Effects of neuropeptide Y on LH, FSH and TSH release in male rats.

These experiments were undertaken to investigate the effects of systemically administered neuropeptide Y (NPY) on gonadotropin secretion in the intact male rat and to determine whether the effects observed might be mediated by a direct action of NPY alone on the anterior pituitary gland (APG). Subcutaneous administration of 10 micrograms of NPY caused a greater than 2-fold increase in serum luteinizing hormone (LH) concentration at 15 min after injection but was without effect on serum follicle-stimulating hormone (FSH) or thyrotropin-stimulating hormone (TSH) levels. The addition of NPY (final concentrations of 10(-8) to 10(-11) M) or the structurally similar neuropeptide, rat pancreatic polypeptide, to culture medium containing hemi-APG did not alter the release of LH, FSH, or TSH. The results indicate that systemically administered NPY can elevate serum LH concentration in intact male rats. This effect does not appear to be due to NPY acting alone at the level of the APG.