Regional Brain Variations of Tryptophan, Monoamines, Monoamine Oxidase Activity, Plasma Free and Total Tryptophan during the Estrous Cycle of the Rat

Publisher Website
Google Scholar
Abstract
Normal 4 day cyclic rats were sacrificed at 10 a.m. and 3 p.m. on proestrus or estrus and at 10 a.m. on metestrus. Noradrenaline (NA) [norepinephrine] dopamine (DA) and tryptophan (T) concentrations varied only slightly. Serotonin (5-HT) concentrations showed characteristics changing patterns in many hypothalamic, limbic and midbrain structures with a decrease during proestrus and an increase during estrus being observed. Monoamine oxidase (MAO) activity changes were often parallel to the 5-HT changes, but were not as great. The marked changes in 5-HT early in proestrus are a further indication of its inhibitory effect on gonadotropin release mechanisms before the critical period.