Consequences of Nitric Oxide Synthase Inhibition During Bovine Oocyte Maturation on Meiosis and Embryo Development

Author(s)

Schwarz, K. R. L. ; Pires, P. R. L. ; de Bem, T. H. C. ; Adona, P. R. ; Leal, C. L. V. ^[1]

Affiliation

^[1] USP, ZAB, FZEA, Dept Ciencias Basicas, BR-13635900 Pirassununga, SP - Brazil

• Document type: Journal article
• Source: REPRODUCTION IN DOMESTIC ANIMALS; v. 45, n. 1, p. 75-80, FEB 2010.
• Web of Science Citations: 23

Abstract

The importance of nitric oxide synthase (NOS) in bovine oocyte maturation was investigated. Oocytes were in vitro matured with the NOS inhibitor N(w)-L-nitro-arginine methyl-ester (10(-7), 10(-5) and 10(-3) M L-NAME) and metaphase II (MII) rates and embryo development and quality were assessed. The effect of L-NAME (10(-7) M) during pre-maturation and/or maturation on embryo development and quality was also assessed. L-NAME decreased MII rates (78-82%, p < 0.05) when compared with controls without L-NAME (96%). Cleavage (77-88%, p > 0.05), Day 7 blastocyst rates (34-42%, p > 0.05) and total cell numbers in blastocysts were similar for all groups (146-171 cells, p > 0.05). Day 8 blastocyst TUNEL positive cells (3-4 cells) increased with L-NAME treatment (p < 0.05). For oocytes cultured with L-NAME during pre-maturation and/or maturation, Day 8 blastocyst development (26-34%) and Day 9 hatching rates (15-22%) were similar (p > 0.05) to controls pre-matured and matured without NOS inhibition (33 and 18%, respectively), while total cell numbers (Day 9 hatched blastocysts) increased (264-324 cells, p < 0.05) when compared with the controls (191 cells). TUNEL positive cells increased when NOS was inhibited only during the maturation period (8 cells, p < 0.05) when compared with the other groups (3-4 cells). NO may be involved in meiosis progression to MII and its deficiency during maturation increases apoptosis in embryos produced in vitro. Nitric oxide synthase inhibition during pre-maturation and/or maturation affects embryo quality. (AU)