Peripheral ablation of type III adenylyl cyclase induces hyperalgesia and eliminates KOR-mediated analgesia in mice

Ca(2+)/calmodulin-stimulated group I adenylyl cyclase (AC) isoforms AC1 and AC8 have been involved in nociceptive processing and morphine responses. However, whether AC3, another member of group I ACs, is involved in nociceptive transmission and regulates opioid receptor signaling remains elusive. Here, we report that conditional KO of AC3 (AC3 CKO) in L3 and L4 DRGs robustly facilitated the mouse nociceptive responses, decreased voltage-gated potassium (Kv) channel currents, and increased neuronal excitability. Furthermore, we report AC3 CKO eliminated the analgesic effect of κ-opioid receptor (KOR) agonist and its inhibition on Kv channel by classical Gα(i/o) signaling or nonclassical direct interaction of KOR and AC3 proteins. Interestingly, significantly upregulated AC1 level and cAMP concentration were detected in AC3-deficient DRGs. Inhibition of AC1 completely reversed cAMP upregulation, neuronal excitability enhancement, and nociceptive behavioral hypersensitivity in AC3-CKO mice. Our findings suggest a crucial role of peripheral AC3 in nociceptive modulation and KOR opioid analgesia.