The effect of basic fibroblast growth factor 2 on the bovine corpus luteum depends on the stage of the estrous cycle and modulates prostaglandin F2α action

The roles of fibroblast growth factor 2 (FGF2) in the corpus luteum (CL) function and its modulatory effect on prostaglandin (PG) F_2α during the bovine estrous cycle were studied using the following design of in vivo and in vitro experiments: (1) effects of FGF2 and FGF receptor 1 inhibitor (PD173074) on bovine CL function in the early (PGF_2α-resistant) and mid (PGF_2α-responsive) luteal stage in vivo, (2) the modulatory effect of FGF2 on PGF_2α action during the luteal phase in vivo and (3) effects of FGF2 and PD173074 on bovine CL secretory function in vitro. Cows were treated by injection into the CL with: (1) saline (control), (2) FGF2, (3) PD173074, (4) FGF2 followed by intramuscular (i.m.) PGF_2α, (5) PD173074 followed by i.m. PGF_2α and (6) i.m. PGF_2α as a positive control. For in vitro experiments, CL explants were treated with the aforementioned factors. Progesterone (P₄) concentrations of blood samples or culture media were determined by radioimmunoassay. Relative mRNA expressions of the genes involved in angiogenesis and steroidogenesis were determined by quantitative real-time PCR. Although FGF2 treatment on day 4 of the estrous cycle did not change the cycle length, FGF2 with PGF_2α decreased the P₄ concentrations observed during the estrous cycle compared to the control group (P < 0.001). Moreover, FGF2 treatment on day 10 prolonged CL function as indicated by a significantly greater concentration of P₄ on day 21 compared to the control group. In the in vitro study, FGF2 decreased cytochrome P450 family 11 subfamily A member 1 (CYP11A1) and hydroxy-delta-5-steroid dehydrogenase (HSD3B1) mRNA expression (P < 0.01) and decreased P₄ production in the early-stage CL (P < 0.001). However, FGF2 + PGF_2α or PGF_2α alone resulted in an elevation of steroidogenic acute regulatory protein and CYP11A1 mRNA expression and P₄ secretion in the early-stage CL (P < 0.01). In the mid-luteal phase, FGF2 upregulated CYP11A1 and HSD3B1 mRNA expression (P < 0.01), while FGF2 + PGF_2α increased only HSD3B1 mRNA expression (P < 0.001). In conclusion, FGF2 seems to play a modulatory role in CL development or luteolysis, differentially regulating steroidogenesis and angiogenic factors as well as PGF_2α actions.     

Opposite effects of methanandamide on lipopolysaccharide-induced prostaglandin E2 and F2α synthesis in uterine explants from pregnant mice

Prostaglandins (PG) are effective abortifacients and are important mediators of lipopolisaccharide (LPS)-induced embryonic resorption (ER). Besides, anandamide (AEA) has been described as one of the major endocannabinoids present in the uterus suggesting that it might play a role in reproduction. It has been reported that high levels of AEA are associated with pregnancy failure and that LPS increases AEA production. Also, it has been observed that AEA modulates PG production in different tissues. In this sense, we studied whether LPS-induced PG production is modulated by AEA and we also assessed the effect of this endocannabinoid on PG metabolism in an in vitro model. Uterine explants from BALB/c implantation sites were cultured in the presence of LPS plus cannabinoid receptor (CB) specific antagonists and PG production was assessed. Then, we studied the effect of exogenous AEA on different steps of PG metabolic pathway. We showed that AEA is involved in LPS-induced PG biosynthesis. Also, we observed that AEA exerts opposite effects on PGE(2) and PGF(2α) biosynthesis, by inhibiting PGE(2) production and increasing PGF(2α) levels. We suggest that AEA could be involved in the mechanisms implicated in LPS-induced ER. A better understanding of how AEA could be affecting ER could help developing specific interventions to prevent this pathology.     

