text: This is the site you want\n\nThe effect of 48 hours of water deprivation on the colonic temperature response to intrahypothalamic injection of prostaglandin E1 (PGE1) was investigated in adult male rats. Water deprivation did not alter colonic temperature of rats at a neutral ambient temperature. Administration of PGE1 at doses of 50, 200 and 400 ng gave rise to a short latency dose dependent hyperthermia in both control and water deprived rats. Water deprived rats had significantly greater increases in colonic temperature following the two higher doses of PGE1. Control rats and water deprived rats exposed to the cold (5 degrees C) had decreases in colonic temperature which were not significantly different. Water deprivation, which should increase the plasma levels of the putative endogenous antipyretic vasopressin, does not attenuate PGE1 hyperthermia but has a slight enhancing effect. Following food deprivation for 48 hours rats had a slight but significantly greater increase in colonic temperature following intrahypothalamic injection of 200 ng PGE1. Thus the water deprivation induced change in responsiveness to PGE1 may be due to the decrease in food intake which accompanies water deprivation. The mechanism by which rats exhibit an enhanced febrile response to PGE1 administration following food or water deprivation is not yet known.