A Comprehensive Review of Mechanistic Insights of Cobalt and Nickel Induced Reproductive Toxicity

ABSTRACT Environmental deterioration can elevate the chances of human exposure to heavy metals, leading to health issues. The transition metals nickel and cobalt are known as occupational and environmental contaminants that have a significant negative impact on mammalian reproductive systems. Reproductive organs are vital to an individual's life for the survival and advancement of the species, and they may be a perfect “barometer” for the harmful effects of environmental pollution on animals and human health since their reaction to hazardous compounds is different from that of other target organs. The current review focuses on reproductive and developmental damage caused by environmental exposure to cobalt and nickel and the mechanism by which they affect the structure and function of reproductive organs as both the testis and ovary are highly susceptible due to their significant cellular activity, where essential processes such as spermatogenesis, oogenesis, and folliculogenesis take place. The toxic effects in females were observed as reduced follicular development, increased instances of follicular atresia, PCOS contributor, altered steroidogenesis, degeneration of the corpus luteum, and changes in the reproductive cycle. In the testes, exposure to these metals resulted in alterations to the seminiferous tubules and testicular stroma, as well as a decline in spermatozoa count, motility and viability, along with abnormal morphology of the spermatozoa, caused histopathological lesions of the epididymis and testis. Serum testosterone levels were significantly decreased; downregulation in the expression of various genes was noted. Cobalt and nickel are active biochemical disruptors that degrade the integrity of the germ cell.