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  • Author: M A Mirando x
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Intrauterine injection of ovine interferon-τ alters oestrogen receptor and oxytocin receptor expression in the endometrium of cyclic ewes

T E Spencer, N H Ing, T L Ott, J S Mayes, W C Becker, G H Watson, M A Mirando, and F W Bazer

ABSTRACT

This study determined the effects of intrauterine injections of recombinant ovine interferon-τ (roIFN-τ; 2 × 107 antiviral units/day) or control proteins (6 mg/day) from day 11 to day 14 post-oestrus (oestrus=day 0) on endometrial expression of receptors for oestrogen, progesterone and oxytocin in cyclic ewes. Plasma concentrations of progesterone were greater on day 15 in ewes receiving roIFN-τ compared with control proteins (P<0·02, treatment × day). Ewes injected with roIFN-τ had lower endometrial levels of oestrogen receptor mRNA (P<0·10) and protein (P<0·01) on day 15 compared with ewes receiving control proteins. In situ hybridization analysis indicated that oestrogen receptor mRNA was more abundant in the luminal and glandular epithelium of control ewes compared with roIFN-τ-treated ewes. Immunoreactive oestrogen receptor was also present in the luminal and glandular epithelium of control, but not roIFN-τ-treated ewes. Endometrial levels of progesterone receptor mRNA and protein were not different (P>0·10) between control and roIFN-τ-treated ewes. In situ hybridization analyses indicated that progesterone receptor mRNA abundance was low in endometrial epithelium and stroma of both control and roIFN-τ-injected ewes. Immunoreactive progesterone receptors were present in the endometrial stroma and epithelium of control ewes, but confined to the stroma of roIFN-τ-treated ewes. Oxytocin receptor density was lower (P<0·10) in the endometrium of ewes injected with roIFN-τ than control proteins; however, oxytocin receptor affinity was not affected (P>0·10) by treatment. Concentrations of 13,14-dihydro-15-keto-prostaglandin F2α (PGFM) were not increased by exogenous oxytocin administration in control and roIFN-τ-treated ewes on days 10 or 12 post-oestrus. However, on day 14, control ewes responded to oxytocin with increased plasma concentrations of PGFM, whereas ewes receiving roIFN-τ remained unresponsive to oxytocin. These results indicate that the antiluteolytic effects of IFN-τ are to prevent increases in endometrial oestrogen receptor mRNA and protein and oxytocin receptor density which abrogates uterine release of prostaglandin F2α during maternal recognition of pregnancy. IFN-τ may inhibit the synthesis of oestrogen receptor mRNA by a transcriptional or post-transcriptional regulatory mechanism to suppress oxytocin receptor formation during early pregnancy in ewes.

DOI:
https://doi.org/10.1677/jme.0.0150203
Volume 15: Issue 2,
Pages:
203–220 (18 total)
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Changes in progesterone and oestrogen receptor mRNA and protein during maternal recognition of pregnancy and luteolysis in ewes

