA levels were not coincident with variation of plasma levels of sex steroid Hormones. The sensitivity to sex steroid Hormones of VT and IT gene expression may be different between the ordinary and precocious male masu salmon.
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changes in expression of Neurohypophysial Hormone genes during spawning migration in chum salmon oncorhynchus keta
Journal of Molecular Endocrinology, 1997Co-Authors: S Hiraoka, Masatoshi Ban, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:We analyzed changes in the hypothalamic levels of vasotocin (VT) and isotocin (IT) mRNA in chum salmon during spawning migration to the Ishikari river. The fish were caught at Atsuta, a fisherman's village facing the Ishikari bay, and at Chitose, an upstream branch of the Ishikari river. The former are referred to as sea water (SW) fish, and the latter as freshwater (FW) fish. The levels of VT and IT mRNA in the forebrains were determined by quantitative Northern blot analysis using single-stranded DNA with the same mRNA sequences as the standards. Levels of VT mRNA were higher in the FW males than the FW females, although no such difference was seen in the SW fish. Changes in the levels of VT mRNA were markedly different in males and females. In the males, no significant differences were seen in the levels of VT-I and VT-II mRNA between the SW and FW fish. However, in the females, the levels of VT mRNA in the FW fish were significantly lower than those in the SW fish. Changes in the levels of IT-I and IT-II mRNA were essentially similar in the males and females. These results suggest that the control of VT gene expression is different in males and females during spawning migration, although the neuroendocrine mechanism is not known.
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effects of osmotic stimulation on expression of Neurohypophysial Hormone genes in pre spawning chum salmon
Zoological Science, 1996Co-Authors: Hironori Ando, Susumu Hyodo, Shuichi Hiraoka, Kaoru Kubokawa, Akihisa UranoAbstract:Abstract Changes in expression of vasotocin (VT) and isotocin (IT) genes were analyzed in chum salmon during the last stages of spawning migration. Pre-spawning chum salmon were caught at following four locations in the Sanriku coast of the Pacific Ocean in Japan: 1) the off-coast area north to the Otsuchi Bay, 2) the mouth of the Otsuchi Bay, 3) inside of the Otsuchi Bay, and 4) the place 500 m upstream to the mouth of the Otsuchi River. In addition, effects of hypo-osmotic stimulation by transition from sea water (SW) to freshwater (FW) were examined in animals caught at the mouth of the Otsuchi Bay. The levels of VT and IT mRNAs in the forebrains were determined by Northern blot analysis. The plasma osmolality and the levels of Na+ and Cl− were also analyzed. Expression patterns of VT and IT genes were different between the males and the females. In the males, VT and IT gene expression were maintained essentially at the same levels from the off-coast area to the Otsuchi River. In contrast, in the femal...
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Sexually Different Expression of Neurohypophysial Hormone Genes in the Preoptic Nucleus of Pre-Spawning Chum Salmon
Zoological Science, 1996Co-Authors: Yuki Ota, Hironori Ando, Masatoshi Ban, Hiroshi Ueda, Akihisa UranoAbstract:Abstract Vasotocin (VT) and isotocin (IT) are teleost Neurohypophysial Hormones produced by neurosecretory neurons in the magnocellular part of preoptic nucleus (PM) of the hypothalamus. Several previous studies indicated that Neurohypophysial Hormones are involved in teleost reproductive behavior. The changes in the expression of VT and IT genes were thus studied by an in situ hybridization technique and an immunohistochemical avidin-biotin-complex method in pre-spawning chum salmon (Oncorhynchus keta). Male and female fish were caught at Atsuta, the mouth of the Ishikari Bay, and at Chitose, upstream to the Ishikari River in October, 1994. The former and the latter are referred to as bay fish and river fish, respectively. The intensity of autoradiographic hybridization signals were determined in individual neurosecretory neurons in the rostroventral, middle, and dorsocaudal parts of the PM. in the females, the levels of VT and IT mRNAs in the river fish were significantly lower than those in the bay fis...
Mary L. Forsling - One of the best experts on this subject based on the ideXlab platform.
