[Frontiers in Bioscience S3, 822-845, June 1, 2011]

Effects of opioids, cannabinoids, and vanilloids on body temperature

Scott M. Rawls1,2, Khalid Benamar2

1Department of Pharmaceutical Sciences, Temple University Health Sciences Center, 2Center for Substance Abuse Research, Temple University, Philadelphia, PA 19140

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Opioid effects on body temperature
3.1. Kappa opioid receptors and body temperature
3.2. Delta opioid receptors and body temperature
3.3. Mu opioid receptors and body temperature
4. Sigma sites and body temperature
5.Cannabinoids and body temperature
5.1. Cannabinoid ligands and receptors
5.2. Cannabinoid agonists produce hypothermia
5.3. Endogenous cannabinoid and vanilloid effects on body temperature
5.4. Cannabinoid interactions and body temperature
6. Conclusions
7. Acknowledgements
8. References

1. ABSTRACT

Cannabinoid and opioid drugs produce marked changes in body temperature. Recent findings have extended our knowledge about the thermoregulatory effects of cannabinoids and opioids, particularly as related to delta opioid receptors, endogenous systems, and transient receptor potential (TRP) channels. Although delta opioid receptors were originally thought to play only a minor role in thermoregulation compared to mu and kappa opioid receptors, their activation has been shown to produce hypothermia in multiple species. Endogenous opioids and cannabinoids also regulate body temperature. Mu and kappa opioid receptors are thought to be in tonic balance, with mu and kappa receptor activation producing hyperthermia and hypothermia, respectively. A particularly intense research focus is TRP channels, where TRPV1 channel activation produces hypothermia whereas TRPA1 and TRPM8 channel activation causes hyperthermia. The marked hyperthermia produced by TRPV1 channel antagonists suggests these warm channels tonically control body temperature. A better understanding of the roles of cannabinoid, opioid, and TRP systems in thermoregulation may have broad clinical implications and provide insights into interactions among neurotransmitter systems involved in thermoregulation.