GABA-A receptors in mPOAH simultaneously regulate sleep and body temperature in freely moving rats

Sleep-wakefulness and body temperature are two circadian rhythmic biologica l phenomena. The role of GABAergic inputs in the medial preoptico-anterior hypothalamus (mPOAH) on simultaneous regulation of those phenomena was inve stigated in freely moving normally behaving rats. The GABA-A receptors were blocked by microinjecting picrotoxin, and the effects on electrophysiologi cal parameters signifying sleep-wakefulness, rectal temperature and brain t emperature were recorded simultaneously. The results suggest that, normally , GABA in the medial preoptic area acts through GABA-A receptor that induce s sleep and prevents an excessive rise in body temperature. However, the re sults do not allow us to comment on the cause and effect relationship, if a ny, between changes in sleep-wakefulness and body temperature. The changes in brain and rectal temperatures showed a positive correlation, however, th e former varied within a narrower range than that of the latter. (C) 2001 E lsevier Science Inc. All rights reserved.