TRPV1 and Parkinson disease: In addition, its co-expression with 5-HT3A receptors in the rat dorsal root ganglion (DRG) and ability of TRPV1 blockers to inhibit the pain induced by 5-HT3A receptor agonists makes it a useful target for pain modulation in PD (Zeitz et al., 2002; Li et al., 2020).