Biomedical subjects

W C Becker

Publications and source records attributed to W C Becker.

At least 19 recordsLinked to original sources

PubMed1995

Relationship between phosphoinositide hydrolysis and prostaglandin F2 alpha secretion in vitro from endometrium of cyclic pigs on day 15 postestrus.

The mechanism for the luteolytic release of prostaglandin (PG)F2 alpha in swine is not known. This study examined the potential role of oxytocin (OT)-induced phosphoinositide (PI) hydrolysis in promoting PGF2 alpha secretion in vitro from the endometrium of cyclic gilts on Day 15 postestrus. In Experiment 1, endometrial PI hydrolysis was increased (P < 0.05) by 100 nM OT and was increased quadratically (P < 0.05) by LiCl, but was not affected by the LiCl x OT interaction (P > 0.30). PI hydrolysis was maximal at 50 mM LiCl and declined at 100 mM LiCl. In Experiment 2, endometrial PI hydrolysis and PGF2 alpha secretion were similarly increased (P < 0.01) by 0, 0.1, 1, 10, and 100 nM OT in a dose-dependent manner. In Experiment 3, the linear increase in PI hydrolysis occurring 0, 3, 5, 10, and 20 min after treatment was greater (P = 0.01) for tissue treated with 100 nM OT than for the tissue treated with 0 nM OT. The quadratic increase (P < 0.05) in PGF2 alpha secretion occurring 0, 3, 5, 10, and 20 min after treatment was greater (P < 0.05) for tissue treated with 100 nM OT than for the tissue treated with 0 nM OT. In Experiment 4, AlF4- (an activator of Gp and phospholipase C) similarly increased (P < 0.01) PI hydrolysis and PGF2 alpha secretion. In Experiment 5, PI hydrolysis (P < 0.01) and PGF2 alpha secretion (P < 0.05) were increased by 100 nM OT but were not stimulated by cholera toxin (an activator of Gs and adenylate cyclase). Cholera toxin also did not enhance PI hydrolysis and PGF2 alpha secretion in response to 0.1 or 100 nM OT. These results are consistent with the hypothesis that OT may induce PI hydrolysis to stimulate the endometrial secretion of PGF2 alpha during corpus luteum regression in swine.

Aging↗

PubMed1995

Ovine interferon-tau regulates expression of endometrial receptors for estrogen and oxytocin but not progesterone.

Ovine interferon-tau (oIFN-tau) may stabilize endometrial progesterone receptor (PR) and/or inhibit estrogen receptor (ER) gene expression during pregnancy recognition to suppress endometrial oxytocin receptor (OTR) formation and production of luteolytic prostaglandin (PG) F2 alpha pulses. This study determined whether or not oIFN-tau stabilized PR expression in the endometrium during PR down-regulation by continuous exposure to progesterone. Twenty cyclic ewes were bilaterally ovariectomized and fitted with uterine catheters on Day 2 of the estrous cycle (Day 0 = estrus). Ewes were then assigned randomly to be treated, in a 2 x 2 factorial arrangement, with recombinant oIFN-tau (roIFN-tau; 2 x 10(7) antiviral units per ewe per day) or control proteins (6 mg/day) by intrauterine injection from Days 10 to 14, and with daily i.m. injections of 20 mg progesterone from Days 2 to 14 (P) or progesterone from Days 2 to 14 plus 50 micrograms estradiol-17 beta from Days 12 to 14 (P+E). All ewes were hysterectomized on Day 15. Endometrial PR mRNA (p < 0.01) and protein (p < 0.03) were higher in ewes receiving P+E than in those receiving P alone. However, the increase in PR mRNA and protein was not as great in the endometrium of roIFN-tau-treated ewes as compared to controls (p < 0.08, treatment x steroid). In ewes receiving P alone, PR mRNA and immunoreactive PR were localized to stroma and deep glandular epithelium and were not present in endometrial luminal and shallow glandular epithelium. Values for endometrial ER mRNA (p < 0.02) and ER protein (p < 0.01) were greater in controls than in roIFN-tau-treated ewes regardless of steroid treatment. Among controls, ER mRNA and immunoreactive ER protein were present in the luminal and glandular epithelium and were increased in the epithelium and stroma in ewes receiving estrogen. In contrast, endometrial ER mRNA and immunoreactive ER protein were very low or absent in the endometrium of roIFN-tau-treated ewes and were not increased by estrogen. Among controls, endometrial OTR density was greater (p < 0.09) in ewes treated with P+E than in those treated with P alone. In roIFN-tau-treated ewes, endometrial OTR density was lower (p < 0.01) than in the controls. Results indicate that roIFN-tau did not stabilize or prevent autologous down-regulation of PR mRNA or protein expression in the endometrium. However, roIFN-tau did suppress endometrial ER expression and OTR formation in ewes regardless of steroid treatment. The results support the hypothesis that the antiluteolytic effects of oIFN-tau are to suppress endometrial ER gene expression in the endometrial epithelium, thereby inhibiting formation of OTR and production of luteolytic PGF2 alpha pulses.