The effects of trans linoleic acid on the concentration of serum prostaglandin f2α and platelet aggregation

In order to determine the effects of dietary trans linoleate on the concentration of PGF_2α and its precursor acid, and on platelet aggregation, four groups of rats were fed a diet containing hydrogenated coconut oil (HCO, treatment A); 9 trans, 12 trans linoleate (trans linoleate, treatment B); an equal mixture of 9 cis linoleate (cis linoleate) and trans linoleate (treatment C); and cis linoleate (treatment D); respectively for 12 weeks. The levels of arachidonic acid as a percent of total serum lipids were 5.8, 0.8, 25.2 and 30.0, respectively for treatments A, B, C, and D. The serum concentrations of PGF_2α were 3.2, 0.31, 14.1 and 27.4 ng/ml, respectively for treatments A, B, C, and D. Thus, trans linoleate caused decreased biosynthesis of PGF_2α probably resulting from decreased level of its precursor acid. The magnitude of the inhibition of the platelet aggregation by indomethacin was greater in treatment A than in treatment B. The difference in the magnitude of the inhibition between treatment C and D was not apparent at a high concentration of indomethacin, however, at a lower concentration (0.01 mM) the percent inhibition was 3 and 42 for treatments C and D, respectively. These results indicate that levels of dietary linoleate can affect physiological responses through an effect on the amount of PG synthesized in animal tissues.     

Physiologic and nonphysiologic effects of exogenous prostaglandin F2α on reproductive hormones in mares

Responses to intravenous treatment of mares with prostaglandin F2α (PGF) 8 d after ovulation were studied in three groups (n = 4/group): control (no treatment), bolus (single treatment with 2.5 mg PGF), and infusion (0.1 mg PGF during 2 h). Infusion resulted in a 13,14-dihydro-15-keto-PGF2α (PGFM) concentration (559 ± 44 pg/mL) that was not different from the mean concentration for the major portion of a natural PGFM pulse associated with luteolysis (569 ± 45 pg/mL; n = 5). Progesterone in the bolus group increased (P < 0.03) between 0 (17.8 ± 3.5 ng/mL) and 2 min (25.3 ± 4.8 ng/mL), peaked at 10 min (28.5 ± 4.6 ng/mL), and then decreased. In the infusion group, progesterone decreased (P < 0.05) during 1 min (17.2 ± 1.3 ng/mL) to 15 min (13.5 ± 1.5 ng/mL) after the beginning of infusion and decreased (P < 0.05) similarly to the bolus group during 2 to 12 h; concentrations were lower (P < 0.05) at each hour than in controls. Interval between ovulations was shorter (P < 0.05) in the bolus (19.3 ± 2.0 d) and infusion (18.8 ± 2.1 d) groups than in controls (24.3 ± 1.3 d). Concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and cortisol increased (P < 0.05) within 10 min in the bolus group but did not change in the infusion group. Results supported the hypothesis that increases in progesterone, FSH, LH, and cortisol after a bolus luteolytic PGF treatment are nonphysiologic. Past conclusions on the nature of the luteolytic mechanism are problematic if based on responses to treatment with a single luteolytic bolus of PGF.     

Antiluteogenic effects of serial prostaglandin F2α administration in cycling mares

A single dose of PGF2α does not consistently induce luteolysis in the equine CL until at least 5 days after ovulation, leading to the erroneous assumption that the early CL is refractory to the luteolytic effects of PGF2α. We hypothesized that serial administration of PGF2α in early diestrus would induce a return to estrus similar to mares treated with a single injection in mid-diestrus, and fertility of the induced estrus would not differ. The objectives of the study were to evaluate the effects of the 2 approaches as reflected by: (1) concentrations of plasma progesterone; (2) interovulatory and treatment-to-ovulation intervals; (3) the proportion of mares pregnant after artificial insemination. The study consisted of a balanced crossover design in which 10 reproductively normal Quarter Horse Mares were exposed to 2 treatments on 2 consecutive reproductive cycles. At detected ovulation (Day 0), mares were randomly allotted to 1 of 2 treatment groups: I, mid-diestrus treatment, administration of a single 10-mg dose of dinoprost tromethamine (PGF2α) im on Day 10; II, early diestrus treatment, administration of 10-mg PGF2α im twice daily on Days 0, 1, and 2 and once daily on Days 3 and 4. Mares in estrus and with a follicle 35 mm or greater in diameter were artificially inseminated with at least 2 billion motile sperm from a fertile stallion. Pregnancy was defined as detection of a growing embryonic vesicle on 2 consecutive examinations approximately 14 days after ovulation. Serial plasma samples were collected throughout the study period, and concentration of plasma progesterone was determined by RIA. A mixed-model ANOVA for repeated measures was used to analyze hormonal data. Interovulatory and treatment-to-ovulation intervals were compared by a paired t test and fertility by a McNemar chi-square analysis. All mares in group I underwent luteolysis after PGF2α administration denoted by mean (±SD) concentration of plasma progesterone of 0.25 ± 0.21 ng/mL detected 2 days after treatment. In group II, mean concentration of plasma progesterone remained below 1.0 ng/mL during treatment and until the onset of the next estrus. The mean interovulatory interval in group I was 18.5 ± 2.0 days compared with 13.1 ± 3.7 days in group II (P < 0.01). Treatment-to-ovulation intervals were 8.5 ± 2.0 days and 13.1 ± 3.7 days for groups I and II, respectively (P < 0.05). In both groups, 9 of 10 mares were pregnant (P = 1.0). Serial PGF2α administration beginning at ovulation consistently prevented luteal function in 10 of 10 mares in the present study without adversely affecting pregnancy rate of post-treatment cycles.     

