The effect of chroni̇c ni̇coti̇ne on the expressi̇on of cart mrnaand pepti̇des in the mesocorti̇coli̇mbi̇c system of the rat brai̇n

Cocaine and amphetamine regulated transcript (CART) mRNA and peptides are intensely expressed in the brain regions comprising mesocorticolimbic system. In addition to anatomical observations, there is also physiological evidence linking CART peptides with mesocorticolimbic system. Studies suggest that CART peptides have a role in drug abuse. The initiation of nicotine addiction involves mesocorticolimbic system. The aim of the study is to examine the effects of nicotine on CART expression in the mesocorticolimbic system. Three different doses of nicotine (0.2, 0.4, 0.6 mg/kg free base) were injected subcutaneously for 5 days and on the 6. day rats were decapited following a challange dose. CART mRNA and peptide levels in medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum (DST), amygdala (AMG), lateral hipotalamic area (LHA), ventral tegmental area (VTA) were measured by quantitative real-time PCR (qPCR) and Western Blot analysis. In the mPFC, 0.4 and 0.6 mg/kg nicotine, in the VTA 0.2 and 0.6 mg/kg nicotine decreased CART peptide levels. In the AMG 0.4 and 0.6 mg/kg nicotine increased CART mRNA levels . Nicotine did not affect CART peptide and mRNA expression in the NAc, DST, LHA. Nicotine regulate CART expression in the mPFC, VTA and AMG which are located in the mesocorticolimbic system.