Sonja Vuckovic (1), Milovan Ivanovic (2), Milica Prostran (1,*), Zoran
Todorovic (1), Zorana Ristovic (3), Ivan Micovic (2) and Dusan Beleslin
(1) Department of Clinical Pharmacology, Pharmacology and Toxicology, School of Medicine, University of Belgrade, Dr Subotica 1, P.O. Box 662, 11000 Belgrade, Yugoslavia
(2) Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 158, 11001 Belgrade, Yugoslavia
(3) Institute of Oncology and Radiology, Pasterova 14, 11000 Belgrade, Yugoslavia
(*) To whom correspondence should be addressed.
Abstract: The influence of higher environmental temperature (HET=30+/-1C) on fentanyl-induced behavior was studied in unrestrained rats. Subacute exposure (3 days) of rats to HET significantly (P<0.01) increased the cataleptic effect of fentanyl citrate (0.5 mg/kg), in comparison to the corresponding exposure to normal environmental temperature (NET=22+/-1C). Also, the hyperthermic response of rats to a low dose of fentanyl citrate (0.2 - O.5 mg/kg) was significantly (P<0.01) potentiated, and the hypothermic response to a high dose of fentanyl citrate (1.5 mg/kg) was significantly (P<0.05) attenuated after exposure to HET. Fentanyl-induced hyperexcitability, loss of righting reflex, loss of corneal reflex and analgesia were not significantly affected by HET. This study provides the first evidence on the influence of environmental temperature on drug-induced catalepsy. HET-induced potentiation of the cataleptic response to fentanyl could be the result of an interference with behavioral thermoregulation.
Keywords: Fentanyl, Behavior, Environmental temperature