Saridaki E, Carter D A, Lightman S L
Medical Unit, Charing Cross and Westminster Medical School, Westminster Hospital, London.
J Endocrinol. 1989 May;121(2):343-9. doi: 10.1677/joe.0.1210343.
The role of gamma-aminobutyric acid (GABA) in the control of oxytocin and arginine vasopressin (AVP) release from the posterior pituitary was investigated using the GABA agonist muscimol and the GABA antagonists bicuculline and picrotoxin. Two perifusion model systems were studied using (a) intact isolated posterior pituitaries (IPP) and (b) neurosecretosomes from both male and female rats. In experiments on tissue from male rats, the stimulated release of oxytocin and AVP in both models was inhibited by muscimol, an effect which was reversed in the presence of bicuculline. Bicuculline alone increased the release of oxytocin only. Although similar responses to muscimol or bicuculline were seen in neurosecretosomes from female animals, neither agent affected oxytocin and AVP release from the intact IPP. Picrotoxin had a similar effect to bicuculline on oxytocin in isolated posterior pituitaries from male as well as female rats, although at the neurosecretosome level a paradoxical inhibition was observed. These results provide evidence for an endogenous GABA receptor mechanism at the level of the neurosecretory terminals in both male and female rats. The sexually dimorphic IPP response suggests a second more complex mechanism involving either pituicytenerve terminal interactions and/or a secondary role of other neurotransmitters in the GABA regulation of neurohypophysial hormones.
使用γ-氨基丁酸（GABA）激动剂蝇蕈醇以及GABA拮抗剂荷包牡丹碱和印防己毒素，研究了GABA在控制垂体后叶催产素和精氨酸加压素（AVP）释放中的作用。使用（a）完整的离体垂体后叶（IPP）和（b）来自雄性和雌性大鼠的神经分泌小体，研究了两种灌流模型系统。在对雄性大鼠组织进行的实验中，两种模型中催产素和AVP的刺激释放均被蝇蕈醇抑制，在存在荷包牡丹碱的情况下这种作用被逆转。单独使用荷包牡丹碱仅增加催产素的释放。尽管在雌性动物的神经分泌小体中观察到对蝇蕈醇或荷包牡丹碱有类似反应，但两种药物均未影响完整IPP中催产素和AVP的释放。印防己毒素对雄性和雌性大鼠离体垂体后叶中的催产素的作用与荷包牡丹碱相似，尽管在神经分泌小体水平观察到了矛盾的抑制作用。这些结果为雄性和雌性大鼠神经分泌终末水平存在内源性GABA受体机制提供了证据。IPP的性别二态性反应表明存在另一种更复杂的机制，该机制涉及垂体细胞 - 神经终末相互作用和/或其他神经递质在GABA对神经垂体激素调节中的次要作用。
