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Expression of NPY and POMC in the hypothalamic arcuate nucleus of genetically lean and fat sheep
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Abstracts / Frontiers in Neuroendocrinology 27 (2006) 4–11
CRBP1. These latter discoveries suggest that the ependymal layer has a role to play in seasonal response but also may have important implications for the role of the ependymal layer in general. (This work was supported by Scottish Executive Environment and Rural Affairs Department.)
maturation of reproductive functions. The regulatory mechanism of the expression of the GALP gene is different from that of NPY and POMC during postnatal development. doi:10.1016/j.yfrne.2006.03.017
doi:10.1016/j.yfrne.2006.03.016
Postnatal developmental change of the gene expression of galanin-like peptide in rat hypothalamus Rinko Kawagoe a, Yukiyo Yamamoto a, Kazushige a Dobashi , Kohtaro Asayama b, Yoichi Ueta c, Akira Shirahata a a Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan b Kanagawa Health Service Association, Kanagawa 231-0021, Japan c Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan Galanin-like peptide (GALP) is a neuropeptide which is implicated in the regulation and integration of feeding behavior, energy metabolism, and reproduction. We examined the developmental change of GALP gene expression in the rat hypothalamus during postnatal day 1 to day 60, using in situ hybridization histochemistry. The expression of neuropeptide Y (NPY) and proopiomelanocortin (POMC) in the hypothalamus were also examined because they are known to be important in the regulation of food intake. GALP mRNA was not observed at postnatal day 1 and first detected in the arcuate nucleus (ARC) at postnatal day 8. GALP mRNA was gradually increased between postnatal day 8 and day 14 and markedly increased between postnatal day 14 and day 40, which is the weaning period and pubertal period in rats. In contrast to GALP, NPY and POMC mRNAs were detected in the ARC from postnatal day 1 to day 60. NPY mRNA increased gradually from postnatal day 1 to day 21 and significantly decreased at postnatal day 40 and day 60. POMC gene expression was increased throughout postnatal development from postnatal day 1 to day 40. There were no significant differences of the expression of the POMC gene between postnatal day 40 and day 60. Next, we examined the effects of milk deprivation for 24 h on the expression of the GALP, NPY, and POMC gene in pups. GALP gene expression did not change after milk deprivation for 24 h on postnatal day 9 and day 15, while milk deprivation for 24 h had a significant effect on NPY and POMC gene expression on postnatal day 15. These results suggest that the development of GALP, which increased dramatically during weaning and the pubertal period, may be associated with developmental changes such as weaning, feeding, and
Expression of NPY and POMC in the hypothalamic arcuate nucleus of genetically lean and fat sheep Chantacha Anukulkitch a, Alexandra Rao a, John b McEwan , Iain Clarke a a Department of Physiology, Monash University, Clayton Vic. 3168, Australia b AgResearch Invermay, P.O. Box 50034, Mosgiel, New Zealand Genetic selection has created flocks of sheep that are Lean or Fat, with unselected Normal animals being of average adiposity [1]. These animals have similar food intake with similar body weight, despite differences in body composition [1,2]. Lean animals have higher plasma GH levels than the Fat, consistent with their body composition. Our aim was to determine the expression of genes for neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) in the hypothalamic arcuate nucleus (ARC) of genetically Lean, Fat, and Normal ovariectomized ewes (n = 5/group), to ascertain whether genetic selection has caused aberrant expression of these important metabolic regulators. Body weights and voluntary food intake (VFI) were not different between the Lean, Fat, and Normal animals. Compared to Normal, mean (±SEM) fat index was higher (P < 0.01) in the Fat and lower (P < 0.05) in Lean groups and plasma leptin levels were lower (P < 0.05) in the Lean. The brains of the animals were perfused for in situ hybridisation analysis of NPY and POMC gene expression. The level of NPY gene expression/cell was higher (P < 0.05) in the Lean animals than in Normal animals, but similar in Fat and Normal animals. POMC gene expression was similar in all groups. Leptin negatively regulates NPY gene expression in normal animals [3], so low plasma leptin levels in the Lean sheep may be the reason for increased NPY expression. NPY is orexigenic but elevated expression in the Lean animals is not translated into increased food intake. NPY also reduces energy expenditure, but this is inconsistent with a lean phenotype. Products of POMC (the melanocortins) also regulate food intake and energy expenditure, but the lack of differences in the expression of this gene across the three phenotypes cannot explain the differences in body composition. It is possible that gene expression for other appetite regulating peptides is changed in relation to phenotype, which may alter energy expenditure. Alternatively, altered function in adipose and/or other peripheral organs may be responsible for lean and fat phenotypes.
