Barrell G K, Ridgway M J, Wellby M, Pereira A, Henry B A, Clarke I J
Faculty of Agriculture & Life Sciences, Lincoln University, Lincoln 7647, Canterbury, New Zealand.
Faculty of Agriculture & Life Sciences, Lincoln University, Lincoln 7647, Canterbury, New Zealand.
Gen Comp Endocrinol. 2016 Apr 1;229:1-7. doi: 10.1016/j.ygcen.2016.02.020. Epub 2016 Feb 17.
Red deer are seasonal with respect to reproduction and food intake, so we tested the hypothesis that their brains would show seasonal changes in numbers of cells containing hypothalamic neuropeptides that regulate these functions. We examined the brains of male and female deer in non-breeding and breeding seasons to quantify the production of kisspeptin, gonadotropin inhibitory hormone (GnIH), neuropeptide Y (NPY) and γ-melanocyte stimulating hormone (γ-MSH - an index of pro-opiomelanocortin production), using immunohistochemistry. These neuropeptides are likely to be involved in the regulation of reproductive function and appetite. During the annual breeding season there were more cells producing kisspeptin in the arcuate nucleus of the hypothalamus than during the non-breeding season in males and females whereas there was no seasonal difference in the expression of GnIH. There were more cells producing the appetite stimulating peptide, NPY, in the arcuate/median eminence regions of the hypothalamus of females during the non-breeding season whereas the levels of an appetite suppressing peptide, γ-MSH, were highest in the breeding season. Male deer brains exhibited the converse, with NPY cell numbers highest in the breeding season and γ-MSH levels highest in the non-breeding season. These results support a role for kisspeptin as an important stimulatory regulator of seasonal breeding in deer, as in other species, but suggest a lack of involvement of GnIH in the seasonality of reproduction in deer. In the case of appetite regulation, the pattern exhibited by females for NPY and γ-MSH was as expected for the breeding and non-breeding seasons, based on previous studies of these peptides in sheep and the seasonal cycle of appetite reported for various species of deer. An inverse result in male deer most probably reflects the response of appetite regulating cells to negative energy balance during the mating season. Differences between the sexes in the seasonal changes in appetite regulating peptide cells of the hypothalamus present an interesting model for future studies.
马鹿在繁殖和食物摄入方面具有季节性，因此我们检验了这样一个假设，即它们的大脑会在含有调节这些功能的下丘脑神经肽的细胞数量上表现出季节性变化。我们检查了非繁殖季节和繁殖季节的雄性和雌性马鹿的大脑，使用免疫组织化学方法来量化亲吻素、促性腺激素抑制激素（GnIH）、神经肽Y（NPY）和γ-黑素细胞刺激激素（γ-MSH——促阿片黑素皮质素产生的一个指标）的产生情况。这些神经肽可能参与生殖功能和食欲的调节。在年度繁殖季节，下丘脑弓状核中产生亲吻素的细胞比非繁殖季节的雄性和雌性马鹿更多，而GnIH的表达没有季节性差异。在非繁殖季节，雌性马鹿下丘脑的弓状核/正中隆起区域产生刺激食欲的肽NPY的细胞更多，而抑制食欲的肽γ-MSH的水平在繁殖季节最高。雄性马鹿的大脑表现出相反的情况，NPY细胞数量在繁殖季节最高，γ-MSH水平在非繁殖季节最高。这些结果支持了亲吻素在马鹿季节性繁殖中作为重要刺激调节因子的作用，就像在其他物种中一样，但表明GnIH不参与马鹿繁殖的季节性。在食欲调节方面，基于之前对绵羊中这些肽的研究以及各种马鹿物种报道的食欲季节性周期，雌性马鹿中NPY和γ-MSH表现出的模式与繁殖和非繁殖季节预期的一致。雄性马鹿的相反结果很可能反映了交配季节食欲调节细胞对负能量平衡的反应。下丘脑食欲调节肽细胞季节性变化的性别差异为未来研究提供了一个有趣的模型。