Animals↗

PubMed1995

Ovine interferon-tau inhibits estrogen receptor up-regulation and estrogen-induced luteolysis in cyclic ewes.

This study determined whether intrauterine injection of interferon-tau (IFN tau) could block luteolysis in cyclic ewes treated with a luteolytic dose of 17 beta-estradiol benzoate (E) on day 12 of the estrous cycle. Thirty-two ewes were fitted with uterine catheters on day 5 of the estrous cycle and treated with recombinant ovine IFN tau (2 x 10(7) antiviral units/ewe/day) or control proteins (6 mg/day) by intrauterine injection from day 10 until hysterectomy. At 1900 h on day 12, all ewes received 750 micrograms E, im, and were hysterectomized 12, 24, 36, or 48 h post-E administration. Plasma concentrations of progesterone declined in control animals but increased in IFN tau-treated ewes after E injection (P < 0.01, treatment x day interaction). Likewise, total corpus luteum weight decreased in control but not IFN tau-treated ewes after E administration (P < 0.02, treatment x time interaction). In control ewes, endometrial estrogen receptor (ER) messenger RNA (mRNA; P < 0.03) and progesterone receptor (PR) mRNA (P < 0.10) increased after 12 h, whereas concentrations of ER protein (P < 0.02) and PR protein (P < 0.04) increased after 24 h. In situ hybridization and immunohistochemical analyses indicated that ER gene expression increased first in the epithelium at 12 h and then in the stroma by 48 h, whereas PR gene expression first increased in the stroma and then in the epithelium. In control ewes, endometrial oxytocin receptor (OTR) density increased (P < 0.10) after 12 h, with the largest increase occurring between 36-48 h. In IFN tau-treated ewes, endometrial ER mRNA and protein and OTR density did not increase after E administration. Levels of PR mRNA increased (P < 0.01) between 12-36 h, but decreased after 36 h. PR mRNA abundance increased between 12-36 h in the stroma, but not in the epithelium. Concentrations of PR protein were low and did not change in IFN tau-treated ewes. Immunoreactive PR protein was present at low levels in the stroma of all IFN tau-treated ewes. The results indicate that induction of luteolysis by E in control ewes involved sequential increases in endometrial ER mRNA and ER protein in the epithelium that preceded maximal increases in OTR density. Intrauterine injection of recombinant ovine IFN tau prevented luteolysis by inhibiting estrogen-induced increases in endometrial ER and OTR gene expression.

Animals↗

PubMed1995

Intrauterine injection of ovine interferon-tau alters oestrogen receptor and oxytocin receptor expression in the endometrium of cyclic ewes.

