Cisplatin induces duplex 3' overhangs and 5' blunt ends in epididymal epithelium in a Bax-dependent manner without any protection from L-ascorbic acid

Abstract

The ability of cisplatin (cis-diaminedichloroplatinum-II) to induce DNA double-strand breaks and expression of p53, Bax and Bcl-2 and possible protective effects of L-ascorbic acid was investigated in epididymis. Adult BALB/C mice were treated (ip) as follows: group I-- control; group II--L-ascorbic acid (10 mg/kg); group III--two cycles of 5 days each of cisplatin 1 mg/kg; group IV--cisplatin 1 mg/kg + L-ascorbic acid; group V--cisplatin 2.5 mg/kg; and group VI--cisplatin 2.5mg/kg + L-ascorbic acid. A recovery period of 17 days was given between the cycles. All animals were sacrificed within 72 h after the last treatment of cisplatin. The organ weight was decreased and the structural changes were observed. The tubular diameter and epithelial thickness were decreased in groups III to V, but recovered in groups IV and VI, except the epithelial thickness in group VI. The oxidative stress marker, 8-oxo-dG was expressed in groups III to VI without any protection by L-ascorbic acid. Intensive nuclear in situ oligo ligation (ISOL) and cytoplasmic Bax expression was observed in groups III-VI without any protective effects from L-ascorbic acid. p53 expression was reduced in groups III and V. Bcl-2 staining was weakly positive in all groups except groups III and V. In conclusion, cisplatin induces structural changes, oxidative stress, irreparable DNA double-strand breaks bearing duplex 3' dT overhangs and 5' P-blunt ends in a Bax-dependent manner, but L-ascorbic acid has little, if any, preventive effects on cisplatin-induced epididymal damage.