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the effect of exogenous melatonin on stimulated Neurohypophysial Hormone release in man
Clinical Endocrinology, 2002Co-Authors: Mary L. Forsling, A J WilliamsAbstract:Summary objective Melatonin is known to have a dose-dependent effect on basal Neurohypophysial Hormone release in man, low physiological doses being stimulatory and high doses inhibitory. We have performed a study to determine if this is true also for stimulated release. design This was a double-blind randomized crossover study with subjects being given oral doses of melatonin (0·5 mg or 5·0 mg) or placebo, before infusion of hypertonic saline or exercise. subjects Studies were performed on a total of 24 male subjects aged 19–23 years, who were entrained to a normal light–dark cycle and who refrained from taking heavy exercise, alcohol and smoking for 24 h prior to study. measurements Plasma vasopressin, oxytocin, sodium and osmolality and packed cell volume were measured in control samples and at regular intervals after the administration of melatonin and the challenge tests. Blood pressure and urine flow, sodium potassium and osmolality were determined during hypertonic saline infusion and blood pressure and pulse rate during exercise. results Plasma vasopressin increased during hypertonic saline infusion and exercise, the responses being attenuated by 5·0 mg melatonin and augmented with 0·5 mg melatonin. Although exercise had no effect on oxytocin release, there was a small but statistically significant (P < 0·05) increase in plasma oxytocin after hypertonic saline administration, which was inhibited by 5·0 mg and augmented by 0·5 mg melatonin. conclusions Melatonin modulates the Neurohypophysial response to different stimuli, low doses enhancing the response. This effect could contribute to the night-time increase in circulating concentrations of the Hormones.
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the effect of 3 4 methylenedioxymethamphetamine mdma ecstasy and its metabolites on Neurohypophysial Hormone release from the isolated rat hypothalamus
British Journal of Pharmacology, 2002Co-Authors: Mary L. Forsling, John K Fallon, Darshna Shah, Gary S Tilbrook, David A Cowan, Andrew T Kicman, Andrew J HuttAbstract:Methylenedioxymethamphetamine (MDMA, “ecstasy”), widely used as a recreational drug, can produce hyponatraemia. The possibility that this could result from stimulation of vasopressin by MDMA or one of its metabolites has been investigated in vitro. Release of both oxytocin and vasopressin from isolated hypothalami obtained from male Wistar rats was determined under basal conditions and following potassium (40 mM) stimulation. The results were compared with those obtained for basal and stimulated release in the presence of MDMA or metabolites in the dose range 1 μM to 100 pM (n=5 – 8) using Student's t-test with Dunnett's correction for multiple comparisons. All compounds tested affected Neurohypophysial Hormone release, HMMA (4-hydroxy-3-methoxymethamphetamine) and DHA (3,4-dihydroxyamphetamine) being more active than MDMA, and DHMA (3,4-dihydroxymethamphetamine) being the least active. The effect on vasopressin release was greater than that on oxytocin. In the presence of HMMA the ratio test:control for basal release increased for vasopressin from 1.1±0.16 to 2.7±0.44 (s.e.m., P<0.05) at 10 nM and for oxytocin from 1.0±0.05 to 1.6±0.12 in the same hypothalami. For MDMA the ratio increased to 1.5±0.27 for vasopressin and to 1.28±0.04 for oxytocin for 10 nM. MDMA and its metabolites can stimulate both oxytocin and vasopressin release in vitro, the response being dose dependent for each drug with HMMA being the most potent. Keywords: Oxytocin, vasopressin, hypothalamus, 3,4-methylenedioxymethamphetamine, 4-hydroxy-3-methoxymethamphetamine, 3,4-dihydroxyamphetamine, 3,4-dihydroxymethamphetamine, 4-hydroxy-3-methoxyamphetamine, 3,4-methylenedioxyamphetine Introduction Methylenedioxymethamphetamine (MDMA, “ecstasy”) is a phenethylamine with structural similarities to both mescaline and amphetamine and is a relatively widely used recreational drug. Its acute effects include rapid release of serotonin (5HT) from central neurones resulting in well-documented changes including behavioural excitation and hyperthermia (Green et al., 1995). Less well-documented are the neuroendocrine changes. Administration of the drug to rats results in an increase in the circulating concentrations of cortisol and prolactin (Nash et al., 1988). Cortisol and prolactin release are similarly stimulated in man, although higher doses of MDMA are required to stimulate prolactin (Mas et al., 