Attenuated fever response in mice lacking TRPV1

Nonthermal Activation of Transient Receptor Potential Vanilloid-1 Channels in Abdominal Viscera Tonically Inhibits Autonomic Cold-Defense Effectors

“…One potential way to dissociate the analgesic and hyperthermic effects of TRPV1 antagonists is to take advantage of the fact that the hyperthermic effect fades away with repeated administration of an antagonist, whereas the analgesic effect shows no attenuation. Such a dissociation seen for two TRPV1 antagonists (N. R. Gavva (Szelenyi et al, 2004;Iida et al, 2005), but their responses to painful stimuli are suppressed (Caterina et al, 2000;Davis et al, 2000). The present study may serve as a first step for developing alternative strategies for dissociating the hyperthermic and analgesic effects of TRPV1 antagonists.…”

“…A role of the TRPV1 channel in thermal nociception has been confirmed by studies with genetic deletion (Caterina et al, 2000;Davis et al, 2000) or pharmacological blockade (GarciaMartinez et al, 2002;Gavva et al, 2005b) of this channel. The noninvolvement of the TRPV1 channel in the physiological regulation of deep body temperature (T b ) has been accepted based on the fact that TRPV1-deficient mice regulate T b similarly to wild-type mice when exposed to various thermal environments (Szelenyi et al, 2004;Iida et al, 2005). Most recently, the idea that the TRPV1 channel does not play a role in T b regulation has been challenged by the observation that some drugs that block the TRPV1 channel can increase T b of rats, dogs, and monkeys (Swanson et al, 2005;Gavva et al, 2007).…”

Non-Pungent Capsaicin Analogs (Capsinoids) Increase Metabolic Rate and Enhance ThermogenesisviaGastrointestinal TRPV1 in Mice

“…Furthermore, it has been reported that the amplitude of the daily body temperature rhythm of TRPV1 KO mice was higher than that of WT mice, although another study has indicated that TRPV1 KO mice exhibited no obvious difference in daily body temperature rhythm. 32,33) It therefore seems that the daily energy metabolism rhythm may also be different between TRPV1 KO and WT mice. However, the present experiment is considered sufficient to compare the effects on metabolic rate of capsinoids and capsaicin between WT and TRPV1 KO mice, because the respiratory quotients after 3 h of fasting were almost the same between the two strains.…”

The Transient Receptor Potential Vanilloid-1 Channel in Thermoregulation: A Thermosensor It Is Not

“…Pharmacological Desensitization versus Genetic Ablation. In contrast to the impaired thermoregulation of desensitized animals, genetic ablation of TRPV1 does not cause gross changes in T b regulation in response to either heat or cold challenges (Szelényi et al, 2004;Iida et al, 2005). There is, however, a report showing that Trpv1 KO mice can defend their deep T b against severe environmental cooling better than their wild-type coun- Szikszay et al (1982).…”