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Neuronal deletion of PDE7A averts morphine-induced behavioral plasticity and impairs downstream AKT signaling
Zizhen Liu1, Axiang Li2,3, Chengyou Zheng1,4
1State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, People's Republic of China.
Background:
Phosphodiesterase 7 A (PDE7A) is a key regulator of cyclic adenosine monophosphate (cAMP) signaling, expressed prominently in brain regions associated with reward and addiction. Despite its strategic localization within reward-related neurocircuitry, the functional contribution of PDE7A to substance use disorders remains poorly defined.
Methods:
We investigated the role of PDE7A in morphine-induced behavioral plasticity using a combination of genetic deletion (Nestin-Cre-mediated neuronal PDE7A knockout) and pharmacological inhibition (BRL-50481) in male C57BL/6J mice (8-10 weeks of age). Behavioral assessments included conditioned place preference (CPP) and locomotor sensitization. Biochemical analyses (ELISA, Western blotting, co-immunoprecipitation) were performed on striatal tissue to assess dopamine levels, cAMP levels, and signaling pathways (AKT/GSK3β, D2R-β-arrestin2 complex).
Results:
Mice with neuronal PDE7A deficiency failed to develop morphine-induced CPP, highlighting a critical requirement for PDE7A in drug-associated memory formation. Consistently, administration of the PDE7 inhibitor BRL-50,481 (10 mg/kg, i.p.) significantly disrupted established drug memories and attenuated morphine-induced behavioral sensitization in wild-type mice. Mechanistically, PDE7A deletion led to a hyper-dopaminergic state in the striatum, characterized by elevated dopamine levels and D1 receptor expression, yet a paradoxical impairment in downstream signaling. Specifically, the behavioral effects of PDE7 inhibition were reversed by the D2 receptor antagonist haloperidol and the AKT inhibitor oridonin, suggesting a reliance on the D2R-AKT-GSK3β axis. Biochemical analyses further revealed that PDE7A deficiency suppresses the AKT/GSK3β signaling pathway, a defect validated through pharmacological manipulation of PDE7, D2R, and AKT.
Conclusion:
Collectively, these findings identify PDE7A as a pivotal modulator of morphine-induced addiction and suggest that targeting the PDE7A-D2R-AKT signaling cascade represents a novel therapeutic strategy for managing substance use disorders.
