title: The role of inducible nitric oxide synthase in gamete interaction and fertilization: a comparative study on knockout mice of three NOS isoforms.
abstract: Nitric oxide (NO), which is produced from l-arginine by three isoforms of NO synthase (NOS), has been implicated in reproductive functions. However, the specific role of NOS isoforms in gamete function and fertilization is not clear. Three types of NOS knockout mice were super ovulated and fertilized in vitro and in vivo. The sperm count and motility, in vivo and in vitro fertilization rate as indicated by two-cell embryos and blastocyst rate were examined. The sperm count and motility from all three knockout mice were not significantly different from that of the wild type. Inducible NOS (iNOS) knockout mice were found to have the largest number of two-cell embryos/mouse collected after fertilization in vivo (P<0.01), but the rate of blastocyst formation from two-cell embryos in vitro was similar for all three knockouts. The rate of in vitro fertilization using either iNOS-deficient sperm or oocytes, but not those deficient in the other two NOS isoforms, was significantly elevated when compared to that in the wild type (P<0.001). While all three types of NOS do not seem to play a significant role in pre-ejaculated sperm function, iNOS may play an inhibitory role in sperm and oocyte functions affecting the process of fertilization and early embryo development.
authors.affiliation: Epithelial Cell Biology Research Center, Department of Physiology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region, PR China.
authors.forename: Jian Zhi
authors.initials: JZ
authors.lastname: Yang
authors.forename: Louis Chukwuemeka
authors.initials: LC
authors.lastname: Ajonuma
authors.forename: Dewi Kenneth
authors.initials: DK
authors.lastname: Rowlands
authors.forename: Lai Ling
authors.initials: LL
authors.lastname: Tsang
authors.forename: Lok Sze
authors.initials: LS
authors.lastname: Ho
authors.forename: Sun Yee
authors.initials: SY
authors.lastname: Lam
authors.forename: Wen Yin
authors.initials: WY
authors.lastname: Chen
authors.forename: Chen Xi
authors.initials: CX
authors.lastname: Zhou
authors.forename: Yiu Wa
authors.initials: YW
authors.lastname: Chung
authors.forename: Cheuk Yin
authors.initials: CY
authors.lastname: Cho
authors.forename: John Yeuk Hoi
authors.initials: JY
authors.lastname: Tse
authors.forename: Anthony Edward
authors.initials: AE
authors.lastname: James
authors.forename: Hsiao Chang
authors.initials: HC
authors.lastname: Chan
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000201:enzymology / Q000502:physiology; D004622:Embryo, Mammalian / Q000201:enzymology / Q000502:physiology; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000502:physiology; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000502:physiology*; D010063:Ovum / Q000201:enzymology* / Q000502:physiology; D011247:Pregnancy; D013084:Sperm-Ovum Interactions / Q000502:physiology; D013094:Spermatozoa / Q000201:enzymology* / Q000502:physiology; D013480:Superovulation
chemical_list: D007527:Isoenzymes; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II