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

1 We have systematically reviewed the presence, functional responses and regulation of a 1 -, a 2 -and b-adrenoceptors in the bladder, urethra and prostate, with special emphasis on human tissues and receptor subtypes. 2 a 1 -Adrenoceptors are only poorly expressed and play a limited functional role in the detrusor. a 1 -Adrenoceptors, particularly their a 1A -subtype, show a more pronounced expression and promote contraction of the bladder neck, urethra and prostate to enhance bladder outlet resistance, particularly in elderly men with enlarged prostates. a 1 -Adrenoceptor agonists are important in the treatment of symptoms of benign prostatic hyperplasia, but their beneficial effects may involve receptors within and outside the prostate. 3 a 2 -Adrenoceptors, mainly their a 2A -subtype, are expressed in bladder, urethra and prostate. They mediate pre-junctional inhibition of neurotransmitter release and also a weak contractile effect in the urethra of some species, but not humans. Their overall post-junctional function in the lower urinary tract remains largely unclear. 4 b-Adrenoceptors mediate relaxation of smooth muscle in the bladder, urethra and prostate. The available tools have limited the unequivocal identification of receptor subtypes at the protein and functional levels, but it appears that the b 3 -and b 2 -subtypes are important in the human bladder and urethra, respectively. b 3 -Adrenoceptor agonists are promising drug candidates for the treatment of the overactive bladder. 5 We propose that the overall function of adrenoceptors in the lower urinary tract is to promote urinary continence. Further elucidation of the functional roles of their subtypes will help a better understanding of voiding dysfunction and its treatment.

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Effects of Chronic Ethanol Ingestion on the Vasoactive Intestinal Peptide Receptor‐Effector System From Rat Seminal Vesicle Membranes

Juarranz

Marinero

Bodega

et al. 1999

Alcoholism Clin & Exp Res

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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.

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

Cited by 3 publications

References 37 publications

Influence of hormonal replacement on the ventral lobe of the prostate of rats (Rattus norvegicus albinus) submitted to chronic ethanol treatment

Influence of hormonal replacement on the ventral lobe of the prostate of rats (Rattus norvegicus albinus) submitted to chronic ethanol treatment

α₁‐, α₂‐ and β‐adrenoceptors in the urinary bladder, urethra and prostate

Effects of Chronic Ethanol Ingestion on the Vasoactive Intestinal Peptide Receptor‐Effector System From Rat Seminal Vesicle Membranes

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

Cited by 3 publications

References 37 publications

Influence of hormonal replacement on the ventral lobe of the prostate of rats (Rattus norvegicus albinus) submitted to chronic ethanol treatment

Influence of hormonal replacement on the ventral lobe of the prostate of rats (Rattus norvegicus albinus) submitted to chronic ethanol treatment

α1‐, α2‐ and β‐adrenoceptors in the urinary bladder, urethra and prostate

Effects of Chronic Ethanol Ingestion on the Vasoactive Intestinal Peptide Receptor‐Effector System From Rat Seminal Vesicle Membranes

Contact Info

Product

Resources

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α₁‐, α₂‐ and β‐adrenoceptors in the urinary bladder, urethra and prostate