title: Neural control of circadian rhythms in plasma ACTH, plasma corticosterone and motor activity.
abstract: The circadian rhythms for plasma ACTH and corticosterone (B), as well as motor activity, were explored in female rats after ocular enucleation (O-X), stereotaxic lesion of the suprachiasmatic nuclei (SCN-X) or of midbrain raphe nuclei (R-X), or both O-X and R-X, pharmacological blockade of the serotoninergic (5HT) system by pCPA, sometimes bypassed by 5-HTP, or 5-HT denervation of the SCN by local injection of 5,7-DHT. The three circadian rhythms explored responded quite differently to the treatments. In particular, the ACTH and B rhythms lost their usual close correlations. The amplitude and mean level of ACTH fluctuations were depressed after all treatments, but remained normal or were enhanced for B rhythm. ACTH rhythmicity actually was undetectable after SCN-X, pCPA and, in several rats, combined O-X and R-X, whereas persisting circadian and/or ultradian B and locomotor activity rhythms were always measured. The participation of the suprachiasmatic nuclei, the midbrain raphe nuclei and other possible 5-HT components in a complex circadian pacemaker system is discussed.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D001921:Brain / Q000502:physiology*; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood*; D005260:Female; D009043:Motor Activity / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000324:Adrenocorticotropic Hormone; D003345:Corticosterone