Circuit-Wide Gene Network Analysis Reveals Sex-Specific Roles for Phosphodiesterase 1b in Cocaine Addiction.

Cocaine use disorder is a significant public health issue without an effective pharmacological treatment. Successful treatments are hindered in part by an incomplete understanding of the molecular mechanisms that underlie long-lasting maladaptive plasticity and addiction-like behaviors. Here, we leverage a large RNA sequencing dataset to generate gene coexpression networks across six interconnected regions of the brain's reward circuitry from mice that underwent saline or cocaine self-administration. We identify phosphodiesterase 1b (Pde1b), a Ca2+/calmodulin-dependent enzyme that increases cAMP and cGMP hydrolysis, as a central hub gene within a nucleus accumbens (NAc) gene module that was bioinformatically associated with addiction-like behavior. Chronic cocaine exposure increases Pde1b expression in NAc D2 medium spiny neurons (MSNs) in male but not female mice. Viral-mediated Pde1b overexpression in NAc reduces cocaine self-administration in female rats but increases seeking in both sexes. In female mice, overexpressing Pde1b in D1 MSNs attenuates the locomotor response to cocaine, with the opposite effect in D2 MSNs. Overexpressing Pde1b in D1/D2 MSNs had no effect on the locomotor response to cocaine in male mice. At the electrophysiological level, Pde1b overexpression reduces sEPSC frequency in D1 MSNs and regulates the excitability of NAc MSNs. Lastly, Pde1b overexpression significantly reduced the number of differentially expressed genes (DEGs) in NAc following chronic cocaine, with discordant effects on gene transcription between sexes. Together, we identify novel gene modules across the brain's reward circuitry associated with addiction-like behavior and explore the role of Pde1b in regulating the molecular, cellular, and behavioral responses to cocaine.

CREB Binding at the Zfp189 Promoter Within Medium Spiny Neuron Subtypes Differentially Regulates Behavioral and Physiological Adaptations Over the Course of Cocaine Use.

BACKGROUND: Over the course of chronic drug use, brain transcriptional neuroadaptation is thought to contribute to a change in drug use behavior over time. The function of the transcription factor CREB (cAMP response element binding protein) within the nucleus accumbens (NAc) has been well documented in opposing the rewarding properties of many classes of drugs, yet the gene targets through which CREB causally manifests these lasting neuroadaptations remain unknown. Here, we identify zinc finger protein 189 (Zfp189) as a CREB target gene that is transcriptionally responsive to acute and chronic cocaine use within the NAc of mice. METHODS: To investigate the role of the CREB-Zfp189 interaction in cocaine use, we virally delivered modified clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9 constructs capable of selectively localizing CREB to the Zfp189 gene promoter in the NAc of mice. RESULTS: We observed that CREB binding to the Zfp189 promoter increased Zfp189 expression and diminished the reinforcing responses to cocaine. Furthermore, we showed that NAc Zfp189 expression increased within D1 medium spiny neurons in response to acute cocaine but increased in both D1- and D2-expressing medium spiny neurons in response to chronic cocaine. CREB-mediated induction of Zfp189 potentiated electrophysiological activity of D1- and D2-expressing medium spiny neurons, recapitulating the known effect of CREB on these neurons. Finally, targeting CREB to the Zfp189 promoter within NAc Drd2-expressing neurons, but not Drd1-expressing neurons, was sufficient to diminish cocaine-conditioned behaviors. CONCLUSIONS: Together, these findings point to the CREB-Zfp189 interaction within the NAc Drd2+ neurons as a molecular signature of chronic cocaine use that is causal in counteracting the reinforcing effects of cocaine.