Effect of prostaglandins on sperm transport and fertilization in the rabbit

Endogenous prostaglandin F2α concentrations in bovine whole semen, seminal plasma, and extended semen

A series of experiments were conducted to quantify PGF2α in bovine semen, seminal plasma, and extended semen, and to determine if PGF2α was synthesized or released during extension of bovine semen. Concentrations of PGF2α were measured in paired samples of whole and extended semen from beef and dairy bulls. Concentrations of PGF2α did not differ between beef and dairy (mean±SEM, 273.8±42.8 vs. 210.3±18.5 pg/mL, respectively; P=0.12), but tended (P=0.08) to be greater for whole compared with extended semen (255.5±29.8 vs. 194.5±17.0 pg/mL). Whole semen was extended at eight dilution rates (regardless of initial sperm concentration), using a diluent consisting of two fractions. Samples collected after each dilution step resulted in four subsamples. Concentrations of PGF2α in subsamples decreased (P<0.001) at higher dilution rates and later steps of extension. Subsequently, whole semen and seminal plasma were extended at three dilution rates. Initial PGF2α concentration was greater (P<0.001) for whole semen compared with seminal plasma. During extension, PGF2α synthesis or release resulted in less disparity, but the amount synthesized or released was greater (P=0.03) for semen compared with seminal plasma. We concluded that synthesis or release of PGF2α during extension resulted in concentrations similar to whole semen.

Effect of intrauterine treatment with prostaglandin E2 prior to insemination of mares in the uterine horn or body

Two trials were conducted to investigate the effects of intrauterine infusion of PGE2 and uterine horn insemination on pregnancy rates in mares achieved by breeding with a suboptimal number of normal spermatozoa. Estrus was synchronized and mares were teased daily with a stallion to detect estrus. Mares in estrus were examined by transrectal palpation and ultrasonography to monitor follicular status. On the first day a 35-mm diameter follicle was present, hCG (1500 IU, iv) was administered and the mares were bred the next day. Mares (Trial 1, n = 34; Trial 2, n = 28) were inseminated with 25 million total spermatozoa from either a stallion with good semen quality (Trial 1) or poor semen quality (Trial 2). In each trial, mares were assigned to 1 of 4 treatment groups as follows: Group PGE-HI - infusion of 0.25 mg PGE2 into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the proximal end of the same uterine horn; Group PGE-BI - infusion of 0.25 mg PGE2 into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the uterine body; Group SAL-HI - infusion of 1 mL sterile saline into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the proximal end of the same uterine horn; or Group SAL-BI - infusion of 1 mL sterile saline into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the uterine body. After breeding, mares were examined daily by transrectal ultrasonography to confirm ovulation, and were re-examined 14 to 16 d after ovulation for pregnancy status. Data were analyzed by Chi-square. Overall pregnancy rates were 59% for stallion 1 and 29% for stallion 2. Group pregnancy rates did not differ for mares bred by either stallion (P > 0.10). Pregnancy rates were not altered by horn insemination for either stallion (P > 0.10). Intrauterine infusion of PGE2 improved pregnancy rate in mares bred by the stallion with good quality semen (P < 0.05), but did not alter pregnancy rate in mares bred by the stallion with poor quality semen (P > 0.10). Further research is warranted to determine if intrauterine infusion of PGE2 will enhance spermatozoal colonization of the oviduct and pregnancy rates in mares, and if PGE-treatment will improve pregnancy rates achieved by subfertile stallions.

Effect of prostaglandin F2α at insemination on sperm cell numbers and pregnancy rate in beef cattle

Fourteen cycling, nonlactating, multiparous beef cows were artificially inseminated (AI) 10 to 12 h after the onset of natural estrus. One unit of frozen-thawed semen containing 100 x 10(6) total sperm cells was deposited into the body of the uterus. Immediately after AI, alternating cows were injected i.m. with either 25 mg (5 ml) of prostaglandin F(2)alpha (PGF) or 5 ml of 0.9% saline-benzyl alcohol control solution. Cows were slaughtered 16 +/- 1 h post AI, oviducts were retrieved, segmented into thirds (upper, middle and lower) and flushed with 1 ml of 0.2% gluteraldehyde in phosphate buffered saline. The number of sperm cells was counted using a phase contrast microscope. There were no right or left side effects (P=0.61) on the number of sperm cells recovered per oviduct within cow (389 vs 553; average SEM = 219). PGF had no effect (P=0.77) on the number of sperm cells recovered per oviduct (642 vs 300; average SEM = 231 for PGF and control females, respectively). More sperm cells were recovered from the lower third segment (P<0.05) compared with the middle and upper segments. Ovulation tended to affect (P=0.10) the number of sperm cells recovered per oviduct (742 vs 200; average SEM = 231). Additionally, 114 beef females (68 Angus x Hereford heifers and 46 Chianina crossbred postpartum suckled cows) were treated as described above following AI at natural estrus with 20 x 10(6) motile sperm cells. Pregnancy rates did not differ significantly in heifers (70.6 vs 58.8%) or in Chianina cows (34.8 vs 52.2%) for control and PGF-treated females, respectively. Overall, pregnancy rates were identical between control and PGF-treated females at 56.1%. In this study, PGF treatment immediately following AI in beef cattle had no effect on the number of sperm cells in the oviducts or on the pregnancy rate.