Abstracts / Frontiers in Neuroendocrinology 27 (2006) 4–11
References [1] J. Afonso et al., Animal Science 63 (1996) 395. [2] S.M. Francis et al., General and Comparative Endocrinology 116 (1) (1999) 104. [3] B.A. Henry et al., Endocrinology 140 (3) (1999) 1175. doi:10.1016/j.yfrne.2006.03.018
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in VFI that occur with changing photoperiod and that these effects are due to alterations in the expression of NPY, POMC, and Ob-Rb. The differences in neuropeptide gene expression and VFI between castrates and intact animals may be due to changes in testosterone levels in the latter. Reference [1] I.J. Clarke et al., Am. J. Physiol. 284 (2003) R101.
Influence of photoperiod and gonadal status on changes in gene expression for appetite regulating peptides and leptin receptor (Ob-Rb) in the hypothalamus of Soay rams Chantacha Anukulkitch a, Alexandra Rao a, Gerald b Lincoln , Iain Clarke a a Department of Physiology, Monash University, Clayton Vic. 3168, Australia b MRC Human Reproductive Sciences Unit, The Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK In Soay rams, food intake is reduced under short-day photoperiod (SD) and increased under long-day photoperiod (LD) [1]. This appears to be driven by upregulation of the orexigenic factor neuropeptide Y (NPY) gene expression in the arcuate nucleus (ARC) [1]. In this species, the reproductive axis is activated by SD, with a rise in plasma testosterone levels. The aim of the present study was to dissect the interaction of photoperiod and gonadal status and quantify the level of neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and leptin receptor (ObRb) gene expression in the ARC of gonad-intact (n = 15) and castrated (n = 16) male sheep made hyperphagic under LD and then hypophagic under SD. The animals which were preconditioned to LD for 12 weeks, were abruptly switched to SD and remained on SD for up to 30 weeks. Groups of gonad-intact and castrated rams were euthanased at 6, 18, and 30 weeks (n = 5–6/group) for in situ hybridization quantification of neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and leptin receptor (Ob-Rb) gene expression in the arcuate nucleus of the hypothalamus. Plasma testosterone levels of intact animals were low under LD, but increased under SD to reach maximum at 16 weeks. Testosterone levels had fallen by 30 weeks due to photorefractoriness. In both intact and castrated animals, voluntary food intake (VFI) was high under LD and declined to a minimal level at 18 weeks. Thereafter, VFI increased in the gonad-intact group, but remained low in the castrated group. NPY mRNA expression paralleled VFI at all times. POMC mRNA levels were low when VFI was high (week 6) and high when VFI was low (week 18) in both intact and castrated animals. By week 30, POMC expression had risen further in the castrates, but remained similar to week 18 levels in the intact animals. ObRb expression was highest in week 6 and was reduced to a similar extent at weeks 18 and 30 in both intact and castrated animals. We conclude that gonadal status influences the changes
doi:10.1016/j.yfrne.2006.03.019
Localization of the thyrotropin releasing hormone (TRH) secretory system in the Siberian hamster Francis J.P. Ebling a, Dana Wilson b, Joanne Wood a, Debbie Hughes a, Julian G. Mercer b, Perry Barrett b a School of Biomedical Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, UK b Department of Molecular Endocrinology, Rowett Research Institute and Aberdeen centre for energy regulation and obesity (ACERO), Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK Thyrotropin releasing hormone (TRH) not only plays an essential role in the regulation of the pituitary–thyroid axis, but may also exert complementary effects on energy metabolism within the central nervous system. It has been hypothesised that in seasonal mammals such as the Siberian hamster, increased activity of the TRH secretory system contributes to winter adaptations whereby food intake is decreased, and catabolism of fat stores increases to support thermogenesis. The aim of this study was therefore to determine the anatomical distribution of TRH producing neurons and TRH-R1 receptor distribution in the hypothalamus of the Siberian hamster. A partial sequence encoding TRH-R1 was cloned from hamster hypothalamic cDNA and used to generate a riboprobe for in situ hybridization studies. This was complemented by immunocytochemical mapping of TRH-immunoreactive cell soma and processes and in situ hybridization analysis of the localization of a rat preproTRH riboprobe. TRH-ir cell soma and mRNA expression were found to be widely distributed throughout the hypothalamus, with particular aggregations in the paraventricular nucleus, the medial preoptic area and periventricular nucleus, and in the dorsomedial hypothalamus extending into the lateral hypothalamic area. There was dense innervation of TRH projections at the median eminence, consistent with the role of TRH as a hypothalamic-releasing hormone, but there was also widespread innervation of many other areas in particular the preoptic area, anterior hypothalamic area and dorsomedial hypothalamus. Likewise, TRH-R1 mRNA expressing cells were abundant throughout the hypothalamus, both in the regions highly innervated by TRH-ir fibers and throughout the arcuate nucleus. This wide distribution of TRH-produc-
Abstracts / Frontiers in Neuroendocrinology 27 (2006) 4–11
CRBP1. These latter discoveries suggest that the ependymal layer has a role to play in seasonal response but also may have important implications for the role of the ependymal layer in general. (This work was supported by Scottish Executive Environment and Rural Affairs Department.)