This study determined the effects of intrauterine injections of recombinant ovine interferon-tau; (roIFN-tau; 2 x 10(7) antiviral units/day) or control proteins (6 mg/day) from day 11 to day 14 post-oestrus = day 0) on endometrial expression of receptors fro oestrogen, progesterone and oxytocin in cyclic ewes. Plasma concentrations of progesterone were greater on day 15 in ewes receiving roIFN-tau compared with control proteins (P < 0.02, treatment x day). Ewes injected with roIFN-tau had lower endometrial levels or oestrogen receptor mRNA (P > 0.10) and protein (P < 0.01) on day 15 compared with ewes receiving control proteins. In situ hybridization analysis indicated that oestrogen receptor mRNA was more abundant in the luminal and glandular epithelium of control ewes compared with roIFN-tau-treated ewes. Immunoreactive oestrogen receptor was also present in the luminal and glandular epithelium of control, but not roIFN-tau-treated ewes. Endometrial levels of progesterone receptor mRNA and protein were not different (P > 0.10) between control and roIFN-tau-treated ewes. In situ hybridization analyses indicated that progesterone receptor mRNA abundance was low in endometrial epithelium and stroma of both control and roIFN-tau-injected ewes. Immunoreactive progesterone receptors were present in the endometrial stroma and epithelium of control ewes, but confined to the stroma of roIFN-tau-treated ewes. Oxytocin receptor density was lower (P < 0.01) in the endometrium of ewes injected with roIFN-tau than control proteins; however, oxytocin receptor affinity was not affected (P > 0.10) by treatment. Concentrations of 13,14-dihydro-15-ketoprostaglandin F2a (PGFM) were not increased by exogenous oxytocin administration in control and roIFN-tau-treated ewes on days 10 or 12 post-oestrus. However, on day 14, control ewes responded to oxytocin with increased plasma concentrations of PGFM, whereas ewes receiving roIFN-tau remained unresponsive to oxytocin. These results indicate that the an tiluteolytic effects of IFN-tau are to prevent increases in endometrial oestrogen receptor MRNA and protein and oxytocin receptor density which abrogates uterine release of prostaglandin F2a during maternal recognition of pregnancy. IFN-tau may inhibit the synthesis of oestrogen receptor mRNA by a transcriptional or post-transcriptional regulatory mechanism to suppress oxytocin receptor formation during early pregnancy in ewes.

Analysis of Variance↗

PubMed1995

Exogenous oxytocin decreases interestrous interval of cyclic gilts.

Oxytocin (OT) stimulates pulsatile secretion of uterine PGF2 alpha in ruminants, but the role of OT in regulation of the estrous cycle of pigs is not clear. four experiments were performed to examine the effect of exogenous OT on interestrous interval of intact cyclic and hysterectomized gilts. In Exp. 1, i.v. injections of 20 USP units (equivalent to 20 IU) of OT, once/day via an ear vein on d 10, 12, 14, and 16 after estrus, decreased (P < .01) interestrous interval (19.9 +/- .2 d) compared with vehicle-injected control gilts (20.8 +/- .2 d), without affecting ovulation rate (12.1 vs. 12.0 +/- .7 corpora lutea; OT vs control gilts) at subsequent estrus. In Exp. 2, i.v. infusions of 20 USP units of OT, twice/day via an indwelling jugular catheter on d 10 to 16 after estrus, did not alter interestrous interval (20.6 +/- .3 d) compared with control gilts (20.4 +/- .3 d). Concentrations of progesterone in jugular vein plasma did not differ between treatment groups on d 9 to 21 after estrus. In Exp. 3, i.m. injections of 20 USP units of OT, twice/day on d 10 to 16 after estrus, decreased (P < .05) interestrous interval (20.6 +/- .4 d) compared with control gilts (22.3 +/- .4 d). In Exp. 4, i.m. injections of 20 USP units of OT, twice/day on d 10 to 16 after estrus, decreased (P < .05) interestrous interval (20.7 +/- .3 d) compared with control injections in uterine-intact gilts (21.8 +/- .3 d). None of the gilts hysterectomized on d 7 and treated on d 10 to 16 after estrus with either OT or control injections returned to estrus by d 28, and all had increased plasma progesterone on d 21 to 27. Mean weight of individual corpora lutea (502 vs 449 +/- 28 mg; OT vs control gilts) and total weight of corpora lutea (5,758 vs. 5,126 +/- 298 mg; OT vs control gilts) of hysterectomized gilts did not differ between treatment groups at ovariectomy on d 28. These results indicate that 1) exogenous OT administered on d 10 to 16 shortened the interestrous interval of intact cyclic gilts and 2) the effect of OT was uterine-dependent.

