Beta adrenergic receptor alterations in diabetic rat prostate: effects of insulin and dietary myoinositol.

As sexual dysfunction is a well-recognized manifestation of diabetes mellitus and as the function of the prostate, a major accessory organ in the male reproductive system, is regulated by the autonomic nervous system, we studied beta adrenergic receptors in the prostate of streptozotocin-induced diabetic rats, using radioligand receptor binding techniques. Four groups of rats were maintained for 8 weeks: controls, diabetics, insulin-treated diabetics, and myoinisitol-treated diabetics. The diabetic and myoinisitol-treated diabetic animals were smaller, had higher blood glucose levels, higher water intake and urine output, smaller prostates, and lower serum insulin levels than the other groups. Saturation experiments with [3H]dihydroalprenolol showed that the induction of diabetes decreased the density of beta adrenergic receptors in prostatic membrane particulates. Inhibition studies with selective beta adrenergic antagonists demonstrated that these receptors were of the beta 2 subtype. Furthermore, insulin but not myoinositol treatment normalized blood glucose and insulin levels, maintained normal prostate and body weight-gain, and prevented the decrease in the density, i.e., down-regulation, of the prostatic beta adrenergic receptors.