Characteristics of organization of the rat circadian locomotor rhythm after pinealectomy

As compared with sham operated animals, an increase in night and daytime locomotion and a shift of the acrophase of the circadian locomotor rhythm to earlier night hours were observed in pinealectomized rats. A reorganization of the rhythm spectral characteristics took place with increase in the share of ultradian waves (14-20 h) and decrease in the number of short periodic (2-5 h) fluctuations.