OBJECTIVETo quantitatively evaluate the murine model of spermatogenesis regeneration induced by two-dose busulfan injection.

METHODSFifty-four male mice were randomly divided into a control and two model groups of equal number, the former treated by two-dose intraperitoneal injection of 50% DMSO solution at 10 ml/kg, and the latter by that of busulfan at 10 mg/kg and 15 mg/kg respectively to establish spermatogenesis regeneration models, both at the interval of 24 days between the two doses. Spermatogenesis in seminiferous epithelia was evaluated by Johnsen score, and the expressions of GATA-4 and GDNF mRNA in Sertoli cells were detected by real time quantitative PCR at 3, 4 and 8 weeks after the treatment.

RESULTSJohnsen score kept stable in the control group at all stages (P > 0.05), but higher than in the model groups at 3 and 4 weeks (P < 0.01). It was lower in the 15 mg/kg than in the 10 mg/kg model group at 4 and 8 weeks (P < 0.01) , and than in the control group at 8 weeks (P < 0.05), but had no significant difference between the 10 mg/kg and the control groups (P > 0.05). Nor did the expression of GATA-4 mRNA in Sertoli cells show any significant difference among the three groups at different stages after the treatment (P > 0.05), and that of GDNF mRNA at different stages in the control group (P > 0.05). Compared with the controls, the level of GDNF mRNA in Sertoli cells was significantly higher at 3 weeks but lower at 4 weeks in the model groups (P < 0.01), and lower in the 15 mg/kg group (P < 0.01) and comparable in the 10 mg/kg group at 8 weeks (P > 0.05); and it was lower in the 15 mg/kg than in the 10 mg/kg group at all stages (P < 0.01).

CONCLUSIONTwo-dose intraperitoneal injection of 10 mg/kg busulfan at the interval of 24 days is an optimal option for the establishment of a murine model of spermatogenesis regeneration. Higher dose of busulfan may induce deficient expression of GDNF in Sertoli cells and result in incomplete restoration of spermatogenesis.