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Biomedical subjects

H D Guthrie

Publications and source records attributed to H D Guthrie.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effect of charcoal-extracted porcine follicular fluid and 17 beta-estradiol on follicular growth and plasma gonadotropins in gilts fed a progesterone agonist, altrenogest.

Thirty-four gilts in two experiments were fed altrenogest for 18 d to block spontaneous growth of ovulatory follicles after luteolysis. They were injected with estradiol or charcoal-extracted porcine follicular fluid (pFF) to determine 1) whether gonadotropin secretion could be depressed and 2) whether exposure to reduced levels of gonadotropins would result in decreased numbers of medium follicles (3 to 6 mm in diameter). Gilts in Exp. 1 received treatments in a 2 X 2 X 2 factorial arrangement starting 48 h before the last feeding of altrenogest. Corn oil or estradiol (2 micrograms/kg body weight), 5 ml of charcoal-extracted porcine serum (pS) or pFF were injected im four times at 8-h intervals and gilts were sacrificed 24 or 96 h after last feeding of altrenogest. In Exp. 2, gilts received one of four treatments consisting of 1) pS, injected iv nine times at 8-h intervals starting 48 h before the last feeding of altrenogest; 2) pFF, with injection protocol the same as for pS; 3) estradiol injected im three times and 4) four times at 8-h intervals starting 0 and 24 h, respectively, before the last feeding of altrenogest. Compared with pS or corn oil, estradiol increased (P less than .001) plasma estrogen and decreased (P less than .05) plasma luteinizing hormone (LH) without a significant effect on plasma follicle stimulating hormone (FSH). Estradiol, compared with corn oil, decreased (P less than .01) the number of medium follicles from 24.8 to 0/gilt and decreased (P less than .05) the weight of ovarian follicular fluid from 4.2 to 2.1 g/gilt at 72 h after the first injection. Five milliliters of pFF had no significant effect on plasma gonadotropins or number of medium follicles. However, 20 ml of pFF, compared with pS, decreased (P less than .05) plasma FSH from 45 ng/ml to 9 ng/ml 32 h after the first injection, had no effect on plasma LH, decreased (P less than .01) the number of medium follicles from 29.2 to 2.2/gilt and decreased (P less than .01) follicular fluid weight from 3.9 to 1.6 g/gilt by 72 h after the first injection. These results indicate that estradiol or a non-steroidal component of follicular origin can decrease secretion of gonadotropins and suppress recruitment of medium follicles in the pig.

Animals↗
PubMed1987

Effect of altrenogest and Lutalyse on parturition control, plasma progesterone, unconjugated estrogen and 13,14-dihydro-15-keto-prostaglandin F2 alpha in sows.

To investigate control of parturition time, 154 sows farrowing 220 litters at three locations were treated with altrenogest and Lutalyse (PG). The four treatment groups were: 1) no treatment (control group); 2) an im injection of 15 mg of PG at 1000 on d 111, 112 or 113 of gestation (d 0 = first day of estrus and gestation); 3) altrenogest (20 mg X sow-1 X d-1) fed twice daily for 4 d starting on d 109, 110 or 111; and 4) altrenogest and an injection of PG at 1000 on the day after the last feeding of altrenogest. Control sows at the University of Delaware (UD), University of Maryland (UM) and USDA, Beltsville Agricultural Research Center (BARC) had mean gestation lengths of 113.5, 114.2 and 115.7 d and live pigs/litter were 10.5, 11.0 and 7.4, respectively. Altrenogest started by d 110 prevented unscheduled early farrowing and increased (P less than .01) gestation length by 1.7 and 1.1 d, respectively, at UD and UM, but had not effect at BARC. The time from PG to parturition was 24.3, 22.6 and 34.4 h, respectively, at UD, UM and BARC. More sows at UD and UM farrowed between 0700 and 1700 on the expected day of parturition after injection of PG (59.3%) than with no PG (20.7%; P less than .05). The high incidence of small litters (less than six pigs) from sows inseminated with frozen semen at BARC resulted in negative correlations of live pigs/litter with gestation length (r = -.533, P = .0001) and with time from PG injection to birth of first pig (r = -.425, P = .017); these correlations were not significant at UD and UM where only natural service was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Pituitary and ovarian hormone secretion and ovulation in gilts injected with gonadotropins during and after oral administration of progesterone agonist (Altrenogest).

