High concentration of leptin induced the expression of SOCS3 and inhibited the phosphorylation of STAT3. The expression of SOCS3 and STAT3/pSTAT3 were detected by western blotting. Representative expressions of SOCS3 and STAT3/pSTAT3 for testes of each age point were shown (A). Expression of SOCS3 in d56 MSG-treated mice testes increased compared with 56NS mice, whereas SOCS3 expression had no obvious change in the d14 or d28 groups. However, the expression of pSTAT3 was opposite that of SOCS3. Total STAT3 had no obvious change. To further confirm the effects of leptin on the expression of SOCS3 and on the phosphorylation of STAT3, leptin concentrations of 0, 10 and 100 nM were used to stimulate the incubation of testes (B). The lower panel represented graphs of western blotting band intensity. Statistical method was performed by a one-way analysis of variance followed by Student-Newman-Keuls test to conduct multiple comparisons. *, p < 0.05 compared with 56NS-treated mice group; #, p < 0.05 compared with 0 nM leptin-treated mice group.