Posterior hypothalamic activity and cortical control during the PGE1 hyperthermia.

The firing rate of the posterior hypothalamic neurones and interscapular brown adipose tissue and colonic temperatures (TIBAT and TC) were monitored in 36 urethane-anaesthetized male Sprague-Dawley rats before and after an intracerebroventricular (i.c.v.) injection of 400 ng prostaglandin E1 (PGE1) or saline. The i.c.v. injection was preceded by functional decortication in half of each group. The results show an increase of firing rate, TIBAT and TC after PGE1 injection in the rats without decortication. Functional decortication significantly reduced these enhancements. These findings demonstrate that the posterior hypothalamus plays a significant role in the hyperthermia induced by PGE1 and that the cerebral cortex is involved in the control of posterior hypothalamic activity.