We determined changes in plasma hormone concentrations in gilts after treatment with a progesterone agonist, Altrenogest (AT), and determined the effect of exogenous gonadotropins on ovulation and plasma hormone concentrations during AT treatment. Twenty-nine cyclic gilts were fed 20 mg of AT/(day X gilt) once daily for 15 days starting on Days 10 to 14 of their estrous cycle. The 16th day after starting AT was designated Day 1. In Experiment 1, the preovulatory luteinizing hormone (LH) surge occurred 5.6 days after cessation of AT feeding. Plasma follicle-stimulating hormone (FSH) increased simultaneously with the LH surge and then increased further to a maximum 2 to 3 days later. In Experiment 2, each of 23 gilts was assigned to one of the following treatment groups: 1) no additional AT or injections, n = 4; 2) no additional AT, 1200 IU of pregnant mare's serum gonadotropin (PMSG) on Day 1, n = 4); 3) AT continued through Day 10 and PMSG on Day 1, n = 5, 4) AT continued through Day 10, PMSG on Day 1, and 500 IU of human chorionic gonadotropin (hCG) on Day 5, n = 5; or 5) AT continued through Day 10 and no injections, n = 5. Gilts were bled once daily on Days 1-3 and 9-11, bled twice daily on Days 4-8, and killed on Day 11 to recover ovaries. Termination of AT feeding or injection of PMSG increased plasma estrogen and decreased plasma FSH between Day 1 and Day 4; plasma estrogen profiles did not differ significantly among groups after injection of PMSG (Groups 2-4). Feeding AT blocked estrus, the LH surge, and ovulation after injection of PMSG (Group 3); hCG on Day 5 following PMSG on Day 1 caused ovulation (Group 4). Although AT did not block the action of PMSG and hCG at the ovary, AT did block the mechanisms by which estrogen triggers the preovulatory LH surge and estrus.

Animals↗
PubMed1985

Control of time of parturition in pigs.

Injection of prostaglandin (PG) F-2 alpha or its analogues has provided a technique to induce parturition after Day 110 of gestation in the sow. The mean interval from PG injection to parturition ranges from 24 to 28 h, but only 50-60% of the sows farrow during an 8-10 h working day, and as many as 20% of sows may begin parturition before the injection of PG or less than 22 h after the injection. The duration of parturition is positively associated with the incidence of stillbirths and perinatal death so that techniques to reduce the duration of parturition may save piglets. Early parturition has been prevented by feeding sows progestagens, PG synthesis inhibitors and hypothalamic function inhibitors. These compounds were detrimental to piglet survival if they delayed parturition too long after the expected time of parturition. Parturition was delayed in sows up to 1.5 days by altrenogest, 1.6 days by meclofenamic acid, 2.7 days by indomethacin, and 3 days by methallibure without increased incidence of stillborn piglets compared with control sows. Injection of PG after administration of altrenogest or meclofenamic acid was successful in experiments with sows; parturition could be confined to a 5-day working week with no increase in stillborn piglets compared with control sows. Relaxin injected at 48 and 24 h before or only 24 h before injection of PG increased the proportion of sows farrowing 22-32 h after PG to 86.2% compared with sows injected only with PG (53.3%, P less than 0.01). Oxytocin injected 20 h after injection of PG increased the proportion of sows farrowing 20-28 h after PG to 90.4% compared with sows injected only with PG (49.2%, P less than 0.005). Injection of 25-60 i.u. ACTH on Day 110 of gestation did not shorten the length of gestation, but did decrease the incidence of still born piglets by 0.2 piglets/litter (P less than 0.05). An injection of the beta-adrenergic antagonist, carazolol, during labour before the birth of the first piglet decreased the duration of parturition and the incidence of stillborn piglets particularly in primiparous sows (P less than 0.05). Carazolol injected with oxytocin 20 h after injection of PG decreased the interval from PG to parturition by 2 h compared with sows injected with only PG and oxytocin.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic beta-Antagonists↗
PubMed1984

Effects of Cloprostenol administration on neutral lipid and prostaglandin F metabolism by porcine luteal tissue.