Cationic dependency of high affinity prostaglandin F2α receptors in bovine corpus luteum cell membranes

The specific binding of [³H] Prostaglandin (PG) F₂α to bovine corpus luteum cell membranes prepared in homogenizing buffer containing either 1 mM EDTA (H-EDTA) or 1 mM Ca²⁺ (HCa²⁺) was examined. The membranes prepared in H-EDTA buffer bound less [³H] PGF₂α and had a single class of PGF₂α receptors with an apparent dissociation constant (Kd) of 2.7 × 10^?8M. The addition of Ca²⁺ to these membranes resulted in increased binding with the appearance of new PGF₂α receptors of Kd = 4.3 × 10^?9M. The membranes prepared in HCa²⁺ buffer contained two classes of receptors with Kds = 2.9 × 10^?9M and 2.9 × 10^?8M. The removal of Ca²⁺ from these membranes resulted in lower binding as well as a complete disappearance of receptors of Kd = 2.9 × 10^?9M. These results suggest the dependency of high affinity PGF₂α receptors, in bovine corpus luteum cell membranes, on cations.     

Effect of prostaglandin F2α on anterior pituitary function in man

Five healthy adult men received iv PGF_2α at dosages of 0.05, 0.20 and 2.0 μg/kg/min for 30 min. There were no significant changes in serum FSH, LH or TSH levels. Serum GH and cortisol levels were slightly increased at the highest dosage. These responses were associated with, and presumably a result of, stressful side effects. Thus, PGF_2α cannot be used as a provocative test of pituitary hormone reserve.Prostaglandins (PG's) have recently been implicated in the release of a number of hormones from the anterior pituitary gland. The stimulation of GH release by PG's of the E series from incubated rat pituitary slices has been demonstrated. $\text{In vivo}$ stimulation by PGE₁ of ACTH in rats and of GH release in man has also been shown.The present study was undertaken in order to examine the efficacy of iv administration of PGF_2α as a provocative test of anterior pituitary hormone reserve in man. The responses in circulating levels of gonadotropins, TSH, GH, and cortisol (as an index of ACTH) were measured.     

Development of corpus luteum susceptibility to an analog of prostaglandin F2α, throughout the luteal phase in llamas (Lama glama)

The aim of the present study was to evaluate the susceptibility of the corpus luteum to d-cloprostenol (synthetic analog of PGF(2α)) throughout the luteal phase in llamas. Female llamas (n=43) were induced to ovulate by GnRH injection in the presence of an ovulatory follicle and randomly assigned into one of six groups: control and treated with an injection of d-cloprostenol on Day 3, 4, 5, 6 or 8 post GnRH. Blood samples were collected to determine plasma progesterone concentrations. There was no effect of treatment on animals injected on Day 3 or 4 post-GnRH. In animals treated on Day 5, different responses were observed. No effect of treatment was recorded in 27% of the animals whereas 55% of the llamas showed a transitory decrease followed by a recovery in plasma progesterone concentrations after d-cloprostenol injection, indicative of a resurgence of the corpus luteum, extending the luteal phase a day more than in control animals. In the remaining 18% of the animals injected on Day 5, (corresponding to those exhibiting the greatest plasma progesterone concentrations at the day of injection), complete luteolysis was observed. Plasma progesterone concentrations decreased to below 1 ng ml(-1) 24 h after d-cloprostenol in llamas injected on Day 6 or 8 post-GnRH. In conclusion, the corpus luteum of llamas is completely refractory to PGF(2α) until Day 4 after induction of ovulation, being partially sensitive by Day 5 and fully responsive to PGF(2α), by Day 6 after induction of ovulation.     

