Mediation of mPFC-LHb pathway in acupuncture inhibition of cocaine psychomotor activity

Abstract

The medial prefrontal cortex (mPFC) and the lateral habenula (LHb) play roles in drug addiction and cognitive functions. Our previous studies have suggested that acupuncture at Shenmen (HT7) points modulates mesolimbic reward system in order to suppress drug-induced addiction behaviours. To explore whether an mPFC-LHb circuit mediates the inhibitory effects of acupuncture on addictive behaviours, we examined the projection from mPFC to LHb, excitation of mPFC neurons during acupuncture stimulation, the effects of optogenetic modulation of mPFC-LHb on HT7 inhibition of cocaine-induced locomotion and the effect of mPFC lesion on HT7 inhibition of nucleus accumbens (NAc) dopamine release. Acupuncture was applied at bilateral HT7 points for 20 s, and locomotor activity was measured in male Sprague-Dawley rats. Although cocaine injection significantly increased locomotor activity, HT7 acupuncture suppressed the cocaine-induced locomotion. The inhibitory effect of HT7 on cocaine-enhanced locomotion was blocked by optogenetic silencing of the mPFC-LHb circuit. In vivo extracellular recordings showed that HT7 acupuncture evoked an increase in the action potentials of mPFC neurons. Optopatch experiment proved glutamatergic projections from mPFC to LHb. HT7 acupuncture suppressed NAc dopamine release following cocaine injection, which was blocked by electrolytic lesion of mPFC. These results suggest the mediation of mPFC-LHb circuit in the inhibitory effects of acupuncture on cocaine psychomotor activity in rats.

Keywords: acupuncture; cocaine; dopamine; glutamatergic projection; lateral habenula; medial prefrontal cortex.