Binge alcohol drinking alters the differential control of cholinergic interneurons over nucleus accumbens D1 and D2 medium spiny neurons

Abstract Background Ventral striatal cholinergic interneurons (ChIs) play a central role in basal ganglia function by regulating associative learning and reward processing. In the nucleus accumbens (NAc), ChIs regulate glutamatergic, dopaminergic, and GABAergic neurotransmission. However, it is unclear how ChIs orchestrate the control of these neurotransmitters to determine the excitability of medium spiny neurons (MSNs) expressing either dopamine D1 or D2 receptors. Additionally, the effects of binge alcohol drinking on ChIs-mediated modulation of glutamatergic synaptic transmission in NAc MSNs are also undefined. Methods We optogenetically stimulated ChIs while recording evoked and spontaneous excitatory postsynaptic currents (sEPSCs) in D1- and D2-MSN of ChAT.ChR2.eYFPxDrd1.tdtomato mice. To determine the effect of ChIs on mouse behavior and alcohol consumption, we implanted ChAT.ChR2.eYFP mice with fiber optic cannulas and stimulated ChIs while mice were allowed to drink 20% alcohol using the binge alcohol drinking- in-the-dark (DID) paradigm. Results We demonstrated that NAc ChIs decrease the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in both D1- and D2-MSNs,. While inhibition of D1-MSNs glutamate release by ChIs depends on dopamine release, that of D2-MSNs results from a direct interactions between ChIs and glutamatergic terminals. Interestingly, after two weeks of binge alcohol drinking, the effect of ChIs stimulation on glutamate release was reversed in D1-MSNs, while its effect on D2-MSNs remained unchanged. Finally, in vivo optogenetic stimulation of NAc ChIs significantly increased alcohol consumption. Conclusions These results identify ChIs as a key target for the regulation of NAc circuitry and as a potential treatment of alcohol addiction.