Mechanism Of Dihydropyrimidinase-related Protein-2 Change In Amphetamine-induced Injury In Mouse Brain

ObjectiveTo explore mechanism of dihydropyrimidinase-related protein-2 (DRP-2) change in amphetamine-induced injury in mouse brain.MethodsSixty male C57BL/6 mice with 5-7 weeks of age were randomly divided into the normal group (n=10), the saline group (n=10)and the amphetamine group(n=40). The amphetamine group was subdivided into four subgroups:1 d,7d,14 d and 28 d groups. Mice were treated with amphetamine 2 mg/kg/d via intraperitoneal inject-ion in the amphetamine group. Mice were treated with the same dose of saline in the saline group, and the control group received no treatment. Autonomous behavior activities were tested during establishing amphetamine model. Total moving distance, Total moving time, average speed, maximum speed, slow moving time, fast moving time/total time, fast moving time, slow moving time/total time were automatic recorded by computer for the evolution of animals'autonomous behavior activities in the study of neruopsychiatric drugs ATS. After animal models were established, mice brains were dissected and stored. Sliver staining (Nauta) method, immunohistochem-istryand Western blotting were used to study the injury of mouse brain induce by amphetamine and the change of AKT/GSK-3β/DRP-2 signal pathway.Results1. Results of mouse's autonomous behavior:Before drug injection, there were no significant differences in the maximum speed, average speed, total moving distance, fast moving time/total time between the amphetamine group and others groups(P>0.05). After drug injection, total moving distance, average speed, fast moving time/total time, Maximum speed in the amphetamine groups for 7-28 days were increased as compared with the normal group and saline group (P<0.05). There was no difference in slow moving time/total time between the amphetamine group and others groups (P>0.05). 2. Results of the degenerated nerve fibers and their terminals:Using Nauta staining method, the black degenerated nerve fibers in striatum were observed in the amphetamine groups for 14-28 days. Degenerated nerve fibers were not observed in the normal group and saline group.3. Changes of dopaminergic neurons and fibers:there were less dopaminergic neurons in substantia nigra compact part in amphetamine groups for 28 d compared with those in the other groups (P＜0.05). The density of dopaminergic fibers of globus pallidus part in the amphetamine group for 1 day and saline group were increased as compared with that in the normal group (P＜0.05). But the density of dopaminergic fibers of globus pallidus part in amphetamine groups for 14-28 days was lesser than that in the normal group and saline group (P<0.05).4. Changes of DRP-2 and AKT/GSK-3βsignaling pathway:The expression of DRP-2 in striatum was significantly decreased in the amphetamine group compared with the normal and saline groups (P＜0.05).The expression of P-DRP-2 of striatum had no significant change in amphetamine group for 1 day compared with the normal and saline groups (P>0.05). However, the expression of P-DRP-2 in the amphetamine groups for 7-14 days and saline group was increased compared with the normal group (P＜0.05). The expression of AKT of striatum in the amphetamine groups for 28 days was decreased than that in the normal group and saline groups (P<0.05). GSK-3βexpression of striatum in the amphetamine groups for 7-28 days was increased as compared with that in the normal group(P<0.05).Conclusion1.Amphetamine may increase the mouse's autonomous behavior activity.2. Long-time use of amphetamine may cause degeneration of nerve fibers in the mouse striatum.3. Long-time use of amphetamine may cause the decrease of dopaminergic neurons in substantia nigra compact part and dopaminergic fibers in globus pallidus4. Administration of amphetamine may increase expression of phosphorylation of DRP-2 and decrease expression of DRP-2 in striatum, and its mechanism was closely related with the inhibition of AKT-GSK-3βsignal pathway.