Pompolo S, Pereira A, Kaneko T, Clarke I J
Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
J Neuroendocrinol. 2003 May;15(5):538-45. doi: 10.1046/j.1365-2826.2003.01030.x.
The seasonal pattern of breeding in sheep offers an opportunity to examine plasticity of neuronal inputs to gonadotropin-releasing hormone (GnRH) neurones. We used conventional fluorescence microscopy and confocal microscopy to compare the extent of input to GnRH neurones from various neuropeptide/neurotransmitter systems in ewes during the breeding and anestrous seasons. Using double-labelling immunohistochemistry, we counted close appositions between GnRH cells and varicosities that were immunoreactive for either glutamic acid decarboxylase (GAD; for gamma-amino butyric acid-GABA-neurones), dopamine beta hydroxylase (DBH; for noradrenergic neurones), vesicular glutamate transporter-1 (VGluT-1, for glutamatergic neurones), neuropeptide Y (NPY) and tyrosine hydroxylase (TH; for dopaminergic/noradrenergic neurones). The percentage of GnRH cells displaying close appositions to GABA-ergic varicosities was higher (P < 0.02) in anestrus than in the breeding season. The percentage of GnRH cells receiving input from varicosities that were positive for TH, DBH and VGluT-1 was similar in both seasons. Approximately 26-49% of GnRH neurones were seen to receive inputs from NPY, TH, GABAergic or noradrenergic neurones, while a larger number of GnRH cells (72-75%) received input from glutamatergic neurones. Conventional microscopy consistently overestimated the number of close contacts on GnRH neurones compared to confocal microscopy. For TH-immunoreactive varicosities in the preoptic area, only 16-35% were also immunoreactive for DBH, suggesting that the remainder are dopaminergic. Approximately half of the noradrenergic inputs in the preoptic area were also immunoreactive for NPY. In conclusion, we present numerical data on the consensus between light and confocal microscopy and the level of input of various neuronal systems to GnRH cells; the data indicate a seasonal change in the GABAergic input to GnRH neurones.
绵羊繁殖的季节性模式为研究促性腺激素释放激素（GnRH）神经元的神经输入可塑性提供了契机。我们运用传统荧光显微镜和共聚焦显微镜，比较了繁殖季节和非繁殖季节母羊中，来自各种神经肽/神经递质系统的GnRH神经元输入程度。通过双标记免疫组织化学法，我们计数了GnRH细胞与对谷氨酸脱羧酶（GAD；代表γ-氨基丁酸 - GABA - 神经元）、多巴胺β羟化酶（DBH；代表去甲肾上腺素能神经元）、囊泡谷氨酸转运体 - 1（VGluT - 1，代表谷氨酸能神经元）、神经肽Y（NPY）和酪氨酸羟化酶（TH；代表多巴胺能/去甲肾上腺素能神经元）呈免疫反应的曲张体之间的紧密毗邻情况。与繁殖季节相比，非繁殖季节中显示与GABA能曲张体有紧密毗邻的GnRH细胞百分比更高（P < 0.02）。两个季节中，接受来自对TH、DBH和VGluT - 1呈阳性的曲张体输入的GnRH细胞百分比相似。约26 - 49%的GnRH神经元被观察到接受来自NPY、TH、GABA能或去甲肾上腺素能神经元的输入，而更多的GnRH细胞（72 - 75%）接受来自谷氨酸能神经元的输入。与共聚焦显微镜相比，传统显微镜始终高估了GnRH神经元上的紧密接触数量。对于视前区中TH免疫反应性曲张体，只有16 - 35%也对DBH呈免疫反应，这表明其余的是多巴胺能的。视前区中约一半的去甲肾上腺素能输入也对NPY呈免疫反应。总之，我们给出了关于光学显微镜和共聚焦显微镜一致性以及各种神经元系统对GnRH细胞输入水平的数值数据；这些数据表明GnRH神经元的GABA能输入存在季节性变化。
