Biomedical subjects

R D Geisert

Publications and source records attributed to R D Geisert.

At least 55 records · Page 3Linked to original sources

PubMed1993

Uterine cellular changes in 2',5'-oligoadenylate synthetase during the bovine estrous cycle and early pregnancy.

The signal for maternal recognition of pregnancy in cattle is bovine trophoblast protein-1 (bTP-1), a Type I trophoblast interferon. One of the many functions of interferons is the induction of the 2',5'-oligoadenylate (2-5[A]) system, which is involved in cell division and selective degradation of mRNA. The present study focused on the cellular changes of 2-5(A) synthetase in bovine endometrium during the estrous cycle and early pregnancy. Ability of recombinant bTP-1 to stimulate activity of the enzyme in uterine cells throughout the estrous cycle was also evaluated in vitro. Surface epithelium, glandular epithelium, and stroma were enzymatically separated in cows on Day 5, 10, 15, or 18 postestrus and on Day 15 or 18 of pregnancy. Cell samples were lysed and frozen for determination of the endogenous cellular content of 2-5(A) synthetase. Additional cells obtained during the estrous cycle were cultured and treated with increasing doses of recombinant bovine interferon alpha (rbIFN-alpha) or recombinant bTP-1 (rbTP-1). During the estrous cycle, 2-5(A) synthetase was greatest on Day 5 and declined approximately 10-fold by Day 15 (p < 0.01). Cellular content of 2-5(A) synthetase was similar among all three endometrial cell types. In the gravid horn of pregnant animals, presence of a conceptus significantly increased (p < 0.01) 2-5(A) synthetase in all endometrial cell types compared to levels on Days 15 and 18 of the estrous cycle. On Day 18, levels of 2-5(A) synthetase were 30-fold greater (p < 0.01) in epithelium (surface and glandular) from pregnant cows compared to that from cyclic cows.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗

PubMed1993

Retinol-binding protein gene expression in cyclic and pregnant endometrium of pigs, sheep, and cattle.

Retinol-binding protein (RBP) is a major secretory product of conceptuses and endometrium of the large domestic animals. The present study examined the abundance of RBP mRNA in cyclic and early pregnant endometrium of pigs, sheep, and cattle and confirmed the presence of RBP mRNA in preiimplantation conceptuses of the large domestic animals. Northern blot analysis, using porcine liver RBP cDNA as the probe, detected a 1.0-1.1-kb transcript in conceptuses and endometrium collected during the preiimplantation period of pregnancy in pigs (Day 15), sheep (Day 16), and cows (Day 18). Slot-blot analysis of RBP mRNA in endometrium of pigs, sheep, and cows indicated differential RBP gene expression across days and statuses in pigs and sheep and across days alone in cows. In pigs, RBP gene expression was low to undetectable at Days 0, 5, and 10 of the estrous cycle and Day 10 of pregnancy. Levels of RBP mRNA increased (p < 0.06) from Days 10 to 12 and further (p < 0.001) to Day 15 across both statuses. At Day 18, RBP mRNA levels decreased (p < 0.01) in cyclic pigs but remained elevated in endometrium of pregnant pigs. In sheep, levels of RBP mRNA increased between Days 10 and 12 and 14 in both cyclic and pregnant ewes; however, between Days 14 and 16, RBP mRNA levels remained elevated in cyclic endometrium but decreased (p < 0.01) in endometrium of pregnant ewes. In a second experiment, RBP mRNA levels increased (p < 0.01) between Days 0-5 and Days 13-15 of the estrous cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Failure of luteolysis and extension of the interoestrous interval in sheep treated with the progesterone antagonist mifepristone (RU 486).