Effect of progesterone administration on the release of uterine prostaglandin F2α and ovarian oxytocin in the goat

The effects of intramuscular progesterone administration (20 mg·day⁻¹) on plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F_2α (PGFM-pulmonary metabolite of prostaglandin F_2α) and oxytocin were examined in seventeen goats after either bilateral ovariectomy, hysterectomy or during days 12–16 of the estrous cycle. Daily mean values of PGFM in animals treated with progesterone after ovariectomy were significantly greater (P<0.001) than in their corresponding controls on the last two treatment days (10 and 11); concentrations of oxytocin, however, remained at or near the limits of assay sensitivity. In hysterectomized goats PGFM concentrations remained extremely low and oxytocin release appeared steady rather than pulsatile. In the intact animals, undergoing luteolysis, daily mean concentrations of both PGFM and oxytocin were significantly greater (P<0.01) in progesterone-treated goats than in their oil-treated controls; furthermore, in the progesterone-treated goats, increases in PGFM concentrations, observed after the peaks of progesterone, were either coincident with or prior to pulses of oxytocin. These results demonstrate that uterine PGF_2α stimulates the pulsatile release of oxytocin from the ovary during luteolysis in the goat.     

Effects of indomethacin and prostaglandin F2α on ovulation and ovarian contractility in the rabbit

The present investigation was carried out to determine whether inhibition of ovulation in the rabbit by administration of indomethacin can be correlated with any change in ovarian contractility at ovulation time and can be reversed by administration of prostaglandins. Indomethacin was adminstered intra-muscularly using three different schedules in a dose of 5 mg/kg. A reduced number of ruptured follicles following HCG was noted in all groups treated with indomethacin. Infusion of PGF_2α into the aorta (1 μg/kg/min.) could reverse this effect. Less pronounced ovarian contractility was observed after indomethacin treatment, but infusion of PGF_2α immediately enhanced contractility in ovaries from indomethacin treated rabbits. The inhibition of ovulation in the rabbit associated with indomethacin adminstration may be related to suppression of ovarian contractions. These data also suggest that prostaglandins may play a significant role in the mechanism of ovulation through an influence on ovarian contractility.     

Biasing the prostaglandin F2α receptor responses toward EGFR-dependent transactivation of MAPK

The G protein-coupled prostaglandin F2α (PGF2α) receptor [F prostanoid (FP) receptor] has been implicated in many physiological events including cardiovascular, respiratory, immune, reproductive, and endocrine responses. Binding of PGF2α to FP receptor elicits inositol production and protein kinase C-dependent MAPK activation through Gα(q) coupling. Here we report that AL-8810, previously characterized as an orthosteric antagonist of PGF2α-dependent, Gα(q)-mediated signaling, potently activates ERK1/2 in a protein kinase C-independent manner. Rather, AL-8810 promoted ERK1/2 activation via an epidermal growth factor receptor transactivation mechanism in both human embryonic kidney 293 cells and in the MG-63 osteoblast-like cells, which express endogenous FP receptors. Neither AL-8810- nor PGF2α-mediated stimulation of FP receptor promoted association with β-arrestins, suggesting that MAPK activation induced by these ligands is independent of β-arrestin's signaling scaffold functions. Interestingly, the spatiotemporal activation of ERK1/2 promoted by AL-8810 and PGF2α showed almost completely opposite responses in the nucleus and the cytosol. Finally, using [(3)H]thymidine incorporation, we noted differential regulation of PGF2α- and AL-8810-induced cell proliferation in MG-63 cells. This study reveals, for the first time, the signaling biased nature of FP receptor orthosteric ligands toward MAPK signaling. Our findings on the specific patterns of ERK1/2 activation promoted by FP receptor ligands may help dissect the distinct roles of MAPK in FP receptor-dependent physiological responses.     

