Effects of indium chloride exposure on sperm morphology and DNA integrity in rats

Indium, a Group IIIA element of the periodic chart and a rare earth metal characterized by high plasticity, corrosion resistance, and a low melting point, is widely used in the electronics industry where released streams can contaminate the environment. Consequently, indium can reach humans mainly by natural ways, which could result in a health hazard. Although reproductive toxicities have been surveyed in some studies in animal models, the infertility effects of sperm function induced by indium compounds have not been greatly investigated. We designed a study to investigate the toxicities of subacute exposure to indium compounds on male sperm function and the process of spermatogenesis in a rodent model. Fourteen Sprague-Dawley rats on postnatal Day (PND) 84 were randomly divided into exposure and control groups, and weekly received intraperitoneal injections of indium chloride (1.5 mg/kg body weight) and normal saline, respectively, for 8 weeks. Cauda epididymal sperm count, motility, morphology, chromatin DNA integrity, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) generation, and testis DNA content were investigated. The indium chloride exposed group showed significant toxicity to sperm function, as well as an increased percentage of sperm morphological abnormality and chromatin DNA damage. Furthermore, positive correlations between abnormal sperm morphology, chromatin DNA damage, and superoxide anion generation were also noted. The results of this study demonstrated the toxic effect of subacute low dose indium exposure during sexual maturation on sperm function, resulting in sperm chromatin DNA damage through an increase in sperm ROS generation in a rodent model.