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

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‐pituit...

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Published in:The Prostate Vol. 36; no. 4; pp. 226 - 234
Main Authors: Juarranz, Maria G., Guijarro, Luis G., Bodega, Guillermo, Prieto, Juan C.
Format: Journal Article
Language:English
Published: New York Wiley Subscription Services, Inc., A Wiley Company 01-09-1998
Wiley-Liss
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Summary: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 (αs) and inhibitory (αi1–2) 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 [γ‐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 β‐adrenergic agonist isoproterenol were enhanced in prostatic membranes after ethanol intake. Moreover, an increase in the content of G‐protein subunits (αs and αi1–2) 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. Prostate 36:226–234, 1998. © 1998 Wiley‐Liss, Inc.
Bibliography:ark:/67375/WNG-M4W26BPW-F
ArticleID:PROS3
istex:7A5E370FA0FB6C0BFA6FE0760A537612F5C0E0CD
Dirección General de Investigación Cientifica y Técnica - No. PM 92/44; No. PB 94/360
ISSN:0270-4137
1097-0045
DOI:10.1002/(SICI)1097-0045(19980901)36:4<226::AID-PROS3>3.0.CO;2-D