Lambert G M, Rubin B S, Baum M J
Department of Biology, Boston University, Massachusetts 02215.
Endocrinology. 1992 Sep;131(3):1473-80. doi: 10.1210/endo.131.3.1505478.
The pulsatile secretion of LH was previously found to rise in female ferrets after receipt of an intromission, whereas in males that achieved an intromission, both LH and testosterone secretion were either reduced or unchanged. We sought to determine whether this sexually dimorphic pattern of LH secretion reflects a sex difference in the effect of mating on the activity of forebrain neurons that secrete LHRH. Immunocytochemical methods were used to localize the nuclear protein product of the immediate early gene, c-fos, as an index of increased neuronal activity after mating. Nuclear FOS immunoreactivity (FOS-IR) was monitored in LHRH-IR neurons as well as other non-LHRH forebrain neurons. In confirmation of previous reports, LHRH-IR perikarya in ferrets of both sexes were located medially along the base of the brain at rostral, medial, and caudal levels of the preoptic-hypothalamic continuum. In each of these regions a significantly higher percentage of LHRH-IR neurons was colabeled with nuclear FOS-IR in mated than in unpaired females. By contrast, an equivalent low percentage of LHRH-IR neurons was colabeled with FOS-IR in mated and unpaired male ferrets. Significantly more FOS-IR neurons (not colabeled with LHRH) were detected in the bed nucleus of the stria terminalis, the medial preoptic area, the dorsal-medial hypothalamus, and the medial amygdala (MA) of mated vs. unpaired females. By contrast, mating significantly augmented FOS-IR only in the MA of male ferrets. The results suggest that the sexually dimorphic pattern of LH secretion that occurs in ferrets after mating reflects a selective activation of LHRH neurons in the female forebrain. This sex-specific increase in the responsiveness of LHRH neurons to mating may depend on input from a limbic circuit which includes the medial amygdala, bed nucleus of the stria terminalis, and medial preoptic area.
先前发现，雌性雪貂在接受插入后促黄体激素（LH）的脉冲式分泌会增加，而在成功插入的雄性雪貂中，LH和睾酮的分泌要么减少，要么没有变化。我们试图确定这种LH分泌的性别差异模式是否反映了交配对分泌促性腺激素释放激素（LHRH）的前脑神经元活性影响的性别差异。免疫细胞化学方法用于定位即刻早期基因c-fos的核蛋白产物，作为交配后神经元活性增加的指标。在LHRH免疫反应性（LHRH-IR）神经元以及其他非LHRH前脑神经元中监测核FOS免疫反应性（FOS-IR）。正如先前报道所证实的，两性雪貂的LHRH-IR胞体沿脑底部内侧分布于视前区-下丘脑连续体的嘴侧、内侧和尾侧水平。在这些区域中的每一个，交配后的雌性雪貂中与核FOS-IR共标记的LHRH-IR神经元百分比显著高于未配对的雌性。相比之下，交配和未配对的雄性雪貂中与FOS-IR共标记的LHRH-IR神经元百分比相当低。在交配后的雌性雪貂与未配对的雌性相比，终纹床核、内侧视前区、背内侧下丘脑和内侧杏仁核（MA）中检测到显著更多的FOS-IR神经元（未与LHRH共标记）。相比之下，交配仅显著增加了雄性雪貂MA中的FOS-IR。结果表明，交配后雪貂中出现的LH分泌性别差异模式反映了雌性前脑中LHRH神经元的选择性激活。LHRH神经元对交配反应性的这种性别特异性增加可能依赖于一个边缘回路的输入，该回路包括内侧杏仁核、终纹床核和内侧视前区。
