Collection and phagocytic evaluation of uterine neutrophilic leukocytes

The study of phagocytosis in the bovine uterus requires the collection of large numbers of uterine leukocytes. A method of stimulating polymorphonuclear neutrophil (PMN) invasion into the bovine uterus with oyster glycogen was tested. Following glycogen treatment, uterine aspirates contained large numbers (10(6)-10(9)) of viable uterine PMN. In Experiment 1, six cows were treated at one-week intervals by intrauterine infusion with 0.1, 1.0 and 10.0% oyster glycogen, respectively. Uterine lumens were lavaged at 0, 12, 24, 48, 72 and 168 hours post-infusion with each concentration of glycogen. The mean peak response for PMN was at 12 hours post-infusion of glycogen. In Experiment 2, uterine and peripheral blood PMN were collected from each of 12 cows. Phagocytosis was measured as the percent of (32)Phosphorus-labeled Staphylococcus aureus ingested by PMN during a one-hour incubation. Mean (+/- standard deviation) percent phagocytosis was not statistically different between blood (53.6 +/- 11.0%) and uterine (43.8 +/- 13.0%) PMN. This indicates that phagocytic activity was similar for PMN collected either from the uterine lumen or peripheral blood.     

Influence of GnRH infusion on endocrine parameters and duration of postpartum anestrus in beef cows

The effect of an intravenous infusion of gonadotrophin releasing hormone (GnRH) on the duration of postpartum anestrus in suckled beef cows was studied. Twenty-eight, mature, suckled beef cows were assigned in equal numbers to one of four treatment groups which were based on infusion with saline or GnRH (15ug/hour for 12 hours) and stage postpartum (pp) (20 or 35 days). Serum LH and progesterone were determined by radioimmunoassay for the period which began 5 days pre-infusion and ended at 55 days postpartum (ie: 35 or 20 days post-infusion). Serum LH remained below 5ng/ml during infusion in all control cows. Peak serum LH values, times of LH peaks, and duration of LH responses (means +/- SE) during infusion were 49 +/- 12 ng/ml, 162 +/- 42 minutes and 7.8 +/- 1.3 hours for the 20 day group and 44 +/- ng/ml, 144 +/- 6 minutes, and 8.2 +/- 1.1 hours for the 35 day group respectively. Serum progesterone levels indicated that the proportion of cows showing the onset of estrous cycles within 10 days of infusion was greater in the 20 day pp GnRH group (4/7) than the 20 day pp saline group (0/7) (p < .05) but was not significantly different between the 35 day pp GnRH (4/7) and 35 day pp saline (2/6) groups. The incidence of estrus was not affected by GnRH treatment and was 37% in all cows prior to 55 days pp. It was concluded that infusions of GnRH for 12 hours at a rate of 15 ug/hour could induce estrous cycles in suckled beef cows treated at 20 days postpartum.     

Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply.

Blood flow to each uterine horn of cows during the oestrous cycle and early pregnancy was determined daily by use of electromagnetic blood flow probes placed around both middle uterine arteries. The pattern of blood flow to uteri of pregnant and non-pregnant cows was similar until Day 14 after mating or oestrus. Between Days 14 and 18 of pregnancy blood flow to the uterine horn containing the conceptus increased (P less than 0.01) 2- to 3-fold, whereas blood flow to the non-gravid uterine horn in these cows remained constant. No corresponding increase in blood flow to the uterine horn ipsilateral to the ovary bearing the CL was observed in non-pregnant cows during this 4-day period. By Day 19 of pregnancy, blood flow to the gravid uterine horn had returned to a level similar to that observed on Day 13. Blood flow to both uterine horns of pregnant cows remained constant from Days 19 to 25 and then increased to the gravid horn (P less than 0.01) markedly until Day 30 whereas blood flow to the non-gravid horn remained low. Uterine blood flow during the oestrous cycle of non-pregnant cows was positively correlated (P less than 0.01) with systemic concentrations of oestradiol and the ratio of oestradiol (pg/ml) to progesterone (ng/ml). There was no association between oestradiol concentrations and blood flow to the gravid uterine horn. These data indicate local control of uterine blood flow by the bovine conceptus which may function to create optimal conditions for the continuation of pregnancy.     