1999; de la Torre et al., 2000a). No effect on growth Hormone was observed. The release of cortisol is consistent with the activation of serotonergic pathways, but dopaminergic or adrenergic mechanisms could also be involved as effects on monoaminergic transmission have been described (White et al., 1996). Similarly, serotonin and the catecholamines are involved in the release of vasopressin (Kostoglou-Athanassiou & Forsling, 1998; Renaud & Bourque, 1991) and release of this Hormone in man on ingestion of MDMA has been reported, although it is not known if this is a direct effect or secondary to other changes (Henry et al., 1998; Forsling et al., 2001). Following oral administration of a low dose (40 mg) of racemic MDMA to eight healthy male volunteers, vasopressin release was stimulated in all subjects, but shortly after administration an inverse correlation between plasma MDMA and vasopressin concentrations was observed (Forsling et al., 2001). This could result from a number of factors including the formation of an active metabolite, with the lower MDMA concentrations being associated with greater metabolite formation and enhanced vasopressin release. A number of metabolites are formed from MDMA, with N-demethylation and demethylenation being important pathways in the formation of most of them (de boer et al., 1997; Ortuno et al., 1999; Kreth et al., 2000). Thus, as shown in Figure 1, the metabolism of MDMA involves N-demethylation to methylenedioxyamphetamine (MDA) and both undergo O-demethylenation to 3,4-dihydroxymethamphetamine (DHMA) and 3,4-dihydroxyamphetamine (DHA), respectively. The major cytochrome P-450 (CYP) mediating demethylenation is CYP2D6, with possible contributions from 1A2, 2B6 and 3A4 (Kreth et al., 2000). Both DHMA and DHA are subsequently methylated by catechol-O-methyl transferase (COMT) to 4-hydroxy-3-methoxymethamphetamine (HMMA) and 4-hydroxy-3-methoxyamphetamine (HMA) respectively. These four metabolites, in particular HMMA and HMA are excreted in the urine as conjugated glucuronide or sulphate metabolites. In order to examine the hypothesis that a metabolite, as well as, or in addition to, the parent compound could contribute to enhanced vasopressin release, the activity of MDMA and the five metabolites have been investigated. Release of oxytocin was also investigated to determine if any effects are specific for vasopressin. To exclude any systemic effects of the drugs, the observations were performed on the isolated hypothalamus in vitro using a previously validated method (Tsagarakis et al., 1988). This model was chosen for these investigations because the Neurohypophysial Hormone responses to centrally acting compounds have been demonstrated to reflect the physiological responses in vivo following administration of, for example, dopamine (Bridges et al., 1976) or melatonin (Yasin et al., 1993). Figure 1 MDMA and its metabolites. Methods Sources of compounds (±)-(R,S)-MDMA hydrochloride, (±)-(R,S)-MDA hydrochloride were purchased from the Sigma Chemical Company Ltd, Poole, U.K.; (−)-(R)- and (+)-(S)-MDMA hydrochloride and (−)-(R)- and (+)-(S)-MDA hydrochloride were generously donated by the Research Technology Branch of the National Institute on Drug Abuse, Rockville, MD, U.S.A.
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Effect of 5-hydroxytryptamine and pineal metabolites on the secretion of Neurohypophysial Hormones
Brain research bulletin, 1998Co-Authors: Ifigenia Kostoglou-athanassiou, Mary L. ForslingAbstract:It has been shown that 5-hydroxytryptamine and melatonin, an indoleamine for which 5-hydroxytryptamine is a precursor, influence the release of vasopressin and oxytocin from the rat hypothalamus both in vivo and in vitro. The oral administration of melatonin has been shown to decrease oxytocin release and modulate the nocturnal vasopressin release in humans. 5-Hydroxytryptamine and its metabolites, 5-hydroxytryptophol, 5-methoxytryptamine and 5-methoxytryptophol, are detected within the pineal, and there is evidence that 5-methoxytryptamine and 5-methoxytryptophol may have some physiological role. The aim of this study was to evaluate the effects of 5-hydroxytryptamine, 5-hydroxytryptophol, 5-methoxytryptamine and 5-methoxytryptophol on Neurohypophysial Hormone release from the rat hypothalamus in vitro. It was found that 5-hydroxytryptamine and 5-hydroxytryptophol increased Neurohypophysial Hormone release, 5-methoxytryptamine decreased the release of vasopressin and oxytocin and 5-methoxytryptophol was found to have no effect, thus providing further evidence for a role of indole compounds in the control of Neurohypophysial Hormone secretion.
