RBP synthesis and secretion increase in the oviduct and uterus coincident with the transport of the egg or embryo into these organs. The cumulus oocyte comple may be a target for retinol, since the cells that nurture selleck inhibitor and communicate with the oocyte, contain transcripts and protein for several RARs and R Rs, RBP and retinaldehyde 2 dehydrogenase a metabolizing enzyme. Bovine oocytes and embryos from the 2 cell to hatched blastocyst stage, also e press transcripts for several RARs, R Rs, RBP and RALDH 2, and the inner cell mass and trophectoderm of blastocysts e press immunoreactive protein for RAR and R R. It has been shown recently that addition of 9 cis RA to in vitro oocyte maturation medium affects trophec toderm differentiation, total cell number and inner cell mass trophoblast cell ratios, following fertilization in cat tle oocytes.

Together, these studies suggest that the reproductive tract delivers retinol to the oocyte and early embryo which possess key elements of retinoid metabo lizing and signaling mechanisms. thus, influencing gene e pression, differentiation, and development. The mechanism by which retinol or retinoic acid admin istration influences oocyte maturation and positively impacts early embryonic development is not known and is the subject of much investigation. Retinoic acid may influence oocyte maturation through its effects on FSH or LH receptor e pression as demonstrated in porcine and rat granulosa cells. Alternatively, it has been sug gested that retinoic acid may increase mRNA quality and processing during maturation mediated by increases in polyadenylation.

E pression of several growth factors is influenced by RA. Midkine, a member of the heparin binding growth differentiation family, is induced by RA and has been shown Drug_discovery to improve bovine oocyte and embryonic developmental competence. In addition, retinoids may promote development through participa tion in an endogenous o idative stress protection mecha nism. In the present study, we investigated the effects of retinol administration to in vitro matured oocytes, and cultured bovine embryos under atmospheric O2 and reduced O2 conditions. Results suggest beneficial effects of retinol administration during maturation especially to less com petent oocytes, and improved development of embryos cultured under atmospheric o ygen conditions, indicating protection from o idative stress. Materials and Methods Reagents and Media All chemicals were purchased from Sigma Chemical Com pany, St. Louis, MO unless otherwise noted. Bovine oocyte collection medium was composed of mod ified M199, 4. 2 mM NaHCO3, 12 mM HEPES, and sup plemented with 2 mM glutamine, 2% fetal bovine serum, and penicillin strep tomycin.