THE INTERRELATIONSHIP BETWEEN GONADAL-STEROIDS AND POMC PEPTIDES, BETA-ENDORPHIN AND ALPHA-MSH, IN THE CONTROL OF SEXUAL-BEHAVIOR IN THE FEMALE RAT

Estradiol benzoate (10 mu g EB) given to ovariectomized-adrenalectomiz ed rats induced sexual receptivity in half the animals and increased a lpha-MSH in the preoptic area, ventromedial nucleus (VMN) and arcuate nucleus (ARC), in all the animals, although levels were significantly higher in the VMN and ARC of the receptive (R) subgroup. EB also raise d levels of beta-endorphin in the VMN and ARC in the R rats only. POMC expression was not altered. EB did not affect alpha MSH in extra-hypo thalamic areas, but addition of progesterone, raised levels in the sep tum, amygdala, hippocampus and caudate putamen. Only in the VMN, ARC a nd septum were the steroid-induced increases correlated with onset of sexual behavior. (C) 1998 Elsevier Science Inc.