The neural clock regulating estrous cyclicity in hamsters: gonadotropin release following barbiturate blockade.

Abstract

1 2 or 3 consecutive daily injections of phenobarbital (100 mg/kg) were given to female hamsters in order to study the mechanism timing periovulatory gonadotropin release. ormone (LH) and follicle stimulating hormone (FSH) were determined by radioimmunoassay. s delayed 24 48 or 72 hours respectively. um LH and FSH levels occurred at nearly the same time of day as that of the controls. al injection plateauing at approximately 25% of peak levels and then declining gradually over the next 2 days. FSH were delayed. hypothesis that periovulatory gonadotropin release in golden hamsters is timed by a neural clock.