Cobb V J, Williams B C, Mason J I, Walker S W
Department of Clinical Biochemistry, University of Edinburgh, Scotland, UK.
J Hypertens. 1997 Dec;15(12 Pt 2):1735-8. doi: 10.1097/00004872-199715120-00081.
To investigate a possible direct action of vasoactive intestinal polypeptide (VIP) on adrenal cortisol secretion and to define its mechanism of action.
The human adrenocortical carcinoma cell line NCI H295, which is not contaminated by medullary chromaffin cells, was used to aid distinction between a direct action of VIP on adrenocortical cells and an indirect mechanism involving VIP-stimulated release of catecholamines.
NCI H295 cells were challenged with 10(-11)-10(-7) mol/l VIP for 4 h, with or without prior exposure for 72 h to 10 micromol/l forskolin. Cortisol and cyclic AMP contents of the overlying media were measured using in-house radioimmunoassays. Cells were treated with 10(-8)-10(-6) mol/l adrenaline or 3.3 x 10(-8) mol/l VIP with and without 10(-8)-10(-6) mol/l propranolol to exclude the possibility that an indirect mechanism of action involving beta-adrenoceptors was operating.
VIP treatment produced an increase in cortisol secretion without pre-incubation, but this was markedly enhanced by prior exposure of cells to forskolin. VIP was potent, with a threshold of 10(-11) mol/l (n = 4), reaching a maximum 3.9+/-0.9-fold increase in effect on cells pre-exposed to forskolin (n = 4) by 3.3 x 10(-8) mol/l. This increase matched the 4 h response to 10 micromol/l forskolin. Cortisol secretion was accompanied by a parallel, dose-dependent increase in accumulation of cAMP.
VIP potently and directly stimulates secretion of cortisol from these adrenocortical cells of human origin via an adenylate cyclase-coupled VIP receptor. These findings raise the possibility of a significant and direct effect of VIP in the control of steroid secretion from the adrenal cortex in humans.
研究血管活性肠肽（VIP）对肾上腺皮质醇分泌的可能直接作用，并确定其作用机制。
使用未被髓质嗜铬细胞污染的人肾上腺皮质癌细胞系NCI H295，以帮助区分VIP对肾上腺皮质细胞的直接作用和涉及VIP刺激儿茶酚胺释放的间接机制。
用10(-11)-10(-7)mol/L的VIP刺激NCI H295细胞4小时，细胞在有或没有预先暴露于10μmol/L福司可林72小时的情况下接受刺激。使用内部放射免疫分析法测量上层培养基中皮质醇和环磷酸腺苷（cAMP）的含量。用10(-8)-10(-6)mol/L肾上腺素或3.3×10(-8)mol/L VIP处理细胞，同时加入或不加入10(-8)-10(-6)mol/L普萘洛尔，以排除涉及β-肾上腺素能受体的间接作用机制起作用的可能性。
VIP处理在未预先孵育的情况下导致皮质醇分泌增加，但细胞预先暴露于福司可林后，这种增加明显增强。VIP作用显著，阈值为10(-11)mol/L（n = 4），对预先暴露于福司可林的细胞（n = 4），3.3×10(-8)mol/L的VIP可使其效应最大增加3.9±0.9倍。这种增加与对10μmol/L福司可林的4小时反应相当。皮质醇分泌伴随着cAMP积累的平行、剂量依赖性增加。
VIP通过腺苷酸环化酶偶联的VIP受体有力且直接地刺激这些人源肾上腺皮质细胞分泌皮质醇。这些发现增加了VIP在人类肾上腺皮质类固醇分泌控制中具有显著直接作用的可能性。
