Effect of capsaicin on thermoregulation: an update with new aspects.
Level 5 - mechanism / opinion, no new human data
Narrative review of animal models and mechanistic neurophysiological studies
PubMed 27227029 · doi:10.1080/23328940.2015.1048928
What was done
This narrative review synthesized findings on the thermoregulatory effects of capsaicin and transient receptor potential vanilloid 1 (TRPV1) channels, focusing on rodent models (including capsaicin-pretreated rodents and single or combined TRPV1, TRPV2, and TRPM8 knockout mice) and the roles of peripheral, visceral, and preoptic warm-sensitive neural pathways.
What was found
Systemic capsaicin pretreatment in rodents produced long-lasting (months-long) thermoregulatory disturbances characterized by preserved normal core body temperature in cool environments at subcutaneous doses up to 150 mg/kg, accompanied by an upward shift in activation set points for vasodilation, heat-loss effectors, and thermopreference. Avoidance of warm ambient temperatures (35°C and 40°C) was severely impaired, while cool-temperature preferences remained intact. Combined TRP knockout mice had impaired regulation in warm or cold (4°C) environments despite normal core temperature in thermoneutral settings. In desensitized rats, fever responses were enhanced. No quantitative human effect sizes were reported in the abstract.
Why it matters
The review outlines how TRPV1 receptors in visceral, cutaneous, and preoptic circuits contribute to innocuous warmth sensing, set point adjustments, and heat-loss effector regulation.
Limits
The findings are derived entirely from preclinical rodent and knockout models with no human clinical data reported. As a narrative review, systematic search criteria, exact study counts, and quantitative pooled estimates were not provided.
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