title: Role of ovarian progesterone and potential role of prostaglandin F2alpha and prostaglandin E2 in modulating the uterine response to infectious bacteria in postpartum ewes.
abstract: In sheep and cattle, the postpartum uterus is resistant to bacterial challenge until after corpora lutea develop. A 2 x 2 factorial arrangement of treatments was used to determine whether prostaglandins may mediate the effects of progesterone in transforming the postpartum uterus from resistant to susceptible. On d 14 postpartum, ewes (n = 6/group) were ovariectomized or sham ovariectomized, and the vena cava was catheterized for daily collection of uteroovarian-enriched blood. From d 15 to 20, ewes received twice daily intramuscular injections of progesterone in sesame oil or plain sesame oil. On d 20, each uterus received 75 x 10(7) cfu of Arcanobacterium pyogenes and 35 x 10(7) cfu of Escherichia coli. Uteri were collected on d 25 and examined for signs of infection. For each blood sample, unstimulated and mitogen-stimulated lymphocyte proliferation was measured as [3H]thymidine incorporation, smears were prepared for differential white blood cell (WBC) counts, and progesterone, prostaglandin F2alpha, (PGF2alpha), and prostaglandin E2 (PGE2) were quantified. All 12 progesterone-treated, but only two of the 12 oil-treated, ewes developed uterine infections (P < 0.001). Progesterone treatment increased (P < 0.001; 3.1 vs 1.5 ng/mL) and ovariectomy decreased (P < 0.001; 3.7 vs 0.9 ng/mL) vena caval progesterone. Progesterone treatment reduced (P < 0.01) PGF2alpha, (303.9 vs 801.3 pg/mL), and PGF2alpha was greater (P < 0.05) before than after inoculation (626.4 vs 478.8 pg/mL). The PGE2 concentration was greater in progesterone-treated, ovary-intact ewes than in ewes in the other groups (ovariectomy x progesterone treatment; P < 0.01). Ovariectomy increased (P < 0.005; 4.4 vs 2.9 pmol) and progesterone treatment decreased (P < 0.05; 3.2 vs 4.1 pmol) concanavalin A-stimulated lymphocyte proliferation. Ovariectomy increased lipopolysaccharides-stimulated proliferation (P < 0.05; 2.4 vs 1.9 pmol). For neutrophils per 100 WBC, the ovariectomy x progesterone and progesterone x period interactions were significant (P < 0.01). The ovariectomy x progesterone interaction was significant (P < 0.01) for lymphocytes per 100 WBC. Ovariectomy decreased monocytes (P < 0.001; 10 vs 13) and increased eosinophils (P < 0.001; 10 vs 5) per 100 WBC. Progesterone makes the postpartum uterus in ewes susceptible to infection, but ovariectomy allows ewes to remain resistant; uterine prostaglandins may mediate this change. This model creates opportunities to determine the mechanisms responsible for the shift from resistance to susceptible.
authors.affiliation: ARS, USDA, US Sheep Experiment Station, Dubois, ID 83423-9602, USA. glewis@pw.ars.usda.gov
authors.forename: G S
authors.initials: GS
authors.lastname: Lewis
mesh_terms: D000193:Actinomycetales Infections / Q000276:immunology / Q000662:veterinary; D000818:Animals; D015237:Dinoprost / Q000502:physiology*; D015232:Dinoprostone / Q000502:physiology*; D004198:Disease Susceptibility / Q000662:veterinary; D004927:Escherichia coli Infections / Q000276:immunology / Q000662:veterinary; D005260:Female; D010052:Ovariectomy / Q000662:veterinary; D049590:Postpartum Period / Q000276:immunology; D011374:Progesterone / Q000494:pharmacology* / Q000502:physiology; D011645:Puerperal Infection / Q000276:immunology / Q000662:veterinary; D011897:Random Allocation; D012756:Sheep / Q000276:immunology*; D012757:Sheep Diseases / Q000276:immunology* / Q000382:microbiology; D014591:Uterine Diseases / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D014599:Uterus / Q000187:drug effects / Q000276:immunology
chemical_list: D011374:Progesterone; D015237:Dinoprost; D015232:Dinoprostone