| Objective:1.To investigate the neuroprotective effects of a novel dual agonist(DA-JC1) in the1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP) mouse model of Parkinson’s disease.2.To explore its neuroprotection mechanisim of the novel dual agonist(DA-JC1) on Parkinson’s disease model.Methods:Male C57BL/6 mice(20–22g) were divided into four groups with 10 in each. were studied in the following experimental groups:(A)Control(saline 0.2ml/day i.p.);(B)DA-JC1(50 nmol/kg/day i.p.);(C) MPTP(20 mg/kg/day i.p.);(D) MPTP(20 mg/kg/day i.p.)+ DA-JC1(50 nmol/kg/day i.p.);The part II add the group:(E) MPTP(20 mg/kg i.p.) +DA-JC1(50 nmol/kg/day i.p.)+LY294002(0.6 mg/kg iv).DA-JC1 treatment was given30 min after the MPTP administration. In group E,LY294002 treatment was given 30 min after the DA-JC1 injection. Animals in groups B–E received DA-JC1 and/or MPTP daily for 7 consecutive days,On the eighth day, took the behavioral tests(Rotarod performance),then we collected the brain tissues and analysed the expression levels of TH,BDNF, Bcl-2, Bax using immunohistochemical method, and the expression of Bax, Bcl-2,Akt, p-Akt using western blot method.Results:1.Behavioral Tests1.1.In the Rotarod performance,animals that had received treatment with MPTP showed significantly impairments on the rotating rod for 180 seconds compared to the control animals that had received saline,the mean time is 41.20±26.21s(P<0.001).DA-JC1 partially reversed from MPTP-induced impairments,the mean is 63.40±25.83.1.2.In the Traction Test,MPTP-induced muscle strength impairments in the traction Test,Treatment of DA-JC1 significantly reversed the impairments by MPTP-induced(P <0.05).DA-JC1 was able to partially reverse some of the impairments of MPTP.2.Immunohistochemistry2.1.There were significant reductions in the number of TH-positive cells in the substantia nigra for the MPTP group compared with the control group(36.83±4.62,P<0.001). With the treatment of DA-JC1, the number of TH-positive cells was significantly higher than those in MPTP treated mice(48.50±5.32, P<0.05).2.2.There were reduced numbers of BDNF-positive cells in the MPTP group compared with the control group(in the substantia nigra :36.83±4.62, P<0.001 and striatum:16.00±3.16, P<0.001). With the treatment of DA-JC1, the number of BDNF-positive cells was significantly higher than those in MPTP treated mice(in the substantia nigra :48.50±5.32, P<0.01 and striatum:24.33±2.42,P<0.001).2.3.The number of Bcl-2-positive cells for the MPTP group was reduced compared with the control group(P<0.001), and there was an increase in the number of Bax-positive cells for the MPTP group compared with the control group(P<0.001). After treatment with DA-JC1, the number of Bcl-2-positive cells was significantly higher than those in MPTP treated mice(P<0.001) and the number of Bax-positive cells was significantly lower. Also,the Bcl-2-positive cells with the MPTP+DA-JC1+LY294002 treatment were significantly lower in number than those in MPTP+DA-JC1 treated mice and the Bax-positive cell numbers with the MPTP+DA-JC1+LY294002 treatment were significantly higher than those in MPTP+DA-JC1 treated mice.3.Western blot The results show that MPTP treatment decreased the Bcl-2/Bax and phospho-Akt(Ser473)/Akt ratio, compared with the control group(P<0.001). However, the decrease in Bcl-2/Bax and phospho-Akt(Ser473)/Akt ratio was reversed when treated with DA-JC1(P<0.001) compared with the MPTP group. Furthermore, the ratio was lower after treatment with LY294002 compared to the MPTP+DA-JC1 group, but was higher than in the MPTP group.Conclusion:1.DA-JC1 was able to attenuat the loss of nigral TH-positive neurons,increase expression of BDNF, partially reverse some of the impairments of MPTP. Show the protective effects in PD.2.DA-JC1 increase the expression of p-Akt,promote the expression of antiapoptotic proteins the Bcl-2, inhibit the expression of apoptosis proteins Bax, show that DA-JC1-mediated neuroprotection in PD mice involves an Akt-dependent pathway. |
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