Microinjection of CART peptide into the nucleus accumbens medial shell attenuates methamphetamine-induced anxiety-like behaviors via restoration of GABAB receptor membrane expression

Methamphetamine (METH) abuse often leads to anxiety-like behaviors, and the cocaine- and amphetamine-regulated transcript (CART) peptide, which is abundant in the nucleus accumbens (NAc), has shown promise in mitigating behavioral effects of psychostimulants. However, the role of CART peptide in the NAc medial shell in METH-induced anxiety remains poorly understood. In this study, following METH withdrawal and reinstatement, rats exhibited significant anxiety-like behaviors. Immunofluorescence analysis revealed a substantial increase in the proportion of c-Fos⁺/NeuN⁺ and CART⁺/NeuN⁺ cells within the NAc medial shell. Western blot and immunofluorescence consistently showed upregulated CART peptide expression and reduced gamma aminobutyric acid type B receptor (GABABR) levels in this region. Further immunofluorescence staining confirmed decreased GABABR expression specifically within CART-positive neurons. Microinjection of CART peptide into the NAc medial shell attenuated METH-induced anxiety-like behaviors, normalized the hyperactivity of neurons, and restored GABABR expression to baseline levels. Molecular docking and co-immunoprecipitation suggest a potential interaction between CART and GABABR. These protective effects were abolished by the GABABR antagonist CGP55845. Overall, our findings demonstrate that CART peptide delivery into the NAc medial shell alleviates METH-induced anxiety-like behaviors by rescuing GABABR membrane expression, highlighting a potential therapeutic pathway for METH-related anxiety.