HYPERTHERMIA INDUCES C-FOS EXPRESSION IN THE PREOPTIC AREA

To identify thermosensitive areas of brain, we exposed rats to warm or cool environments and used the expression of the protein Fos as a mar ker of neuronal activity. In hyperthermic, heat-exposed rats, the medi an preoptic nucleus, and the medial and lateral preoptic areas had sig nificantly more Fos immunoreactive neurons than control or cold-expose d animals. These observations add to the physiologic evidence that neu rons of the preoptic area participate in thermoregulation and provide a means to identify the neurotransmitter systems involved.