Thyroid gland influences the period of hamster circadian oscillations

Summary The locomotor activity of ovariectomized, adult golden hamsters was monitored under constant dim illumination. Thiourea treatment lengthened the period () of locomotor activity of thyroidectomized hamsters in comparison to pre-operative s and in comparison to the s of control hamsters. The results confirm hormonal modulation of the circadian system.Acknowledgments. This study was supported by grant HD-02982. L.J.B. was the recipient of a N.I.M.H. Traineeship (T32-MH-15860-01). We thank D. Frost, J. Budd, B. Ries, M. Darragh and J. Schutz for technical assistance. We are grateful to Drs I. Zucker and L. L. Rosenberg for guidance and helpful comments throughout this study.