Protein, prostaglandin and steroid synthesis in caruncular and intercaruncular endometrium of sheep before implantation

Abstract

The effect of the presence of a preimplantation embryo on protein concentration, rate of protein synthesis, beta-glucuronidase and acid phosphatase activities, steroid metabolism and prostaglandin F production in caruncular and intercaruncular tissue have been studied for sheep at Day 15 of pregnancy. The rate of protein synthesis in both tissues was greater in pregnant than in non-pregnant animals, although the difference was only significant in caruncular endometrium. The effect in caruncular tissue was mimicked in ovariectomized animals treated with oestradiol. Localized changes in the caruncular tissue were observed in respect of PGF with an increased tissue concentration, an enhanced basal release when the tissue was incubated in the presence of indomethacin, and a decreased net production. Maximum production of PGF in the 2 tissues was unaffected by the presence of an embryo but it was enhanced by oestradiol or progesterone treatment in intercaruncular tissue of ovariectomized ewes. beta-Glucuronidase and acid phosphatase activities and steroid metabolism were unaffected by pregnancy. However, in ovariectomized animals oestradiol treatment stimulated beta-glucuronidase activity in endometrium and myometrium. Progesterone treatment stimulated acid phosphatase activity in the intercaruncular endometrium. The results show that amongst several endometrial constituents investigated relatively few changes were detected by Day 15 post coitum, one day before definitive attachment. Those changes that did occur were associated with the dynamics of PGF production and the rate of protein synthesis, and were consistent with the production of a PGF binding component in caruncular endometrium which may be concerned with the protection of luteal function by redirection of uterine PGF production. Canonical variate analysis revealed that changes on Day 15 of pregnancy were mimicked most closely in caruncular tissue by treatment of ovariectomized ewes with oestradiol and progesterone, and in intercaruncular tissue by oestradiol treatment only.

Oestrogen receptors and protein synthesis in caruncular and intercaruncular endometrium of sheep before implantation

“…The presence of a blastocyst on or before Day 15 is associated with changes in the rate of protein synthesis and in prostaglandin (PG) F-2a and PGE-2 content and concentration in the endometrium (Lewis et al, 1977;Lewis, Jenkins, Fogwell & Inskeep, 1978 Findlay et al, 1981). Furthermore, uterine flushings collected on or before Day 15 of pregnancy contain higher levels of protein (Roberts, Parker & Symonds, 1976;Ellinwood et al, 1979), (Ellinwood et al, 1979), glycosidase activity (Roberts et al, 1976) and pregnancy-associated antigen (Staples, Lawson & Findlay, 1978) than do those from non-pregnant ewes.…”

“…That synthesis of protein in endometrium of non-pregnant ewes is under the control of ovarian steroids is now well established (Stone, Murphy & Miller, 1978;Stone et al, 1979;Miller et al, 1979;Findlay et al, 1981 (Greiss & Anderson, 1970;Greiss & Miller, 1971), suggesting that this is unlikely. Although oestradiol-17 ß can mimic the effects of pregnancy on endometrial protein synthesis Miller et al, 1979;Findlay et al, 1981) and uterine blood flow (Huckabee, Crenshaw, Curet, Mann & Barron, 1970) there is no conclusive evidence that this steroid is involved. Neither the trophoblast (Gadsby et al, 1980) nor the endometrium (Findlay et (Koligian & Stormshak, 1977b;Stone et al, 1979;Miller et al, 1979).…”

“…Neither the trophoblast (Gadsby et al, 1980) nor the endometrium (Findlay et (Koligian & Stormshak, 1977b;Stone et al, 1979;Miller et al, 1979). Whilst progesterone can decrease oestrogen receptors, it is without effect on oestradiol-induced protein synthesis, RNA : DNA ratio and enzyme activities in endometrial tissue of ovariectomized ewes Miller et al, 1979;Findlay et al, 1981). This apparent discrepancy may reflect differences in the function of the two major cell types in the endometrium (McCormack & Glasser, 1980), stromal cells predominantly in caruncular endometrium and epithelial cells predominantly in intercaruncular endometrium (Huslig, Fogwell & Smith, 1979).…”

Arylsulphatase A activity and sulphatide concentration in the female rabbit oviduct are under physiological hormonal influence

“…These enzymes play a part in several important reproductive processes, such as ovulation (Dimino & Elfont, 1980), capacitation (Gwatkin & Hutchinson, 1971), acrosome reaction (McRorie & Williams, 1974), implantation and early pregnancy (Moulton et al, 1978). Several workers have demonstrated the hormonal regulation of lyso-somal hydrolases in the reproductive system (Jelinek & Jelinkova, 1975;Findlay et al, 1981;Rahi & Srivastava, 1983;Vitaioli et al, 1987bVitaioli et al, , 1988b. Obviously, by control of the enzyme systems, sex hormones also regulate concentrations of the respective natural substrates.…”

Retinol-Binding Protein Gene Expression in Cyclic and Pregnant Endometrium of Pigs, Sheep, and Cattle1

“…In fact, since conceptuses of large domestic farm animals undergo noninvasive epitheliochorial placentation and the uterine epithelium is never eroded during pregnancy, uterine secretions may be required for nutritional support of the conceptus throughout gestation [1]. For this reason, uterine secretions of cattle [3][4][5][6][7][8], sheep [9][10][11][12], and pigs [13][14][15][16][17] have received considerable attention.…”