[Role of the suprachiasmatic nuclei of the anterior hypothalamus in regulating the circadian rhythms of rat locomotor activity].

Effect of bilateral lesions of suprachiasmatic nuclei (SCN) of anterior hypothalamus on circadian rhythms of locomotor activity in a treadmill was studied in blinded rats. Immediately after the SCN lesion the free-run circadian rhythm of locomotor activity disappeared: the animals became arrhythmic. Partial lesion of SCN weakened the circadian component of rhythm and led to irregular oscillations within 0.5--3.5 hrs range which put on circadian periodicity. Significance of the anterior hypothalamus SCN in organization of circadian rhythms in rats was discussed.