Fertility and uterine hemodynamic in cows after artificial insemination with semen assessed by fluorescent probes

Fluorescent probes (propidium iodide, Hoechst 33342, fluorescein isothiocyanate–conjugated Pisum sativum agglutinin, and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolcarbocyanine iodide) were used to simultaneously evaluate the integrity of plasma and acrosomal membranes as well as mitochondrial membrane function in cryopreserved bovine semen and to verify its influence on fertility and postinsemination uterine vascularization. One hundred eighty-two Nellore cows were distributed for artificial insemination (AI) using semen batches separated according to the cell percentage presenting intact plasma membrane, intact acrosome, and high mitochondrial function (IPIAH): group G (44.5% IPIAH, n = 68), group M (23.0% IPIAH, n = 56), and group R (8.5% IPIAH, n = 58). The uterine hemodynamic was evaluated by Doppler sonogram in three periods: 30 hours before AI, 4 and 24 hours after AI were considered the resistance index and the uterine vascularization score. The pregnancy rate of group G (64.7%) was greater (P > 0.05) compared with group R (36.2%), but both did not differ from group M (50.0%). There was no effect (P > 0.05) of semen quality on uterine vascularization. Greater vascularization was noticed 4 hours after AI than 30 hours before and 24 hours after AI. Semen evaluation using fluorescent probes contributes to predicting fertilizing potential of semen. The use of semen with less percentage of IPIAH sperm does not alter uterine hemodynamic in cows.     

Involvement of nitric oxide in cardioprotective effect of endothelin receptor antagonist during ischemia-reperfusion

The interaction between the cardioprotective effect of endothelin (ET) receptor blockade and nitric oxide (NO) during ischemia-reperfusion injury was investigated. Anesthetized pigs were subjected to 45 (protocol 1) or 30 min (protocol 2) coronary artery ligation and 4 h reperfusion. In protocol 1, five groups were given vehicle, the ET(A) receptor antagonist LU-135252 (LU), the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine (L-NNA), L-NNA in combination with LU, or L-NNA in combination with the NO precursor L-arginine (L-Arg) and LU intravenously before ischemia. In protocol 2, two groups were given vehicle or L-NNA. In protocol 1, the infarct size (IS) was 79 +/- 5% of the area at risk in the vehicle group and 93 +/- 2% in the L-NNA group. LU reduced the IS to 43 +/- 7% (P < 0.001). The cardioprotective effect of LU was abolished in the presence of L-NNA (IS 76 +/- 6%), whereas addition of L-Arg restored its cardioprotective effect (IS 56 +/- 2%; P < 0.05 vs. vehicle and L-NNA + LU groups). In protocol 2, the IS was 49 +/- 6% in the vehicle group and 32 +/- 4% in the L-NNA group (P = not significant). Myocardial ET-like immunoreactivity (ET-LI) increased in the vehicle group of protocol 1. ET-LI in the ischemic-reperfused myocardium was lower in the groups given LU (P < 0.01) and L-NNA + L-Arg + LU (P < 0.05) but not in the group given L-NNA + LU compared with the vehicle group. These results suggest that the cardioprotective effect of the ET(A) receptor antagonist is mediated via a mechanism related to NO.     

Uterotropic actions of relaxin in prepubertal gilts

Uterotropic actions of relaxin (RLX) have been demonstrated in rats and mice but not in other species. Experiments were conducted to assess (1) if RLX has uterotropic effects in prepubertal gilts and (2) if RLX-induced imbibition of water by uterine tissues is mediated by histamine. Prepubertal gilts received (i.m.) either 0.5 mg pRLX (greater than or equal to 3000 U/mg; n = 10) in 0.1 M phosphate-buffered saline (PBS) or PBS vehicle (n = 8) every 6 h for 54 h. Additionally, one-half of each group received either (1) the histamine receptor antagonists (300 mg i.m. of each), pyrilamine maleate (H1) and cimetidine (H2), in PBS and corn oil, respectively, or (2) control vehicles every 6 h for 66 h beginning 12 h prior to initiation of RLX treatment. Treatment with RLX stimulated a twofold increase (p less than or equal to 0.05) in uterine weight in prepubertal gilts. Increases in total uterine weight were manifested by greater (p less than or equal to 0.05) uterine water content and dry weight in RLX-treated gilts. Cotreatment with histamine receptor antagonists did not alter RLX-induced changes in uterine water content or dry weight. Uterine contents of soluble protein and DNA were greater (p less than or equal to 0.05) in RLX-treated gilts compared to controls. Treatment with RLX tended (p approximately 0.08) to reduce protein; DNA ratio of uterine tissues and increased (p less than or equal to 0.05) uterine DNA as a percentage of uterine dry weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of intrauterine infections and follicular development on the response to GnRH administration in postpartum dairy cows

