Do long-term glucocorticoid treatments induce behavioral rhythm disturbances in rats?
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.
Department of Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan. endoyuta@med.uoeh-u.ac.jp
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Endo
D000375:Aging / Q000187:drug effects* / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D005938:Glucocorticoids / Q000009:adverse effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D005938:Glucocorticoids