Analysis of Variance↗

PubMed1994

Detection of functional oxytocin receptors on endometrium of pigs.

Oxytocin (OT) stimulates phosphoinositide (PI) hydrolysis and prostaglandin (PG) F2 alpha secretion from the endometrium of cyclic pigs, but the presence of specific endometrial receptors for OT has not been demonstrated in this species. Two experiments were performed to detect the presence of functional OT receptors on endometrium collected 15 days post estrus from cyclic gilts. OT receptor density and Kd were determined by receptor assay and Scatchard analysis. Hydrolysis of PI (i.e., incorporation of [3H]inositol into total inositol phosphates) and PGF2 alpha secretion were studied with use of incubations of endometrial explants. Concentrations of PGF2 alpha were log-transformed for analysis of variance and are expressed as means +/- standard error of log-transformed data. In experiment 1, mean density and mean Kd of OT receptors on endometrium of gilts were 29.2 +/- 5.54 fmol/mg protein and 1.59 +/- 0.23 nM, respectively. OT receptor density was significantly correlated with the ability of 100 nM OT to stimulate PI hydrolysis (r = 0.83, p < 0.05) and PGF2 alpha secretion (r = 0.87, p < 0.10), but was not highly correlated with receptor Kd (r = -0.08, p = 0.85). In contrast, OT receptor Kd was not highly correlated with OT-stimulated PI hydrolysis (r = -0.19, p = 0.68) or OT-stimulated PGF2 alpha secretion (r = 0.14, p = 0.86). OT-stimulated PI hydrolysis was also significantly correlated (r = 0.80, p < 0.05) with OT-stimulated PGF2 alpha secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Relationships among endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and prostaglandin F2 alpha secretion in vitro, and plasma concentrations of ovarian steroids before and during corpus luteum regression in cyclic heifers.

Oxytocin stimulates secretion of endometrial prostaglandin (PG) F2 alpha and induces endometrial phosphoinositide hydrolysis around the time of regression of the corpus luteum (CL) in cows. This study investigated the relationship between endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and PGF 2 alpha secretion in vitro, and plasma concentrations of ovarian steroids before and during CL regression in cyclic heifers (i.e., Days 13-19 post-estrus). Reproductive tracts were collected from 16 cyclic heifers on Days 13 (n = 5), 16 (n = 5), and 19 (n = 6). Decreases in mean CL weight (4.7, 4.6, and 3.0 +/- 0.6 g for Days 13, 16, and 19, respectively; p < 0.05) and plasma progesterone (12.2, 10.5, and 4.3 +/- 1.5 ng/ml for Days 13, 16, and 19, respectively; p < 0.01) were detected between Days 16 and 19, indicating that CL regression had been initiated in the group of Day 19 heifers. Mean concentration of plasma estradiol (3.4, 3.8, and 5.6 +/- 1.7 pg/ml for Days 13, 16, and 19, respectively) did not differ significantly (p > 0.5) among days of the estrous cycle. Concentration of endometrial oxytocin receptors increased (p < 0.06) during the estrous cycle (36, 49, and 789 +/- 234 fmol/mg protein on Days 13, 16, and 19, respectively), but the greatest increase (p < 0.05) occurred between Days 16 and 19. Similarly, incorporation of [3H]inositol into endometrial inositol phosphates induced in vitro with 100 nM oxytocin also increased (p < 0.01) during the estrous cycle (5121 vs. 5819, 4529 vs. 7239, and 5888 vs 68,096 +/- 18,564 dpm/g tissue for control vs. oxytocin-treated endometrium on Days 13, 16, and 19, respectively) with the greatest increase (p < 0.01) in responsiveness to oxytocin occurring between Days 16 and 19.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Effect of group thawing on post-thaw viability of bovine spermatozoa packaged in .5-milliliter French straws.

