Preventive and protective effects of silymarin on doxorubicin-induced testicular damages correlate with changes in c-myc gene expression

This study aimed to investigate the preventive and protective effects of silymarin (SMN) on doxorubicin (DOX)-induced damages in the testis. Wistar rats were divided into six groups (n=8), including: control (C), DOX-treated (DOX, 15mg/kg, i.p.), DOX- and SMN-treated and SMN-treated animals (SMN, 50mg/kg, orally). Those groups, which received either compounds, were sub-grouped based on the preventive (PVT), protective (PTT) and/or therapeutic regimens (TPT) of SMN administration. The antioxidant status analyses, hormonal assay, and histopathological examinations in the testis were conducted. The expression of c-myc at mRNA level also was analyzed. SMN in preventive and protective forms significantly (p<0.05) improved the DOX-induced weight loss and lowered the alkaline phosphatase level. Pretreatment and co-treatment with SMN attenuated the DOX-induced carbonyl stress. The DOX-induced histopathological damages including negative TDI and IR were significantly (p<0.05) improved with SMN pretreatment and co-administration. SMN in preventive and protective forms prevented from DOX-induced DNA fragmentation in the testis. SMN ameliorated the DOX-reduced serum level of sexual hormones including testosterone, inhibin B, LH and FSH in PVT and PTT groups. The c-myc expression at mRNA level was completely and relatively down regulated in the testis of animals that received SMN as pretreatment and concurrent administration, respectively. Our data suggests that the DOX-induced biochemical and histopathological alterations could be prevented and/or protected by SMN. Moreover, the SMN protective and preventive effects attribute to its capacity in the reduction of DOX-induced carbonyl stress and DNA damage, which may be mediated by c-myc expression.