Medial preoptic area affects sleep-wakefulness independent of associated body temperature change in free moving rats

Sleep-wakefulness and body temperature may modulate each other. Though both the functions are influenced by the medial preoptic area, the mechanism of action was not clear. This study was aimed at finding out whether the tonic influence of the medial preoptic area on sleep-wakefulness was independent of or secondary to simultaneous change in body temperature. The effects of inactivation of the area by a long acting local anaesthetic, marcain, on those physiological functions were investigated during the night and the day in freely moving rats. Though medial preoptic area influenced sleep-wakefulness and body temperature simultaneously, the effect on the latter was prolonged. The results suggest that the influence on sleep-wakefulness is unlikely to be associated with simultaneously changing body temperature. However, this study fails to differentiate whether the observed effects were due to inactivation of the cell body or the fibers passing through the area.