N-type calcium channel

N-type calcium channel (CaV2.2) is localized at nerve terminals, including nociceptive fibers, where it initiates neurotransmitter release and supports synaptic transmission in ascending pain pathways^[1]. Mechanistically, nociceptin opioid peptide receptor activation regulates CaV2.2 through G protein-dependent inhibition, reducing calcium currents and changing presynaptic calcium levels and neurotransmission^[2]. In inflammatory pain models, CaV2.2 expression increases after CFA injection in thermal-responsive sensory neurons, and specific CaV2.2 inhibition blocks thermal hyperalgesia and sensory nerve growth involving ERK1/2 signaling^[3]. Compared with related isoforms, exon 37a-containing N-type channel splice variants are enriched in nociceptive neurons, downregulated in neuropathic pain, and specifically required for basal thermal nociception and inflammatory or neuropathic hyperalgesia^[4]. For experimental applications, CaV2.2 blockers such as C2230 stabilize inactivated CaV2.2, inhibit high-frequency channel activity, reduce spinal excitatory neurotransmitter release, and mitigate neuropathic, orofacial, and osteoarthritic pain-like behaviors^[5]. Peptide inhibitors also provide research value, because Eu1.6 inhibits N-type calcium channel currents in dorsal root ganglion neurons and shows analgesic activity in sciatic nerve injury and chronic constriction injury pain models^[6].