The progesterone antagonist mifepristone (RU 486) was injected i.m. into ewes during the early luteal phase of the oestrous cycle to test the hypothesis that duration of uterine exposure to progesterone from the corpus luteum initiates luteolysis through the proper timing of endometrial oxytocin receptor expression and pulsatile secretion of PGF2 alpha coincident with release of luteal oxytocin. In Expt 1, duration of cycle, the PGF2 alpha metabolite 15-keto-13,14-dihydro-PGF2 alpha (PGFM) and oxytocin concentrations were measured in ewes treated on days 5, 6, 7 and 8 of the oestrous cycle with either 2.5 or 5.0 mg RU 486 kg-1 day-1 (n = 4 per group); control ewes (n = 6) were injected i.m. with 80% ethanol (diluent). In Expt 2, the presence of functional uterine oxytocin receptors was determined indirectly on day 12 of the cycle by measuring the plasma PGFM response to oxytocin challenge (20 iu, i.v.) in diluent-treated ewes (n = 3) and in ewes treated with 2.5 mg RU 486 kg-1 day-1 on days 6, 7 and 8 of the oestrous cycle. Duration of the oestrous cycle of control ewes (16 +/- 1 days) was extended beyond day 24 (day 0 = oestrus) in 10 of 11 ewes treated with RU 486 as determined by daily exposure of ewes to a ram and by measurement of progesterone concentrations in plasma in the two experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Concentrations of insulin-like growth factor-I, estradiol and progesterone in follicular fluid of ovarian follicles during early pregnancy in cattle.

To determine if the presence of the developing conceptus is associated with changes in intrafollicular concentrations of insulin-like growth factor-I (IGF-I), estradiol (E2) and/or progesterone during early pregnancy in cattle, either pregnant (n=16) or nonpregnant (n=15) cows were slaughtered on Day 10, 15 or 18 postestrus. Ovaries and follicular fluid were collected. Follicles were grouped by diameter: 1.0 to 3.9 mm (small; n=63), 4.0 to 7.9 mm (medium; n=128), and >/= 8.0 mm (large; n=38). The average diameter of large follicles was greater (P<0.05) in pregnant than in nonpregnant cows on Day 10, but on Day 18 it was greater (P<0.05) in nonpregnant than in pregnant cows (11.3 vs 9.7 mm). Status (pregnant vs nonpregnant) did not affect (P>0.10) follicular fluid progesterone nor IGF-I concentrations. In contrast, the status and days postestrus affected (P<0.05) follicular fluid E2 concentrations. Follicular fluid E2 levels in the three follicle size-categories on Day 10 did not differ (P>0.10) between pregnant and nonpregnant cows. However, on Days 15 and 18 postestrus, follicular fluid E2 concentrations in pregnant cows was lower (P<0.05) in large follicles than in nonpregnant cows. We conclude that the presence of a developing conceptus early in pregnancy may alter follicular growth and inhibit follicular E2 production in cattle. These effects appear to be mediated by factors other than IGF-I.

Journal Article↗

PubMed1992

Endocrine events associated with endometrial function and conceptus development in cattle.

Regulation and timing of luteolysis during the bovine oestrous cycle is controlled by the initiation and length of progesterone stimulation. Results have demonstrated that early administration of progesterone shortens the interoestrous interval in the ewe and cow, and removal of progesterone stimulation through a progesterone receptor antagonist delays luteolysis in sheep. Current data suggest that down-regulation of progesterone receptors in the uterine epithelium may initiate events involved in the synthesis and release of prostaglandin F2 alpha (PGF2 alpha) for luteolysis. Progesterone is also involved in the stimulation of the uterine secretions that regulate conceptus growth and the release of the bovine trophoblast protein-1 (bTP-1) necessary for inhibiting endometrial PGF2 alpha release. Conceptus secretion of bTP-1, a Type I trophoblast interferon, increases the concentration of the cellular enzyme 2',5'-oligoadenylate synthetase within the endometrium. The biological role of 2',5'-oligoadenylate synthetase in the establishment of pregnancy is discussed.

Animals↗

PubMed1992

Porcine conceptus proteins: antiviral activity and effect on 2',5'-oligoadenylate synthetase.