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Mechanisms of Melatonin Inhibition of Neurohypophysial Hormone Release From the Rat Hypothalamus In Vitro
Brain research bulletin, 1998Co-Authors: Sharifah A. Yasin, Mary L. ForslingAbstract:Abstract Although melatonin has been reported to influence Neurohypophysial Hormone release, no binding has been demonstrated in the Neurohypophysial system, suggesting melatonin could affect afferent inputs. The effect of neurotransmitter receptor antagonists on the inhibitory effect of melatonin on Neurohypophysial Hormone release from the rat hypothalamus in vitro was therefore determined. The agents employed were atropine, a muscarinic cholinergic antagonist; mecamylamine, a nicotinic cholinergic antagonist; atenolol, a β-adrenergic antagonist; phentolamine, a nonselective α-adrenergic antagonist; prazosin, a selective α-adrenergic antagonist; haloperidol, a dopaminergic antagonist; naloxone, an opioid antagonist; and ibuprofen, a cyclooxygenase inhibitor. Rat hypothalami were incubated in either medium alone or medium containing melatonin or melatonin and antagonist, and Hormone release determined. Melatonin (43 nM) significantly inhibited ( p p
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Neurohypophysial Hormone and melatonin secretion over the natural and suppressed menstrual cycle in premenopausal women
Clinical endocrinology, 1998Co-Authors: Ifigenia Kostoglou-athanassiou, Panagiotis Athanassiou, David F. Treacher, Michael J. Wheeler, Mary L. ForslingAbstract:Objective Vasopressin oxytocin and melatonin have been reported to be influenced by ovarian steroids. The Neurohypophysial Hormones have also been shown to display a diurnal pattern of secretion in men. We therefore studied the diurnal pattern of Neurohypophysial Hormone and melatonin secretion in premenopausal women and in women on oral contraceptives. Design Healthy normally cycling premenopausal women were studied over 24 hours during the mid-follicular and midluteal phases of the menstrual cycle. Healthy premenopausal women on oral contraceptives were studied over 24 hours at similar times. Subjects Eight healthy normally cycling women and 7 healthy premenopausal women on oral contraceptives. Measurements Plasma vasopressin oxytocin and melatonin were measured by radioimmunoassay. Results Vasopressin concentrations and its nocturnal peak were highest in the follicular phase of the natural menstrual cycle and attenuated in the women on oral contraceptives. Oxytocin concentrations did not vary between the two phases of the menstrual cycle but increased on oestrogen administration. Overall melatonin secretion was augmented in the women on oral contraceptives. Conclusions Vasopressin release and its nocturnal peak were greatest in the follicular phase of the menstrual cycle while melatonin secretion was augmented in the women on oral contraception. (authors)
Susumu Hyodo - One of the best experts on this subject based on the ideXlab platform.
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Neurohypophysial Hormone Family
Handbook of Hormones, 2016Co-Authors: Susumu HyodoAbstract:After the first discovery of the pressor activity in the bovine neurohypophysis, two physiologically active mammalian principles, vasopressin (VP) and oxytocin (OT), and non-mammalian orthologs thereof have been identified. For a long period it was believed that VP and OT act through the three VP receptors and one OT receptor. In 2012 a novel fifth receptor was discovered, and this discovery brought a new insight on the evolution of receptors. Moreover, homologous peptides (genes) and receptors have also been found from a wide variety of invertebrate classes. Major peripheral actions are body fluid and cardiovascular regulation, control of reproductive events, and stress response. In particular, renal antidiuresis and milk ejection are impaired by deficiencies of VP and OT, respectively. Neurohypophysial Hormones are also involved in social recognition and sexual behaviors, and involvement in neuropsychiatric disorders has been implicated.
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australian lungfish Neurohypophysial Hormone genes encode vasotocin and phe2 mesotocin precursors homologous to tetrapod type precursors
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Susumu Hyodo, Susumu Ishii, Jean M.p. JossAbstract:In view of the well-established role of Neurohypophysial Hormones in osmoregulation of terrestrial vertebrates, lungfishes are a key group for study of the molecular and functional evolution of the hypothalamo-Neurohypophysial system. Here we report on the primary structure of the precursors encoding vasotocin (VT) and [Phe2]mesotocin ([Phe2]MT) of the Australian lungfish, Neoceratodus forsteri. Genomic sequence analysis and Northern blot analysis confirmed that [Phe2]MT is a native oxytocin family peptide in the Australian lungfish, although it has been reported that the lungfish neurohypophysis contains MT. The VT precursor consists of a signal peptide, VT, that is connected to a neurophysin by a Gly-Lys-Arg sequence, and a copeptin moiety that includes a Leu-rich core segment and a glycosylation site. In contrast, the [Phe2]MT precursor does not contain a copeptin moiety. These structural features of the lungfish precursors are consistent with those in tetrapods, but different from those in teleosts where both VT and isotocin precursors contain a copeptin-like moiety without a glycosylation site at the carboxyl terminals of their neurophysins. Comparison of the exon/intron organization also supports homology of the lungfish [Phe2]MT gene with tetrapod oxytocin/MT genes, rather than with teleost isotocin genes. Moreover, molecular phylogenetic analysis shows that Neurohypophysial Hormone genes of the lungfish are closely related to those of the toad. The present results along with previous morphological findings indicate that the hypothalamo-Neurohypophysial system of the lungfish has evolved along the tetrapod lineage, whereas the teleosts form a separate lineage, both within the class Osteichthyes.
