Androgen-specific critical periods for the organization of the major pelvic ganglion

Abstract

Previous studies indicate that the major pelvic ganglion (PG) is dependent on testosterone for normal development. Tyrosine hydroxylase (T-OH), DOPA decarboxylase, and choline acetyltransferase (CAT) activities are significantly reduced by postnatal castration on day 10-11, while testosterone replacement therapy reversed all developmental enzyme activity deficits (Melvin and Hamill, 1987). In the present studies castration on the day of birth combined with various testosterone-replacement paradigms produced effects demonstrating that the PG is sensitive to testosterone dosage and time of administration during early postnatal development. Gonadal hormone replacement experiments show that the androgens testosterone and dihydrotestosterone were effective in restoring T-OH and CAT activity deficits produced by neonatal castration. Estrogen therapy reversed the deficits in CAT activity, but was ineffective in reversing the alterations in T-OH activity. Treatment of pregnant dams with the anti-androgen flutamide altered the ontogeny of T-OH and CAT activities in pups despite replacement therapy on the day of birth. Thus, androgen-critical periods exist prenatally as well as postnatally. These studies suggest that the organization of PG development is critically dependent on both the time of exposure and dose of testosterone. Prenatal and postnatal critical periods appear to exist. In addition, the lack of an effect of estradiol on tyrosine hydroxylase activity suggests that androgens are specifically responsible for organizing the noradrenergic development of the PG.

Postnatal Maturational Changes in Rat Pelvic Autonomic Ganglion Cells: A Mixture of Steroid-Dependent and -Independent Effects

“…This indicated an increase in soma size and is in agreement with previous anatomical studies (Keast and Saunders 1998;Melvin and Hamill 1989;Melvin et al 1988). Together the results showed that testosterone is required to induce growth of sympathetic pelvic ganglion neurons at puberty and to maintain this larger soma size during adulthood.…”

Reduction of the Number of Neurones in the Caudal Mesenteric Ganglion Innervating the Ovary in Sexually Mature Gilts Following Testosterone Administration

“…It was reported earlier that castration of immature and sexually mature rats does not cause PG cells death (9,37,38). Moreover, in male rats, androgenic steroids do not affect PG TH-, nNOS-and VIP-positive neuronal survival in culture (10,14), although they were significant in maintaining the TH-and nNOS-immunoreactive somata size in vivo (10) and stimulating the noradrenergic somata growth in vitro (14).…”

Autonomie Control of Penile Erection: Modulation by Testosterone in the Rat

“…An activational role of testosterone towards the major pelvic ganglion has been recently demonstrated in the rat. Biochemical maturation of neurotransmitter-synthesizing enzymes is dependant on a normal testosterone level (26 response induced by electrical stimulation of the cavernous nerve in this model.…”