Interferon-like proteins synthesized by conceptuses of domestic ruminants inhibit luteolysis during early pregnancy. Although pig conceptuses secrete trophoblast interferons during the period of CL maintenance, estrogen is involved with maintenance of the CL. The principal purposes of this work were to confirm production of trophoblast interferons by porcine conceptuses and to compare the effect of trophoblast interferons on endometrium of pigs and cattle. When measured using Madin-Darby bovine kidney (MDBK) cells challenged with vesicular stomatitis virus, antiviral activity in uterine flushings from cyclic gilts was not detectable throughout the estrous cycle; however, in pregnant gilts, antiviral activity increased from undetectable amounts to 4-11 x 10(3) U on Days 14, 16, and 18. Porcine embryos in culture produced 1,100 U/embryo/ml/24 h. Porcine conceptus secretory proteins induced 2',5'-oligo(A) synthetase in MDBK cells and in endometrial explants of cows but had no measurable effect on 2',5'-oligo(A) synthetase activity of endometrial explants of pigs. Similarly, endometrial 2',5'-oligo(A) synthetase of pregnant pigs was unaffected in vivo during the period of maximal synthesis of conceptus secretory proteins. Porcine conceptus secretory proteins produced no detectable increase in serum antiviral activity or 2',5'-oligo(A) synthetase activity of blood mononuclear leukocytes in utero-ovarian venous blood. These results suggest that conceptus interferons of pigs play different roles in the establishment of pregnancy compared to their roles in ruminants.

2',5'-Oligoadenylate Synthetase↗

PubMed1992

Differential expression, during the estrous cycle and pre- and postimplantation conceptus development, of messenger ribonucleic acids encoding components of the pig uterine insulin-like growth factor system.

The temporal patterns of endometrial expression for mRNAs encoding insulin-like growth factor-I (IGF-I), IGF-II, IGF-binding protein-2 (IGFBP-2), and the type I IGF receptor (IGF-IR) were elucidated in cyclic and pregnant pigs. Peak levels of IGF-I mRNAs occurred on day 12 in cyclic and early pregnant gilts, while IGFBP-2 mRNA levels were lowest on day 10. Pregnant gilt endometrium had higher levels of both RNA classes than the corresponding cyclic endometrium. IGF-II and IGF-IR mRNAs remained low during this period. In pregnant pig endometrium and rat uterus, levels of IGF-I mRNA decreased, while those of IGF-II and IGFBP-2 mRNAs increased with stage of pregnancy. Decreased endometrial production of IGF-I mRNA during pregnancy paralleled that in the myometrium. IGF-II mRNA tissue abundance was placenta greater than endometrium greater than myometrium. In contrast, IGFBP-2 mRNA levels were higher in endometrium than in placenta and myometrium. Endometrial expression of IGF-II mRNAs was limited to surface and glandular epithelial cells; epithelial and stromal cells expressed IGFBP-2 mRNAs at comparable levels. Expression of IGF-IR mRNAs was low and did not change with pregnancy. The endometria of two breeds of pigs that exhibit different levels of prolificacy were also examined for IGF mRNAs. On day 12, endometrium from the Large White breed with high conceptus mortality had higher levels of IGF-II and IGFBP-2 mRNAs than did endometrium from the Meishan breed with low conceptus mortality. Expression of IGF-I mRNAs was higher in endometria of Meishan than Large White gilts on day 12. The differential expression of IGF mRNAs with stage of gestation and the correlation of relative ratios of IGF mRNAs with prolificacy during the critical period of maternal recognition of pregnancy suggest an important role(s) for IGFs in conceptus and fetal development.

Animals↗

PubMed1992

Steroidogenic enzyme expression in porcine conceptuses during and after elongation.

The following studies were performed to investigate levels of expression of steroidogenic enzymes in porcine conceptuses between days 12 and 21 postmating and to correlate these findings with estrogen levels in conceptus tissues. In the first experiment, levels of steroidogenic enzymes in individual day 12 blastocysts were examined by Western immunoblot analyses. In a second experiment, Northern blot, slot blot, and Western immunoblot analyses for 17 alpha-hydroxylase cytochrome P450 (P450(17) alpha) were performed on conceptus tissue pooled for each uterine horn of sows on days 12, 14, 16, and 21 postmating. On day 12, P450(17) alpha) protein was detectable in 6-mm blastocysts, with highest levels apparent in 10- to 15-mm (tubular) blastocysts. Filamentous blastocysts appeared to have less P450(17) alpha) protein than did littermate tubular blastocysts. Side-chain cleavage cytochrome P450 (P450scc) and aromatase cytochrome P450 (P450arom) followed a pattern similar to that of P450(17) alpha. 3 beta-Hydroxysteroid dehydrogenase was undetectable by Western analysis in blastocysts at the stages examined, but was detectable in placenta from fetuses at later stages of gestation. In pooled tissue, P450(17) alpha) protein and mRNA were greater in day 12 conceptuses than in conceptuses from all other days. However, transition from the tubular to the filamentous form on day 12 postmating was associated with a dramatic decline in the level of P450(17) alpha) mRNA. The conceptus 17 beta-estradiol concentration was highly correlated with immunoreactive P450(17) alpha) protein and hybridizable P450(17) alpha) mRNA over days 12, 14, 16, and 21 postmating. These data suggest that the decrease in blastocyst estrogen secretion occurring after the time of elongation in porcine conceptuses may be due to a decrease in P450(17) alpha expression.