The effects of intrauterine infections and prior follicular development on the response to gonadotropin releasing hormone (GnRH) administration in postpartum dairy cows were studied. Fifty lactating Holstein cows were assigned at random to one of two groups after calving. Group I (control) consisted of 25 cows given a single intramuscular injection of saline on Day 15 postpartum. Group II (treated) consisted of 25 herdmates given a single i.m. injection of 100 mug of GnRH on Day 15 postpartum. Palpation per rectum and real-time ultrasonography were used to monitor ovarian activity, and endometrial swabs were cultured to determine the presence of uterine infection. Blood samples were collected for progesterone (P(4)) and luteinizing hormone (LH) analysis. Fourteen cows (control, n = 5; treated, n = 9) did not ovulate during the first 60 d postpartum. Ovaries in these cows contained 4 to 8-mm size follicles and both P(4) and LH remained at basal concentrations. Fourteen other cows (control, n = 6; treated, n = 8) ovulated by Day 15 postpartum. Follicles >/= 10 mm were demonstrable in the ovaries of these cows before or by Day 12 postpartum. GnRH treatment had no effect on the lifespan of the existing corpus luteum in these cows. In the remaining cows, 7 of 14 Control and all 8 Treated cows ovulated within 3 d of treatment. All cows ovulating within this period were free of uterine infection and the ovaries contained follicles 相似文献   

Postpartum uterine motility measurements in dairy cows retaining their fetal membranes

Postpartum uterine contraction variables were measured in 15 parturient Holstein dairy cows and heifers: 8 assigned to dexamethasone (DEX) treatment and 7 to control (CON) treatment. The DEX animals were induced to calve early with an injection of dexamethasone and estradiol benzoate, administered on days 270 to 274 of gestation. At this time, the CON animals were injected with sterile saline and allowed to calve at term. Six of the eight DEX animals and one of the seven CON animals retained their fetal membranes longer than 12 hours postpartum. The uterine contraction variables determined were: the number of contractions over a 10 minute period (C 10 ), the average amplitude of contractions (AMP), the average duration of contractions (DUR), Montevideo units (MONT) and Alexandria units (ALEX). Recordings were taken at 1 hour, 6 hours and 48 hours postpartum, for a period of 20 minutes each. The contraction variables were measured using a catheter which was fluid-filled and inserted into the pregnant horn and connected to a pressure transducer, amplifier and recorder. The data were analyzed in terms of DEX vs. CON animals and animals with retained fetal membranes (RET) vs. animals with a normal release (NRET). Treatment with dexamethasone and estradiol benzoate resulted in an increase in C 10 at 48 hours (P < .05). The AMP, MONT and ALEX variables were also higher in the DEX animals, as compared to controls at that time. Significant differences (P < .01) were observed at 48 hours postpartum between the RET and NRET animals in terms of AMP, MONT and ALEX variables, and at that time the RET animals had a higher rate of uterine contractility than the NRET animals. No significant differences in the amount of uterine work between either the DEX and CON animals or the RET and NRET animals were observed, at 1 and 6 hours postpartum. The treatment with dexamethasone and estradiol benzoate prolonged uterine motility up to 48 hours postpartum, and the retention of the fetal membranes was not a result of the lack of uterine contractility during the early stages postpartum.     

