Terrier C, Chabot J G, Pautrat G, Jeandel L, Gray D, Lutz-Bucher B, Zingg H H, Morel G
CNRS URA 1454, Faculté de Médecine, Lyon-Sud, Oullins, France.
Neuroendocrinology. 1991 Sep;54(3):303-11. doi: 10.1159/000125892.
The hypothalamic nonapeptide arginine-vasopressin (AVP) exerts several distinct receptor-mediated actions on pituitary cells. Although hypothalamic AVP reaches the anterior pituitary via well-defined pathways, there is now accumulating evidence that AVP may also be produced endogenously in anterior pituitary cells. Using in situ hybridization, we demonstrate here the presence of AVP mRNA in the anterior pituitary of the rat. The observed grain density over pituitary cells was, however, greater than 10-fold lower than the one observed over AVP producing neurons present in the supraoptic and paraventricular nuclei of the hypothalamus. Immunoelectron microscopic analysis using two different AVP-specific antibodies revealed that the distribution of AVP-like immunoreactivity (AVP-LI) in the anterior pituitary is cell-specific. AVP-LI is most abundant in corticotrophs, followed by lactotrophs, gonadotrophs and thyrotrophs. On the other hand, there is complete absence of AVP-LI from somatotrophs. Interestingly, all pituitary cells in which AVP-LI is detected also represent potential target sites for AVP action. A minor fraction of AVP-LI was found to be membrane-associated and may originate, at least in part, from extrapituitary sources. This fraction likely represents receptor-bound peptide. The bulk of AVP-LI, however, was present in the cellular cytoplasm, not associated with any specific ultracellular structure. Specifically in corticotrophs, AVP-LI was excluded from secretory granules. However, our finding of AVP mRNA in anterior pituitary cells indicates that intracellular AVP-LI includes endogenously produced peptide, suggesting a paracrine and/or autocrine action.
下丘脑九肽精氨酸加压素（AVP）对垂体细胞具有多种不同的受体介导作用。尽管下丘脑AVP通过明确的途径到达垂体前叶，但现在有越来越多的证据表明，AVP也可能在垂体前叶细胞内源性产生。我们通过原位杂交证明了大鼠垂体前叶中存在AVP mRNA。然而，在垂体细胞上观察到的颗粒密度比在下丘脑视上核和室旁核中产生AVP的神经元上观察到的颗粒密度低10倍以上。使用两种不同的AVP特异性抗体进行免疫电子显微镜分析表明垂体前叶中AVP样免疫反应性（AVP-LI）的分布具有细胞特异性。AVP-LI在促肾上腺皮质激素细胞中最丰富，其次是催乳激素细胞、促性腺激素细胞和促甲状腺激素细胞。另一方面，生长激素细胞中完全没有AVP-LI。有趣的是，所有检测到AVP-LI的垂体细胞也代表了AVP作用的潜在靶点。发现一小部分AVP-LI与膜相关，并且可能至少部分源自垂体外来源。这部分可能代表受体结合肽。然而，大部分AVP-LI存在于细胞质中，与任何特定的超微结构无关。特别是在促肾上腺皮质激素细胞中，AVP-LI被排除在分泌颗粒之外。然而，我们在垂体前叶细胞中发现AVP mRNA表明细胞内AVP-LI包括内源性产生的肽，提示旁分泌和/或自分泌作用。