The objective of this study was to determine the effects of thawing groups of 2, 5, 10, 15, or 20 .5-ml French straws on post-thaw spermatozoal viability. Thermostatically controlled and nonthermostatically controlled thawing baths were compared. Using a split-plot design, semen from 10 bulls was extended in egg yolk citrate, frozen, and then thawed (in the respective groups) at 36 degrees C in two types of thawing baths. Motility and percentage of intact acrosomes were determined immediately after thawing (0 h) and again after 4 h of incubation at the respective temperature of each thawing bath. Neither percentage of intact acrosomes nor motility was influenced by the number of straws thawed at 0 h (P greater than .05). Thawing bath had no effect (P greater than .05) on motility or percentage of intact acrosomes at 0 h. Bull variation was significant in both the 0- and 4-h evaluations. After 4 h of incubation, there was a significant (P less than .05) straw number x thawing bath interaction. When 15 or 20 straws were thawed in the thermostatically controlled bath there was a reduction (P less than .05) in motility and percentage of intact acrosomes. However, in the nonthermostatically controlled bath there was no reduction in motility and percentage of intact acrosomes as the size of straw group increased. Our results indicate that, when using a nonthermostatically controlled thawing bath, semen packaged in .5-ml straws can be thawed in groups of 20 without an effect on post-thaw sperm viability.

Analysis of Variance↗

PubMed1988

Influence of cornual insemination on conception in dairy cattle.

The objective of this study was to compare conception to artificial insemination (AI) services in dairy cattle when semen was deposited into the uterine body or into both uterine horns (cornual insemination). Nine herdsman inseminators (HI) in four commercial dairy herds in Washington constituted the experimental units. Herds ranged in size from 393 cows to 964 cows. The duration of the experiment was 12 mo in three herds and 18 mo in the fourth herd. At the beginning of the experiment all inseminators were trained to deposit semen in the body of the uterus. Inseminators were instructed to use this method for 6 mo. Following employment of body deposition, the same inseminators were retrained to deposit one-half of the semen into the right uterine horn and one-half into the left uterine horn. Cornual inseminations were performed for 6 mo. A total of 4,178 services constituted the data set. Milk samples were collected from cows on the day of insemination and later were assayed for progesterone (P4). There was variation (P less than .01) in conception associated with month of insemination and insemination method (P less than .001). The monthly variation was not associated with season of the year. Least squares means for conception when semen was deposited in the uterine body was 44.7%, compared with 64.6% when cornual insemination was employed. The insemination treatment X inseminator interaction was not significant. Results suggest that cornual insemination provides an alternative to deposition of semen in the uterine body.

Animal Husbandry↗

PubMed1987

Inequality in function of the right and left ovaries and uterine horns of the mouse.

Inequality in function of the left and right ovaries and uterine horns of mice was evaluated in three separate experiments. In Exp. 1, the effect of position in the reproductive tract on various reproductive characteristics was evaluated in 158 pregnant hybrid mice. Ovulation rate, number of fetuses, total fetal weight and total placental weight were higher (P less than 0.05) on the right than the left on Day 18 of pregnancy (vaginal plug = Day 1). In Exp. 2, the effect of previous sham or unilateral ovariectomy (right or left) in mated Swiss-Webster mice was compared with unoperated mated controls (N = 17-24/treatment). In control mice, ovulation rate, total fetal weight and ovarian weight were higher (P less than 0.05) on the right than left side. Surgery (sham or unilateral, ovariectomy) decreased (P less than 0.005) ovulation rates, number of fetuses, ovarian weights, total fetal weight and total placental weight on Day 18 of pregnancy. Unilateral ovariectomy decreased (P less than 0.05) ovulation rates and ovarian weights more than did sham operation. Ovulation rates were higher (P less than 0.01) when the left ovary was manipulated or removed rather than the right ovary. For Exp. 3, pairs of 8 hybrid mouse embryos each (morulae and blastocysts) were surgically transferred to the left and right uterine horns of the same (bilateral, N = 15) or different (unilateral, N = 28) Swiss-Webster recipients. In almost all incidences, embryo survival (to Day 18 of pregnancy) was twice as high (P less than 0.05) in right than left uterine horns. We conclude that the left and right ovaries and uterine horns are not equal in function in Swiss-Webster and a hybrid strain of mice.