T L Ott, Y Zhou, M A Mirando, C Stevens, J P Harney, T F Ogle, and F W Bazer

ABSTRACT

This study characterized changes in levels of mRNA and protein for endometrial oestrogen receptors (ERs) and progesterone receptors (PRs) during luteolysis and maternal recognition of pregnancy. For cyclic and pregnant ewes, endometrium was collected on days 10, 12, 14, or 16 post-oestrus (4 ewes/day for each status) for the measurement of ER and PR mRNA and protein. The amount of receptor mRNA is expressed in relative units above background, measured from radiographs of dot-blot hybridization of total endometrial RNA with ER and PR cDNAs. At hysterectomy, jugular vein blood samples were collected and assayed for progesterone, total corpus luteum weight was recorded and, in vitro, endometrial oxytocin-stimulated inositol phosphate formation was estimated. In pregnant ewes, plasma progesterone increased gradually between days 10 and 16 (P<0·01), corpus luteum weight was stable at approximately 08 g and oxytocin did not stimulate endometrial formation of inositol phosphates in vitro. In contrast, in cyclic ewes, plasma progesterone decreased from day 10 to day 16 (P<0·01), corpus luteum weight decreased after day 14 to approximately 0·48 g (P=0·05) and oxytocin stimulated an increase of approximately 1300% in the endometrial formation of inositol phosphates on day 16. cDNAs specifically hybridized with 1·6 and 31 kb transcripts for PR mRNA and a 6·5 kb transcript for ER mRNA. In cyclic ewes, the amount of PR mRNA increased from day 10 to maximum levels on days 14–16. The number of PRs decreased from day 10 (225 pmol/mg DNA) to day 12 (0·98 pmol/mg DNA) and then increased from day 14 to day 16 (2·8 pmol/mg DNA). In pregnant ewes, PR mRNA levels were greatest on days 10–12 and decreased by approximately 50% by day 16. In contrast, the number of PRs was relatively unchanged from day 10 to day 16 (1·53 to 103 pmol/mg DNA). In cyclic ewes, the amount of ER mRNA was lowest at day 10 and increased fivefold by day 16. The number of ERs remained relatively unchanged from day 10 to day 14 (607 pmol/mg DNA) and increased by day 16 (1612 pmol/mg DNA). In pregnant ewes, ER mRNA decreased by approximately 80% from day 12 to day 16. Similarly, the number of ERs decreased from day 10 to day 16 (5·41 to 205 pmol/mg DNA). Correlations between ER mRNA and PR mRNA (r=0·68), ERs and PRs (r = 0·50) and ER mRNA and ERs (r=0·50) were high (P<0·01). PR mRNA and PRs, PR mRNA and ERs, and ER mRNA and PRs were not correlated (P>0·1). Pregnancy had the apparent effect of stabilizing the number of endometrial PRs and inhibiting ER production by decreasing both the amount of ER mRNA and ER protein.

DOI:
https://doi.org/10.1677/jme.0.0100171
Volume 10: Issue 2,
Pages:
171–183 (13 total)
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Changes in progesterone and oestrogen receptor mRNA and protein and oxytocin receptors in endometrium of ewes after intrauterine injection of ovine trophoblast interferon

M A Mirando, J P Harney, Y Zhou, T F Ogle, T L Ott, R J Moffatt, and F W Bazer

ABSTRACT

This study determined whether twice-daily intrauterine injections of ovine conceptus secretory proteins (oCSP) containing type-I trophoblast interferon (25 μg/uterine horn) from day 11 to day 15 post-oestrus (oestrus = day 0) could alter the binding capacities of endometrial receptors for oxytocin, progesterone and oestrogen in cyclic ewes when compared with control ewes receiving serum protein (SP) injections. Injections of oCSP on days 11–15 post-oestrus decreased concentrations of oestrogen receptors (P<0·06), oestrogen receptor mRNA (P<0·05) and progesterone receptors (P<0·08) in endometrium on day 16 when compared with SP-infused control ewes, which were undergoing corpus luteum regression on days 14–16. Injection of oCSP also decreased the number (P<0·10) and affinity (P<0·06) of oxytocin receptors. Inositol phosphate formation induced in the endometrium on day 16 by 100 nm oxytocin in vitro was highly correlated with the concentration (r≥0·93, P<0·001) and K d (r= –0·91, P<0·01) of oxytocin receptors in SP-infused ewes, but was not as highly correlated with concentration (r≤0·83, P<0·06) and K d (r≤ –0·40, P>0·40) of oxytocin receptors in oCSP-infused ewes. This indicates that oCSP disrupted the relationship between oxytocin receptor binding and oxytocin-induced activation of its second messenger system. These results indicate that antiluteolytic type-I trophoblast interferon may prevent oxytocininduced luteolytic pulsatile secretion of prostaglandin F2α during maternal recognition of pregnancy in sheep, by reducing the synthesis and affinity of endometrial oxytocin receptors. Inhibition of other components of the oxytocin receptor—phospholipase C system by ovine trophoblast interferon may also be involved in reducing endometrial responsiveness to oxytocin. Ovine trophoblast interferon may inhibit the synthesis of endometrial oestrogen receptors to inhibit responsiveness to oxytocin during early pregnancy in ewes.

DOI:
https://doi.org/10.1677/jme.0.0100185
Volume 10: Issue 2,
Pages:
185–192 (8 total)