The Different Effects Of Two Forms Of Recombinant CART Peptides On The Conditioned Place Preference Induced By Morphine In Mice

Abstract: CART (Cocaine and Amphetamine Regulated Transcript) peptides are neurotransmitters that received much attention due to their effects on modulating psychostimulant drug actions. To Study the effects of CART peptides on the morphine dependence, the mice conditional place preference (CPP) model was used to test the two kinds of recombinant peptides which were the unfold and refold forms of the CART_40-102 peptides (with a 6-HIS tag at the C terminus). The results showed neither the unfold form(10mg/kg) nor the refold form(10mg/kg) of the CART_40-102 peptides could singly induced CPP in mice. CPP induced morphine in mice was not modified significantly by the injection of either form of CART_40-102 peptides (5mg/kg) i.v. two hours before daily morphine training. However, the unfold form of CART_40-102 peptide given after morphine training, had different effects on morphine induced CPP with the refold form .The unfold form (5mg/kg) inhibited morphine induced CPP (p<0.01), while the refold form (both 1mg/kg and 5mg/kg) could significantly promote morphine induced CPP(p<0.05 and p<0.01). These studies showed that two forms of CART peptides had different effects on morphine dependence in mice.