CCK2R regulates METH-induced CPP acquisition within VTA-BLA-BNST circuit in male mice

Methamphetamine (METH) addiction is a severe public health issue driven by maladaptive neuroplasticity in reward circuits. Cholecystokinin (CCK), a neuropeptide abundant in the ventral tegmental area (VTA), modulates addiction-related behaviors through its receptors (CCK1R/CCK2R), yet its role in METH-induced conditioned place preference (CPP) remains unclear. Here, we investigated the involvement of CCK2R in the VTA→basolateral amygdala (BLA)→bed nucleus of the stria terminalis (BNST) circuit during METH CPP acquisition. Using CCK^flox/flox male mice, we selectively knocked out CCK in VTA dopaminergic neurons, which attenuated METH CPP and reduced neuronal excitability. Optogenetic and chemogenetic manipulations revealed that METH enhanced CCK release from VTA → BLA projections, while CCK2R knockout in BLA glutamatergic neurons abolished CPP and normalized synaptic plasticity. Further, chemogenetic inhibition of the VTA → BLA → BNST pathway disrupted METH reward encoding, and CCK2R deletion in this circuit reversed METH-induced increases in AMPA/NMDA ratios, paired-pulse facilitation, and dendritic spine density in BNST. Electrophysiological and Golgi staining analyses confirmed CCK2R's critical role in regulating neuronal excitability and structural plasticity. Our findings demonstrate that CCK2R in the VTA^DA→BLA^Glu → BNST circuit is essential for METH CPP acquisition, highlighting its potential as a therapeutic target for addiction.