Briaud B, Koch B, Lutz-Bucher B, Mailhe C
Neuroendocrinology. 1980 May;30(5):262-7. doi: 10.1159/000123012.
Alterations in the ionic composition of the medium and different secretagogues have been used in order to study the mechanism of release of ACTH from superfused neurointermediate lobes (NIL) of rat hypophysis. We showed that: (a) a tenfold increase of K+ in the medium caused a reversible and repeatable stimulation of the ACTH release; (b) removal of Ca++ reversibly abolished the stimulating effect of high K+; (c) removal of Ca++ had no effect on the stimulating effect of a hypothalamic extract (HE); (d) in the latter case, a reversible significant weakening was obtained by the addition of EDTA in the Ca++-free medium; (e) dbc-AMP caused a reversible and repeatable stimulation of the ACTH release; (f) comparable results were obtained for anterior lobes (AL) superfused in the same conditions. From these data we can conclude that Ca++ is necessary for the stimulation of the hormonal release and that factors such as K+ or dbc-AMP can mimic the in vitro stimulating effect of a HE. Similarities, which appear in this study, between the modulation of the ACTH release from NIL and AL, led us to support the idea that, in vivo, a release of ACTH from the NIL, may occur in physiological conditions.
为了研究大鼠垂体神经中间叶（NIL）超灌流时促肾上腺皮质激素（ACTH）释放的机制，人们使用了培养基离子组成的改变和不同的促分泌素。我们发现：（a）培养基中K⁺浓度增加10倍可引起ACTH释放的可逆性和重复性刺激；（b）去除Ca²⁺可使高K⁺的刺激作用可逆性消失；（c）去除Ca²⁺对下丘脑提取物（HE）的刺激作用无影响；（d）在后一种情况下，在无Ca²⁺培养基中加入乙二胺四乙酸（EDTA）可使刺激作用出现可逆性显著减弱；（e）二丁酰环磷腺苷（dbc-AMP）可引起ACTH释放的可逆性和重复性刺激；（f）在相同条件下对前叶（AL）进行超灌流也得到了类似结果。从这些数据我们可以得出结论，Ca²⁺对于激素释放的刺激是必需的，而K⁺或dbc-AMP等因素可模拟HE的体外刺激作用。本研究中NIL和AL的ACTH释放调节之间出现的相似性，使我们支持这样一种观点，即在生理条件下，NIL可能会在体内释放ACTH。
