Relationships Between Behavioral Rhythms, Plasma Corticosterone and Hypothalamic Circadian Rhythms

摘要

Circadian rythms in physiological processes and behaviors were compared with hypothalamic circadian ryhthms in norepinephrine (NE) metabolites, adrenergic transmitter receptors, cAMP, cGMP and suprachiasmatic nucleus (SCN) arginine vasopressin (AVP) in a single population of rats under D : D conditions. Eating, drinking and locomotor activity were high during the subjective night (the time when lights were out in L : D) and low during the subjective day (the time when lights were on in L : D). Plasma corticosterone concentration rose as subjective dusk and remained high until subjective dawn. Binding to hypothalamic alpha and beta adrenergic receptors also peaked during the subjective night. Cyclic cGMP concentration was elevated through out the 24-hr period except for a trough at dusk, whereas DHPG concentration peaked at dawn. Arginine vasopressin levels in the suprachiasmatic nucleus peaked in the middle of the day. No rhythm was found either in binding to the alpha 2-adrenergic receptor, or in MHPG or cAMP concentration. Behavioral and corticosterone rhythms, therefore, are parallel to rhythms in hypothalamic alpha and beta receptors binding and NE-release. Cyclic GMP falls only at dusk, suggesting the possibility that cGMP inhibits activity much of the day and that at dusk the inhibition of nocturnal activity is removed. SCN AVP.