Partial inhibition of nitric oxide synthase activity stimulates the nuclear maturation progression of bovine cumulus–oocyte complex in vitro in the presence of hemisections of the follicular walls

• Published in: Zygote (Cambridge) Vol. 28; no. 5; pp. 388 - 396
• Main Authors: Dubeibe, Diego Fernando, Caldas-Bussiere, Maria Clara, Maciel, Valter Luiz, Sampaio, Wlaisa, Gonçalves, Paulo B.D., De Cesaro, Matheus P., Quirino, Celia Raquel, Faes, Márcia R., Paes de Carvalho, Carla S.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.10.2020
• Subjects: 17β-Estradiol; Antibiotics; Arginine; Cell culture; Cultivation; Cyclic AMP; Cyclic GMP; Enzymes; Fatty acids; Gametocytes; Laboratories; Life sciences; Maturation; Meiosis; Metaphase; NG-Nitroarginine methyl ester; Nitric oxide; Nitric-oxide synthase; Oocytes; Ovaries; Polyvinyl alcohol; Progesterone; Sex hormones; Steroids; Supplements; Walls; Brazil; Canada; United States > US; Cumulus cells integrity; Cyclic nucleotides; Cattle; Meiotic progression; Steroids
• ISSN: 0967-1994; 1469-8730
• DOI: 10.1017/S0967199420000234

This study aimed to assess the effects of the inhibition of nitric oxide synthase (NOS) on events that modulate bovine in vitro oocyte maturation. Cumulus–oocyte complexes (COCs) were cultured with hemisections (HSs) of the follicular walls in a maturation medium supplemented with different concentrations (0.1–10.0 mM) of Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME). Controls consisted of COCs cultured in the presence (+HSs) or absence of HSs (–HSs) with no additional l-NAME supplementation. The following parameters were assessed: oocyte nuclear maturation stage; cumulus cell (CC) membrane integrity; nitrate/nitrite, progesterone, and estradiol concentrations in the culture medium at 22 h of cultivation; and the concentrations of cGMP and cAMP in COCs during the first hour of maturation. The addition of 1.0 mM l-NAME increased the percentage of oocytes that reached metaphase II (MII) and the percentage of intact CCs (P < 0.05). All l-NAME concentrations reduced the nitrate/nitrite concentrations (P < 0.05), but none affected steroid concentrations compared with control +HSs (P > 0.05). The addition of 1.0 mM l-NAME reduced cGMP concentrations at 3 h and increased cAMP concentrations in the first hour of culture (P < 0.05). Our findings suggest that the NOS/NO/cGMP pathway participates in meiosis progression (MI to MII) of the bovine oocytes matured in vitro in the presence of hemisections of the follicular walls. Lastly, the mechanisms that lead to the progression of meiosis after NOS inhibition do not involve changes in steroid production.