Stachowiak A, Macchi C, Nussdorfer G G, Malendowicz L K
Department of Histology and Embryology, School of Medicine, Poznan, Poland.
Res Exp Med (Berl). 1995;195(5):265-74. doi: 10.1007/BF02576797.
The effects of oxytocin (OX) on the function and morphology of the rat adrenal cortex were studied in vivo and in vitro. OX exerted a potent stimulatory action on basal, but not 10(-8) M ACTH-stimulated corticosterone (B) secretion of dispersed rat inner (zona fasciculata and zona reticularis) adrenocortical cells (maximal effective concentration: 10(-9) M); in contrast, at higher concentrations (10(-7)/10(-6) M) OX inhibited maximally ACTH-stimulated B output. A single subcutaneous (s.c.) injection of 1.2 nmol/100 g body weight OX resulted in a long-lasting (up to 12 h) rise in plasma B concentration (PBC). The prolonged administration of OX (daily s.c. injections of 0.6 or 1.2 nmol/100 g for 10 days) caused a marked lowering in the adrenal weight and volume of all adrenocortical zones, that in turn was due to a decrease in the number of their parenchymal cells; however, the average volume of inner adrenocortical cells was significantly increased. Basal PBC was lowered, but its response to ether stress was unchanged in comparison with control rats. Prolonged OX treatment did not change B secretion by adrenal slices, but it markedly raised that of dispersed inner adrenocortical cells. Our present findings clearly show that the effects of OX on the adrenal cortex depend on the experimental model employed (in vitro versus in vivo) and the duration of treatment (acute versus chronic). Taken together they allow us to conclude that OX exerts an acute direct stimulatory effect on the rat adrenal cortex, and a chronic inhibitory one, that at least in part could be due to the interference of OX with the mechanism(s) of intracellular transduction of the ACTH secretagogue signal.
在体内和体外研究了催产素（OX）对大鼠肾上腺皮质功能和形态的影响。OX对分散的大鼠肾上腺皮质内层（束状带和网状带）细胞的基础皮质酮（B）分泌具有强大的刺激作用，但对10^(-8) M促肾上腺皮质激素（ACTH）刺激的皮质酮分泌无此作用（最大有效浓度：10^(-9) M）；相反，在较高浓度（10^(-7)/10^(-6) M）时，OX最大程度地抑制了ACTH刺激的B分泌。皮下（s.c.）注射1.2 nmol/100 g体重的OX可使血浆B浓度（PBC）持续升高（长达12小时）。长期给予OX（每天皮下注射0.6或1.2 nmol/100 g，共10天）导致所有肾上腺皮质区的肾上腺重量和体积显著降低，这反过来又归因于其实质细胞数量的减少；然而，肾上腺皮质内层细胞的平均体积显著增加。基础PBC降低，但与对照大鼠相比，其对乙醚应激的反应未改变。长期OX处理并未改变肾上腺切片的B分泌，但显著提高了分散的肾上腺皮质内层细胞的B分泌。我们目前的研究结果清楚地表明，OX对肾上腺皮质的影响取决于所采用的实验模型（体外与体内）以及治疗持续时间（急性与慢性）。综合来看，我们可以得出结论，OX对大鼠肾上腺皮质具有急性直接刺激作用和慢性抑制作用，至少部分原因可能是OX干扰了ACTH促分泌素信号的细胞内转导机制。
