慢性乙醇摄入后大鼠前列腺膜中腺苷酸环化酶活性的G蛋白调节

G-protein regulation of adenylate cyclase activity in rat prostatic membranes after chronic ethanol ingestion.

作者信息

Juarranz M G, Guijarro L G, Bodega G, Prieto J C

机构信息

Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares, Spain.

出版信息

Prostate. 1998 Sep 1;36(4):226-34. doi: 10.1002/(sici)1097-0045(19980901)36:4<226::aid-pros3>3.0.co;2-d.

DOI:10.1002/(sici)1097-0045(19980901)36:4<226::aid-pros3>3.0.co;2-d

PMID:9719022

Abstract

BACKGROUND

The possibility that long-term ethanol ingestion might alter either vasoactive intestinal peptide (VIP) content, VIP binding to membrane receptors, G-protein levels or adenylate cyclase activity in rat prostate was tested, as ethanol produces serious alterations in the hypothalamic-pituitary-gonadal axis and several modifications on different elements on signal transduction pathways in other systems.

METHODS

Prostatic membranes from control and ethanol-treated (for 4 weeks) rats were used to study adenylate cyclase stimulation as well as for the immunodetection of stimulatory (alpha(s)) and inhibitory (alpha(i)1-2) G-protein subunits. Studies on VIP binding and cross-linking to receptors were performed using [125I]VIP. Prostatic VIP content was estimated by radioimmunoassay. GTPase activity was quantified by measuring the amount of 32Pi released from [gamma-32P]GTP.

RESULTS

Chronic ethanol ingestion resulted in an increased presence of VIP in the rat prostate without any change on the VIP receptor/effector system in this gland. By contrast, the basal adenylate cyclase activity as well as the dose-dependent stimulation of this enzyme by either the nonhydrolyzable GTP analogue Gpp(NH)p or the beta-adrenergic agonist isoproterenol were enhanced in prostatic membranes after ethanol intake. Moreover, an increase in the content of G-protein subunits (alpha(S) and alpha(i)1-2) was observed without any change in GTPase activity in this condition. These modifications were accompanied by a significant decrease in rat prostate weight and, consequently, the height of the secretory epithelium in this gland.

CONCLUSIONS

Considering the role of VIP in the mechanisms of secretion and cell proliferation in the prostate, the observed increases in the prostatic content of VIP and G-protein subunits make conceivable that VIP and cAMP signal transduction could be involved in the atrophy of the rat prostate and in the alterations in the composition of seminal fluid that appear in the alcoholic syndrome.

摘要

背景

由于乙醇会对下丘脑 - 垂体 - 性腺轴产生严重影响，并对其他系统信号转导途径的不同元件进行多种修饰，因此测试了长期摄入乙醇是否可能改变大鼠前列腺中血管活性肠肽（VIP）的含量、VIP与膜受体的结合、G蛋白水平或腺苷酸环化酶活性。

方法

使用来自对照和乙醇处理（4周）大鼠的前列腺膜来研究腺苷酸环化酶的刺激作用，以及对刺激性（α(s)）和抑制性（α(i)1 - 2）G蛋白亚基进行免疫检测。使用[125I]VIP进行VIP与受体的结合及交联研究。通过放射免疫测定法估计前列腺VIP含量。通过测量从[γ - 32P]GTP释放的32Pi量来定量GTP酶活性。

结果

长期摄入乙醇导致大鼠前列腺中VIP含量增加，而该腺体中的VIP受体/效应系统无任何变化。相比之下，摄入乙醇后，前列腺膜中的基础腺苷酸环化酶活性以及该酶由非水解性GTP类似物Gpp(NH)p或β - 肾上腺素能激动剂异丙肾上腺素引起的剂量依赖性刺激均增强。此外，在此条件下观察到G蛋白亚基（α(S)和α(i)1 - 2）含量增加，而GTP酶活性无任何变化。这些改变伴随着大鼠前列腺重量显著降低，进而导致该腺体分泌上皮高度降低。