Animals↗

PubMed1987

In-vivo and in-vitro effects of ethanol on mouse preimplantation embryos.

In Exp. 1A, hybrid mice (N = 10) were provided with food and 25% (v/v) ethanol as the only source of liquid for 72 h, beginning at the detection of the copulatory plug (08:00 h, Day 1). Control mice received food and tap water. Food consumption (P less than 0.001) but not total caloric intake (P greater than 0.05) was less for the alcohol-treated mice than the controls. Ethanol-derived calories averaged 35% of caloric intake during the 72 h of treatment. Alcohol-treated animals showed a dramatic weight loss until Day 5 while controls gained weight (P less than 0.05). Ethanol consumption did not influence pregnancy rate, litter size or litter weight. In Exp. 1B, animals were treated as in Exp. 1A, but were killed at various times between 24:00 h, Day 1, and 08:00 h, Day 4. Trunk blood was used to determine haematocrit and serum to determine alcohol concentration. Haematocrit was greater (P less than 0.05) for all alcohol-treated mice than for controls at all time periods sampled except one. Dehydration was therefore probably responsible for the weight loss seen in Exps 1A and 1B. Average blood alcohol concentrations fluctuated with time of day and day of treatment. Average maximum concentration was 91.4 mg ethanol/100 ml serum. In Exp. 2, hybrid mouse 2-cell embryos were cultured in vitro in 0 or 0.1% ethanol (Exp. 2A) and 0 or 1.0% ethanol (Exp. 2B) for 8 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

The effect of restraint stress in early pregnancy in mice.

Mice were exposed to 5 h of restraint stress on Days 1-3, 4-6, or 1-6 of pregnancy in the morning (08:30-13:30 h, a.m.) or afternoon (13:30-18:30 h, p.m.). Stress reduced the pregnancy rate from 90 to 52% (P less than 0.005) and average litter size on Day 18 from 8.2 to 5.2 young (P less than 0.005). Stress for 6 days was more effective than for 3 days (P less than 0.005) and an a.m. stress was more effective than a p.m. stress (P less than 0.005) in reducing the average litter size. Animals examined on Day 7 after 6 days of a.m. stress had decreased numbers of normal corpora lutea (CL), increased numbers of abnormal CL, decreased serum progesterone concentrations and tended to have fewer implantation sites. Abnormalities of embryo transport and implantation were also present. Changes in CL morphology and embryo transport and development were evident on Day 4 after only 3 days of restraint stress. These results show that many reproductive events of early pregnancy can be disrupted by restraint stress.

Animals↗

PubMed1980

Quality of semen stored in on-the-farm semen tanks.

We assessed the damage to frozen semen packaged in French straws stored for 2 yr in 60 on-the-farm semen tanks on 56 Washington dairy farms. Percentage of motile spermatozoa and percentage of spermatozoa with intact acrosomes were not affected significantly by position of the semen on the rack (top or bottom goblet). The semen in 3 of the 60 tanks was lost to tank failure.

Acrosome↗

PubMed1978

The relationship of sperm viability and concentration to serum-induced head-to-head agglutination of bovine spermatozoa.

Individual samples of bull semen were treated by filtration to remove immotile spermatozoa and by the addition of 10% heifer serum. There was significantly (P less than 0.01) greater serum-induced agglutination in the filtered than in the unfiltered samples. Head-to-head agglutination was also greater (P less than 0.01) in dilute sperm suspensions when compared to concentrated sperm suspensions.

Animals↗

PubMed1977