title: Circadian variations in beta-endorphin concentrations in pituitary and in some brain nuclei of the adult male rat.
abstract: Using both the 'punch' microdissection and a radioimmunological technique, circadian variations in beta-endorphin concentrations can be observed in the pituitary and in some discrete brain regions of the male rat (Wistar CFY). Animals were synchronized with light from 06.00 to 18.00 h, then darkness. Water and food were available ad libitum. Very well marked circadian rhythms were in evidence in the anterior lobe of the pituitary, the septum, the pons, the medulla oblongata and the cerebellum. There crest time locations were situated between 20.00 and 24.00 h. No significant circadian rhythms but biphasic variations were observed in the intermediate lobe of the pituitary, the POA, the thalamus, the central gray and the caudatus. There crest time locations were synchronized around 08.00 and 20.00 h. The most striking finding was that, regardless of the brain area investigated so far, maximal values were observed a short time after the beginning of the activity period of rats. This fact is identical with the one which has been observed for substance P and LH-RH contents in brain areas where these peptides are mostly present in nerve terminals in high concentrations.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002940:Circadian Rhythm; D004723:Endorphins / Q000032:analysis*; D008297:Male; D010902:Pituitary Gland / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D001615:beta-Endorphin