The use of dimenhydrinate in conjunction with dexamethasone for induction of parturition in beef cattle

Forty-eight crossbred Chianina cows (3 to 5 years of age), with an expected gestation length of 288 days, were randomly divided into four treatment groups to evaluate the use of dimenhydrinate (an antihistamine agent) in conjunction with dexamethasone (DEX) for inducing parturition in beef cattle. Group (A) received a 20 mg dose of DEX (im) on day 282 of gestation and a carrier vehicle (iv) 24 hours later (day 283); Group (B) was given a carrier vehicle (im) on day 282 and 500 mg of dimenhy-drinate (DMH) diluted in 200 ml of 2.5% dextrose-0.9% saline solution given (iv) on day 283 and Group (C) received 20 mg of DEX (im) on day 282 and 500 mg of DMH in solution (iv) on day 283 of gestation. The remaining 12 cows assigned to Group (D) were not handled and were allowed to calve under natural conditions. The number of cows calving and percent calving within 60 hours after the first injection were: 10(91%), none(0%) and 12(100%) for the DEX, DMH and DEX plus DMH groups, respectively. The mean gestation length of the control cows in Group (D) was 288.6 days. Frequency of dystocia was: 18.2, 8.3, 0 and 0% and retained placentae (>/=24 hours) was: 72.8, 16.6, 33.3 and 0% for DEX, DMH, DEX plus DMH and control groups, respectively. In this study, a 20 mg dose of DEX (im) followed 24 hours later with 500 mg of DMH (iv) was more successful for calving induction than when DEX or DMH was used alone. The combination DEX and DMH treatment induced calving in a shorter interval from treatment (P<.05) and decreased the incidence of retained placentae (P<.01) when compared with those induced following DEX treatment.     

Characteristics of bovine early puerperal uterine contractility recorded under farm conditions

A non-invasive, digital technique was used to measure and quantify intrauterine pressure (IUP) changes in early postpartum dairy cows kept under farm conditions in order to document physiological changes in uterine contractility after uncomplicated calvings. In addition, possible relationships between characteristics of uterine contractility and blood ionized calcium (Ca(2+))-concentrations were investigated. Recordings of uterine contractility were made by using a transcervically inserted open tip catheter in 12 healthy cows during their first 48h after calving. The IUP recording technique appeared easily applicable under farm conditions. Although mean frequency (FREQ), amplitude (AMP) and area under the curve (AUC) of the myometrial contractions significantly decreased due to time, untreated early postpartum cows showed a high variability in characteristics of uterine contractility. There was no correlation between blood Ca2+ -concentrations and any of the contractility parameters.     

Albumin-induced plasma volume expansion: diurnal and temperature effects

To develop a reliable procedure for the acute expansion of plasma volume (PV), 26 male volunteers were randomly assigned to either a thermoneutral (25 degrees C and 40% relative humidity) or hot-dry (37 degrees C and 25% relative humidity) environment; subsequently each subject was seated for at least 1 h and then infused intravenously with either 100 or 200 ml of a 25% albumin solution or 0.9% saline. On the day before each infusion, PV was estimated by dye dilution using indocyanine green. Net percent change in PV (using hematocrit and hemoglobin values) was calculated at 1, 3, 6, 9, 12, and 24 h postinfusion. The PV of subjects residing in the heat after a 100-ml saline infusion increased significantly over 1-h values at 6, 9, and 12 h postinfusion but not at 24 h. The same trend, although not significant, was apparent at room temperature. The data suggest a slow isooncotic circadian pattern of PV expansion and contraction. The infusion of hyperoncotic albumin produced rapid expansion of plasma volume. With the low dose (25 g) at 1 h postinfusion, the expansion was 379 +/- 102 ml in the heat and 301 +/- 160 ml at room temperature. With the high dose (50 g) at 1 h postinfusion, the expansion was 479 +/- 84 ml in the heat and 427 +/- 147 ml at room temperature. The high dose produced an expansion that persisted for at least 9 h in subjects in either environment. The data suggest a mechanism for the retention of fluid during heat acclimatization and a useful procedure for plasma volume expansion in humans.     

Conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone and/or prostaglandin F2 alpha

This study was designed to determine conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone (GnRH) and/or prostaglandin F2 alpha (PGF2alpha). A total of 2352 cows was randomly assigned to six groups. Cows in Groups 1 to 5 were palpated per rectum to determine the presence of a corpus luteum (CL) on the ovary, and blood samples were obtained for the determination of plasma progesterone (P4) concentrations. Cows with a CL and P4 concentrations >1 ng/ml were treated (Day 0) with PGF2alpha (25 mg, i.m.) and were observed for estrus. Cows in estrus prior to 72 hours after treatment (Group 5, n = 106) were bred, but were not treated. Cows not observed in estrus by 72 hours were divided into four remaining groups, were bred between 72 and 80 hours and were assigned as follows: Cows in Group 1 (n = 203) were not treated; Cows in Group 2 (n = 200) were treated with GnRH (100 ug, i.m.); Cows in Group 3 (n = 201) were treated with PGF2alpha (25 mg, i.m.); and cows in Group 4 (n = 202) were treated with both GnRH and PGF2alpha. Cows in Group 6 (n = 1440) were not treated with PGF2alpha on Day 0 and were estrual cows that were bred on days when cows in Groups 1 to 5 were time-inseminated. The percentage of cows in all groups pregnant at 45 to 50 days after one insemination was compared using analysis of variance (P<0.05). The conception rate of cows in Group 2 was significantly higher than that of cows in Groups 1 to 4. There was a significant group-by-season interaction. Cows treated with GnRH during the spring had a higher conception rate than at other times of the year. Conception rates of cows in Groups 1 to 4 that were inseminated during the summer were low and not significantly different from each other. Conception rates of cows in Groups 5 and 6 inseminated during the summer were not significantly different from each other, but were significantly higher than that of cows in Groups 1 to 4 that were inseminated during the summer.     

Fetal-maternal secretion of prostaglandins in the cow

A study was conducted to measure the blood plasma concentrations of prostaglandin F2 alpha (PGF2 alpha), 13,14-dihydro-15-keto-prostaglandin F (PGFM), 6-keto-prostaglandin F1 alpha (6-keto), prostaglandin uterine artery, uterine vein, umbilical artery and umbilical vein in 24 cows from days 80 to 260 of pregnancy. Blood was collected during surgery and all prostaglandins were measured using specific radioimmunoassay procedures. Results indicate that PGF2 alpha blood levels are higher in the umbilical vessels and uterine vein than in the ovarian vein and uterine artery. PGFM and PGE2 showed a trend towards higher values in the umbilical than in the maternal vessels, but the levels of 6-keto and TBX2 were not different among the vessels studied. No differences across time could be observed in any of the prostaglandins measured, partly due to the great variability in blood levels among animals during the same stage of pregnancy.     

Hormonal interelationships and physiological responses of lactating dairy cows to a shade management system in a subtropical environment

Lactating cows (n = 64) were assigned randomly to shade or no shade treatments for a continuous trial (20 wk) during summer of 1976. Respirations/min and rectal temperatures were higher for no shade cows. Dry matter forage intake was 9.7% higher for shade cows, whereas water intake was 19% greater for no shade cows. Milk yield and conception rates were higher for shade managed cows. Mean plasma corticoid concentrations were high throughout the entire estrous cycle in no shade compared to shade cows (13.04 > 8.72 ng/ml). No shade cows had higher progesterone and LH concentrations, and a lower estradiol to progesterone ratio during the cycle. Results indicated that endocrine changes were indicative of recurring estrous cycles in thermal stressed lactating dairy cows. However, alterations in water intake and thermoregulation of stressed cows were associated with decreased fertility and milk production, and changes in steroid concentrations that may reduce uterine blood flow.     

Effect of gonadotropin-releasing hormone and prostaglandin F2α on reproduction in postpartum dairy cows

