Nitric oxide levels and nitric oxide synthase expression in uterine samples from mares susceptible and resistant to persistent breeding-induced endometritis.
OBJECTIVE
Breeding-induced endometritis (BIE) in the mare is resolved by 36 hr after insemination in resistant mares. However, 10-15% susceptible broodmares fail to do so because of impaired uterine contractility between 7 and 19 hr after exposure to seminal or bacterial challenge, which reduces their fertility.


METHODS
Nitric oxide (NO) in uterine secretions, and expression of nitric oxide synthase (NOS) in uterine biopsies were compared between susceptible and resistant groups 13 hr after insemination.


RESULTS
Susceptible mares had a higher NO in their uterine secretions and greater inducible NOS (iNOS) expression in their biopsies compared with resistant mares.


CONCLUSIONS
The NO mediates smooth muscle relaxation, but its role in persistent BIE has not been determined. Our data suggests a possible role of NO, either directly or in a NO-associated pathway, in delayed uterine clearance.
Alghamdi
Abdorrahman S
AS
Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN 55108, USA. algh0007@umn.edu
Foster
Douglas N
DN
Carlson
Cathy S
CS
Troedsson
Mats H T
MH
D000818:Animals; D001947:Breeding; D004716:Endometritis / Q000209:etiology / Q000276:immunology / Q000378:metabolism* / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000209:etiology / Q000276:immunology / Q000378:metabolism*; D006736:Horses; D007150:Immunohistochemistry; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000276:immunology / Q000378:metabolism*
D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase