Effect of growth hormone releasing hormone (GHRH) and vasoactive intestinal peptide (VIP) on in vitro bovine oocyte maturation

The aim of this study was to investigate the effects of growth hormone rele asing hormone (GHRH) and the structural-related peptide vasoactive intestin al peptide (VIP) on nuclear maturation, cortical granule distribution and c umulus expansion of bovine oocytes. Bovine cumulus oocyte complexes (COCs) were cultured in M199 without FCS and gonadotropins and in the presence of either 100 ng/mL bovine GHRH or 100 ng/mL porcine VTP. The COCs were incuba ted at 39 degrees C in a humidified atmosphere with 5% CO2 in air, and the nuclear stage was assessed after 16 or 24 h of incubation using DAPI staini ng. Cortical granule distribution was assessed after 24 h of incubation usi ng FITC-PNA staining. To assess the effects of GHRH and VIP on cumulus expa nsion, COCs were incubated for 24 h under the conditions described above. I n addition, 0.05 IU/mL recombinant human FSH was added to GHRH and VIP grou ps. Cultures without GHRH/VIP/FSH or with only FSH served as negative and p ositive controls, respectively.