Effect of in-vitro heat stress on prostaglandin and protein secretion by endometrium from pregnant and cyclic gilts at day 14 after oestrus

Endometrium from cyclic (N = 4) and pregnant (N = 4) gilts at Day 14 after oestrus was placed into three bilateral perifusion devices which allow separate perifusion of luminal and myometrial sides. Perifused endometrium was subjected to 39 or 42 degrees C. Incorporation of [3H]leucine into secreted and tissue proteins by endometrial explants following incubation at 39 or 42 degrees C was examined using trichloroacetic acid (TCA) precipitation and one-dimensional SDS polyacrylamide gel electrophoresis. Secretion of PGF was greater from the myometrial side for cyclic gilts (endocrine orientation), but greater from the luminal side for pregnant gilts (exocrine orientation). Regardless of reproductive status or endometrial side, heat stress induced a rapid increase (P less than 0.01) in PGF secretion rates. However, PGF secretion in response to heat stress was greater (P less than 0.01) from the myometrial side and greater (P less than 0.01) for pregnant gilts. PGF secretion rates increased by 63% and 42% from the luminal side, and 40% and 156% from the myometrial side in response to heat stress for cyclic and pregnant gilts, respectively (status x treatment x side interaction; P less than 0.01). Heat stress did not alter incorporation of [3H]leucine into secreted proteins regardless of reproductive status, while incorporation into tissue proteins was decreased (P less than 0.05) by heat stress for pregnant gilts, but not altered for cyclic gilts. Heat stress, in vitro, redirects PGF secretion for endometria of pregnant gilts from an exocrine to an endocrine orientation where it would be available to effect luteolysis and compromise the establishment of pregnancy.     

Prostaglandin secretion by endometrium of pregnant and cyclic cattle at day 17 after oestrus in response to in-vitro heat stress

Bilateral perifusion devices were utilized to measure prostaglandin F-2 alpha (PGF) secretion by bovine endometrium in response to in-vitro heat stress. Tissues were collected at Day 17 after oestrus from cyclic (N = 4) and pregnant (N = 5) cows, placed into 3 perifusion devices, perifused (3 ml/10 min, Krebs-Ringer-bicarbonate [KRB]) for 5 h, and fractions were collected every 10 min. Endometrial tissues within each device were subjected to a different temperature and oxytocin (1 i.u./ml KRB) treatment sequence: (1) control-oxytocin: 1 h at 39 degrees C; 2 h at 39 degrees C, 0.5 h at 39 degrees C with oxytocin, 0.5 h at 39 degrees C and 1 h at 39 degrees C; (2) heat-oxytocin: 1 h at 39 degrees C, 2 h at 42 degrees C, 0.5 h at 42 degrees C with oxytocin, 0.5 h at 42 degrees C and 1 h at 39 degrees C; (3) heat-KRB: 1 h at 39 degrees C, 2 h at 42 degrees C, 0.5 h at 42 degrees C, 0.5 h at 42 degrees C and 1 h at 39 degrees C. Regardless of reproductive status, heat stress induced a rapid increase (P less than 0.01) in PGF secretion rates. Oxytocin induced an increase (P less than 0.01) in PGF secretion for endometrium from cyclic cows regardless of temperature. Endometria from pregnant cows did not respond to oxytocin when perifused at 39 degrees C. However, PGF secretion rates from endometrium of pregnant cows increased (P less than 0.01) in response to oxytocin when perifused under heat stress conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of mineral supplementation on bovine serum, liver and endometrium at day 1 and day 12 of the estrous cycle

The effects of diet on mineral concentrations in serum, liver and endometrium were determined at points in the reproductive cycle in heifers. Dietary treatments extended 134 d and included feeding a basal hay (negative control), basal hay with concentrate (feed control), feed control with phosphorus and feed control with both phosphorus and trace minerals. Samples of serum and liver were taken at the beginning and end of the trial. Within an estrous cycle during the trial (endometrial biopsy) the cows were sampled either at Day 1 or Day 12 for determining progesterone levels and mineral elements in the blood, liver and endometrial tissue. Trace element concentrations in serum and liver did not differ among collection periods pretrial, endometrial biopsy and post breeding nor among treatment groups. However, endometrial tissue concentrations of copper, manganese and zinc were higher at Day 1 than at Day 12 (P < 0.05) in reverse of serum progesterone, which was higher at Day 12 (P < 0.05). Supplemental trace minerals appeared to increase concentrations of copper (P < 0.20), manganese (P < 0.10) and zinc (P < 0.20) at Day 1 but decrease concentrations of these same elements at Day 12 (P < 0.05, P < 0.10 and P < 0.05, respectively). The large differences in trace element concentrations observed in endometrial tissue at the estral phases and under different diets suggest the possible importance of trace elements and trace element nutrition in fertilization and (or) embryo survival.     

