OBJECTIVE

To investigate the role of extracellular regulated protein kinase( ERK) pathway activation in the testicular injury induced by dibutyl phthalate( DBP) in KM mice.

METHODS

A total of fifty-six male KM mice were randomly divided into 8 groups: control group, 50 mg/( kg·d) DBP group, 50 mg/( kg·d) vitamin E( VE)group, 2 mg/( kg·d) nimodipine( Ni) group, DBP + VE group, DBP + Ni group, Ni +VE group and DBP + Ni + VE group. After consecutive 28 days of treatment, the body weight, testis weight, organ coefficient and sperm density of mice were measured. The histomorphological damage of testis was observed by light microscope. The contents of reactive oxygen species( ROS) and malondialdehyde( MDA) in testicular homogenate of mice in each group were detected by DCFH-DA fluorescence and thiobarbituric acid( TBA) colorimetric method, respectively. The contents of calmodulin( CaM) and level of phosphorylated ERK( p-ERK) were measured by enzyme-linked immunosorbent assay( ELISA).

RESULTS

Compared with control group, the body weight, testis weight and testicular organ coefficient of mice in 50 mg/( kg·d) DBP group decreased to( 36. 48 ±0. 99) g, ( 0. 25 ± 0. 01) g, ( 0. 54 ± 0. 09) %( P < 0. 05), sperm density decreased to( 11. 70 ± 0. 23) × 106/m L( P < 0. 05), and the degree of testicular tissue injury increased with the fluorescence intensity of ROS and the content of MDA increased to( 1698. 18 ± 77. 58), ( 1. 65 ± 0. 13) μmol/g prot( P < 0. 05) respectively. Meanwhile the content of CaM decreased to( 45. 61 ± 2. 69) μg/m L( P < 0. 05) as well as the level of p-ERK increased to( 1150. 43 ± 48. 79) pg/m L( P < 0. 05). After adding VE as antioxidant and Ni as a calcium channel antagonist, compared with 50 mg/( kg·d) DBP group, the body weight and testicular organ coefficient of mice in DBP + Ni + VE group increased to( 40. 69 ± 0. 75) g, ( 0. 69 ± 0. 03) %( P < 0. 05), sperm density increased to( 13. 50 ± 0. 16) × 106/m L( P < 0. 05), and the degree of testicular tissue injury decreased with the fluorescence intensity of ROS and the content of MDA decreased to( 1080. 60 ± 98. 64), ( 1. 06 ± 0. 13) μmol/g prot( P < 0. 05) respectively. Meanwhile the content of CaM increased to( 54. 76 ± 1. 74) μg/m L( P < 0. 05) as well as the level of p-ERK decreased to( 904. 55 ± 64. 73) pg/m L( P < 0. 05).

CONCLUSION

VE as antioxidant and Ni as calcium channel antagonist can reduce the damage of mouse testicular tissue induced by DBP in varying degrees, suggesting that DBP may activate ERK1/2 pathway through oxidative stress and Ca2 +signal, which may lead to testicular tissue damage in mice.