Effect of Mephedrone (4-methylmethcathinone, ''meow'') on Conditioned Place Preference in Rats

• Main Authors: XIANXIU CHEN, 陳賢修
• Other Authors: Fang-Yang Wu
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/95043182051579434460

碩士 === 中國醫藥大學 === 公共衛生學系碩士班 === 100 === Background / Purpose : Mephedrone, also known as 4-methylmethcathinone (4-MMC), or 4-methylephedrone, is a synthetic stimulant drug of the amphetamine and cathinone classes. Mephedrone is hypothesized to possess abuse liability, abuse of the dangerous street drug has become commonplace in the Europe and United States, which has caused many deaths in Europe. Knowledge about the pharmacology of mephedrone has been obtained primarily from surveys of drug abusers and emergency room visits rather than experimental studies. The present study used the conditioned place preference (CPP) assays to investigate behavioral effects of mephedrone. Methods : An unbiased place conditioning protocol was used to examine the expression of the rewarding effects of mephedrone and related dose response. Male Sprague–Dawley rats were used in this experiment. Rats were divided into five groups, saline controlled group and four different doses of mephedrone treated groups (5 mg/kg, 10 mg/kg, 20 mg/kg, and 40 mg/kg), three rats in each group. The body weight of rats was taken on the beginning of the habituation phase (day 1) and before the mephedrone injection during the conditioning phase. The change of preference was calculated as the difference (in seconds) between the time spent in the drug-paired compartment on the testing day and the time spent in this compartment in the pre-conditioning session. One-way, ANOVA, repeated measures were used to analyse the differences. Results : The mean body weight gain showed no significant difference among the saline controlled group and four mephedrone treated groups. The mean differences of the time spent in the drug-paired compartment of the five groups had no significant differences in day 3 (pre-conditioning) (5 mg/Kg P=1; .10 mg/Kg P=0.674; 20 mg/Kg P=0.876; 40 mg/Kg P=0.975). At day 11 (post-conditioning), there was no significant difference among low doses (5 mg/Kg P=0.893; 10 mg/Kg P=0.804), while with significant difference among high doses (20 mg/Kg P=0.012; 40 mg/Kg P=0.001) when they were compared with the saline controlled group. Conclusion : Our results indicated that previous repeated mephedrone exposure enhanced subsequent CPP drug reward behavior. Future studies that various factors such as dose, dosing frequency, and forced abstinence interval are needed to further assess the motor activating properties of mephedrone. Furthermore, we will examine phosphorylation levels of various relevant signaling molecules in the brain regions implicated in addictive behaviors after acute and repeated mephedrone administration.