title: [Persistance of phase-coupling between the circadian rhythms of hypophyseal hormones in free-running rats].
abstract: The circadian rhythms in plasma ACTH, TSH, LH and PRL were explored in sighted or blind, spayed and estrogen-implanted rats. A marked endogenous circadian rhythmicity was shown to persist in the blind animals for the 4 endocrine rhythms. The endogenous rhythms also kept very close reciprocal phase relationship as in the synchronized state, and they were peaking almost simultaneously, after 60 d. of free-running. Finally the endogenous hormonal rhythm maintained their usual phase relationships with the endogenous activity rhythm, so that the circadian phase of increased hormonal secretion coincided with the circadian resting phase of the sleep/wake rhythm. These results are discussed in the light of the alternate theory of one vs multiple but phase-locked circadian pacemakers driving endocrine and behavioral circadian rhythms.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D001766:Blindness / Q000503:physiopathology*; D002369:Castration; D002940:Circadian Rhythm / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006065:Gonadotropins, Pituitary / Q000378:metabolism; D010908:Pituitary Hormones, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006065:Gonadotropins, Pituitary; D010908:Pituitary Hormones, Anterior; D004958:Estradiol; D000324:Adrenocorticotropic Hormone
vernacular_title: Persistance du couplage de phases entre les rythmes circadiens des hormones hypophysaires chez des rattes évoluant "en libre cours".