Effect of unilateral inactivation of cerebral hemisphere on rhythmic nociception variations in mice

Abstract

Changes in the biological rhythms of nociception in the circadian and ultradian range were studied with thermal noxious heat and tail-flick test in mice subjected to unilateral inactivation of cerebral hemispheres. Spectral analysis showed that sham operation suppresses initial circadian rhythm but augmens the arnplitude of 12-h rhythm against this background. During isolated activity of the right hemisphere, the high-power circadian rhythm was restored, although its phase and that of the 12-h rhythm were inverted. During isolated activity of the left hemisphere, the acrophase of circadian rhythm (occurring in the middle of daytime) coincided with that in intact mice, although the frequency of ultradian rhythms was increased. Our data attest to existence of functional interhemisphere asymmetry in regulation of mice nociception rhythm which is characterized by the dominant role of the left hemisphere. Such individual functional features of cerebral hemispheres are not manifested in the averaged daily data, but they can be revealed by the chronobiological methods.