Peripheral ablation of type III adenylyl cyclase induces hyperalgesia and eliminates KOR-mediated analgesia in mice
Wen-Wen Zhang, Hong Cao, Yang Li, Xian-Jun Fu, Yu-Qiu Zhang
Wen-Wen Zhang, Hong Cao, Yang Li, Xian-Jun Fu, Yu-Qiu Zhang
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Research Article Neuroscience

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

Abstract

Ca2+/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 Gαi/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.

Authors

Wen-Wen Zhang, Hong Cao, Yang Li, Xian-Jun Fu, Yu-Qiu Zhang

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Figure 5

The levels of cAMP concentration and expression of AC1 and AC8 in the DRG.

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The levels of cAMP concentration and expression of AC1 and AC8 in the DR...
(A) cAMP concentration was markedly increased in AC3-CKO DRGs. **P < 0.01; 2-tailed Student’s t test; n = 6 Ctrl and 5 CKO (mice). (B and C) RNAscope ISH showing the expression levels of AC3, AC1, and AC8 mRNA in DRG neurons. Scale bar: 50 μm. (D and E) RNAscope ISH showing a robustly increased expression level of AC1 mRNA in AC3-CKO DRGs. ****P < 0.0001; 2-tailed Student’s t test; n = 12 Ctrl and 12 CKO (DRG slices from 4 mice). (F) Western blot analysis showing the increased AC1 protein level in AC3-CKO DRGs. Data are represented as fold changes compared with the intensity of GAPDH. *P < 0.05; 2-tailed Student’s t test; n = 4 Ctrl and 4 CKO (mice). (G and H) RNAscope ISH showing an increased expression level of AC8 mRNA in AC3-CKO DRGs. *P < 0.05; 2-tailed Student’s t test; n = 12 Ctrl and 12 CKO (DRG slices from 4 mice). (I) Lumbar puncture of AC1 antagonist NB001 (2.5 μg) significantly blocked AC3-CKO–induced upregulation of cAMP concentration in the DRGs. *P < 0.05; 2-tailed Student’s t test; n = 6 Ctrl and 6 CKO (mice). (J and K) NB001 (2.5 μg) significantly reversed AC3-CKO–induced the mechanical allodynia (J) and thermal hyperalgesia (K). *P < 0.05, **P < 0.01; 2-way RM ANOVA followed by Bonferroni’s test; n = 8 Ctrl and 8 CKO (mice).