Prostaglandin secretion by perifused bovine endometrium: secretion towards the myometrial and luminal sides at day 17 post-estrus as altered by pregnancy

Bilateral perifusion devices were utilized to measure prostaglandin secretion towards luminal and myometrial sides of bovine endometria. Tissues were collected at Day 17 post-estrus from cyclic (n = 4), pregnant (n = 5) and bred but subsequently non-pregnant (n = 6) cows. Tissue from each cow was placed into two perifusion devices, perifused with Krebs-Ringer Bicarbonate solution (3 ml/10 min) for 2.5 h and fractions collected every 10 min. Oxytocin (1 IU/ml) was perifused during fractions 7-12 to the luminal side of one device and to the myometrial side of the other device. Regardless of status, prostaglandin secretion rates (PGF and PGE2) were higher (P less than 0.01) from the luminal side than the myometrial side. Secretion rates of PGF were lower (P less than 0.01) for endometria from pregnant cows than for endometria from cyclic or bred/non-pregnant cows, whereas secretion rates of PGE2 were not affected by pregnancy status. Regardless of the side of perifusion, secretion rates of PGF and PGE2 from endometria of cyclic and bred/non-pregnant cows were elevated (P less than 0.01) throughout the period of oxytocin treatment, whereas prostaglandin secretion by endometria from pregnant cows was not stimulated by oxytocin. Decreased secretion of PGF from endometria of pregnant cows suggests that the corpus luteum and pregnancy are maintained because of an inhibition of endometrial prostaglandin synthesis or an inability to respond to stimulators of prostaglandin synthesis (i.e. oxytocin).     

The effect of trenbolone acetate on the bovine oestrous cycle

The anabolic steroid, trenbolone acetate, affected the bovine oestrous cycle in different ways depending on the timing of administration relative to oestrus and the plasma concentration of trenbolone achieved. Administration before oestrus caused failure of ovulation and a high incidence of a syndrome similar to cystic ovarian disease. High plasma concentrations of trenbolone during the luteal phase of the oestrous cycle prevented luteolysis and maintained progesterone secretion for up to 42 days. Subsequent cycles were not affected.     

Progesterone production, LH receptors, and oxytocin secretion by ovine luteal cell types on days 6, 10 and 15 of the oestrous cycle and day 25 of pregnancy

Corpora lutea were collected from sheep on Days 6, 10, and 15 of the oestrous cycle and Day 25 of pregnancy and dissociated into single cell suspensions. Purified preparations of large and small luteal cells were prepared by elutriation on all days except Day 6. Basal progesterone production by large cells was 6-8-fold higher than by small cells (36-65 vs 6-9 fg/cell/min). Oxytocin secretion was maximal on Day 6 (1.0 fg/cell/min) and declined thereafter. The number of receptors for LH increased between Day 6 and Day 10 and the two cell types had an equal number of receptors on Days 10 and 15 (19,000-23,000). Large cells on Day 25 of pregnancy had fewer receptors (12,000) than did small cells (26,000). Progesterone secretion by small luteal cells from all days examined was stimulated by LH (0.01-1000 ng/ml) in a dose-dependent manner; maximum sensitivity to LH occurred on Day 10. Despite the presence of receptors for LH on large cells, LH failed to stimulate progesterone production. Basal production of progesterone by large and small cells, and the response of small cells to LH, was not influenced by day examined. Re-combinations of large and small cells from Day 10 synergized to increase progesterone secretion. Prostaglandin E-2 (0.1-1000 ng/ml) did not stimulate progesterone secretion by large or small cells.     

Effects of benzyl alcohol on the bovine oestrous cycle and subsequent fertility

A uterine infusion varying in volume from 5 to 40 ml and containing from 0.5 to 2.0 ml of benzyl alcohol shortened the length of the oestrous cycle in cows treated in the early luteal phase and prolonged the oestrous cycle in some cows in the late luteal phase. Results with 399 infusions produced a concentration of cows in oestrus from 8 to 13 days after treatment. The conception rate for 198 inseminations at the first post-treatment oestrus was 59.6% compared to 59.2% obtained in 471 untreated cows.     

Effect of heat stress on conceptus and uterine secretion in the bovine

This study examined the effects of heat stress on conceptus secretion of bovine trophoblastic proteins (bTP) and the uterine secretory environment on Day 17 of pregnancy. After mating to fertile bulls, cows were placed in an environmental chamber at 21 degrees C, 45% RH on Day 7 and were assigned to one of the following treatments on Day 8: Control (21 degrees C, 45% RH), Treatment 1 (37 degrees C, 30% RH) and Treatment 2 (37 degrees C, 40% RH). Cows were slaughtered on Day 17 and each uterine horn was flushed separately with physiological saline to recover the conceptus and uterine contents. The wet weight of the conceptus was recorded and uterine flushings were analyzed for quantitative and qualitative protein changes, prostaglandin F and calcium concentrations. Conceptus tissue was cultured in vitro with 100 muCi of [(3)H]-leucine and the polypeptides released into the medium were analyzed by 2D-PAGE followed by fluorography. Heat stress increased rectal temperature of cows and reduced conceptus wet weight. Uterine content of protein and calcium were increased in the uterine horn ipsilateral to the CL of heat-stressed cows. Although uterine protein increased in heat-stressed cows, no qualitative difference was observed in the polypeptides present in the uterine lumen. Conceptus synthesis and release of bTP were enhanced in treated cows. These responses indicate that heat stress between Days 8 to 17 of pregnancy altered the uterine environment as well as growth and secretory activity of the conceptus.     

