Expression of epidermal growth factor (EGF) and its receptor in bovine endometrium throughout the luteal phase: effects of EGF on prostaglandin production in endometrial cells

Epidermal growth factor (EGF) is produced in bovine endometrium throughout the estrous cycle. However, little is known about the expression of the EGF receptor (EGFR) and the roles of EGF in bovine endometrium. To clarify whether EGF is involved in local regulation of bovine endometrial function, first we determined the EGF protein and the expression of EGFR mRNA in endometrial tissues throughout the luteal stages. EGF protein concentration was higher(P < 0.05) in the mid (days 8-12) luteal stage than in the other luteal stages. EGFR mRNA expression was higher (P < 0.05) in the mid and late (days 15-17) luteal stages than in the other luteal stages. To investigate the protein concentrations of EGF and EGFR mRNA expression in cultured bovine endometrial cells, epithelial and stromal cells were isolated between day 0 and day 4 post-ovulation from 22 uteri. Both EGF protein concentration and EGFR mRNA expression were higher (P < 0.05) in epithelial cells than in stromal cells. Then, to examine the possible role of EGF in the regulation of prostaglandin F2α (PGF2α) and prostaglandin E2 (PGE2), cultured endometrial epithelial and stromal cells were exposed to EGF (0, 1, 10 and 100 nm) for 24 h. In epithelial cells, EGF (10 and/or 100 nm) increased (P < 0.05) PGF2α and PGE2 secretion, but in stromal cells EGF (100 nm) increased (P < 0.05) PGF2α, but not PGE2 secretion. These results indicate that 1) the highest amount of EGF is produced by bovine endometrium at the mid-luteal stage, 2) endometrial EGFR mRNA expressions are higher at mid and late-luteal stages than other stages, 3) EGF is expressed mainly by uterine epithelial cells and 4) EGF has the ability to increase PGE2 and PGF2α production in both epithelial and stromal cells and therefore may play a role in local regulation of uterine function.

Expression of epidermal growth factor (EGF) and its receptor in bovine endometrium throughout the luteal phase: effects of EGF on prostaglandin production in endometrial cells

Epidermal growth factor (EGF) is produced in bovine endometrium throughout the estrous cycle. However, little is known about the expression of the EGF receptor (EGFR) and the roles of EGF in bovine endometrium. To clarify whether EGF is involved in local regulation of bovine endometrial function, first we determined the EGF protein and the expression of EGFR mRNA in endometrial tissues throughout the luteal stages. EGF protein concentration was higher(P < 0.05) in the mid (days 8-12) luteal stage than in the other luteal stages. EGFR mRNA expression was higher (P < 0.05) in the mid and late (days 15-17) luteal stages than in the other luteal stages. To investigate the protein concentrations of EGF and EGFR mRNA expression in cultured bovine endometrial cells, epithelial and stromal cells were isolated between day 0 and day 4 post-ovulation from 22 uteri. Both EGF protein concentration and EGFR mRNA expression were higher (P < 0.05) in epithelial cells than in stromal cells. Then, to examine the possible role of EGF in the regulation of prostaglandin F2α (PGF2α) and prostaglandin E2 (PGE2), cultured endometrial epithelial and stromal cells were exposed to EGF (0, 1, 10 and 100 nm) for 24 h. In epithelial cells, EGF (10 and/or 100 nm) increased (P < 0.05) PGF2α and PGE2 secretion, but in stromal cells EGF (100 nm) increased (P < 0.05) PGF2α, but not PGE2 secretion. These results indicate that 1) the highest amount of EGF is produced by bovine endometrium at the mid-luteal stage, 2) endometrial EGFR mRNA expressions are higher at mid and late-luteal stages than other stages, 3) EGF is expressed mainly by uterine epithelial cells and 4) EGF has the ability to increase PGE2 and PGF2α production in both epithelial and stromal cells and therefore may play a role in local regulation of uterine function.(AU)

Catalase and glutathione peroxidase expression in bovine corpus luteum during the estrous cycle and their modulation by prostaglandin F2α and H2O2

Antioxidant enzymes seem to play roles in controlling the luteal function and the luteolytic action of prostaglandin F2 α (PGF). The aim of this study was to clarify the roles of catalase (CAT) and glut athione peroxidase (GPx) in the luteolytic action of PGF in both corpus luteum (CL) and cultured luteal cells. Corpora lutea were collected at the early ( days 2 - 3), developing ( days5 - 6), mid ( days8 - 12), late ( days15 - 17) and regressed ( days19 - 21) luteal stages (n = 5 CL/stage) and at 0 , 2 and 24 h after luteolytic PGF administration (0 h) on d ay 10 (n = 5 cows / time point ) . Catalase protein and the activities of CAT and GPx increased from the early to mid - luteal stage, then all decreased (P < 0.05), reaching their lowest levels at the regressed luteal stage. The levels of GPx1 protein were lower in the regressed luteal stage than in other stages (P < 0.05). Immunohistochemical examination also revealed the expression of CAT and GPx1 protein in the bovine C L tissue. Injection of a luteolytic dose of PGF increased luteal GPx1 protein and GPx activities at 2 h but suppressed them at 24 h. Catalase protein and CAT activity did not change at 2 h but CAT activity decreased (P < 0.05) at 24 h. Prostagla ndin F2α (1 μ M ) and H 2 O 2 (10 μ M ) decreased CAT and GPx1 protein expression and activity at 24 h in cultured luteal cells isolated from mid - luteal stage CL (n = 3 CL per each experiment). Interestingly, CAT protein and activity did not change while GPx1 protein and activity increased at 2 h in luteal cells treated with PGF and H 2 O 2 (P < 0.05). The down - regulation of CAT and GPx, and their activities during structural luteolysis might enhance the accumulation of reactive oxygen species, which would result in both increasing luteal PGF production and cell death to complete CL regression in cattle.