3-Hydroxysteroid Dehydrogenases↗

PubMed1991

Effect of estrogen inhibitors on conceptus estrogen synthesis and development in the gilt.

Two estrogen antagonists (keoxifene and clomiphene) and two aromatase inhibitors (LY56110 and 4-hydroxyandrostenedione, 4-OHA) were utilized to determine the role of conceptus estrogen in trophoblastic elongation and maintenance of pregnancy in the pig. Pregnant gilts were unilaterally hysterectomized on day 10.5, and infused via a uterine arterial catheter with 200 mg of keoxifene or vehicle. The remaining uterine horn was removed based on time estimated for conceptus elongation. In a second study, pregnant gilts were injected daily with 200 mg (i.m.) of clomiphene or vehicle during pregnancy (days 10-16) and hysterectomized on day 30. A third study assessed in vitro aromatase inhibition by 4-OHA and LY56110 using trophoblastic microsomes incubated with [1 beta, 2 beta-3H]-androstenedione for 6 hr. In a fourth study, in vivo inhibition of aromatase activity was determined. For this study pregnant gilts, unilaterally hysterectomized on day 10.5, received either 4-OHA, LY56110, or vehicle. Conceptus development and uterine estrogens were quantified. None of the estrogen antagonists and aromatase inhibitors interferred with conceptus elongation. Uterine protein, calcium and acid phosphatase were similar (P greater than .10) between keoxifene- and vehicle-treated gilts. Embryonic survival of clomiphene- and vehicle-treated gilts was similar (91.5 vs 87.4%). In vitro, 4-OHA and LY56110 had 50% inhibitory concentrations of 0.1 microM and 13 nM. Treatment of gilts with 4-OHA reduced total estrogens in uterine flushings by 57% (P less than .02), whereas treatment with LY56110 did not significantly lower total estrogen content in uterine flushings. Estrogen antagonists were not effective in blocking conceptus elongation and maintenance of pregnancy. Although estrogen synthesis can be inhibited in vitro, dosages of aromatase inhibitors used were not totally effective in vivo.

Acid Phosphatase↗

PubMed1991

Expression of antiviral activity and induction of 2',5'-oligoadenylate synthetase by conceptus secretory proteins enriched in bovine trophoblast protein-1.

Establishment of pregnancy in cattle has been proposed to depend on production of a conceptus protein, bovine trophoblast protein-1 (bTP-1), which has a high degree of sequence homology with bovine interferon-alpha (bIFN-alpha), especially the alpha II subfamily. A preparation of bovine conceptus secretory proteins enriched for bTP-1 has antiviral and physico-chemical properties similar to other bIFN-alpha. Antiviral activity is initially detectable in uterine flushings on Day 14 of pregnancy, when the conceptus measures 4-5 mm in length, and increases as the conceptus elongates through Day 18. Day 17 conceptuses produce more than 10(6) U antiviral activity during 24 h of culture. All IFNs induce the enzyme 2',5'-oligoadenylate synthetase, which catalyzes production of 2',5'-oligo(A), which in turn is involved in antiviral and growth inhibitory effects of IFNs. This enzyme activity is induced in Madin-Darby bovine kidney cells by the partially purified bTP-1 preparation similarly to IFN-alpha, -beta, and -gamma. Likewise, the partially purified bTP-1 and bIFN-alpha 1 induce 2',5'-oligo(A) synthetase activity in monolayers of endometrial epithelial and stromal cells. Compared to epithelial cells, stromal cells have higher baseline activity of 2'-5'-oligo(A) synthetase activity (p less than 0.01) and show a greater degree of induction in the presence of either the partially purified bTP-1 or bIFN-alpha 1 (p less than 0.01). Also, 2',5'-oligo(A) synthetase of endometrial stromal cells is induced to a greater degree by our enriched bTP-1 preparation than by bIFN-alpha 1 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗

PubMed1991

Endometrial surface and secretory alterations associated with embryonic mortality in gilts administered estradiol valerate on days 9 and 10 of gestation.