Prostaglandin secretion by perifused bovine endometrium: Secretion towards the myometrial and luminal sides at day 17 post-estrus as altered by pregnancy

Bilateral perifusion devices were utilized to measure prostaglandin secretion towards luminal and myometrial sides of bovine endometria. Tissues were collected at Day 17 post-estrus from cyclic (n=4), pregnant (n=5) and bred but subsequently non-pregnant (n=6) cows. Tissue from each cow was placed into two perifusion devices, perifused with Krebs-Ringer Bicarbonate solution (3 ml/10 min) for 2.5h and fractions collected every 10 min. Oxytocin (1 IU/ml) was perifused during fractions 7–12 to the luminal side of one device and to the myometrial side of the other device. Regardless of stratus, prostaglandin secretion rates (PGF and PGE₂) were higher (P< 0.01) from the luminal side than the myometrial side. Secretion rates of PGF were lower (P< 0.01) for endometria from pregnant cows than for endometria from cyclic or bred/non-pregnant cows, whereas secretion rates of PGE₂ were not affected by pregnancy status. Regardless of the side of perifusion, secretion rates of PGF and PGE₂ from endometria of cyclic and bred/non-pregnant cows were elevated (P< 0.01) throughout the period of oxytocin treatment, whereas prostaglandin secretion by endometria from pregnant cows wasnot stimulated by oxytocin. Decreased secretion of PGF from endometria of pregnant cows suggests that the corpus luteum and pregnancy are maintained because of an inhibition of endometrial prostaglandin synthesis or an inability to responsd to stimulators of prostaglandin synthesis (i.e. oxytocin).     

Effect of progesterone on protein synthesis and secretion by cultured epithelial cells from guinea-pig endometrium

Summary The pattern of proteins synthesized and secreted in response to progesterone by guinea-pig endometrial epithelial cell cultured with estradiol-17 was investigated. Glandular epithelial cells were maintained in culture for 3 days on growth medium, then washed three times with a steroid-free medium. After this period, 2 × 10^-8 M estradiol-17 or 2 × 10^-8 M estradiol-17 plus 5 × 10^-7 M progesterone were added to the medium for 48 h. To study biochemical changes, the proteins were labeled by a 6 h pulse of ³⁵S-methionine. The proteins in medium and in cells were analyzed by one- and two-dimensional polyacrylamide gel electrophoresis, followed by fluorography. The addition of progesterone to estradiol-17 in the culture medium caused a change in the patterns of cellular and secreted proteins: one-dimensional gel electrophoresis showed that variation of 8 cellular proteins and 12 secreted proteins was caused by progesterone. Induction of individual proteins by progesterone treatment was observed by two-dimensional gel electrophoresis: one cellular protein (Mr 49000; pI 5.90) and one secreted protein (Mr 14300; pI 4.80) were specifically induced and might serve as markers of progesterone action.     

Effect of androstenedione on the oestrous cycle of the rat

The implantation of Silastic capsules containing androstenedione (release rate 63.2 +/- 4.4 micrograms/24 h) into 4-day cyclic rats resulted in a prolongation of the cycle (P less than 0.001), most rats showing 5-day cycles after the first, largely unaffected cycle. There was a reduction in ovulation rate (P less than 0.01) and lower serum LH levels on the morning of oestrus (P less than 0.01) but serum FSH levels were unaffected.     

Effects of furazolidone on some reproductive hormones during oestrous cycle in the goat

In non-pregnant goat luteolysis is characterized by a decline in peripheral plasma progesterone level and increased peripheral plasma concentrations of testosterone (T) and 5 alpha-dihydrotestosterone (DHT). Daily oral doses of furazolidone (80 mg/kg) between days 10 and 16 delayed luteolysis and suppressed both the decline in progesterone concentrations and the increase in T and DHT level.     

Effect of Hibiscus rosa sinensis Linn. on oestrous cycle & reproductive organs in rats.

The effect of Hibiscus rosa sinensis Linn. on the estrous cycle and reproductive organs was studied in female albino rats. Depending on the dose and duration of treatment, the benzene extract of the flowers disrupted the estrous cycle. Treatment for 30 days resulted in a significant (p less than .05) reduction in the weight of the ovaries, uterus, and pituitary gland. Ovarian follicular atresia and uterine atrophy were observed. Treatment resulted in degranulated gonadotrophs in the pituitary, with the extent of damage being dose-dependent.