Progesterone-regulated secretion of the serpin-like proteins of the ovine and bovine uterus.

The uterine milk (UTM) proteins are the major progesterone-regulated proteins secreted by the sheep uterus during pregnancy. Recently, proteins related to the UTM proteins have been identified in uterine secretions of the pregnant cow and sow. The present objective was to determine the time course for induction of the UTM proteins in sheep and cattle. Twelve ovariectomized ewes received subcutaneous injections of either vehicle for 10 days or 100 mg/d of progesterone for 10 days or 30 days. The presence of UTM proteins was examined by Western blotting of uterine flushings and by immunoabsorption of radiolabeled UTM proteins from conditioned medium of endometrial explant cultures performed with [35S]methionine precursor. Uterine milk proteins were present in slight amounts in uterine flushings and endometrial-conditioned culture medium of some ewes in the control group, but amounts of proteins were greatly enhanced by progesterone after 10 or 30 days of treatment. Prolonged exposure to progesterone (30 days versus 10 days) increased amounts of UTM proteins. Immunohistochemical analysis of endometrium indicated that the major site of UTM proteins was the glandular epithelium. In the second experiment, nine ovariectomized cows were treated daily with vehicle for 12 days or 750 mg progesterone for 12 or 30 days. Uterine flushings and conditioned endometrial culture medium were examined for UTM proteins by Western blotting. Uterine milk proteins were present to some degree in cows treated with vehicle, and an enhancement in amounts of UTM proteins was not observed until after 30 days of progesterone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Uterine secretions of the cow contain proteins that are immunochemically related to the major progesterone-induced proteins of the sheep uterus.

Proteins that cross-react with antiserum to the major progesterone-induced proteins found in the pregnant sheep uterus, the uterine milk proteins (UTM-proteins), were detected as radiolabelled secretory products of endometrium from pregnant cows. Cross-reactive proteins included a form at 57,000 molecular weight as well as other lower-molecular-weight variants found in lower amounts. Similar proteins were also detected in uterine fluid from a cow at day 270 of gestation. Using immunohistochemical procedures, proteins that cross-reacted with antiserum to sheep UTM-proteins could be localized to the epithelial cells of endometrial glands in the cow. Results indicate that UTM-protein-like molecules are secreted by the endometrium of the cow during pregnancy.

Secretion of the major progesterone-induced proteins of the sheep uterus by caruncular and intercaruncular endometrium of the pregnant ewe from days 20-140 of gestation.

An experiment was performed to evaluate the types and quantity of proteins secreted by intercaruncular endometrium at days 20, 60, 100 and 140 of gestation and caruncular endometrium from days 100 and 140 of gestation. Tissues were obtained from ewes made unilaterally pregnant. Based on SDS polyacrylamide gel electrophoresis (SDS-PAGE), the major proteins present in uterine fluid at days 60-140 of gestation were the uterine milk proteins (UTM-proteins), a pair of structurally-related, progesterone-induced polypeptides with molecular weights of 55,000 and 57,000. These proteins were also present in uterine fluid at day 20, but the major protein at this time migrated coincident with albumin. Cultured explants of endometrium at all days of pregnancy produced UTM-proteins as their major radiolabelled product for both caruncular and intercaruncular endometrium. The amount of protein secretion in vitro was greater (P less than .04) for intercaruncular endometrium than for caruncular endometrium but was not significantly affected by stage of gestation or local presence of the conceptus. Immunohistochemical analysis revealed that UTM-proteins were present in glandular and luminal epithelium of intercaruncular endometrium and in both epithelial and stromal elements of caruncular endometrium. It was concluded that the UTM-proteins are produced earlier than previously described (i.e., day 20). In addition, caruncles contribute to the uterine secretory protein milieu through the secretion of proteins that are similar to that produced by the glandular intercaruncular epithelium.

Effect of intrauterine and intramuscular administration of recombinant bovine interferon alpha 1 on luteal lifespan in cattle.

Intrauterine and intramuscular administration of interferon was tested for effectiveness in extending luteal lifespan in cattle. Intrauterine infusion of 1 mg of recombinant bovine interferon-alpha I1, twice daily, to lactating dairy cows from d 14 to 21 after estrus extended interestrous interval (30.4 +/- 1.91 d versus 24.8 +/- .58 d) and functional lifespan of the corpus luteum (28.4 +/- 2.01 d versus 23.6 +/- .75 d). In another experiment, twice daily intramuscular injection of 20 mg interferon to Simmental heifers from d 15 to 19 extended interestrous intervals (24.6 +/- 1.36 d versus 20.6 +/- .49 d) and functional lifespan of the corpus luteum (23.2 +/- .37 d versus 20.2 +/- .73 d). In a third experiment, pubertal dairy heifers received twice daily intramuscular injections of 0, 2.5, 5.0, or 10.0 mg/injection of interferon from d 14 to 21 after estrus. The three interferon-treated groups had longer interestrous intervals and functional luteal lifespans than the control group. Interestrous intervals were 22.0 +/- .68, 24.0 +/- 1.14, 24.6 +/- 1.17, and 25.4 +/- .97 d, respectively. The present data strengthen the theory that an interferon-alpha-like molecule can regulate luteal function in cattle. Such a regulatory compound might prove useful in schemes to reduce embryonic mortality caused by aberrant secretion of embryonic interferon.

Presence of the major progesterone-induced proteins of the sheep endometrium in fetal fluids.

Allantoic and amniotic fluids were collected on Days 60 (n = 3), 100 (n = 4), and 140 (n = 3) of pregnancy. The presence of uterine milk proteins (UTM-proteins) in these samples was evaluated by Ouchterlony immunodiffusion and enzyme-linked immunoabsorbant assay (ELISA). Eight of ten samples of allantoic fluid and three of ten samples of amniotic fluid produced one or two immunoprecipitin bands against antiserum to UTM-proteins. Each band fused with immunoprecipitin bands from UTM-proteins purified from uterine fluid. Data from a semi-quantitative ELISA indicated that allantoic fluid from all ewes and amniotic fluid from six of ten ewes contained immunoreactive UTM-proteins. Concentrations of UTM-proteins in these fluids were not statistically affected by day of gestation (p greater than 0.10), but tended to decline as gestation advanced. Greater concentrations of UTM-proteins were detected in allantoic fluid than in amniotic fluid (p less than 0.05). The physical characteristics of the immunoreactive material in allantoic and amniotic fluids were examined by polyacrylamide gel electrophoresis and Western blotting. The immunoreactive material was found to possess pIs and molecular weights identical to UTM-proteins. These results indicate that fetal fluids contain material that reacts with antiserum to UTM-proteins and has physical properties similar to UTM-proteins. It is likely, therefore, that the UTM-proteins are transported across the placenta during gestation, perhaps to serve some function in the fetal compartment.