A biochemical and histological approach to investigate comparative reprotoxic effects of Lead, Cadmium and Arsenic in female adult Sprague Dawley rats

Abstract

Infertility is a rapidly emerging concern throughout the world, with female infertility accounting for 37% of couples’ infertility in developed countries. Quality of environment is very important for human health status. Female infertility is mainly caused by exposure to environmental pollutants, including heavy metals. Metals can be released to the environment from different branches of industry, hence in the environment, the amount of heavy metals rises. The current study was designed to evaluate and compare repro-toxic effects of lead, cadmium, and arsenic for 28 days in female Sprague Dawley rats. Stock solution of lead (1.5 and 8mg/kg), cadmium (0.09 and 5mg/kg), and arsenic (1.6 and 24.6mg/kg) were prepared. First group served as control, received normal saline by oral gavage. Second and third group received low and high dose of lead acetate respectively. Fourth and fifth group received contrasting dose of cadmium chloride. Sixth and seventh group received low and high dose of sodium arsenite. Body weight and glucose level was checked at 1st, 14th, and 28th day of the experiment. Animals were dissected at day 29. Vaginal smear was collected every 7th day during a period of 28 days for determination of changes in estrous cyclicity. Ovarian and uterine tissues were collected and stored at -80ºC until analysed. Lead acetate exposure caused significant decline in body weight, while the animal treated with low and high doses of cadmium chloride and sodium arsenite showed normal weight gain when compared to control. Low and high doses of these three heavy metals caused significant decline in reproductive organ weight when compared to control. Heavy metals (Pb, Cd, As) disturbed regularity of estrous cyclicity of treated rats. Lead acetate treatment increased ovarian CAT and decreased ovarian SOD and POD. Both doses of lead acetate also increased ovarian reactive oxygen species (ROS) and malonaldehyde (MDA) levels. Low and high doses of cadmium chloride and sodium arsenite decreased ovarian CAT, SOD, and POD and increased ROS and MDA levels. Histomorphological studies showed changes in the ovaries including reduction in ovarian follicles number, elevation in atretic follicles number, follicular cell dispersion, optical empty spaces, degenerated corpus luteum, corpus luteum cyst, ovarian follicles necrosis, damaged oocytes and follicular cell dispersion. These alterations reduced ovarian tissue function in female rats. In conclusion, the present study demonstrated reprotoxic effect of heavy metals by disrupting antioxidant defence mechanism, ovarian histomorphology, and estrous cyclicity, leading to infertility.