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effects of osmotic stimulation on expression of Neurohypophysial Hormone genes in pre spawning chum salmon
Zoological Science, 1996Co-Authors: Hironori Ando, Susumu Hyodo, Shuichi Hiraoka, Kaoru Kubokawa, Akihisa UranoAbstract:Abstract Changes in expression of vasotocin (VT) and isotocin (IT) genes were analyzed in chum salmon during the last stages of spawning migration. Pre-spawning chum salmon were caught at following four locations in the Sanriku coast of the Pacific Ocean in Japan: 1) the off-coast area north to the Otsuchi Bay, 2) the mouth of the Otsuchi Bay, 3) inside of the Otsuchi Bay, and 4) the place 500 m upstream to the mouth of the Otsuchi River. In addition, effects of hypo-osmotic stimulation by transition from sea water (SW) to freshwater (FW) were examined in animals caught at the mouth of the Otsuchi Bay. The levels of VT and IT mRNAs in the forebrains were determined by Northern blot analysis. The plasma osmolality and the levels of Na+ and Cl− were also analyzed. Expression patterns of VT and IT genes were different between the males and the females. In the males, VT and IT gene expression were maintained essentially at the same levels from the off-coast area to the Otsuchi River. In contrast, in the femal...
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Molecular evolution of Neurohypophysial Hormone precursors.
Progress in brain research, 1992Co-Authors: Akihisa Urano, Susumu Hyodo, Masakuzu SuzukiAbstract:Publisher Summary Neurohypophysial Hormones are peptides produced mainly by hypothalamic magnocellular neurons. Various approaches using morphological, physiological, pharmacological, immunological, and biochemical methods have revealed unequivocally that peptidergic neuroHormones are important agents for intercellular communication. This chapter describes the molecular information to study the evolution of Neurohypophysial Hormones based on the primary structure of their precursors. Many identical or similar peptides, including Neurohypophysial Hormones, occur in the nervous system of a variety of animals, from coelenterates to mammals. Based on the evolutionary distances and the structural organization of complementary DNA (cDNAs) encoding Neurohypophysial Hormone precursors, the chapter proposes a possible evolutionary pathway of Neurohypophysial Hormone precursors. The evolutionary pathway of vasopressin-like peptides in fish seems to be more complicated than that of oxytocin-like peptides. Teleost isotocin and amphibian mesotocin may have been derived directly from vasotocin by gene duplication. Vasotocin appears to be the ancestral molecule of mammalian vasopressin, whereas mesotocin may be ancestral to oxytocin.
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Cloning and sequence analyses of cDNAs encoding vasotocin and isotocin precursors of chum salmon,Oncorhynchus keta: evolutionary relationships of Neurohypophysial Hormone precursors
Journal of Comparative Physiology B, 1991Co-Authors: Susumu Hyodo, Yukio Kato, Akihisa UranoAbstract:The nucleotide sequences of cloned cDNAs were used to determine the primary structures of the precursors of vasotocin (sVT) and isotocin (sIT) from the hypothalamus of the chum salmon, Oncorhynchus keta . Two different cDNAs were obtained for each of sVT and sIT precursors (sVT-I and sVT-II; sIT-I and sIT-II). Both sVT and sIT precursors were found to contain a signal peptide and Hormone that is connected to a neurophysin by a Gly-Lys-Arg sequence. Northern and Southern blot analyses showed that the sVT and sIT genes are expressed by the same chum salmon hypothalamus, but not by the liver and kidney. Microheterogeneity was found in the nucleotide and amino acid sequences of sVT precursors between our results and the previously reported data (Heierhorst et al. 1990). The conspicuous difference is the occurrence of a stop codon in the middle of sVT-II cDNA. The carboxyl termini of both sVT and sIT neurophysins are about 30 amino acids longer than neurophysins of toad and mammalian Neurohypophysial Hormone precursors. Although these extended regions do not contain a glycosylation site, they show striking similarity with the glycopeptide moiety (copeptin) of toad vasotocin and mammalian vasopressin precursors. The central portion of the neurophysins shows highest homology among corresponding regions of sVT and sIT precursors. Moreover, calculation of nucleotide substitution rates suggests that a recent gene conversion may have occurred which encompasses the exon that encodes the central segment of the sVT and sIT precursors. A possible pathway for the evolution of precursor molecules of Neurohypophysial Hormones is discussed.
