Ethanol-Induced Conditioning Place Avoidance Impairs Acute Stimulant Locomotor Effect of Cocaine
Author(s): Carolina Tesone-Coelho, Patricia Varela, JoÃƒÂ£o C Escosteguy-Neto, Luiz E Mello and Jair G Santos-Junior
According to the rewarding properties of ethanol in the place conditioning protocol, outbred Swiss mice may be distinguished in three subgroups: (i) place preference (EtOH Cpp); (ii) place avoidance (EtOH Cpa); (iii) indifference (EtOH Ind). Here we evaluated whether the anxiety-like state and cocaine stimulant locomotor effect are altered in these different phenotypes. No differences were observed in the anxiety-like state before and after conditioning among the different groups. However, animals were generally more anxious-like after the conditioning protocol. EtOH Cpp and EtOH Ind groups (but not EtOH Cpa) increased their locomotor activity after cocaine injection, when compared to Control. We verified an individual variability in outbred Swiss mice regarding the appetitive effects of ethanol. Anxiety-like state apparently is not involved in the expression of these phenotypes. Interestingly, non-aversive hedonic value of ethanol pairing is essential to maintain cocaine-induced hyperlocomotion, since mice aversion to ethanol conditioning impairs acute cocaine-induced stimulating effects.