Heatstroke induces c-fos expression in the rat hypothalamus

We induced heat stress in urethane-anesthetized rats (the animals were expo sed to an ambient temperature at 42 degrees C), and monitored their colon t emperature, mean arterial pressure and local cerebral blood flow. Rats 0, 2 0, 40 or 80 min after heat stress were sacrificed for determination of c-fo s mRNA and protein expression in the paraventricular nucleus (PVN), supraop tic nucleus (SON) and preoptic nucleus (PON). The heatstroke, which appears as profound decreases in both mean arterial pressure and local cerebral bl ood flow and increases in colon temperature, is produced 80 min after heat stress. We show the c-fos mRNA and protein is strongly induced in all these nuclei of rat hypothalamus after the onset of heatstroke. We conclude that c-fos expression in the hypothalamus during rat heatstroke is associated w ith hyperthermia, arterial hypotension and cerebral ischemia. (C) 1999 Else vier Science Ireland Ltd. All rights reserved.