In vitro assessment of reproductive toxicity of cigarette smoke and deleterious consequences of maternal exposure to its constituents

Cigarette smoke is known to be a serious health risk factor and considered reproductively toxic. In the current study, we investigated whether constituents of cigarette smoke, pyrazine, 2-ethylpyridine, and 3-ethylpyridine, adversely affect reproductive functioning such as oocyte maturation and sperm capacitation. Our findings indicated that three smoke components were involved in retardation of oocyte maturation in a dose-dependent manner and the lowest-observed-adverse-effect level (LOAEL) was determined to be 10-10M. However, individual smoke components administrated at the LOAEL did not attenuate oocyte maturation, demonstrating that all three toxicants were equally required for the observed growth impairment. When exposed to all three components at 10-10M during in vitro capacitation, murine sperm lost forward progression and were unable to show adequate hyperactivation, which is indicative of the incompletion of the capacitation process. Only sperm administrated with 3-ethylpyridine alone showed significant reduction in capacitation status, suggesting the chemical is the one responsible for disrupting sperm capacitation. Taken together, this is the first report that documents the effect of cigarette smoke components on oocyte maturation and sperm capacitation. The present findings demonstrate the adverse effects of smoke constituents of mammalian reproduction and the differences in sensitivity to smoke components between male and female gametes. Since both processes take place in the female reproductive system, our data provide new insights into deleterious consequences of maternal exposure to cigarette smoke.

Cytotoxic evaluation of certain insect growth regulators and insect sex pheromones in cho-k1 cells

The cytotoxic effects of Diflubeizuron, pyriproxifen as insect growth regulators, ZZ/ZE-7,11-hexadecadienyl acetate, Z-9- hexadecenal and Z-11-hexadecenal as insect sex pheromones were evaluated in vitro using Chinese hamster ovary [CHO-K1] cells. Total cellular protein [TCP] content and methyl tetrazolium [MTT] assays were carried out using serum free medium and medium supplemented with fetal calf serum [FCS, 10%], bovine serum albumin [BSA, 1%] and/or metabolic activation system [S9-mix]. All the tested compounds displayed cytotoxic effects that rise with time exposure. TCP assay exhibited higher sensitivity than MTT assay with all the tested compounds. In presence of the added extracellular proteins and/or metabolic activation system [S9-mix], the cytotoxic effects significantly decreased which indicate that the tested agents may be binding non-specifically with protein and extensive metabolized to less toxic metabolites