Problem statement: Nitric oxide is a diffusible gas that has been implicated as a signaling molecule in mammalian reproductive tissues and has two isoform of nitric oxide synthase (inducible and endothelial, iNOS and eNOS respectively) in mammalian granulosa cells. It has shown that among preovulatory follicles of leghorn hens, the F1 follicle has the highest level mRNA of iNOS and may has a role in ovulation. In mammalian, the role of eNOS in ovulation is more important than that of iNOS. It seems that eNOS is also express before ovulation, but its expression yet to be investigated, thus in this study we conducted an experiment to clarify the expression of eNOS gene in F1 follicle granulosa layer of broiler breeder hens. Approach: About 34 weeks old broiler breeder hens were anesthetized and then killed 2-4 h before expected oviposition based upon the individual bird’s sequence of laying. Ovarian follicles were separated from the ovary and measured in order to identify the largest (F1) and the granulosa layer of F1 follicle separated. We have selected granulosa layer of follicle because eNOS gene expression from mammalian granulosa has been detected. Highly homologous oligonucleotides were deduced from consensus sequences of human and bovine endothelial nitric oxide synthase gene for its primers (GenBank, Blast). Normalization of the samples was accomplished using RT-PCR for the housekeeping gene β-actin to control the efficacy of the RNA extraction, integrity and amount of eNOS mRNA in the samples. Results: In this study we detected eNOS gene mRNA in the granulosa layer of the largest preovulatory follicle (F1) of chicken for the first time. Conclusion: It concluded that eNOS gene normally expressed in follicular granulosa cells of F1 follicle of broiler breeder hens 2-4 h before ovulation and it seems that this enzyme and its product, nitric oxide, has a role in ovulation.
