Apoptosis and glucocorticoid-related genes mRNA expression is modulated by coenzyme Q10 supplementation during in vitro maturation and vitrification of bovine oocytes and cumulus cells.

Oocyte in vitro maturation (IVM) and vitrification procedures lead to detrimental effects on the overall oocyte quality. The addition of antioxidants during IVM, such as the coenzyme Q10 (Q10), has been demonstrated to positively impact on the cumulus-oocyte complexes due to its role in protection from oxidative damage and modulating gene transcription. Furthermore, glucocorticoids (GC) regulate gene transcription, energy metabolism and apoptosis during the early steps of reproduction. In this sense, most GC actions are mediated by the glucocorticoid receptor (NR3C1), a transcription factor. However, the specific roles of GC in ovarian physiology and oocyte maturation are still unknown. In this regard, a better knowledge on the expression of GC-related and apoptosis-related genes during IVM and cryopreservation procedures could potentially benefit the refinement of assisted reproductive techniques in the bovine species. The present study aims to explore the expression of NR3C1 mRNA in fresh and vitrified bovine oocytes and cumulus cells in response to Q10 (50 µM), and the effect of cortisol addition (0.25 µM, 0.5 µM) on the expression of NR3C1. We also studied the mRNA expression of NR3C1-related genes belonging to the GC regulation pathway, such as hydroxysteroid dehydrogenases (HSD11B1; HSD11B2), immunophilins (FKBP4; FKBP5), signal transducers and activators of transcription (STAT3; STAT5A), the mineralocorticoid receptor (NR3C2), and to the apoptosis pathway, such as the anti- (BCL2) and pro-apoptotic (BAX) mRNA transcripts in oocytes and cumulus cells 1) after IVM, and 2) after vitrification, both in presence or absence of Q10 supplementation during IVM. Our results show that there is an increase in the NR3C1 receptor expression after vitrification of oocytes, but not after exogenous cortisol supplementation during IVM. In addition, Q10 reduces the mRNA expression of HSD11B1 and FKBP5 in oocytes at levels of immature oocytes (HSD11B1 mRNA expression also in cumulus cells), and the BAX:BCL2 ratio mRNA expression. After vitrification in the presence of Q10, HSD11B2 mRNA expression increases in cumulus cells, while HSD11B1 and BAX:BCL2 mRNA expression decreases significantly both in oocytes and cumulus cells. In conclusion, our results show for the first time the effect of IVM, vitrification and Q10 supplementation on the mRNA relative expression of GC-related and apoptosis genes, and the effect of vitrification in the protein expression of NR3C1.

FK506 and its analogs - therapeutic potential for neurological disorders.

Immunophilin ligands such as FK506 and Cyclosporin A, used in immunosuppression, are well-characterized drugs. In the past, they had been the center of attention as a putative therapeutic strategy for neuroregeneration and neuroprotection. In contrast to Cyclosporin A, FK506 readily crosses the brain-blood-barrier and, thus together with its derivatives, may represent a novel approach to the treatment of neurological disorders. FK506 exerts profound neuroprotective and neuroregenerative effects in vivo and in vitro. The mechanism underlying neuroregeneration is fairly well understood. It is independent of the inhibition of calcineurin, which is responsible for the immunosuppression, but operates via the binding of FKBP52 and the heat shock protein (Hsp) 90. In contrast, the underlying pathways of neuroprotection are far less understood. Protection is apparently independent of calcineurin, as shown by non-calcineurin inhibiting derivatives, such as V-10,367 and GPI-1046, but the intracellular actions remain to be defined. FK506 has been shown to interfere with the apoptotic pathway of neuronal cells, including inhibiting JNK activity, cytochrome c release, caspase 3 activation, and CD95 ligand expression. These effects are in part mediated by the inhibition of calcineurin and may not contribute to protection. Our recent studies suggest that the protective properties of FK506 and its non-calcineurin inhibiting derivatives are realized by a fast induction of heat shock proteins. The induction of the heat shock response by immunophilin ligands might prove to be an interesting target for neuroregeneration and neuroprotection.