Administration of estrogen to gilts on Days 9 and 10 of pregnancy results in total embryonic loss by Day 18. The present study examined changes in the uterine endometrial surface and secretion during conceptus attachment in control and estrogen-treated (Days 9 and 10) pregnant gilts. Gilts were unilaterally hysterectomized on either Days 12 and 14 or Days 16 and 18 of gestation. Uterine horns were flushed with saline and conceptuses were evaluated. Intact conceptuses were recovered from all control gilts, whereas estrogen-treated gilts contained normal intact conceptuses only on Day 12 of gestation. Antiviral activity, which reflects conceptus viability, was reduced (p less than 0.01) in uterine flushings after Day 14 in estrogen-treated gilts. Culture of endometrial explants with [3H]glucosamine revealed several glycoproteins that are synthesized during the period of conceptus attachment; however, no difference in glycoprotein synthesis between treatment groups was detected by analysis with two-dimensional PAGE and fluorography. Analyses of the uterine epithelium by scanning and transmission electron microscopy demonstrated that estrogen administration caused an alteration in the uterine surface, a thinning of the uterine epithelial glycocalyx, and a reduction of cationic ferritin binding to the microvilli of the uterine epithelium. Results indicate that conceptus mortality after early administration of estrogen is associated with alterations in the uterine endometrial surface during the period of conceptus attachment in the pig.

Animals↗

PubMed1991

Expression of messenger RNAs encoding insulin-like growth factor-I, -II, and insulin-like growth factor binding protein-2 in bovine endometrium during the estrous cycle and early pregnancy.

The present study characterized the changes in concentrations of insulin-like growth factors-I and -II (IGF-I and IGF-II) in uterine luminal flushings, and the endometrial mRNA levels of IGF-I, IGF-II, and IGF binding protein-2 (IGFBP-2) obtained from Days 0 through 18 of the bovine estrous cycle and early pregnancy. Concentrations of IGF-I and IGF-II in uterine flushings were greater on Days 0 and 5 than on other days of the estrous cycle or pregnancy. Northern blot analysis of endometrial poly(A)+ RNA revealed two major transcripts of 7.5 and 1.0 Kb for IGF-I, one major transcript of 4.0 Kb for IGF-II, and one major transcript of 1.3 Kb for IGFBP-2. RNA dot-blot analyses indicated that endometrial expression of IGF-I mRNA was unaffected by day of the estrous cycle or status (cyclic vs. pregnancy). However, endometrial expression of IGF-II mRNA was greater in pregnant than in cyclic endometrium on Days 15 and 18. Levels of endometrial IGFBP-2 mRNA increased (p less than 0.05) between Days 10 and 18 of the estrous cycle and early pregnancy. Results suggest that the presence of the bovine conceptus has a stimulatory effect on endometrial expression levels of IGF-II, whereas progesterone appears to be involved with enhancement of IGFBP-2.

Animals↗

PubMed1991

Survival of bovine embryos transferred to progesterone-treated asynchronous recipients.

Treatment of recipient cows with 100 mg of progesterone daily from Days 1 to 5 of the oestrous cycle increased plasma progesterone compared with vehicle-treated recipients. Embryo transfer to progesterone-treated recipients which showed oestrus 72 h after the donor cows resulted in pregnancy rates at Day 35 similar to those of synchronous (+/- 12 h) recipients (42 vs. 50%). Only 1 of 22 (4.8%) asynchronous (-72 h) vehicle-treated recipients established pregnancy. Similar treatments of cyclic cows with progesterone shortened (P less than 0.01) the interoestrous interval by 3.2 days. When assessed on Day 7 of pregnancy, administration of progesterone to superovulated donor cows on Days 1-4 of pregnancy did not affect early embryo development compared with superovulated cows treated with vehicle alone. Plasma progesterone increased rapidly in superovulated cows compared with cows during the oestrous cycle. The results indicate that administration of progesterone early in the oestrous cycle of the recipient can effectively advance uterine receptivity for the transfer of older asynchronous embryos.

