Elsevier

Life Sciences

Volume 65, Issue 23, 29 October 1999, Pages 2497-2504
Life Sciences

Neuroactive steroids alter the Crcadian system of the Syrian hamster in a phase-dependent manner

https://doi.org/10.1016/S0024-3205(99)00516-0Get rights and content

Abstract

Several steroid compounds affect neuronal function, primarily by modulating the GABAA receptor complex. A circadian variation in the brain concentration of neurosteroids has been reported in rats and humans. We have previously reported that natural occurring or synthetic neuroactive steroids such as androsterone and alphaxalone also have a rhythmic effect on behavior (anesthetic and anticonvulsant activity) and GABAergic activity. In the present work, we have tested the ability of neuroactive steroids to phase shift circadian rhythms in hamsters. The GABAA negative modulator dehydroepiandrosterone sulphate (DHEAS) elicited phase advances when administered at CT 6, while the positive modulator androsterone lacked any effect at this time. A complete phase response curve for DHEAS revealed a nonphotic-like effect. DHEAS also blocked the circadian effects of light, while androsterone induced photic-like responses. There is also evidence that neurosteroids may be present and even synthesized in the SCN. Collectively, the results so far indicate that some neuroactive steroids might modulate the activity of the circadian clock.

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    Present address: Dr. Diego A. Golombek, CEI/Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, R.S.Peña 180, Bernal, (1876) Pcia. de Buenos Aires, Argentina. Fax: 54-11-4365-7132.

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