Catalase and glutathione peroxidase expression in bovine corpus luteum during the estrous cycle and their modulation by prostaglandin F2α and H2O2

Antioxidant enzymes seem to play roles in controlling the luteal function and the luteolytic action of prostaglandin F2 α (PGF). The aim of this study was to clarify the roles of catalase (CAT) and glut athione peroxidase (GPx) in the luteolytic action of PGF in both corpus luteum (CL) and cultured luteal cells. Corpora lutea were collected at the early ( days 2 - 3), developing ( days5 - 6), mid ( days8 - 12), late ( days15 - 17) and regressed ( days19 - 21) luteal stages (n = 5 CL/stage) and at 0 , 2 and 24 h after luteolytic PGF administration (0 h) on d ay 10 (n = 5 cows / time point ) . Catalase protein and the activities of CAT and GPx increased from the early to mid - luteal stage, then all decreased (P < 0.05), reaching their lowest levels at the regressed luteal stage. The levels of GPx1 protein were lower in the regressed luteal stage than in other stages (P < 0.05). Immunohistochemical examination also revealed the expression of CAT and GPx1 protein in the bovine C L tissue. Injection of a luteolytic dose of PGF increased luteal GPx1 protein and GPx activities at 2 h but suppressed them at 24 h. Catalase protein and CAT activity did not change at 2 h but CAT activity decreased (P < 0.05) at 24 h. Prostagla ndin F2α (1 μ M ) and H 2 O 2 (10 μ M ) decreased CAT and GPx1 protein expression and activity at 24 h in cultured luteal cells isolated from mid - luteal stage CL (n = 3 CL per each experiment). Interestingly, CAT protein and activity did not change while GPx1 protein and activity increased at 2 h in luteal cells treated with PGF and H 2 O 2 (P < 0.05). The down - regulation of CAT and GPx, and their activities during structural luteolysis might enhance the accumulation of reactive oxygen species, which would result in both increasing luteal PGF production and cell death to complete CL regression in cattle. (AU)

Regulation of superoxide dismutase by prostaglandin F2α in the bovine corpus luteum

The interaction between prostaglandin F2 α (PGF) and r eactive o xygen species (ROS) is crucial for regulating the life span of the corp us luteum (CL) . The local accumulation of ROS is mainly controlled by copper/zinc superoxide dismutase (SOD1). Thus, PGF may induce luteolysis by decreas ing the expression of SOD and its bioactivity. Here, we examined whether SOD1 is involved in the luteol ytic action of PGF in the bovine corpus luteum (CL). SOD activity gradually increased from the early to late luteal stage and then decreased to the lowest level at the regressed luteal stage. SOD1 protein expression and SOD activity increased at 2 h but de creased at 24 h after administration of a luteolytic dose of PGF . In addition , PGF and H 2 O 2 increased SOD1 protein expression and SOD activity at 2 h but suppressed it at 24 h in cultured luteal cells . Furthermore, H 2 O 2 increased PGF production by luteal c ells in a dose - and time - dependent manner. PGF , in turn, induced ROS production. T hese results indicate that PGF via interaction with ROS regulate s bovine luteal SOD 1 in a biphasic manner with an initial increase at 2 h followed by a decrease at 24 h . The down regulation of SOD1 during structural luteolysis may enhance ROS production and luteal cell death to ensure the regression of the bovine C .

Regulation of superoxide dismutase by prostaglandin F2α in the bovine corpus luteum

The interaction between prostaglandin F2 α (PGF) and r eactive o xygen species (ROS) is crucial for regulating the life span of the corp us luteum (CL) . The local accumulation of ROS is mainly controlled by copper/zinc superoxide dismutase (SOD1). Thus, PGF may induce luteolysis by decreas ing the expression of SOD and its bioactivity. Here, we examined whether SOD1 is involved in the luteol ytic action of PGF in the bovine corpus luteum (CL). SOD activity gradually increased from the early to late luteal stage and then decreased to the lowest level at the regressed luteal stage. SOD1 protein expression and SOD activity increased at 2 h but de creased at 24 h after administration of a luteolytic dose of PGF . In addition , PGF and H 2 O 2 increased SOD1 protein expression and SOD activity at 2 h but suppressed it at 24 h in cultured luteal cells . Furthermore, H 2 O 2 increased PGF production by luteal c ells in a dose - and time - dependent manner. PGF , in turn, induced ROS production. T hese results indicate that PGF via interaction with ROS regulate s bovine luteal SOD 1 in a biphasic manner with an initial increase at 2 h followed by a decrease at 24 h . The down regulation of SOD1 during structural luteolysis may enhance ROS production and luteal cell death to ensure the regression of the bovine C .(AU)