Animals↗

PubMed1991

Effect of asynchronous transfer and oestrogen administration on survival and development of porcine embryos.

Results indicate that recovery of embryos on Days 11 and 13 of pregnancy was reduced for Day 5 embryos transferred to recipients on Day 6 of their oestrous cycle and was greatly reduced when embryos were transferred to recipients on Day 7 of the cycle (P less than 0.01). Administration of oestradiol-17 beta on Day 11 of the recipient's cycle did not appear to affect embryo development on Day 13. Day 6 embryos transferred to recipients on Day 8 of the oestrous cycle deteriorated rapidly within 24 h of transfer; there was no recovery of embryos from the uterus after 36 h. Treatment of pregnant gilts with 1 mg oestradiol-17 beta (i.v.) on Day 10.5 resulted in total embryonic loss by Day 23, but pregnancy rates of gilts treated with oestradiol-17 beta on Day 12 were similar to those of vehicle-treated gilts (60.6 vs. 71.4%).

Animals↗

PubMed1991

Stimulation of 2',5'-oligoadenylate synthetase activity in sheep endometrium during pregnancy, by intrauterine infusion of ovine trophoblast protein-1, and by intramuscular administration of recombinant bovine interferon-alpha I1.

In Expt 1, activity of 2',5'-oligoadenylate (2',5'-A) synthetase in endometrium collected on Day 16 (oestrus is Day 0) from the uterine horn ipsilateral to the corpus luteum was greater (P less than 0.001) for pregnant (135.5 +/- 1.72 nmol/mg protein/h) than for cyclic ewes (58.5 +/- 0.99 nmol/mg protein/h). In pregnant ewes, activity of 2',5'-A synthetase in endometrium collected from the contralateral uterine horn (119.5 +/- 1.72 nmol/mg protein/h) did not differ from that of the ipsilateral horn. In Expt 2, three ovariectomized ewes were treated with progesterone for 10 days and then with oestrogen for 2 days. Activity of 2',5'-A synthetase on Day 13 was 18% greater (P less than 0.10) in endometrium collected from the uterine horn receiving infusions of 30 micrograms ovine trophoblast protein-1 (oTP-1) twice a day on Days 10, 11 and 12(57.7 +/- 0.22 nmol/mg protein/h) than from the uterine horn receiving control infusions of serum protein (SP; 48.8 +/- 0.22 nmol/mg protein/h). In Expt 3, activity of 2',5'-A synthetase on Day 15 was not significantly greater in endometrium collected from the uterine horn of cyclic ewes receiving infusions of 30 micrograms oTP-1 twice a day on Days 12, 13 and 14 (46.5 +/- 0.37 nmol/mg protein/h) than in endometrium from the uterine horn receiving infusions of SP (38.2 +/- 0.37 nmol/mg protein/h). When results of Expt 2 and Expt 3 were combined, intrauterine infusion of oTP-1 increased (P less than 0.05) activity of 2',5'-A synthetase in endometrium by 20%.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗

PubMed1991

Influence of nutrition and body condition on pituitary, ovarian, and thyroid function of nonlactating beef cows.