Enzymatic formation of prostaglandin F2α in human brain

Prostaglandin (PG)E₂ 9-ketoreductase, which catalyzes the conversion of PGE₂ to PGF₂, was purified from human brain to apparent homogeneity. The molecular weight, isoelectric point, optimum pH, Km value for PGE₂, and turnover number were 34,000, 8.2, 6.5–7.5, 1.0 mM, and 7.6 min^–1, respectively. Among PGs tested, the enzyme also catalyzed the reduction of other PGs such as PGA₂, PGE₁, and 13,14-dihydro-15-keto PGF₂, but not that of PGD₂, 11-PGE₂, PGH₂, PGJ₂, or ¹²-PGJ₂. The reaction product formed from PGE₂ was identified as PGF₂, by TLC combined with HPLC. This enzyme, as is the case for carbonyl reductase, was NADPH-dependent, preferred carbonyl compounds such as 9,10-phenanthrenequinone and menadione as substrates, and was sensitive to indomethacin, ethacrynic acid, and Cibacron blue 3G-A. The reduction of PGE₂ was competitively inhibited by 9,10-phenanthrenequinone, which is a good substrate of this enzyme, indicating that the enzyme catalyzed the reduction of both substrates at the same active site. These results suggest that PGE₂ 9-ketoreductase, which belongs to the family of carbonyl reductases, contributes to the enzymatic formation of PGF₂ in human brain.Special issue dedicated to Dr. Sidney Udenfriend.     

Oestrogenic effects of ICI 182,780, a putative anti-oestrogen,on the secretion of oxytocin and prostaglandin F2α during oestrous cycle in the intact ewe

The effect of ICI 182,780, oestrogen antagonist, on the concentrations of oxytocin and uterine PGF_2α was investigated in intact Border Leicester Merino cross ewes during the late oestrous cycle. Twelve cyclic ewes (n=6 per group) were randomly assigned to receive, at 6 h intervals, intra-muscular injection of either peanut oil or ICI 182,780 (1.5 mg kg⁻¹ day⁻¹) in oil for 2 days, starting at 1900 h on day 13 until 1300 h on day 15 post-oestrus. Hourly blood samples were collected via a jugular catheter from 0800 h on day 14 for 37 h and then daily over days 16, 17 and 18 post-oestrus. Peripheral plasma concentrations of oxytocin, the metabolite of prostaglandin F_2α, 15-keto-13,14-dihydro-prostaglandin F_2α, (PGFM) and progesterone were measured by radioimmunoassay. All ewes treated with ICI 182,780 exhibited functional luteal regression as indicated by a marked reduction in plasma progesterone concentrations to less than 1000 pg/ml over the period of 18–36 h during sampling period on days 14 and 15 of the oestrous cycle. In five of six vehicle-treated ewes, progesterone concentrations declined between day 16 and day 18 post-oestrus. In the remaining control ewe, progesterone concentrations reach less than 1000 pg/ml within 36 h of the commencement of the sampling period. During the frequent sampling period, the number of oxytocin pulses in the ICI 182,780 treated ewes was significantly higher compared to control ewes (2.7±0.3 vs. 0.8±0.3). The mean amplitude of oxytocin pulses observed was also greater (70.4±19.5 pg/ml) in ewes treated with ICI 182,780, but was not significantly different from control ewes (33.5±12.9 pg/ml). Oxytocin pulses may however have occurred following the initial two ICI 182,780 injections but before commencing blood sampling. The oxytocin pulses were detected at a mean of 3.2±0.2 h following each injection with ICI 182,780 during blood sampling. In the ICI 182,780-treated ewes, the pulsatile pattern of plasma PGFM in jugular blood samples over the 37 h sampling period on days 14 and 15 post-oestrus had a higher amplitude (512.9±158.9 vs. 121.7±78.7 pg/ml) and pulse area (618.1±183.3 vs. 151.5±102.9 (pg/ml)τ) compared to the vehicle-treated ewes (P<0.05) respectively. The average number of PGFM pulses observed per ewe was 3.0±0.7 in the ICI 182,780-treated group and was significantly (P<0.02) higher than the number of pulses (0.5±0.3) observed in ewes treated with vehicle alone. The PGFM pulses were detected at 4.2±0.6 h following each injection with ICI 182,780 during blood sampling. The percentage of PGFM pulses that occurred coincidently with a significant elevation of oxytocin concentrations was 44.4% in ICI 182,780-treated compared to 66.6% in control ewes. We conclude that administration of oestrogen antagonist ICI 182,780 accelerated development of the luteolytic mechanism by enhancing pulsatile secretion of oxytocin and PGFM which suggests that ICI 182,780 acts as an agonist for oxytocin and prostaglandin F_2α release in intact ewes when administered at 1.5 mg/kg/day over Day 13 to 15 post-oestrus.     

