van der Beek E M, Wiegant V M, van der Donk H A, van den Hurk R, Buijs R M
Department of Cell Biology, Medical Faculty, University of Utrecht, The Netherlands.
J Neuroendocrinol. 1993 Apr;5(2):137-44. doi: 10.1111/j.1365-2826.1993.tb00373.x.
In non-seasonal breeders like the rat, the influence of the suprachiasmatic nucleus (SCN) on reproduction is most clearly expressed in the female. Complete lesions of the SCN induce persistent oestrus (anovulation) in intact female rats, whereas oestrogen implantation in ovariectomized rats results in daily luteinizing hormone surges. Vasoactive intestinal polypeptide (VIP), a peptide synthesized in cell bodies of the SCN, inhibits the increase in pulsatile luteinizing hormone release observed in ovariectomized female rats. In search of the anatomical basis for these observations, the present study employs an immunocytochemical double staining for VIP and gonadotrophin-releasing hormone (GnRH) at the light microscopical level. It was demonstrated that approximately 45% of the GnRH positive neurons in the diagonal band of Broca, the preoptic and anterior hypothalamic area of female rats are innervated by VIP-containing processes. To investigate whether these VIP-containing fibres represent a direct projection of the SCN to the GnRH system, unilateral thermic SCN lesions were made. Lesions that unilaterally destroyed the majority of the VIP synthesizing cells in the SCN resulted in at least a 50% decrease of the VIP innervation of GnRH cell bodies at the lesioned side compared to the intact side. Lesions not affecting the VIP synthesizing cell population in the SCN did not change the percentage of GnRH neurons innervated by VIP-containing fibres, while partial lesions resulted in intermediate effects. These results indicate that the majority of the light microscopical VIP-containing input on GnRH neurons in the hypothalamus is derived from the SCN.(ABSTRACT TRUNCATED AT 250 WORDS)
在像大鼠这样的非季节性繁殖动物中，视交叉上核（SCN）对繁殖的影响在雌性中表现得最为明显。对完整雌性大鼠进行SCN完全损伤会导致持续性发情（无排卵），而在去卵巢大鼠中植入雌激素则会导致每日促黄体生成素激增。血管活性肠肽（VIP）是一种在SCN细胞体中合成的肽，它能抑制去卵巢雌性大鼠中观察到的促黄体生成素脉冲式释放的增加。为了寻找这些观察结果的解剖学基础，本研究在光学显微镜水平上对VIP和促性腺激素释放激素（GnRH）进行了免疫细胞化学双重染色。结果表明，雌性大鼠布罗卡斜带、视前区和下丘脑前部区域中约45%的GnRH阳性神经元受含VIP的神经纤维支配。为了研究这些含VIP的纤维是否代表SCN到GnRH系统的直接投射，制作了单侧热损伤SCN。单侧破坏SCN中大部分VIP合成细胞的损伤导致损伤侧GnRH细胞体的VIP神经支配比完整侧至少减少50%。不影响SCN中VIP合成细胞群的损伤不会改变受含VIP纤维支配的GnRH神经元的百分比，而部分损伤则产生中间效应。这些结果表明，下丘脑GnRH神经元上大部分光学显微镜下含VIP的输入来自SCN。（摘要截短至250字）
