Prevot V, Dutoit S, Croix D, Tramu G, Beauvillain J C
U 422 Institut National de la Santé et de La Recherche Médicale, Lille, France.
Neuroscience. 1998 May;84(1):177-91. doi: 10.1016/s0306-4522(97)00537-x.
The ultrastructural appearance of gonadotropin releasing hormone-immunoreactive elements was studied in the external zone of the median eminence of adult female Wistar rats. On the one hand, the purpose of the study was to determine the distribution of gonadotropin releasing hormone terminals towards the parenchymatous basal lamina at the level of hypothalamo-hypophyseal portal vessels, throughout the estrous cycle. On the other hand, we have semi-quantified the gonadotropin releasing hormone content in nerve terminals or preterminals during this physiological condition. A morphometric study was coupled to a colloidal 15 mn gold postembedding immunocytochemistry procedure. Animals were killed at 09.00 on diestrus II, 0.900, 10.00, 13.00, 17.00 and 18.00 on proestrus and 09.00 on estrus (n = 4-8 rats/group). A preliminary light microscopic study was carried out to identify an antero-posterior part of median eminence strongly immunostained by anti-gonadotropin releasing hormone antibodies but which was, in addition, easily spotted. This last condition was necessary to make a good comparison between each animal. Contacts between gonadotropin releasing hormone nerve terminals and the basal lamina were observed only the day of proestrus. Such contacts, however, were rare and in the great majority of cases, gonadotropin releasing hormone terminals are separated from basal lamina by tanycytic end feet. The morphometric analysis showed no significant variation in average distance between gonadotropin releasing hormone terminals and capillaries throughout the estrous cycle. Consequently, it did not appear that a large neuroglial plasticity exists during the estrous cycle. However, the observation of contacts only on proestrus together with some ultrastructural images evoke the possibility of a slight plasticity. The semi-quantitative results show that the content of gonadotropin releasing hormone in the nerve endings presented two peaks on proestrus: one at 09.00 (23 +/- 5 particles/micrograms2, P < 0.03) before the onset of luteinizing hormone surge, and the second at 18.00 (16 +/- 2 particles/micrograms2, P < 0.01) concomitantly with the luteinizing hormone surge, when compared to baseline values on proestrus 10.00 (8 +/- particles/micrograms2).
研究了成年雌性Wistar大鼠正中隆起外侧区促性腺激素释放激素免疫反应性元件的超微结构。一方面，本研究的目的是确定在整个发情周期中，促性腺激素释放激素终末在下丘脑-垂体门脉血管水平处向实质基膜的分布。另一方面，我们对这种生理状态下神经终末或终末前的促性腺激素释放激素含量进行了半定量分析。形态计量学研究与胶体15纳米金包埋后免疫细胞化学方法相结合。在动情周期的间情期II的09:00、动情前期的09:00、10:00、13:00、17:00和18:00以及发情期的09:00处死动物（每组4 - 8只大鼠）。进行了初步的光学显微镜研究，以确定正中隆起的前后部分，该部分被抗促性腺激素释放激素抗体强烈免疫染色，而且易于识别。最后这个条件对于在每只动物之间进行良好比较是必要的。仅在动情前期观察到促性腺激素释放激素神经终末与基膜之间的接触。然而，这种接触很少见，在大多数情况下，促性腺激素释放激素终末通过室管膜细胞终足与基膜分离。形态计量学分析表明，在整个发情周期中，促性腺激素释放激素终末与毛细血管之间的平均距离没有显著变化。因此，在发情周期中似乎不存在大量的神经胶质可塑性。然而，仅在动情前期观察到的接触以及一些超微结构图像提示存在轻微可塑性的可能性。半定量结果表明，神经末梢中促性腺激素释放激素的含量在动情前期出现两个峰值：一个在黄体生成素激增开始前的09:00（23±5颗粒/微克²，P < 0.03），第二个在18:00（16±2颗粒/微克²，P < 0.01），此时与动情前期10:00的基线值（8±颗粒/微克²）相比，黄体生成素激增。
