Effects of the destruction of the suprachiasmatic nuclei on the circadian rhythms of ACTH corticosterone and the general activity of female rats exposed to a aperiodic environment
Szafarczyk, A.; Ixart, G.; Alonso, G.; Malaval, F.; Nouguier-Soule, J.; Assenmacher, I.
Comptes Rendus des Seances de la Societe de Biologie et de ses Filiales 175(6): 801-810
1981
ISSN/ISBN: 0037-9026 PMID: 6275963 Document Number: 177591
The effects of bilateral destruction of suprachiasmatic nuclei (SCN) on the temporal patterns of plasma concentrations in ACTH and corticosterone (sequential blood samples from an aortic cannula, at 4 h intervals over 48 h) and of general activity (stabilimeter recordings) were studied in female rats under constant illumination (LL : 10 lx). Under this arrhythmic environment, the SCN lesions induced a syndrome similar to that previously described in a photoperiodic environment (12 L-12 D). This SCN syndrome included : 1) blockade of the ACTH rhythm at baseline levels ; 2) maintained fluctuations of corticosterone, with either circadian or ultradian profiles ; 3) persistent rhythmicity of general activity, with a circadian periodicity in addition to ultradian periods. The persistence of a circadian rhythmicity in the SCN syndrome under arrhythmic environmental conditions, clearly argues in favour of the occurrence of endogenous components of the circadian pacemaker outside the SCN.