Sperm survival and transport in the female reproductive tract

Fertilization failure, mostly due to absence of sperm in the oviducts, is a major cause of reproductive inefficiency of farm animals. Sperm may be transported to the oviducts of cattle and sheep within a few minutes after mating or insemination, but these sperm probably fertilize few ova. Slower transport, with establishment of sperm populations in each segment of the reproductive tract, requires a few to several hours. In swine, sperm capable of fertilizing ova reach the oviducts in less than 1 h. Smooth muscle contractions of the reproductive tract, ciliary beats, fluid currents, and flagellar activity of sperm are primary mechanisms of sperm transport. Sperm become hyperactive in the oviducts in association with capacitation. Most sperm in an inseminate drain from the female reproductive tract within a few minutes or hours after insemination; remaining sperm are removed from the tract by slower drainage or phagocytosis. Sperm survival and transport in estrous ewes is reduced drastically by pastures with high estrogen content and by regulating estrus with progestogen or prostaglandin F2 alpha. The cervix is the initial site of inhibition of sperm transport in ewes, and endocrine imbalances probably are the basis of inhibition. Sperm transport problems generally are associated with immobilization and death of sperm in the uterus and anterior segments of the cervix within 2 h after mating. After gilts are inseminated with frozen-thawed semen, relatively few sperm are retained in the reproductive tract, apparently accounting for lowered fertilization rates. Sperm transport has been improved by adding to semen or administering to females such compounds as prostaglandin F2 alpha, oxytocin, estradiol, phenylephrine, or ergonovine. Estradiol, prostaglandin F2 alpha, phenylephrine, and ergonovine administered to rabbits at insemination each increased fertilization rates.

Effects of prostaglandins E-1, E-2, F-1a and F-2a on human sperm motility

Effects of the addition of 100 micrograms each of prostaglandins E1, E2, F1a and F2a were seen on the motility, fructose utilization and total ATPase activity of human spermatozoa. PGE2 enhanced sperm motility and fructose utilization and decreased the whole sperm ATPase activity. While PGE1 had no effect on any of the parameters studied, PGF1a and PGF2a decreased sperm motility to some extent. Fructose utilization was reduced after PGF1a addition only. No change in the activity of ATPase was observed after treatment with F series of prostaglandins.

Effect of tris (hydroxymethyl) aminomethane salt of prostaglandin F2alpha on post-thaw motility of bovine spermatozoa

The effect of the tris (hydroxymethyl) aminomethane salt of prostaglandin F2alpha on the post-thaw motility of bovine spermatozoa was evaluated for two ejaculates from each of five bulls. This salt of prostaglandin F2alpha was added to the glycerol fraction of the extender to provide 37.5, 112.5, or 337.5 microgram of active prostaglandin F2alpha per .5-ml straw. Post-thaw progressive motility was depressed by the addition of the salt of prostaglandin F2alpha. Motilities averaged over both 0 and 2 h of post-thaw incubation were 19.3, 17.8, 13.6, and 5.8% for 0, 37.5, 112.5, and 337.5 microgram.

The effect of locally administered PGE2 on the contractility of the nonpregnant human uterus in vivo

The effect of locally administered prostaglandin E2 on the sensitivity and reactivity of the nonpregnant human uterus during the menstrual cycle was studied in seven women. An increase in uterine contractility in response to as little as 0.25 mug PGE2 could be observed during both the mid-proliferative and mid-secretory phases of the menstrual cycle, but around ovulation a marked decrease in sensitivity to PGE2 was noted. An inhibition of uterine motility was observed during menstruation in response to 30--40 mug PGE2. Endogenous E prostaglandin normally occurs in the secretory endometrium in levels comparable to the amount of exogenous PGE2 which elicited increased or decreased uterine activity in this study. These findings suggest that PGE2 may play an important role in the cyclical regulation of uterine motility during the menstrual cycle.