Amelioratory Effects Of Testosterone Propionate On The Reduced Activity Of Mitochondrial Complex ?

The brain is a highly differentiated organ with high-energy requirements.The main form of energy for brain is adenosine triphosphate(ATP)molecules produced in mitochondria through oxidative phosphorylation.Mitochondrial complex ? consists of several enzymes,which is essential in producing ATP.The decline of the activity of mitochondrial complex ? may result in the reduction of the ATP production,leading to aging and aging-related neurodegeneration.Taking into account the decline of testosterone level and the mitochondrial dysfunction in aged males,testosterone supplement might ameliorate the defect of mitochondrial energy in aging process.Therefore,the effects of testosterone propionate(TP)on the the activity of mitochondrial complex ? in aged male rats and gonadectomized adult male rats were investigated in the present study,in order to analyze the role of androgen in mitochondrial energy metabolism in brain.Part1 Amelioratory effects of testosterone propionate on the reducedactivity of mitochondrial complex ? in hippocampus andsubstantia nigra of aged male ratsObjective: To observe the effects of testosterone replacement on the activity of mitochondrial complex ? in aged male rats.Methods:1.Male SD rats fell into 6-month group(6Mon),24-month group(24Mon)and 24-month-TP group(24Mon-TP).2.The hippocampus(Hip)and the substantia nigra(SN)were observed.3.Spectrophotometry was used to detect the ATP level and the enzymatic activity of mitochondrial complex ?4.The DNA sequences of mtDNA-encoded ATP6 and ATP8 were analysed by single nucleotide polymorphism.5.Quantitative real-time PCR(qPCR)was used to analyze the expression of ATP6 and ATP8.Results:1.Compared with the 6Mon rats,the activity of complex ? in Hip and SN of 24 Mon rats were reduced by 28.28% and 18.42%(P<0.01),and the ATP level in Hip and SN were reduced by 23.80% and 26.65%(P<0.01),respectively.In the 24Mon-TP rats,compared with the 24 Mon rats,the activity of complex ? in Hip and SN were increased by 35.82% and 15.52%(P<0.01),and the ATP level in Hip and SN were increased by 28.26% and 31.39%(P<0.01)respectively,and reached the levels in 6Mon rats.2.No mutation site was showed in the DNA sequences of ATP6 and ATP8 in Hip or SN of rats.3.In the 24 Mon rats,compared with the 6Mon rats,the mRNA levels of ATP6 and ATP8 were decreased by 63% and 64% in Hip and by 63% and 71% in SN(P<0.01)respectively.In the 24Mon-TP rats,compared with the 24 Mon rats,the supplement of TP(1.0 mg/kg)increased the mRNA levels of ATP6 and ATP8 by 161.53% and 86.84% in Hip and by 130.77% and 183.87% in SN(P<0.01)respectively,and reached the levels in 6Mon rats.Summary:1.TP supplement enhances the activity of complex ? in Hip and SN of aged male rats.2.TP administration increases the ATP level in Hip and SN of aged male rats.3.TP treatment increases the expression of ATP6 and ATP8 in Hip and SN of aged male rats.Part 2 Region-specific amelioratory effects of testosterone propionate onthe reduced activity of mitochondrial complex ? in the brain ofgonadectomize male ratsObjective: To observe whether androgen is involved in regulating the activity of mitochondrial complex ? in rat brain.Methods:1.Adult male SD rats were divided into sham-operated group(Sham),gonadectomized group(GDX)and gonadectomized with TP administration group(GDX-TP).2.The hippocampus(Hip)and the substantia nigra(SN)were observed.3.The ATP level and the activity of mitochondrial complex ? in rat Hipand SN were observed by spectrophotometry methods.4.qPCR and Western blot were used to analyze the expression of mtDNA-encoded ATP6 and ATP8 in Hip and SN of rats.Results:1.The activity of complex ? in SN was significantly lower by 13.11%(P<0.05)in the GDX rats than in the Sham rats.After TP supplementation,the activity of complex ? in SN was significantly increased by 15.91%(P<0.05),in the GDX-TP rats compared with the GDX rats,and reached the level in Sham rats.No significant difference was found among the three groups in Hip.2.In the GDX rats,compared with the Sham rats,the mRNA levels of ATP6 and ATP8 in SN were decreased by 56.85% and 35.29%(P<0.01),and the protein levels of ATP6 and ATP8 in SN were decreased by 63.49%(P<0.01)and 64.70%(P<0.05)respectively.In the GDX-TP rats,compared with the GDX rats,the supplement of TP(1.0 mg/kg)increased the ATP6 and ATP8 by 168.18%(P<0.01)and 68.18%(P<0.05)at mRNA levels,and by 104.35%(P<0.05)and 60%(P<0.01)at protein levels in SN respectively,and reached the level in Sham rats.No significant difference was found among the three groups in Hip.3.There was no significant difference of ATP level among the three groups either in Hip or in SN.Summary:1.Gonadectomy to adult male rats decreases the activity of complex ? and the expression of ATP6 and ATP8 at mRNA and protein level in SN.2.Replacement of TP reverses the activity of complex ? and the expression of ATP6 and ATP8 at mRNA and protein level in SN of male gonadectomized rats.3.Different from Hip,SN shows androgen-dependence in regulating the activity of complex ? and the expression of ATP6 and ATP8.Conclusion:1.TP supplement enhances the activity of mitochondrial complex ? and the expression of ATP6 and ATP8 in aged male rats.2.The regulation of androgen on the activity of mitochondrial complex ? as well as the expression ATP6 and ATP8 shows region-specific effects and SN is androgen-dependent.