Hiroshi Ueda - One of the best experts on this subject based on the ideXlab platform.
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differences in seasonal expression of Neurohypophysial Hormone genes in ordinary and precocious male masu salmon
General and Comparative Endocrinology, 1999Co-Authors: Yuki Ota, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:Our previous study showed the seasonal variations in expression of vasotocin (VT) and isotocin (IT) genes in preoptic magnocellular neurons of female masu salmon (Oncorhynchus masou). The changes in the level of VT mRNA were coincident with those in plasma testosterone and estradiol levels. In the present study, generality of this phenomenon in salmonid was verified in males. We examined changes in expression of VT and IT genes by an in situ hybridization technique and an immunohistochemical avidin–biotin complex method in the preoptic nuclei of ordinary and precocious male masu salmon. Plasma levels of testosterone and estradiol were measured by enzyme immunoassay. Fish were sampled in March, May, August, and November 1994 and January 1995. The intensities of hybridization signals for VT and IT mRNAs, as well as immunoreactivity of VT and IT, showed seasonal variations, although the profiles were different between the ordinary and precocious males. In the ordinary males, the intensities of hybridization signals for VT and IT mRNAs were high in January. These strong hybridization signals, representing elevation of VT and IT gene expression, were accompanied by increases in plasma levels of testosterone and estradiol. However, in precocious males, changes in VT and IT mRNA levels were not coincident with variation of plasma levels of sex steroid Hormones. The sensitivity to sex steroid Hormones of VT and IT gene expression may be different between the ordinary and precocious male masu salmon.
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changes in expression of Neurohypophysial Hormone genes during spawning migration in chum salmon oncorhynchus keta
Journal of Molecular Endocrinology, 1997Co-Authors: S Hiraoka, Masatoshi Ban, Hironori Ando, Hiroshi Ueda, Akihisa UranoAbstract:We analyzed changes in the hypothalamic levels of vasotocin (VT) and isotocin (IT) mRNA in chum salmon during spawning migration to the Ishikari river. The fish were caught at Atsuta, a fisherman's village facing the Ishikari bay, and at Chitose, an upstream branch of the Ishikari river. The former are referred to as sea water (SW) fish, and the latter as freshwater (FW) fish. The levels of VT and IT mRNA in the forebrains were determined by quantitative Northern blot analysis using single-stranded DNA with the same mRNA sequences as the standards. Levels of VT mRNA were higher in the FW males than the FW females, although no such difference was seen in the SW fish. Changes in the levels of VT mRNA were markedly different in males and females. In the males, no significant differences were seen in the levels of VT-I and VT-II mRNA between the SW and FW fish. However, in the females, the levels of VT mRNA in the FW fish were significantly lower than those in the SW fish. Changes in the levels of IT-I and IT-II mRNA were essentially similar in the males and females. These results suggest that the control of VT gene expression is different in males and females during spawning migration, although the neuroendocrine mechanism is not known.
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Sexually Different Expression of Neurohypophysial Hormone Genes in the Preoptic Nucleus of Pre-Spawning Chum Salmon
Zoological Science, 1996Co-Authors: Yuki Ota, Hironori Ando, Masatoshi Ban, Hiroshi Ueda, Akihisa UranoAbstract:Abstract Vasotocin (VT) and isotocin (IT) are teleost Neurohypophysial Hormones produced by neurosecretory neurons in the magnocellular part of preoptic nucleus (PM) of the hypothalamus. Several previous studies indicated that Neurohypophysial Hormones are involved in teleost reproductive behavior. The changes in the expression of VT and IT genes were thus studied by an in situ hybridization technique and an immunohistochemical avidin-biotin-complex method in pre-spawning chum salmon (Oncorhynchus keta). Male and female fish were caught at Atsuta, the mouth of the Ishikari Bay, and at Chitose, upstream to the Ishikari River in October, 1994. The former and the latter are referred to as bay fish and river fish, respectively. The intensity of autoradiographic hybridization signals were determined in individual neurosecretory neurons in the rostroventral, middle, and dorsocaudal parts of the PM. in the females, the levels of VT and IT mRNAs in the river fish were significantly lower than those in the bay fis...