Experimental Study On The Effect Of Low-dose Lindane On The Apoptosis Of Spermatogenic Cells In Rat Testis And Its Mechanism

Objective Pesticides are widely used in agricultural production.Many pesticides are highly persistent even in small amounts,which causes many health problems.According to reports,pesticides,herbicides and other pesticides can be used as environmental endocrine disruptors（EEDs）to destroy the health of male reproductive system.Lindane is a isomer of the organochlorine pesticide HCH,which has a damaging effect on the male reproductive system.This study investigates the effects of low-dose exposure to lindane on the expression of Bcl-2,Cyt C,Cleaved Caspase-3 proteins in spermatogenic cells of SD rats and the levels of serum luteinizing hormone（LH）and testosterone（T）.To explore the damage mechanism of lindane to the male reproductive system,and provide a theoretical basis for controlling its harm to human health and the environment.Methods Randomly divide forty healthy SPF male SD rats into 5 groups,8 rats in each group.With reference to the lindane LD₅₀(126mg·kg^-1)of rats,the low,medium,and high-dose groups were given lindane at 3mg·kg^-1,6mg·kg^-1,and 13mg·kg^-1.The solvent control group was given 10mg·kg^-1corn oil,and 100μg·kg^-1 estradiol as positive control group.The rats were treated with poison by gavage once a day for 8 weeks,and the rats were weighed after 24 hours of last exposure.After an overnight fasting,the rats were injected with10%chloral hydrate solution into the abdominal cavity,and then dissected it after anesthesia.Measure the weight and coefficient of testis and epididymis,sperm density,sperm activity testis,histopathological changes of epididymis,the positive expression of Bcl-2,Cyt C,Cleaved Caspase-3 in spermatogenic cells of testis,and serum luteinizing hormone and testosterone concentration.Results 1.Daily activities and general conditions of rats:With the prolongation of lindane exposure,rats showed symptoms of messy and matt coats,as well as irritability in positive control group and 13mg·kg^-1 lindane-exposed group.Compared with the solvent control group,the rats in the 6mg·kg^-1 and 3mg·kg^-1 lindane-exposed groups showed no significant difference in general conditions;2.The effect of lindane on the body weight of rats:Compared with the solvent control and positive control group,the initial body weight,final body weight and weight gain of rats in each lindane-exposed group had no statistically difference（P>0.05）;3.The effect of lindane on the organ coefficient of rats:Compared with the solvent control group and positive control group,the weight of testicular and epididymis and the organ coefficient in lindane-exposed groups had no significant difference（P>0.05）;the weight of the epididymis in lindane-exposed groups are higher than positive control group（P<0.05）;4.The effect of lindane on the morphology of the testis and epididymis tissue of rats:the testis and epididymis tissues presented varying degrees of damage in each lindane-exposed group,and with the increase of lindane dose,the testis and epididymis tissues are getting worse.The testis is mainly manifested as the increased of seminiferous tubules space,the disarranged of spermatogenic cells,and the reduced of sperm number in lumen;the epididymis is manifested as the disorder of epididymal epithelium,significantly reduced of the number of epithelial cells and the sperm in the lumen;In positive control group,the testicular lumen was enlarged,the sperm count decreased,and shedding spermatogenic cells could be found in lumen,the epididymal epithelial structure was disordered,the sperm number in the lumen was sparse and arranged disorderly,and shedding epithelial cells could be seen in lumen;The damage of testis and epididymis in 13mg·kg^-1 lindane group was similar to positive control group;5.The effect of lindane on sperm density and activity of rats:Compared with the solvent control group,the sperm density in 13mg·kg^-1 lindane-exposed group were decreased（P<0.05）,and the sperm survival rate in 6mg·kg^-1 and 13mg·kg^-1lindane-exposed groups were decreased（P<0.05）;compared with the positive control group,the sperm survival rate in 6mg·kg^-1 and 3mg·kg^-1 lindane-exposed groups were increased（P<0.05）,and the sperm density had no siginificant difference in each lindane-exposed group（P>0.05）;6.The effect of lindane on serum concentration of LH and T:To compare with the solvent control group,the concentration of serum luteinizing hormone was increased in13mg·kg^-1 lindane-exposed group,and the concentration of testosterone was decreased（P<0.05）;compared with the positive control group,serum luteinizing hormone concentration in 3mg·kg^-1,6mg·kg^-1 lindane-exposed group were decreased,and testosterone concentration in each lindane-exposed groups were increased（P<0.05）;7.The effect of lindane on rat testis apoptotic protein:the positive expression of Bcl-2 protein in 13mg·kg^-1 lindane-exposed group was lower than solvent control group（P<0.05）,and in 3mg·kg^-1,6mg·kg^-1lindane-exposed group were higher than positive control group（P<0.05）;the positive expression of Cyt C protein in 13mg·kg^-1 lindane-exposed group was higher than solvent control group（P<0.05）,and in 3mg·kg^-1 and 6mg·kg^-1 lindane-exposed groups was lower than positive control group（P<0.05）.The expression of Cleaved Caspase-3 protein in6mg·kg^-1 and 13mg·kg^-1 lindane-exposed groups was higher than solvent control group（P<0.05）,3mg·kg^-1,6mg·kg^-1 lindane-exposed group was lower than positive control group（P<0.05）.Conclusion Lindane has estrogen-like male reproductive toxicity.Lindane may cause testicular tissue structural damage through its direct toxic effects on the testis,and then down-regulate the expression of Bcl-2 protein in testicular tissue,and up-regulate the expression of Cyt C and Cleaved Caspase-3 protein.The serum testosterone level further decreased,which in turn caused a decrease in the number and activity of sperm in rats,which caused reproductive dysfunction in rats.