{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T16:32:14Z","timestamp":1773419534875,"version":"3.50.1"},"reference-count":33,"publisher":"The Endocrine Society","issue":"12","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[1999,12,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>In the present study, we characterized four myometrial contraction-associated proteins (mCAPs): oxytocin receptor (OTR), prostaglandin H synthase 2 (PGHS2), estrogen receptor \u03b1 (ER\u03b1), and heat shock protein 90 (Hsp90) messenger RNA (mRNA) expression in the nongravid horn of pregnant sheep and compared them with their expression in the gravid horn that is exposed to a greater degree of stretch. We also examined the regulatory effects of estrogen and progesterone on OTR mRNA expression in ovariectomized nonpregnant sheep. In addition, we determined the ontogeny of mCAP expression in the gravid horn throughout late pregnancy and during spontaneous term labor. Gravid horn and nongravid horn myometria were removed under general anesthesia from control ewes not in labor at 130\u2013140 days gestational age (dGA; n = 3) and during betamethasone-induced labor (n = 6) at the same gestational age. Gravid horn myometrium was also collected from ewes not in labor at 95 dGA (n = 3), 101\u2013110 dGA (n = 3), 111\u2013120 dGA (n = 3), 121\u2013130 dGA (n = 3), 131\u2013140 dGA (n = 3), and 141\u2013145 dGA (n = 4) and from ewes in spontaneous term labor (n = 4). All ewes were carrying single fetuses. Myometrium was also collected from ovariectomized nonpregnant ewes treated with saline (n = 5), estradiol (50 \u03bcg\/day; n = 5), progesterone (0.3 g, intravaginally; n = 5), and estradiol plus progesterone (n = 5). Myometrial RNA was extracted and analyzed by Northern blot for OTR, PGHS2, ER\u03b1, and Hsp90 mRNA, normalized for 18S ribosomal RNA or\u03b2 -actin. ER\u03b1, Hsp90, OTR, and PGHS2 mRNA were all significantly up-regulated during betamethasone-induced labor (P&amp;lt; 0.01) in gravid and nongravid horn myometrium. The level of gravid horn OTR mRNA during labor was 3 times the level of nongravid horn OTR mRNA (P &amp;lt; 0.0001). Gravid horn PGHS2 mRNA was also higher than nongravid horn PGHS2 (P &amp;lt; 0.02). In contrast, in spontaneous term labor nongravid horn, ER\u03b1 and Hsp90 mRNA were similar to gravid horn. Myometrial ER\u03b1 and Hsp90 mRNA remained unchanged throughout late pregnancy and increased at spontaneous term labor (P &amp;lt; 0.05). In contrast, myometrial OTR increased around 130 dGA (P &amp;lt; 0.01) and further increased at spontaneous term labor (P&amp;lt; 0.02). Progesterone significantly inhibited myometrial OTR mRNA expression in nonpregnant sheep and estradiol antagonized progesterone\u2019s inhibitory effect. Mechanical stretch differentially regulated mCAP mRNA expression in the ovine gravid horn and nongravid horn. Mechanical stretch appears largely responsible for increased OTR mRNA and to a lesser degree PGHS2 mRNA. In addition, endocrine factors may be required for full activation of OTR and PGHS2 mRNA associated with labor. ER\u03b1 and Hsp90 mRNA are not under the control of uterine stretch in keeping with our previous results, indicating that systemic hormones such as estradiol, are prime regulators for these two mCAP mRNA expression during labor.<\/jats:p>","DOI":"10.1210\/endo.140.12.7201","type":"journal-article","created":{"date-parts":[[2014,1,8]],"date-time":"2014-01-08T16:10:10Z","timestamp":1389197410000},"page":"5712-5718","source":"Crossref","is-referenced-by-count":34,"title":["Differential Expression of Myometrial Oxytocin Receptor and Prostaglandin H Synthase 2, But Not Estrogen Receptor \u03b1 and Heat Shock Protein 90 Messenger Ribonucleic Acid in the Gravid Horn and Nongravid Horn in Sheep during Betamethasone-Induced Labor1"],"prefix":"10.1210","volume":"140","author":[{"given":"Wen Xuan","family":"Wu","sequence":"first","affiliation":[{"name":"Laboratory for Pregnancy and Newborn Research, Cornell University College of Veterinary Medicine, Ithaca, New York 14853"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiao Hong","family":"Ma","sequence":"additional","affiliation":[{"name":"Laboratory for Pregnancy and Newborn Research, Cornell University College of Veterinary Medicine, Ithaca, New York 14853"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toshiyuki","family":"Yoshizato","sequence":"additional","affiliation":[{"name":"Laboratory for Pregnancy and Newborn Research, Cornell University College of Veterinary Medicine, Ithaca, New York 14853"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Norio","family":"Shinozuka","sequence":"additional","affiliation":[{"name":"Laboratory for Pregnancy and Newborn Research, Cornell University College of Veterinary Medicine, Ithaca, New York 14853"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter W.","family":"Nathanielsz","sequence":"additional","affiliation":[{"name":"Laboratory for Pregnancy and Newborn Research, Cornell University College of Veterinary Medicine, Ithaca, New York 14853"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"80","reference":[{"key":"2020071621352138500_R1","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1055\/s-2007-1016409","article-title":"The initiation and inhibition of labor\u2013toward a molecular understanding.","volume":"12","author":"Lye","year":"1994","journal-title":"Semin Reprod Endocrinol"},{"key":"2020071621352138500_R2","doi-asserted-by":"crossref","first-page":"3096","DOI":"10.1210\/endo.139.7.6109","article-title":"Inhibition of prostaglandin production by nimesulide is accompanied by changes in expression of the \u201ccassette\u201d of uterine labor related genes in the pregnant sheep.","volume":"139","author":"Wu","year":"1998","journal-title":"Endocrinology"},{"key":"2020071621352138500_R3","doi-asserted-by":"crossref","first-page":"653","DOI":"10.1016\/0002-9378(80)90083-6","article-title":"The relationship between myometrial 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