Do long-term glucocorticoid treatments induce behavioral rhythm disturbances in rats?

Journal/Book: Physiol Behav. 1999; 66: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 751-755.

Abstract: To examine the influences of a long-term glucocorticoid treatment on behavioral rhythm in rats, I measured motor activity, feeding and drinking, and body temperature in rats that had been treated with corticosterone over a long term, by means of an automatic behavioral measurement system combined with a telemetry system. Either a cholesterol (100 mg, as a control) or corticosterone (100 mg) bead was implanted subcutaneously in rats for 3 months, and the effects of the treatments on behavioral parameters were evaluated 2 to 4 months after the termination of the treatments. Corticosterone did not significantly change daily rhythms of all four parameters and mean values of them. However, three out of six corticosterone-treated rats appeared to show higher the mesor of motor activity compared with the control group. The present study demonstrates that a long-term glucocorticoid treatment does not impair behavioral daily rhythm, then suggests that a long-term glucocorticoid exposures could not damage the endogenous clock of the brain, that is, the suprachiasmatic nucleus.

Note: Article Endo Y, Univ Occupat & Environm Hlth, Sch Med, Dept Physiol, Yahatanishi Ku, 1-1 Iseigaoka, Kitakyushu, Fukuoka 8078555, JAPAN

Keyword(s): glucocorticoid; daily rhythm; motor activity; body temperature; behavior; rat; CEREBRAL BLOOD-FLOW; SUPRACHIASMATIC NUCLEUS; CORTICOSTERONE TREATMENT; SYSTEM; IMMUNOREACTIVITY; HIPPOCAMPUS; VASOPRESSIN; ISCHEMIA; CORTISOL; LESIONS

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