The effects of Cloprostenol administration on porcine luteal lipid metabolism, progesterone production, and prostaglandin F production were examined in 32 pigs at day 12 of the estrous cycle. Pigs were killed between 0 and 18 hours after treatment. Recovered luteal tissue was incubated at 0 C and at 37 C in the absence and presence of dibutyryl cyclic AMP and indomethacin. Net in vitro release of progesterone from luteal tissue was depressed within 1 hour after Cloprostenol treatment whereas net in vitro release of prostaglandin F was accelerated 4 hours after Cloprostenol treatment. Inclusion of dibutyryl cyclic AMP in the incubation media did not alter progesterone production but did enhance prostaglandin F production at 0 and 1 hour after Cloprostenol treatment. Inclusion of indomethacin in the incubation media completely inhibited the Cloprostenol-induced acceleration of in vitro luteal PGF production. Cloprostenol treatment increased luteal triglycerides and decreased luteal free cholesterol and cholesterol esters within 1 hr after treatment. Arachidonic acid percentages in free fatty acids and triglycerides were also increased within 1 hr after treatment. When 37 C and 0 C incubations were compared, in vitro luteal accumulation of free fatty acids was maximum at 1 hr after Cloprostenol treatment. In vitro accumulation of triglycerides in luteal tissue was comparatively uniform at all times examined during the first 18 hr after Cloprostenol treatment. Comparison of 37 C and 0 C incubations further revealed that luteal triglycerides were active in accumulation of arachidonic acid. Inclusion of dibutyryl cyclic AMP and/or indomethacin in the incubation media did not alter luteal lipid contents or fatty acid compositions. Blood plasma progesterone was depressed at 4 hours after Cloprostenol whereas 13,14-dihydro-15-keto-prostaglandin F2a was elevated at 18 hours after treatment. Blood plasma free fatty acids increased 330 percent at 4 hours and free fatty acid compositions also changed at this time. In both luteal tissue and blood plasma, changes in steroid and fatty acid metabolism occurred prior to changes in prostaglandin metabolism, suggesting that Cloprostenol induced functional luteal regression prior to altering prostaglandin metabolism.

Animals↗
PubMed1984

Cytoplasmic and nuclear estrogen receptors and leucine incorporation in endometrium of cyclic and pregnant pigs to day 19 postestrus.

Endometrium was recovered from a total of 37 pigs sacrificed on d 4, 10, 12, 16 and 19 of the estrous cycle and on d 10, 12, 16 and 19 of gestation to determine whether the concentrations of cytoplasmic and nuclear estrogen receptors were altered during pregnancy. In addition, [3H]-leucine incorporation into endometrium was studied in vitro to determine whether any estrogen action mediated through a receptor might involve increased protein synthesis. Cytoplasmic estrogen receptor decreased from d 10 through d 16 in both pregnant and cyclic pigs. The concentration of the cytoplasmic estrogen receptor was less from d 10 through d 16 in pregnant pigs than in cyclic pigs; however, the reduced concentrations did not appear to result from translocation of filled sites to the nucleus, because estrogen and estrogen receptor concentrations in the nucleus were similar in pregnant and cyclic pigs through d 16. The amount of [3H]-leucine incorporated into endometrium did not differ between pregnant and cyclic pigs through d 16 nor did the RNA:DNA ratio. Therefore, no evidence of pregnancy-specific increases in total RNA synthesis mediated by estrogen receptors was found in pregnant pigs through d 16. These observations do not preclude actions of steroids through receptors to induce the synthesis of RNA that codes for specific proteins but that constitutes only a small portion of the total RNA. From d 16 to 19, both [3H]-leucine incorporation and RNA:DNA ratio increased in cyclic pigs (both P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Follicular growth and production of estrogen and progesterone after injection of gilts with human chorionic gonadotropin on day 12 of the estrous cycle.

