INVESTIGATING THE IMPACT OF ENVIRONMENTAL CONTAMINANTS ON PERICONCEPTUAL ENVIRONMENT AND EARLY REPRODUCTIVE EVENTS

The modern environment in which we live is replete with chemicals that have accumulated to levels that have been proposed to impact various aspects of physiology. The impact of a selection of these environment contaminants on the physiology of early reproductive events has been investigated. The contaminants investigated include Bisphenols A and S, as well as triclosan and acetamiprid. Firstly, the effect of individual exposure to these contaminants on periconceptual environment was explored, using bovine oviduct epithelial cells (BOEC) cultured in vitro. Using microfluorometric assays and high-performance liquid chromatography (HPLC), it was discovered that pyruvate concentration and amino acids composition in BOEC secretions were sensitive to treatment to these chemicals. Furthermore, the expression of the amino acids transporters was also altered after exposure. Subsequently, the bovine oocyte function and metabolic profile was assessed after exposure to environmental contaminants during in vitro maturation (IVM). The nuclear status, steroid hormone production, energy substrates consumption after IVM, mitochondrial activity, and the pronuclei formation were assessed. Exposure to Bisphenols decreased 17β-oestradiol production and Triclosan increased progesterone production in a non-monotonic pattern. Meanwhile, both steroid hormones remained unchanged in the presence of Acetamiprid. However, Acetamiprid as well as Triclosan affected the metabolic status of pyruvate irrespective of the administered dose. Furthermore, the mitochondrial activity of oocytes after Triclosan and Acetamiprid exposure was impaired. Finally, pronuclei formation was influenced in the presence of all environmental contaminants. Next, the effects of environmental contaminants on embryo developmental competence and metabolic activity after indirect and direct exposure were assessed. Reduced blastocyst rates and altered energy substrates consumption were observed in embryos derived from chemically exposed oocytes. Altered metabolic activity of embryos was also revealed after direct exposure during the cleavage and blastocyst stage of development. The data generated in this work demonstrate the capacity of common environmental contaminants to alter early development at multiple stages in subtle but significant ways. Taking into consideration the Developmental Origin of Health and Disease (DOHaD) hypothesis, which suggests that environmental changes during early stages of development could influence the health in later on stages of life, highlights the importance of our findings.