Effect of Amphetamine on murine double minute 2 in frontal cortex of mice

Abstract

Objective To determine the expression of murine double minute 2 (Mdm2) in the frontal cortex of mice after intervention with Amphetamine. Methods Male C57BL/6 mice were randomly divided into the normal control group (n=10) , normal saline group (n=10) and Amphetamine group (n=40) . The Amphetamine group was divided into 1, 7, 14 and 28 d subgroups, and was intraperitoneally injected with 2 mg·kg-1·d-1 Amphetamine, 1 time/d. The normal saline group was injected with equal volume of normal saline, and the normal control group received no treatment. The autonomous behavior activities were tested during establishing the models. Immunohistochemistry and Western blotting were used to examine the Mdm2 expression in frontal cortex of the mice. Results The total moving distance, average speed, maximum speed, fast moving time/total time ratio in the 7, 14 and 28 d Amphetamine subgroups were significantly increased compared with those in the normal control group and normal saline group, and there were statistically significant differences (P<0.05) . Immumohistochemistry showed that the grey values of Mdm2-positive inummoreactive products in the Amphetamine group were significantly lower than those in the normal control group and normal saline group, and there were statistically significant differences (P<0.05) . The grey values of the positive inummoreactive products in the Amphetamine 14 d subgroup was significantly decreased compared with those in the Amphetamine 1 d subgroup, and there were statistically significant differences[1 d (213.31±6.78) , 14 d (192.82±7.90) , P<0.05]. The findings of Western blotting showed that Mdm2 protein expression in the frontal cortex was elevated in the Amphetamine group compared with that in the other two groups. Conclusion Amphetamine can significantly increase Mdm2 expression in the frontal cortex of mice. Key words: Amphetamines; Prefrontal cortex; Mice; Double minute 2