Attenuated pain responses in mice lacking CaV3.2 T-type channels

Although T-type Ca²⁺ channels are implicated in nociception, the function of specific subtypes has not been well defined. Here, we compared pain susceptibility in mice lacking Ca_V3.2 subtype of T-type Ca ²⁺ channels (Ca_V3.2^-/-) with wild-type littermates in various behavioral models of pain to explore the roles of Ca _V3.2 in the processing of noxious stimuli in vivo. In acute mechanical, thermal and chemical pain tests, Ca_V3.2^-/- mice showed decreased pain responses compared to wild-type mice. Ca _V3.2^-/- mice also displayed attenuated pain responses to tonic noxious stimuli such as intraperitoneal injections of irritant agents and intradermal injections of formalin. In spinal nerve ligation-induced neuropathic pain, however, behavioral responses of Ca_V3.2^-/- mice were not different from those of wild-type mice. The present study reveals that the Ca_V3.2 subtype of T-type Ca²⁺ channels are important in the peripheral processing of noxious signals, regardless of modality, duration or affected tissue type.