The fine structure of ‘homology’

There is long-standing conflict between genealogical and developmental accounts of homology. This paper provides a general framework that shows that these accounts are compatible and clarifies precisely how they are related. According to this framework, understanding homology requires both (a) an abstract genealogical account that unifies the application of the term to all types of characters used in phylogenetic systematics and (b) locally enriched accounts that apply only to specific types of characters. The genealogical account serves this unifying role by relying on abstract notions of ‘descent’ and ‘character’. As a result, it takes for granted the existence of such characters. This requires theoretical justification that is provided by enriched accounts, which incorporate the details by which characters are inherited. These enriched accounts apply to limited domains (e.g. genes and proteins, or body parts), providing the needed theoretical justification for recognizing characters within that domain. Though connected to the genealogical account of homology in this way, enriched accounts include phenomena (e.g. serial homology, paralogy, and xenology) that fall outside the scope of the genealogical account. They therefore overlap, but are not nested within, the genealogical account. Developmental accounts of homology are to be understood as enriched accounts of body part homology. Once they are seen in this light, the conflict with the genealogical account vanishes. It is only by understanding the fine conceptual structure undergirding the many uses of the term ‘homology’ that we can understand how these uses hang together.     

The effects of cholesterol and β-sitosterol on the structure of saturated diacylphosphatidylcholine bilayers

The structures of DMPC and DPPC bilayers in unilamellar liposomes, in the presence of 33.3 mol% cholesterol or the plant sterol β-sitosterol, have been studied by small-angle neutron scattering. The bilayer thickness d _L increases in a similar way for both sterols. The repeat distance in multilamellar liposomes, as determined by small-angle X-ray diffraction, is larger in the presence of β-sitosterol than in the presence of cholesterol. We observe that each sterol modifies the interlamellar water layer differently, cholesterol reducing its thickness more efficiently than β-sitosterol, and conclude that cholesterol suppresses bilayer undulations more effectively than β-sitosterol.     

The effects of confinement on periparturient behaviour and circulating prolactin,prostaglandin F2α and oxytocin in gilts with access to a variety of nest materials

In a 2×2 factorial experiment, the effects of gestation and farrowing housing on (1) periparturient behaviour and circulating prolactin, prostaglandin F_2α (PGF_2α) and oxytocin in gilts with access to peat, straw and branches, and (2) correlational relationships between the periparturient behaviour and hormones were studied. The treatments consisted of housing in stalls or pens from mating to day 110 of gestation followed by farrowing crates or pens until after parturition. Landrace×Yorkshire gilts were observed from video recordings (n=25) from 20 h prepartum and blood sampled via jugular catheters (n=16) from 24 h prepartum until 2 h after the birth of the first piglet.There was an interaction between gestation and farrowing housing affecting the start of nest-building (P=0.03). Gilts that experienced a change in type of housing accommodation commenced nest-building closer to parturition than gilts that were penned both during gestation and at farrowing (both P<0.05). There were no effects of the housing environment on the timing of termination of nest-building, behaviour during parturition, or the course of parturition. However, relative to base level, crated gilts sat more from 16 to 6 h prepartum, whereas this was the case for penned gilts only from 9 to 7 h prepartum. Crated gilts also tended to change posture more often (P=0.07) and lie more in sternal recumbency (P=0.095). This suggests that familiarity with the environment in combination with space to move about and/or availability of materials is important in the timing of nest-building. Confinement during farrowing did not appear to impair feed-back from the materials and the nest, although increased number of postural changes may reflect the motivation but inability to nest-build, or general discomfort in the crate.There was a development over time in postural and nest-building behaviours as well as in plasma concentrations of prolactin, PGF_2α (measured by the metabolite PGFM) and oxytocin, but there were only few effects of housing treatments on hormones or associations between behaviour and hormones. The results suggest that nest-building occurs independently of a prepartum rise in prolactin, but that oxytocin may be associated with the termination of nest-building as there was a negative correlational relationship with nosing (P<0.01) and arranging nest-building materials (P<0.001).Farrowing crate housing appeared to have fewer effects on periparturient behaviour and course of parturition than reported in previous studies where effects of confinement and provision of nest-building materials may have been confounded. Thus, provision of nest-building materials to crated sows may have beneficial effects on sow behaviour and welfare.     