Thirty dairy cows serving as the treated group (Group A) were injected intramuscularly with 100 mcg gonadotropin-releasing hormone (GnRH) at 10 to 16 days postpartum followed by 25 mg prostaglandin F₂α (PGF₂α) 14 days later. Twenty-nine herdmate dairy cows (Group B) serving as controls were treated in a similar manner using saline injections rather than GnRH or PGF₂α treatments. Only cows without obvious uterine infection were assigned to the experimental groups, and any uterine pathology that developed during the treatment interval was treated accordingly following the experimental period. Internal genitalia were evaluated via rectal palpation prior to each injection. Blood samples were collected for progesterone analysis before each injection and at 30 hours following the PGF₂α or the second saline injection. Experimental animals were artificially inseminated at the first detected postpartum estrus starting 35 to 40 days following calving. Results indicated evidence of enhanced cyclicity when Group A cows were compared with those in Group B. However, there were no significant differences between the two groups for interval to first observed estrus, interval to first serive, first serive pregnancy rate, services per pregnancy and days open. Furthermore, no difference in the incidence of follicular or luteal cysts, incidence of repeat breeders or number of reproductive culls was observed. From observations in this study, the GnRH and PGF₂α treatment scheudule might not be economically beneficial in lactating dairy cows as long as reproductive tract abnormalities are promptly diagnosed and subsequently treated by the attending practitioner.     

Effects of beta-adrenergic agonist infusions on myometrial activity and plasma prostaglandin levels in the nonpregnant sheep

Recent studies have reported that beta-adrenergic agonists stimulate the production of stimulatory prostaglandins (PGs) by intrauterine tissues in vitro. These drugs are used clinically to inhibit uterine contractions; consequently an increase in stimulatory PGs in vivo might have potentially adverse effects. We have, therefore, investigated whether beta-adrenergic agonists increase plasma PG concentrations in vivo. Samples of peripheral (aorta) and uterine venous enriched (vena cava) blood from nonpregnant sheep were collected at 15-min intervals for 1 h before, 3 h during, and 1 h postinfusion of either (a) the beta-adrenergic agonist isoproterenol (Isop) at a dose of 0.16 microgram.kg-1.min-1; (b) Isop at a dose of 0.08 microgram.kg-1.min-1; or (c) saline, 1 mL/h via a jugular vein catheter. The sheep were also equipped with intrauterine recording balloons to record intrauterine pressure and myometrial electromyographic (EMG) electrodes to measure EMG activity. Infusion of Isop at 0.16 microgram.kg-1.min-1 produced a significant initial inhibition of uterine activity, although contractions returned (within 60 min) despite continued administration of Isop. Plasma PGE2 (but not PGF2 alpha or 13,14-dihydro-15-keto-PGF2 alpha (PGFM] concentrations were significantly elevated during the Isop infusion. Administration of Isop at 0.08 microgram.kg-1.min-1 produced no effects on uterine contractile activity but was associated with a significant elevation in plasma PGE2 (but not PGF2 alpha or PGFM) concentrations. No changes in plasma PGE2, PGF2 alpha, or PGFM occurred during saline infusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Uterine blood flow during the first 3 weeks of pregnancy in dairy cows

Transrectal color Doppler sonography was used to compare changes in uterine blood flow between cyclic and early pregnant lactating dairy cows. Examinations were carried out in 53 multiparous lactating cows on days 3, 6, 9, 11, 13, 15, 18 and 21 (day 0=estrus). Fourteen cows were examined during the estrous cycle and thirty-nine cows after insemination with frozen/thawed sperm. Uterine blood flow was reflected by the time-averaged maximum velocity (TAMV) and the pulsatility index (PI) in the uterine artery ipsilateral to the corpus luteum. Twenty-one cows that were not pregnant on day 25 were excluded from the study. There was high inter-individual variability in PI- (CV: 22-62%) and TAMV-values (CV: 22-42%) at all examinations. In cyclic cows, TAMV values increased between days 13 and 18 and PI values decreased between days 15 and 21 (P<0.05). In pregnant cows (n=18), TAMV values increased from days 9 to 11 and then decreased to minimal values by day 18 (P<0.05). The PI values decreased between days 3 and 11 and then increased to maximum levels on day 18 (P<0.05). On day 21, both variables reached (P<0.05) values that did not differ (P>0.05) from those on day 11. The changes in TAMV were correlated with estrogen and progesterone concentrations (r=0.69 and -0.70, respectively; P<0.05) in cycling cows, but not in pregnant cows (P>0.05). The PI values did not correlate with steroid hormone levels (P>0.05). Differences in uterine blood flow between cycling and early pregnant cows were observed only on day 18 (P<0.05). The results show that in pregnant cows changes in uterine blood supply can be detected already in the second week after insemination; these changes do not occur in the second week of the cycle.     

