Steroid modulation of electrochemically-induced gonadotropin release in the male rat

Electrochemical stimulation (ECS) of the medial preoptic area (MPOA) in the male rat produced an attenuated release of pituitary FSH and LH analogous to that induced in the female during Diestrus I and II. However, orchidectomy followed by estradiol-benzoate replacement resulted in a massive release of LH following ECS; FSH was again minimally responsive. Electrode implantation without ECS (sham control) was without effect upon either gonadotropin. Results indicate that the male rat can be provoked to a massive release of LH by ECS when an estrogen environment is provided; androgens appear to interfere. We also conclude that the MPOA connection for releasing-hormore secretion is intact in the male rat, and is sensitive to an external stimulus.