title: [Effect of the time of administration of 5-hydroxytryptophan on the restoration of circadian stimulation of ACTH secretion in rats treated with p-chlorophenylalanine].
abstract: In female rats kept under a photoperiod of 12L-12D (50 lux from 07.00-19.00 h) the pharmacological blockade of serotonin synthesis by pCPA (2 X 300 mg/kg i.p.) obliterated the diel ACTH stimulation, which could, however be restored by an additionnal 5-HTP injection (60 mg/kg i.p.), provided that the serotonin precursor was administered at 11.00 h. If injected at 23.00 h the same dosage of 5-HTP failed to elicit any increase in plasma ACTH. The circadian ACTH rhythm appears, therefore to depend upon a daily activation of the serotoninergic system occurring 4 h after the onset of the light phase.
mesh_terms: D006916:5-Hydroxytryptophan / Q000008:administration & dosage / Q000494:pharmacology*; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D005260:Female; D010134:Fenclonine / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
chemical_list: D000324:Adrenocorticotropic Hormone; D006916:5-Hydroxytryptophan; D010134:Fenclonine
vernacular_title: Influence de l'heure d'administration de 5-hydroxytryptophanne sur la restauration de la stimulation circadienne de la sécrétion de l'ACTH chez des rats traités à la p-chlorophenylalanine.