Effect of an acute ergotamine challenge on reproductive hormones in follicular phase heifers and progestin-treated cows

The objective of this research was to determine if ergotamine, an ergopeptine alkaloid isolated from Neotyphodium-infected grasses and associated with toxicoses in livestock, altered plasma concentrations of reproductive hormones in follicular phase heifers and in cows given a progestin implant. In Experiment 1, blood was sampled for 8h from four cycling heifers 2 days after synchronized luteolysis. Heifers were treated with ergotamine tartrate (19microg/kg) i.v. or saline vehicle in a simple cross-over design after 1h of pre-treatment blood sampling. Heifers received oxytocin (100USP units) i.v. 4h after ergotamine or saline treatment. Ergotamine reduced (P<0.01) prolactin concentrations from 1 to 4h post-treatment and increased (P<0.01) 13,14-dihydro-15-keto prostaglandin F2alpha (PGFM) concentrations from 2 to 5h post-treatment. A PGFM response to oxytocin was not detected. In Experiment 2, blood was sampled for 8h from six cycling cows 10 days after receiving a s.c. norgestomet implant. Cows were treated i.v. with ergotamine (20microg/kg) or saline in a simple cross-over design after 1h of pre-treatment blood sampling. Cows received gonadorelin (GnRH, 100microg) i.v. 1h after ergotamine or saline. Cows received oxytocin (100USP units) i.v. 4h after ergotamine or saline treatment. Ergotamine reduced (P<0.01) serum prolactin concentrations by 120min after treatment, with prolactin returning to pre-treatment concentrations by 200min after treatment. Saline-treated cows had lower (P<0.01) prolactin by 280min after treatment. Ergotamine-treated cows had higher (P<0.01) PGFM concentrations compared to saline-treated cows 120-240min after treatments, but the groups exhibited similar increases in PGFM after oxytocin. Plasma LH and FSH concentrations increased to peaks 100-120min after GnRH for both groups. However, the LH response to GnRH was greater (P<0.01) for ergotamine-treated cows. In summary, ergotamine lowered prolactin and elevated PGFM concentrations in follicular phase heifers and cows on norgestomet therapy. Ergotamine increased the LH response to exogenous GnRH in cows with norgestomet implants. These data highlight the potential of ergopeptine alkaloids to affect reproduction through altered endocrine function.     

Spontaneous uterine infections are associated with elevated prostaglandin F(2)alpha metabolite concentrations in postpartum dairy cows

Postpartum Holstein (n=21) and Jersey (n=4) cows were used to determine if uterine infections are associated with elevated plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F(2)alpha (PGFM). Based upon clinical examinations and bacterial content of intrauterine fluid samples, cows detected with uterine infections between 21 and 28 d post partum were used (infected; n=14). These cows were matched with herdmates that were free of infection (control; n=11). Beginning on the day the cows were assigned to the experiment (Day 1), blood samples were collected on alternate days for the next 14 to 15 d. Plasma samples were stored at -20 degrees C until assayed. From Day 1 until the end of the experiment, uterine fluid samples were collected transcervically twice weekly for aerobic bacterial culture. Endometrial biopsies were collected between Days 6 and 8 and Days 13 and 15. Control cows did not show signs of uterine infection throughout the trial, and bacterial cultures indicated that there were no significant bacterial populations in the uteri of the control cows. The uteri of infected cows harbored numerous microbes. Actinomyces pyogenes was most prominent. Various species of Streptococcus and Pasteurella were also prevalent in the infected cows. Escherichia coli was present in the uterus of both infected and control cows. Biopsies showed that infected cows had more (P<0.05) neutrophils, plasma cells and lymphocytes in the endometrium than did the control cows. As determined by plasma progesterone concentrations, 83% of the control and 50% of the infected cows had functional luteal tissue during the 2-wk sampling period. Plasma PGFM profiles were linear (P<0.03) and did not differ between treatment groups (P>0.01). However, average plasma PGFM concentrations were greater (P<0.0001) in infected than in control cows. These data indicate that plasma PGFM concentrations are greater in postpartum cows with spontaneous uterine infections then in herdmates free of infection.