PERIPHERAL AUTONOMIC REGULATION OF GONADOTROPIN-SECRETION IN PUBERTALRATS - INHIBITION OF POST-CASTRATION RISE OF GONADOTROPINS DURING WALLERIAN DEGENERATION AFTER SYMPATHETIC SUPERIOR CERVICAL GANGLIONECTOMY

Shortly after superior cervical ganglionectomy (SCGx) peripheral sympa thetic nerve terminals in the median eminence degenerate, the neurotra nsmitter is released, and a transient period of increased postsynaptic ensues. The present experiments were undertaken to examine, in the an terograde degeneration paradigm after SCGx, the participation of perip heral sympathetic nerves in feedback regulation of gonadotropin releas e in pubertal rats. Groups of 18 days old or 26 days old rats of both sexes were subjected to castration or its sham-operation, and 4h later to SCGx or sham-SCGx. Twenty-four h later, the rats were decapitated and serum luteinizing hormone (LH) and follicle-stimulating hormone (F SH) levels were measured by RIA. In 19 days old male rats, the post-ca stration increase of circulating LH, but not of FSH, was prevented by the wallerian degeneration of sympathetic nerves after acute SCGx. At the 27th day of life, acute SCGx prevented FSH, but not LH, post-orchi dectomy rise. In female rats, SCGx blunted the oophorectomy-induced in crease of gonadotropin levels at both examined ages. SCGx brought abou t a significant decrease of serum LH levels in 19 days old, sham-castr ated female rats. At the 19th day of life, acute SCGx decreased serum LH and FSH in neonatally orchidectomized rats, but not in neonatally a ndrogenized female rats. The data are in favor of a negative influence of peripheral sympathetic neurons on gonadotropin release in prepuber tal rats, predominantly in female rats.