maturation of reproductive functions. The regulatory mechanism of the expression of the GALP gene is different from that of NPY and POMC during postnatal development. doi:10.1016/j.yfrne.2006.03.017
doi:10.1016/j.yfrne.2006.03.016
Postnatal developmental change of the gene expression of galanin-like peptide in rat hypothalamus Rinko Kawagoe a, Yukiyo Yamamoto a, Kazushige a Dobashi , Kohtaro Asayama b, Yoichi Ueta c, Akira Shirahata a a Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan b Kanagawa Health Service Association, Kanagawa 231-0021, Japan c Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan Galanin-like peptide (GALP) is a neuropeptide which is implicated in the regulation and integration of feeding behavior, energy metabolism, and reproduction. We examined the developmental change of GALP gene expression in the rat hypothalamus during postnatal day 1 to day 60, using in situ hybridization histochemistry. The expression of neuropeptide Y (NPY) and proopiomelanocortin (POMC) in the hypothalamus were also examined because they are known to be important in the regulation of food intake. GALP mRNA was not observed at postnatal day 1 and first detected in the arcuate nucleus (ARC) at postnatal day 8. GALP mRNA was gradually increased between postnatal day 8 and day 14 and markedly increased between postnatal day 14 and day 40, which is the weaning period and pubertal period in rats. In contrast to GALP, NPY and POMC mRNAs were detected in the ARC from postnatal day 1 to day 60. NPY mRNA increased gradually from postnatal day 1 to day 21 and significantly decreased at postnatal day 40 and day 60. POMC gene expression was increased throughout postnatal development from postnatal day 1 to day 40. There were no significant differences of the expression of the POMC gene between postnatal day 40 and day 60. Next, we examined the effects of milk deprivation for 24 h on the expression of the GALP, NPY, and POMC gene in pups. GALP gene expression did not change after milk deprivation for 24 h on postnatal day 9 and day 15, while milk deprivation for 24 h had a significant effect on NPY and POMC gene expression on postnatal day 15. These results suggest that the development of GALP, which increased dramatically during weaning and the pubertal period, may be associated with developmental changes such as weaning, feeding, and
Expression of NPY and POMC in the hypothalamic arcuate nucleus of genetically lean and fat sheep Chantacha Anukulkitch a, Alexandra Rao a, John b McEwan , Iain Clarke a a Department of Physiology, Monash University, Clayton Vic. 3168, Australia b AgResearch Invermay, P.O. Box 50034, Mosgiel, New Zealand Genetic selection has created flocks of sheep that are Lean or Fat, with unselected Normal animals being of average adiposity [1]. These animals have similar food intake with similar body weight, despite differences in body composition [1,2]. Lean animals have higher plasma GH levels than the Fat, consistent with their body composition. Our aim was to determine the expression of genes for neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) in the hypothalamic arcuate nucleus (ARC) of genetically Lean, Fat, and Normal ovariectomized ewes (n = 5/group), to ascertain whether genetic selection has caused aberrant expression of these important metabolic regulators. Body weights and voluntary food intake (VFI) were not different between the Lean, Fat, and Normal animals. Compared to Normal, mean (±SEM) fat index was higher (P < 0.01) in the Fat and lower (P < 0.05) in Lean groups and plasma leptin levels were lower (P < 0.05) in the Lean. The brains of the animals were perfused for in situ hybridisation analysis of NPY and POMC gene expression. The level of NPY gene expression/cell was higher (P < 0.05) in the Lean animals than in Normal animals, but similar in Fat and Normal animals. POMC gene expression was similar in all groups. Leptin negatively regulates NPY gene expression in normal animals [3], so low plasma leptin levels in the Lean sheep may be the reason for increased NPY expression. NPY is orexigenic but elevated expression in the Lean animals is not translated into increased food intake. NPY also reduces energy expenditure, but this is inconsistent with a lean phenotype. Products of POMC (the melanocortins) also regulate food intake and energy expenditure, but the lack of differences in the expression of this gene across the three phenotypes cannot explain the differences in body composition. It is possible that gene expression for other appetite regulating peptides is changed in relation to phenotype, which may alter energy expenditure. Alternatively, altered function in adipose and/or other peripheral organs may be responsible for lean and fat phenotypes.