Twenty cyclic gilts were injected im with either saline (control) or 1,000 IU of human chorionic gonadotropin (hCG) on d 12 of the estrous cycle to determine the effects of hCG on follicular development and steroidogenesis. Blood was collected when gilts were sacrificed on d 13 or 16. Follicles were classified as medium (3 to 6 mm in diameter) or large (greater than 6 mm diameter), dissected from the ovary, measured and weighed. Pieces of follicle wall were incubated 3 h in Krebs Ringer bicarbonate buffer (KRB) on ice in an atmosphere of air or at 37 C in an atmosphere of 95% O2:5% CO2. Unconjugated estrogen and progesterone in blood plasma, follicular fluid and 10,000 X g supernatants of incubated follicular tissue homogenates were quantified by radioimmunoassay. On d 13 follicles on ovaries of control or hCG-injected gilts were less than or equal to 6 mm in diameter. On d 16, one of five control gilts had some large follicles, while all five hCG-treated gilts had large as well as medium follicles. On d 16 follicular fluid of large follicles from hCG-injected gilts contained twofold more estrogen and 40-fold more progesterone than medium follicles on the same ovaries. Tissue from large follicles of hCG-injected gilts produced more progesterone in vitro than did tissue from medium follicles (P less than .05), but estrogen production did not differ. On d 16 medium follicles from control or hCG-injected gilts were larger, contained more estrogen and less progesterone than those recovered on d 13 (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Alpha-adrenergic receptors in myometrium of pregnant and nonpregnant pigs until day 19 postestrus.

Binding of [3H] dihydroergocryptine (DHE) to myometrium was studied in cyclic and pregnant gilts. The binding was saturable and of high affinity (Kd = 2-4 nM). DHE binding was inhibited by phentolamine, phenoxybenzamine, epinephrine and norepinephrine, but almost not at all by propranolol or isoproterenol. DHE appears to be bound to an alpha 2-adrenergic receptor because yohimbine had a much greater ability to compete for DHE binding sites than did prazosin. The concentration of DHE binding sites in the myometrium was greatest during the luteal phase of the estrous cycle as has been previously reported for sheep. The decrease at estrus did not appear to be associated with a change in the alpha 2-adrenergic receptor dominance in myometrial membranes. Embryo migration to the site of implantation may be associated with reduced concentration of DHE binding sites on Days 10 to 12 of pregnancy in pigs.

Animals↗
PubMed1983

Changes in plasma estrogen, luteinizing hormone, follicle-stimulating hormone and 13,14-dihydro-15-keto-prostaglandin F2 alpha during blockade of luteolysis in pigs after human chorionic gonadotropin treatment.

An injection of human chorionic gonadotropin (HCG) or estrogen on d 12 of the estrous cycle delays luteolysis in the pig. In an experiment to determine if HCG stimulated estrogen secretion, 21 cyclic pigs received one of five different amounts of HCG-(A) 0, (B) 125, (C) 250, (D) 500 or (E) 1,000 IU-as a single, im injection in 2 ml of distilled water on d 12 of the estrous cycle. Blood was collected from the jugular vein immediately before HCG injection and once daily thereafter until d 20 of the estrous cycle. Plasma progesterone, estrogen (unconjugated) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were quantified for pigs in all groups; luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were quantified for pigs in groups A and E. The HCG injection exerted a dose-related increase on the mean interestrus interval (groups A, B, C, D and E were 20.5, 20.2, 22.5, 31.0 and 61.4 d, respectively) and on the delay of luteolysis as measured by mean plasma progesterone on d 16 (A, B and C vs D and E, respectively, 1.9, 1.2 and 10.4 vs 34.1 and 47.1 ng/ml; P less than .05). The HCG injection caused a transitory increase in plasma estrogen from d 12 (5 to 10 pg/ml before treatment) to d 15 (35.5 pg/ml, group D) and to d 16 (90.2 pg/ml, group E) before it decreased to preinjection levels on d 17 (group D) and 18 (group E).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Progesterone secretion and prostaglandin F release in vitro by endometrial and luteal tissue of cyclic pigs.