Nonpregnant Hereford cows (n = 70) were used to determine the effect of nutrient intake and body condition on reproductive and thyroid function. Body condition scores (BCS; 1 = emaciated; 9 = obese) of cows averaged 5.0 +/- .2 on July 1, and cows were fed for 4 mo either to lose weight and BCS (thin; n = 22), to maintain weight and BCS (moderate; n = 24), or to gain weight and BCS (fat; n = 24). After November 1, cows received a complete ration to maintain weight and BCS. Cows were slaughtered in December (six thin, eight moderate, and eight fat cows) or the subsequent March (16 cows per group). Before slaughter, cows were given two injections of prostaglandin F2 alpha (PGF) 11 d apart. Six days after the second PGF injection, cows were simultaneously treated with 100 micrograms of gonadotropin releasing hormone (GnRH; i.m.) and 100 micrograms of thyrotropin releasing hormone (TRH; i.v.) and serum samples were obtained. The BCS of cows at slaughter (8 d after PGF) averaged 3.4, 5.3, and 7.1 (P less than .01) and carcass energy content averaged 243, 432, and 714 Mcal (P less than .01) for thin, moderate, and fat cows, respectively. Wet ovarian (P less than .001) and corpora lutea (P less than .01) weights were heavier for fat cows. Content of LH in the pituitary gland and concentrations of thyroxine (T4) in serum after GnRH/TRH were not influenced by nutrient intake or BCS. However, thin cows had greater concentrations (P less than .05) of LH in serum after GnRH/TRH than did moderate or fat cows. We conclude that nutrient intake and body energy reserves of beef cows influenced ovarian function and LH in serum after treatment with GnRH.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Development of a culture system for bovine granulosa cells: effects of growth hormone, estradiol, and gonadotropins on cell proliferation, steroidogenesis, and protein synthesis.

The objectives of the present studies were 1) to develop a culture system that has the positive effect of serum on granulosa cell attachment and allows subsequent expression of hormonal effects in serum-free medium and 2) to determine the effect of insulin, epidermal growth factor (EGF), estradiol (E2), and growth hormone (GH) on growth, steroidogenesis, and(or) protein synthesis of bovine granulosa cells. Cells from small (1 to 5 mm) and large (greater than 8 mm) follicles were collected from cattle and cultured for either 4 or 6 d. When cells from small follicles were cultured, insulin (5 micrograms/ml) increased (P less than .05) cell numbers (cells x 10(5)/well) severalfold compared with controls. Alone, EGF (10 ng/ml), FSH (200 ng/ml), LH (200 ng/ml), E2 (2 micrograms/ml), or GH (0 to 1,000 ng/ml) had no effect on cell numbers. However, when included with insulin, 30, 100, and 300 ng/ml of GH increased (P less than .05) granulosa cell numbers on d 4 of culture. Insulin alone increased (P less than .05) progesterone production (ng.10(5) cells-1.24 h-1) by severalfold on d 4, but EGF, FSH, LH, or GH alone had no effect and E2 inhibited progesterone production. In the presence of insulin, FSH and GH (100 ng/ml) increased (P less than .05) progesterone production on d 4 of culture, whereas EGF (10 ng/ml) elicited a decrease (P less than .05) in production. In cells from both sizes of follicles, GH (300 ng/ml) increased synthesis of cellular proteins (greater than 10 kDa). In cells from only large follicles, LH (200 ng/ml) decreased synthesis and secretion of proteins (greater than or equal to 3.5 kDa). These results support the hypothesis that GH may have direct effects on bovine ovarian function.

Animals↗

PubMed1990

Ovulation and early embryogenesis in swine.

Thirty gilts were used to examine if the sequence in which oocytes were released at ovulation contributed to differences in embryonic development and uterine secretions by Day 12 (Day 0 = onset of estrus). Oocytes of follicles destined to ovulate last were recovered 42 h after injecting proestrous gilts with hCG, incubated with a fluorescent stain, and returned to the donor's oviduct. These later-maturing oocytes subsequently became the lesser-developed (p less than 0.01) embryos on Day 4. In a second experiment, lesser- vs. more-developed Day 4 embryos from additional gilts were transferred to ligated uterine horns of nonpregnant gilts. Subsequently, the lesser-developed Day 4 embryos became the smaller (p less than 0.01) blastocysts within a litter on Day 12. Uterine flushings associated with lesser-developed embryos on Day 12 contained less estradiol (p less than 0.01), less total protein (p less than 0.10), and less acid phosphatase activity (p less than 0.05), but total content of calcium was not different compared to flushings that contained more-developed embryos. Analysis of uterine flushings with two-dimensional PAGE procedures indicated advanced uteroferrin-associated glycoprotein secretion from the horn that contained more-developed embryos. Results of these experiments suggested that oocytes of later-ovulating follicles were progenitors of smaller embryos, which probably stimulated uterine secretion later than more advanced littermates on Day 12.

Acid Phosphatase↗