Study On The Toxicity Of Aluminium To Sperm Mitochondria And Its Effect On Sperm Quality

Objective:To study the damage effect of aluminum on sperm mitochondria,and to elucidate the mechanism of aluminum's negative impact on sperm quality,and provide a theoretical basis for the prevention and treatment of male sperm quality reduction caused by aluminum.Methods:According to the median lethal dose(LD₅₀)of aluminum trichloride in drinking water,male rats exposed to aluminum by drinking water.96 male Wistar rats weighing 180-200 g were randomly assigned into 4 groups,24 in each group.The normal group,the low dose group,and the medium dose group high dose group were set.The doses of aluminum trichloride per kilogram of body weight per day in each group of experimental rats were?distilled water,0 mg?,(¹₂₀LD₅₀,64.18 mg),(¹₁₀LD_50,128.36 mg)and(₅¹LD₅₀,256.72 mg),the time for chronic aluminum exposure was set at 16 weeks.After 16 weeks,the testis tissue of the rat,the head tissue of the epididymis,and the sperm of the epididymis were obtained.For testicular tissue,SOD activity and MDA content were measured.For the head tissue of the epididymis,transmission electron microscopy was performed to observe the sperm mitochondria.For the sperm of the epididymis,sperm quality analysis were performed,and flow cytometry was used to detect sperm mitochondrial membrane potential and mitochondrial membrane permeability transition pore state.In addition,nested PCR technology was used to detect sperm mitochondrial DNA integrity,and real-time fluorescence quantification techniques were used to detect the relative copy number of sperm mitochondrial DNA.Results:The activity of SOD in the testis of rats exposed to aluminum was significantly lower than that of the control group?P<0.01?,and the activity of SOD was negatively correlated with the dose of aluminum?r_s=-0.861,P<0.001?.The MDA content of testis tissue was significantly higher than that of the control group?P<0.01?,and the MDA content was positively correlated with the dose of aluminum?r_s=0.459,P<0.001?.The results of sperm quality test showed that the sperm density?P<0.05?and the percentage of forward-moving sperm?P<0.01?in the epididymis of the rats exposed to aluminum were significantly lower than those in the control group.Moreover,as the dose of aluminum is increased,the value of these two indicators decreases more obviously.The percentage of dead sperm?P<0.01?and the percentage of abnormal spermatozoa?P<0.01?were significantly higher than those of the control group,and the percentage increase was more obvious with the increase of aluminum dose.Transmission electron microscopy showed that the mitochondrial swelling of the epididymal sperm in the aluminum-treated group was more obvious with the increase of aluminum dose.The results of flow cytometry showed that the mitochondrial membrane potential of sperm in the rats exposed to aluminum was lower than that in the control group?P<0.01?,and the mitochondrial membrane potential was negatively correlated with the aluminum dose?r_s=-0.819,P<0.001?.The percentage of sperm mitochondrial membrane permeability transition pores in the pathological open state was higher than that in the control group?P<0.01?,and the percentage of mitochondrial membrane permeability transition pores in the pathological open state was positively correlated with the aluminum dose?r_s=0.867,P<0.001?.The relative copy number of sperm mitochondrial DNA in the rats exposed to aluminum was higher than that in the control group?P<0.01?,and the mitochondrial DNA copy number was positively correlated with the aluminum dose?r_s=0.782,P<0.001?.None of the rats in this experiment detected a deletion of a large DNA fragment in the sperm mitochondrial DNA.Conclusion:Exposure to aluminum can cause sperm mitochondrial swelling,decreased membrane potential,pathological opening of membrane permeability transition pores,and increased mtDNA copy number,and thus lead to decreased sperm quality.The mechanism by which aluminum damages sperm mitochondria may be related to ROS attack.