Trpv1, also known as the transient receptor potential vanilloid 1 or capsaicin receptor, is a non-selective cation channel. It functions as a sensor for noxious heat (above ~42 °C), and can be activated by endogenous lipid-derived molecules, acidic solutions (pH < 6.5), pungent chemicals like capsaicin, and toxins. Structurally, it has six transmembrane domains with intracellular N-and C-termini. TRPV1 is expressed in a subset of peripheral sensory neurons involved in pain sensation and at other neuronal and non-neuronal sites in the mammalian body. It is implicated in multiple biological processes such as pain, thermoregulation, osmoregulation, cough, and overactive bladder [1].

Studies with Trpv1 (- / -) mice have suggested its role in various physiological and disease-related processes. For example, it has been associated with pain, thermoregulation, and osmoregulation, as well as in cough and overactive bladder [1]. In cutaneous studies, activation of TRPV1 + neurons was sufficient to elicit a local type 17 immune response that augmented host defense to certain pathogens, and could also do so at adjacent, unstimulated skin through a nerve reflex arc [2]. In the context of bone cancer pain, TRPV1 in dorsal root ganglion has been considered to be involved, with complex regulatory mechanisms including inflammatory mediators and endogenous formaldehyde [3].

In conclusion, Trpv1 is a crucial channel involved in sensing noxious stimuli and plays significant roles in pain, thermoregulation, immunity, and some disease conditions like bone cancer pain. Gene-knockout mouse models have been instrumental in revealing these functions, providing valuable insights into the underlying mechanisms and potential therapeutic targets for related diseases.