Addition of antio idants to culture medium or culture of embryos in an atmosphere of reduced O2 has been demonstrated to be beneficial to in vitro survival of embryos from a variety of species. Retinoids participate in a biological antio idant this research network, and have been implicated as important regulators of redo signaling pathways. Carotenoids and reti nol can quench single o ygen molecules and interact with other antio idant compounds. Retinoic acid has been shown to protect against o idative stress induced apoptosis by inhibition of the c jun N terminal kinase activator protein 1 pathway in glomerular and mesangial cells. In addition, anti apoptotic effects of RA were mediated by both nuclear receptor dependent and independent pathways.

Retinoids may also protect against o idative damage by maintaining adequate endogenous levels of antio idant compounds and enzymes. Glutathione is the major non protein sulphydryl compound found in mammalian cells responsible for strong basal ROS scavenging activity. Maintenance of adequate GSH levels is essential for oocyte maturation, fertilization and embryonic develop ment. Retinoic acid inhibited staurosporine induced GSH depletion in neuronal cells, preventing o idative damage and apoptosis. A retinoic acid response ele ment has been identified in the promoter region of a specific isoform of glutathione S transferase pi in glioblastoma cells and GP 2, an enzyme necessary for the conversion and utilization of GSH. RA has also been shown to significantly increase sur vival, reduce ROS content and increase protein levels of Cu Zn SOD and Mn SOD in neuronal cells treated with staurosporine.

Recently, microarray analysis revealed that three genes which encode enzymes involved in GSH synthesis and utilization were R R target genes in mouse liver. The same study showed that in hepatocytes of R R deficient mice there was a significant reduction in GSH synthesis rate and GSH content. Together, these data provide strong evidence that in sev eral cell systems, retinoids support and improve endog enous antio idant defense mechanisms. Conclusions Results from the present study indicate that retinol administration during in vitro maturation particularly improved embryonic development in those oocytes that may have been developmentally compromised.

Moreo ver, retinol addition during in vitro culture, under atmos pheric conditions, also improved embryonic development compared to those embryos incubated in a 7% o ygen atmosphere. The mechanisms by which retin oids affect the Brefeldin_A developmental capacity of oocytes and early embryos may include modulation of e pression of growth factors and other developmental genes, improving mRNA quality, and direct and or indirect affects on anti o idant defense mechanisms. Background Capsaicin is a primary pungent and irritating principle present in hot peppers of the genus Capsicum which are widely and fre quently consumed as food additive throughout the world.