Functional development of the rat urinary bladder after pre- or postpubertal castration

Experiments were done to evaluate the role of sex hormones in the functional development of the rat urinary bladder. Rats were orchiectomized or ovariectomized at 30 (prepubertal) or 70 (postpubertal) days of age and bladders were removed 1 month later. An additional group of immature male and female rats was used in which the bladders were removed at 30 days of age. There were only minor differences in contractile responses of bladder strips from any group to electrical field stimulation, ATP, carbachol, or KCl compared to age-matched controls. There were no differences in responses of bladder strips from immature females or males to the adrenergic agonists, isoproterenol, norepinephrine, or methoxamine. Bladders from the pre- and postpubertally castrated rats and their controls relaxed fully in response to isoproterenol, but strips from prepubertally castrated rats relaxed significantly less in response to norepinephrine than those from other groups. Approximately one half of the bladder strips from prepubertally castrated rats failed to relax by at least 50% in response to norepinephrine; these same strips responded to methoxamine with exaggerated contractions. Our data indicate that the normal development of rat bladder alpha-adrenergic responsiveness is adversely altered by prepubertal castration. We postulate that this may result from an alteration in the relative expression of alpha(1)-adrenergic receptor subtypes.