Abstracts / Frontiers in Neuroendocrinology 27 (2006) 4–11
References [1] J. Afonso et al., Animal Science 63 (1996) 395. [2] S.M. Francis et al., General and Comparative Endocrinology 116 (1) (1999) 104. [3] B.A. Henry et al., Endocrinology 140 (3) (1999) 1175. doi:10.1016/j.yfrne.2006.03.018
9
in VFI that occur with changing photoperiod and that these effects are due to alterations in the expression of NPY, POMC, and Ob-Rb. The differences in neuropeptide gene expression and VFI between castrates and intact animals may be due to changes in testosterone levels in the latter. Reference [1] I.J. Clarke et al., Am. J. Physiol. 284 (2003) R101.
Influence of photoperiod and gonadal status on changes in gene expression for appetite regulating peptides and leptin receptor (Ob-Rb) in the hypothalamus of Soay rams Chantacha Anukulkitch a, Alexandra Rao a, Gerald b Lincoln , Iain Clarke a a Department of Physiology, Monash University, Clayton Vic. 3168, Australia b MRC Human Reproductive Sciences Unit, The Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK In Soay rams, food intake is reduced under short-day photoperiod (SD) and increased under long-day photoperiod (LD) [1]. This appears to be driven by upregulation of the orexigenic factor neuropeptide Y (NPY) gene expression in the arcuate nucleus (ARC) [1]. In this species, the reproductive axis is activated by SD, with a rise in plasma testosterone levels. The aim of the present study was to dissect the interaction of photoperiod and gonadal status and quantify the level of neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and leptin receptor (ObRb) gene expression in the ARC of gonad-intact (n = 15) and castrated (n = 16) male sheep made hyperphagic under LD and then hypophagic under SD. The animals which were preconditioned to LD for 12 weeks, were abruptly switched to SD and remained on SD for up to 30 weeks. Groups of gonad-intact and castrated rams were euthanased at 6, 18, and 30 weeks (n = 5–6/group) for in situ hybridization quantification of neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and leptin receptor (Ob-Rb) gene expression in the arcuate nucleus of the hypothalamus. Plasma testosterone levels of intact animals were low under LD, but increased under SD to reach maximum at 16 weeks. Testosterone levels had fallen by 30 weeks due to photorefractoriness. In both intact and castrated animals, voluntary food intake (VFI) was high under LD and declined to a minimal level at 18 weeks. Thereafter, VFI increased in the gonad-intact group, but remained low in the castrated group. NPY mRNA expression paralleled VFI at all times. POMC mRNA levels were low when VFI was high (week 6) and high when VFI was low (week 18) in both intact and castrated animals. By week 30, POMC expression had risen further in the castrates, but remained similar to week 18 levels in the intact animals. ObRb expression was highest in week 6 and was reduced to a similar extent at weeks 18 and 30 in both intact and castrated animals. We conclude that gonadal status influences the changes
doi:10.1016/j.yfrne.2006.03.019
Localization of the thyrotropin releasing hormone (TRH) secretory system in the Siberian hamster Francis J.P. Ebling a, Dana Wilson b, Joanne Wood a, Debbie Hughes a, Julian G. Mercer b, Perry Barrett b a School of Biomedical Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, UK b Department of Molecular Endocrinology, Rowett Research Institute and Aberdeen centre for energy regulation and obesity (ACERO), Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK Thyrotropin releasing hormone (TRH) not only plays an essential role in the regulation of the pituitary–thyroid axis, but may also exert complementary effects on energy metabolism within the central nervous system. It has been hypothesised that in seasonal mammals such as the Siberian hamster, increased activity of the TRH secretory system contributes to winter adaptations whereby food intake is decreased, and catabolism of fat stores increases to support thermogenesis. The aim of this study was therefore to determine the anatomical distribution of TRH producing neurons and TRH-R1 receptor distribution in the hypothalamus of the Siberian hamster. A partial sequence encoding TRH-R1 was cloned from hamster hypothalamic cDNA and used to generate a riboprobe for in situ hybridization studies. This was complemented by immunocytochemical mapping of TRH-immunoreactive cell soma and processes and in situ hybridization analysis of the localization of a rat preproTRH riboprobe. TRH-ir cell soma and mRNA expression were found to be widely distributed throughout the hypothalamus, with particular aggregations in the paraventricular nucleus, the medial preoptic area and periventricular nucleus, and in the dorsomedial hypothalamus extending into the lateral hypothalamic area. There was dense innervation of TRH projections at the median eminence, consistent with the role of TRH as a hypothalamic-releasing hormone, but there was also widespread innervation of many other areas in particular the preoptic area, anterior hypothalamic area and dorsomedial hypothalamus. Likewise, TRH-R1 mRNA expressing cells were abundant throughout the hypothalamus, both in the regions highly innervated by TRH-ir fibers and throughout the arcuate nucleus. This wide distribution of TRH-produc-