Evaluation of male germ cell toxicity in rats: correlation between sperm head morphology and sperm comet assay

The present study was aimed to investigate the germ cell toxicity of doxorubicin and find out the possible correlation between sperm head morphological evaluation and sperm comet assay, which are used to assess male germ cell toxicity. The correlation between these two assays was validated using a potent germ cell toxicant, doxorubicin, in male Sprague-Dawley rats. Doxorubicin was administered intra-peritionally at the doses of 1.25, 2.5 and 5mg/kg weekly once for a period of 5 weeks and all the animals were sacrificed after 1 week of receiving the last dose. The germ cell toxicity of doxorubicin was assessed using oxidative stress parameters, sperm head morphology, sperm comet assay, halo assay and histology in testes as the end point of evaluation. A significant increase in the % abnormality in sperm head was found in the animals treated with 2.5 and 5mg/kg/week doxorubicin. Doxorubicin treatment significantly increased the DNA damage of sperm in a dose-dependent manner as observed by sperm comet assay parameters. A strong positive correlation was observed between the sperm head morphological evaluation and the sperm comet assay. Therefore, it can be concluded that the damage in genetic material of sperm may result into abnormalities in the sperm head morphology. The sperm head morphological evaluation is considered to be essential for the assessment of male germ cell toxicity by several regulatory bodies like the Organization for Economic Cooperation and Development (OECD) and the International Conference on Harmonization (ICH). However, acceptance of the sperm comet assay by regulatory authorities as a standard genotoxicity test for assessing male germ cell toxicity still requires further validation of the assay.