Plasma Concentration Changes in LH and FSH Following Electrochemical Stimulation of the Medial Preoptic Area or Dorsal Anterior Hypothalamic Area of Estrogen- or Androgen-Sterilized Rats1

Abstract

Plasma LH/FSH concentrations were monitored in mature androgen- (ASR) or estrogen-sterilized rats (ESR) and were compared to normal proestrous rats in which spontaneous gonadotropin surges had been blocked with Nembutal (control). LH and/or FSH release was induced by electrochemical stimulation (ECS) of either the dorsal anterior hypothalamic area (DAHA) or the medial preoptic area (MPOA). ECS of control rats, ASR and ESR provoked significant increases in plasma FSH by 120 min and peak levels by 180 min poststimulation. No differences were noted when ESR or ASR plasma levels were compared to control values or to each other (ESR vs. ASR). DAHA-ECS failed to provoke a significant LH increase from baseline in control rats and only small LH rises in ASR and ESR.