ABSTRACT
Intracerebroventricular injection of neokyotorphin (NKT) (0.5-2.0 micrograms) caused a dose-related increase in body temperature (Tb) of rats maintained at 28 degrees C. The change in Tb of the rat induced by the optimal dose of NKT (1 microgram) was attenuated when the rat was exposed to 18 degrees C. At both ambient temperatures, heat production was not affected but heat loss was significantly reduced at 28 degrees C in rats receiving 1 microgram NKT. Pretreatment with naloxone (5 mg/kg, IP) significantly reduced the hyperthermic effect induced by NKT (1 microgram). These results suggest that NKT can affect the prevailing thermoregulatory heat loss activities and this effect may be mediated through stimulated release of endogenous opioids.
Subject(s)
Body Temperature Regulation/drug effects , Endorphins/pharmacology , Amino Acid Sequence , Animals , Body Temperature/drug effects , Dose-Response Relationship, Drug , Injections, Intraventricular , Male , Molecular Sequence Data , Rats , Rats, Inbred Strains , Stereotaxic TechniquesABSTRACT
Seasonal changes in the amount of DSIP-like material have been measured in extracts from the brain of Citellus suslicus. 2. Analysis of extracts from the brain of deeply sleeping ground squirrels shows that the level of enkephalin-like material reliably increases while that of ACTH-like material decreases. 3. It is concluded that the opiate brain activation system is among the factors participating in the induction of hibernation in ground squirrels.