Comparison of various semen extenders and addition of prostaglandin F2α on pregnancy rate in cows

This investigation comprises three trials. Trial 1 consists of an in vitro comparison of three semen extenders: two egg yolk based (customized Tris-egg yolk-glycerol and Triladyl®), the third (AndroMed®) soybean lecithin based. With regard to post-thaw motility, the phytoextender AndroMed® proved to be superior (59±3% v. 53±2% and 53±2%, P<0.05). It had earlier been shown that addition of the commercial prostaglandin F_2α preparation Dinolytic® before freezing compromises post-thaw motility; therefore, in Trial 2, Dinolytic® was added after thawing. Frozen-thawed spermatozoa tolerated addition of Dinolytic® at a concentration of 30% (v/v). In Trial 3, cows were inseminated using straws in which diluted semen and Dinolytic® were frozen in the same straw, separated by an air bubble, so intermingling could only take place in the course of insemination. Pregnancy rates at Dinolytic® dosages of 0%, 30% or 60% amounted to 44%, 41% and 56%, respectively (P>0.05), a result that encourages a large-scale field study, which is envisioned.     

The effect of prostaglandin F(2α) administration at the time of insemination on the pregnancy rate of dairy cows

This paper addresses the question whether the pregnancy rate of dairy cows and heifers may be affected by administering prostaglandin F_2α at the time of artificial insemination. A field trial involving 1031 dairy cows and heifers distributed to a large number of small dairy farms in an area of extensive farming in central Germany provided evidence that intramuscular administration of 25 mg Dinoprost (Dinolytic^®) at the time of insemination has no effect on pregnancy rate (61% of the cows and heifers were pregnant in both prostaglandin F_2α-treated and saline control groups). On the other hand, deposition of 0.5 mL of a 0.5 mg/mL Dinoprost solution in the uterine lumen immediately after artificial insemination gave rise to a pregnancy rate of 66% as compared with 59% in saline controls. The increase in pregnancy rate of 229 prostaglandin F_2α-treated animals (66% pregnant) over that of 226 saline controls (59% pregnant) amounted to 12%. This improvement was not statistically significant (P = 0.12). Factors exerting a significant effect on pregnancy rate were parity (74% pregnancies in heifers versus 57% in cows, P < 0.01 and 65% pregnancies in first parity-cows versus 55% in older cows, P < 0.01) and season (57% during the barn season versus 64% during the pasture season, P < 0.05), whereas length of service period, level of milk production and serum or milk progesterone level at the time of insemination did not. A follow-up trial involving more animals will have to be conducted aimed at confirming the promising results obtained by intrauterine PGF_2α administration.     

Doses of prostaglandin F2α effective for induction of parturition in goats

Twelve mixed breed does were injected with different doses of prostaglandin F₂α (PGF₂α) or saline on day 144 of gestation. Four each received single intramuscular injections of 5.0 or 2.5 mg PGF_2α, or 1.0 ml saline (controls). Systemic progesterone (P₄) concentrations were determined daily from day 144 until the day of kidding. Does receiving 5.0 mg PGF₂α, 2.5 mg PGF₂α, or saline kidded within mean (± SD) hours and range (hours) of 35 ± 8.6 and 28–48, 43 ± 11.8 and 29–57, and 111 ± 79.1 and 41–200, respectively. Mean (± SD) concentrations of P₄ (ng/ml) on the day of injection and on day 1 postinjection were 5.2 ± 2.6 and 0.7 ± 0.9, 5.3 ± 2.2 and 1.1 ± 1.0, and 6.4 ± 3.9 and 4.1 ± 2.6 for does receiving 5.0 mg PGF₂α, 2.5 mg PGF₂α, or saline, respectively. It was concluded that 5.0 mg and 2.5 mg PGF₂α effectively shortened the interval from injection to parturition, but that this interval was not as predictable as that previously reported with 20 mg PGF₂α.