Blood and tissue were collected from 30 pigs on various days of the oestrous cycle to compare progesterone in peripheral plasma and progesterone release in vitro with prostaglandin (PG) F release in vitro by endometrial and luteal tissue (approximately 100 mg in 5 ml Krebs-Ringer-bicarbonate buffer, pH 7.4, for 2 h with three different incubation treatments). Plasma progesterone increased from Days 8 to 12 of the oestrous cycle (25.1 to 42.8 ng/ml, P < 0.05) and decreased from Day 14 to 16 (36.3 to 5.9 ng/ml, P < 0.05). Progesterone release in vitro at 37 degrees C decreased from 18.0 to 2.7 ng/mg tissue from Days 8 to 16 (P < 0.05). Endometrial PGF release in vitro at 37 degrees C increased slightly from Day 8 to 14, then increased significantly from 43.7 to 103.5 ng/100 mg tissue between Days 14 and 16 (P < 0.05). The rapid increase in endometrial PGF release coincided with the decrease in plasma progesterone. A small, non-significant increase in mean luteal PGF release was detected between Days 14 and 16. The results of this experiment did not suggest a critical role for luteal PGF-2 alpha in the process of luteolysis in the pig, but do provide indirect evidence for the involvement of endometrial PGF-2 alpha in luteolysis in the pig.

Animals↗
PubMed1979

Estrone concentration in the peripheral plasma of pregnant and non-pregnant gilts.

A rapid radioimmunoassay for estrone (total unconjugated and sulfated) was developed to determine plasma estrone (E1) concentrations in inseminated gilts that conceived and those that had not. Thirty-one 160 day-old prepuberal gilts were induced to ovulate with gonadotropins and were artificially inseminated 10 hr before the expected time of ovulation (Day 1 - day of insemination). Unconjugated E1 and E1SO4 were extracted from 20 to 500 microl of plasma twice with 5 ml of tetrahydrafuran:ethyl acetate (1:1). Aliquots of a standard E1SO4 preparation were dissolved in 500 microl of distilled water and extracted at the same time as the plasma samples. The dried extracts were solvolyzed for 1 hr at 50 degrees C in 0.6 ml of glacial acetic acid:ethyl acetate (1:1), and the dried residue was redissolved in 0.2 ml of distilled water and extracted once with 2 ml of diethyl ether. Twenty of 31 gilts were pregnant at Days 29 to 31 of the induced cycle. Plasma E1 in pregnant gilts increased from 85 pg/ml on Day 18 to 702, 1879 and 2793 pg/ml, respectively, on Days 22, 25 and 29 to 31. Three of the non-pregnant gilts had plasma progesterone secretion maintained until Day 22; they also had a transitory increase in plasma E1 on Day 22 (215 pg/ml). Some blastocysts may have been present to exert a temporary luteotropic effect, but not enough blastocysts to completely overcome the luteolytic effect of the uterus. Quantification of plasma E1SO4 could be used as a pregnancy test in the pig.

Journal Article↗
PubMed1979

follicular fluid electrolytes and osmolality in cyclic pigs.

Sodium and osmolar concentrations of porcine folliclar fluid in the cyclic pig did not vary significantly during the oestrous cycle, and were similar to those in plasma. The K+ concentration was greater in small (Days 12-13) and medium-sized (Day 16) follicles than in plasma or large (Day 18-oestrus) follicles of cyclic sows. In contrast, follicular fluid obtained from slaughterhouse material had higher potassium and osmolality, and lower sodium values, which are assumed to be due to post-mortem changes.

Animals↗