Capsaicin changes the pattern of brain rhythms in sleeping rat

The heat and capsaicin sensor TRPV1 ion channels were originally discovered from sensory neurons in dorsal root ganglia, and later found in many other tissues and organs. However, whether TRPV1 channels are present in brain regions other than hypothalamus has been a subject of debate. Here we addressed this issue with an unbiased functional test, by recording electroencephalogram (EEG) to examine whether capsaicin injection directly into the rat lateral ventricle could alter brain electrical activity. We observed that EEG during the sleep stage could be significantly perturbed by capsaicin, whereas EEG during the awake stage did not show a detectable change. Our results are consistent with TRPV1 expression in selective brain regions whose activities are dominative during the sleep stage. Support or Funding Information This work is supported by funding from the Qingdao Postdoctoral Research Project to YHT.