A study of the role of the adrenal glands in the initiation of the hiatus in gonadotropin secretion during prepubertal development in the male rhesus monkey (Macaca mulatta)

Abstract

An earlier finding that the decline in LH and FSH secretion which typically occurs in neonatally orchidectomized rhesus monkeys between 8-32 weeks of age was temporally associated with a broad peak in circulating concentrations of immunoreactive testosterone has prompted us to evaluate the role of adrenal androgens in determining the ontogeny of gonadotropin secretion in this species. To this end, six orchidectomized (1 week) infantile rhesus monkeys were bilaterally adrenalectomized between 2 and 5 weeks of age and subsequently maintained on daily glucocorticoid (cortisone acetate or hydrocortisone acetate) and mineralocorticoid (desoxycorticosterone acetate) replacement. Plasma cortisol concentrations and electrolytes (Na+ and K+) were monitored at approximately weekly intervals, and the steroid replacements were titrated in an attempt to maintain the foregoing parameters within physiological limits. Plasma was also obtained at weekly intervals for 50 weeks in order to determine the time courses of LH and FSH secretion during this phase of postnatal development. Bilateral adrenalectomy resulted in an immediate and permanent decline in plasma testosterone to undetectable concentrations. This procedure together with appropriate steroid replacement, however, did not appear to influence the developmental pattern of gonadotropin secretion in neonatally orchidectomized monkeys; most notably, the reduction in the open loop secretion of LH and FSH between 8-32 weeks of age was neither interrupted nor masked by adrenalectomy. The growth rate of the adrenalectomized monkeys, as reflected by weekly body weight determinations, was less than that of adrenally intact animals. These findings suggest that adrenal androgens are not involved in the initiation of the prepubertal restraint of gonadotropin secretion in the rhesus monkey and are consistent with the notion that the adrenal gland does not play a major role in determining the timing of puberty onset in higher primates.