Juarranz M G, Marinero M J, Bodega G, Prieto J C, Guijarro L G
Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares, Spain.
Alcohol Clin Exp Res. 1999 Feb;23(2):318-23.
We studied the modifications of the vasoactive intestinal peptide (VIP) receptor/effector system from the rat seminal vesicle after chronic ethanol ingestion. Ethanol treatment resulted in a decreased height of the secretory epithelium of seminal vesicle as well as in a weight loss of this gland. These morphological changes were accompanied by an increase of immunoreactive vasoactive intestinal peptide (VIP) levels and a decrease of the stimulatory effect of VIP adenylate cyclase activity in the seminal vesicle. The loss of sensitivity of the enzyme to VIP was conceivably related to a decrease in the affinity of VIP receptors rather than to a decrease in their number. The changes in the affinity of the VIP receptors were accompanied with a lower sensitivity of VIP binding to GTP, which suggest an uncoupling between the receptor and the transductor molecules. However, chronic exposure to ethanol did not modify either the levels of G-protein subunits (alpha(s) and alpha(i1/2)) or the GTPase activity from seminal vesicle membranes. Moreover, ethanol feeding did not affect adenylate cyclase activity stimulated by forskolin or by Gpp(NH)p. Thus, ethanol-induced changes in the sensitivity of adenylate cyclase to VIP appear to be attributed to an alteration in the VIP-receptor/G-protein interphase rather than in the G-protein/adenylate cyclase connection.
我们研究了长期摄入乙醇后大鼠精囊血管活性肠肽（VIP）受体/效应系统的变化。乙醇处理导致精囊分泌上皮高度降低以及该腺体重量减轻。这些形态学变化伴随着免疫反应性血管活性肠肽（VIP）水平的升高以及精囊中VIP腺苷酸环化酶活性刺激作用的降低。酶对VIP敏感性的丧失可能与VIP受体亲和力的降低有关，而不是与受体数量的减少有关。VIP受体亲和力的变化伴随着VIP与GTP结合的较低敏感性，这表明受体与转导分子之间发生了解偶联。然而，长期暴露于乙醇并未改变G蛋白亚基（α(s)和α(i1/2)）的水平或精囊膜的GTP酶活性。此外，给予乙醇并不影响福斯可林或Gpp(NH)p刺激的腺苷酸环化酶活性。因此，乙醇诱导的腺苷酸环化酶对VIP敏感性的变化似乎归因于VIP受体/G蛋白界面的改变，而不是G蛋白/腺苷酸环化酶连接的改变。
