Uterine activity in cows during the oestrous cycle, after ovariectomy and following exogenous oestradiol and progesterone.
ABSTRACT Uterine activity was monitored in three, 2-year-old nulliparous Ayrshire heifers using intrauterine balloon-tipped catheters and pressure transducers during the oestrous cycle, after ovariectomy and following the intravenous infusion of progesterone and oestradiol-17 beta. During the oestrous cycle uterine activity, as measured by the frequency and amplitude of contractions, was greatest around oestrus and declined during the luteal phase of the cycle; there was a close correlation with peripheral progesterone concentrations. In two animals after bilateral ovariectomy spontaneous uterine activity persisted, whilst in the third animal the uterus was quiescent. In the first two heifers intravenous progesterone infusions reduced the spontaneous uterine activity, eventually completely abolishing it. There was evidence of a dose response effect at the two infusion rates. Oestradiol benzoate infusions initially inhibited spontaneous uterine activity before stimulating contractions with some evidence of a dose relationship. As demonstrated in normal cyclical and steroid-infused animals, uterine activity appears to be under the influence of both hormones although the influence of progesterone is greater.
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ABSTRACT: Endometritis in breeding cattle occurs during the postpartum period, and is associated primarily with contamination of the reproductive tract involving Arcanobacter pyogenes (formerly Actinomyces pyogenes) together with Gram-negative anaerobes. Polymorphonuclear inflammatory cells (PMNs) contribute partly to the defense mechanisms against micro-organisms contaminating the vagina and uterine lumen, whose phagocytic activity depends on bacterial opsonisation by humoral antibodies; significant numbers of lymphocytes are also present. Whilst leukocyte numbers in the uterine lumen are relatively high during metoestrus and dioestrus compared to other phases of the oestrous cycle, their functional activity is unaffected. Humoral antibody concentrations in the reproductive tract are stimulated following exposure to local antigen, and the response is site dependent; of the several different classes of immunoglobulins, IgG predominates in the uterus and IgA the vagina. Only a portion of the total IgG1 found on the uterine lumen is synthesised locally in the endometrium, the remainder and all of the IgG2 is derived from the local uterine blood supply. Generally, concentrations of immunosuppressant proteins present in the uterine lumen increase under progesterone dominance, and these inhibit lymphocyte proliferation, making the uterus more susceptible to infection. The relationship between uterine susceptibility to micro-organism contamination and the luteal phase of the oestrous cycle is still unclear. Intrauterine infusion of immunomodulators such as E. coli lipopolysaccharides (LPS) or oyster glycogen, in healthy cows and those with endometritis, stimulates leukocytes to migrate into the uterine lumen. At a dosage rate of 100 microg, lipopolysaccharides are not absorbed by the healthy endometrium and do not alter the oestrous cycle length. It is unknown, whether a similar dose can be absorbed through an inflamed endometrium in naturally occurring cases of endometritis to cause systemic illness. Currently, prostaglandin F2alpha is recommended for treating endometritis in both cycling and non-cycling cows, but its mode of action in non-cycling cows is not fully understood. The efficacy of endometritis treatment using an intrauterine infusion of an immunomodulator in cases occurring naturally has not been determined on a large scale.Animal Reproduction Science 10/2001; 67(3-4):135-52. · 1.90 Impact Factor
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ABSTRACT: Inflammation of the reproductive tract of a cow occurs when the physical and functional barriers to contamination are breached or specific infection occurs. Commonly, contamination occurs at parturition and to a lesser extent at estrus. Uterine contamination following calving is common, but most healthy cows are able to clear the uterus of bacteria in the first 2 to 3 wk after calving. Persistent infections are more likely to be caused by Actinomyces pyogenes. Specific venereal infections tend to be more host-adapted and produce a lower grade inflammation. Nonspecific bacterial contamination of the endometrium generally induces a neutrophilic influx into the stratum compactum and uterine lumen. Neutrophils phagocytize bacteria with the aid of opsonins in the uterine fluid. Mast cells and eosinophils may also contribute to the inflammatory reaction, which may damage the surface epithelium and release vasoactive substances that allow leakage of serum antibodies into the uterine secretions. Specific antibodies of immunoglobulin (Ig) isotype A, M, G1, and G2 in uterine secretions have been described. In model species, the immune capability of the uterus is influenced by steroid hormones, especially estradiol, which increases secretory component and both IgA and IgG content in uterine secretions and increases the activity of antigen-presenting cells in the uterus. Similar cyclic fluctuations in immune components have been described for cows, including changes in the population of subsurface cytotoxic and helper T cells and changes in the expression of major histocompatibility II antigen on surface cells.Journal of Animal Science 02/1999; 77 Suppl 2:101-10. · 2.09 Impact Factor
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ABSTRACT: To determine the effects of estradiol cypionate (ECP) on measures of reproductive efficiency in postparturient dairy cows. Randomized clinical trial. 273 cows in a single herd in California. Twenty-four hours after parturition, 122 cows were treated with ECP (4 mg, IM); the remaining 151 cows were untreated controls. Percentages of cattle with abnormal findings during uterine palpation 27 to 40 days after parturition were compared between groups, along with days to first artificial insemination (AI), percentages of cows that were not pregnant after the first AI, and days to pregnancy. Treatment with ECP did not have a significant effect on whether results of uterine palpation 27 to 40 days after parturition were abnormal, days to first AI, or odds that a cow would be pregnant after the first AI. Treatment with ECP appeared to have a negative effect on days to pregnancy (hazard ratio, 0.72) Results suggest that prophylactic administration of ECP during the early postparturient period in dairy cows did not have measurable beneficial effects on reproductive efficiency.Journal of the American Veterinary Medical Association 08/2001; 219(2):220-3. · 1.72 Impact Factor