Postovulatory effect of repeated intravenous administration of ACTH on the contractile activity of the oviduct, ova transport and endocrine status of recently ovulated and unrestrained sows

The effect of repeated intravenous administration of ACTH (Synacthen depot) on the contractile activity of the oviduct, ova transport and endocrine status was studied in 11 Swedish crossbred (Landrace x Yorkshire) multiparous sows. In the second estrus after weaning, the ACTH group (Group A, n=6) sows were administered 0.01 mg/kg body weight of ACTH every 6 h commencing 4 to 8 h after ovulation, whereas the control group (Group C, n=5) sows were administered saline solution. Immediately after standing estrus, a Millar pressure transducer was placed about 3 cm into the isthmus via a laparotomy. Blood samples for hormonal analyses and pressure recordings of the oviduct were collected from all sows until slaughter. After slaughter, the genital tract opposite to the side with the transducer was retrieved, and 3 equal isthmic segments and the first third of the uterine horn portion adjacent to the UTJ were flushed separately for ova recovery. Cortisol levels were significantly (P<0.05) elevated after ACTH administration. Progesterone and PGF2alpha metabolite levels were significantly (P<0.05) elevated only after the first ACTH administration. No significant differences (P>0.05) were seen in the mean pressure and frequencies of phasic pressure fluctuations either before or after every ACTH administration between Groups A and C. No significant difference (P>0.05) was seen in the proportion of ova recovered in the different segments between Groups A and C. It can be concluded from the present study that the administration of ACTH (0.01 mg/kg body weight) to sows at 4 to 8 h after ovulation, and after each subsequent ACTH administration, elevates cortisol levels, whereas progesterone and PGF2alpha metabolite levels are elevated only after the first treatment, and that this has no effect on the mean isthmic pressure, the frequency of phasic pressure fluctuations or ova transport.     

Behavioral and endocrine responses of sows to prostaglandin F2 alpha and cloprostenol

Behavioral and endocrine changes in the sow following injection with prostaglandin F2 alpha (PGF2 alpha) or its analogue, cloprostenol (CLO), were monitored to identify endocrine correlates of prepartum activity (nest-building). On Day 112 postcoitum, within 15 min after injection with 10 mg PGF2 alpha, sows offered straw in pens engaged in intense prepartum activity, but few behavioral changes occurred during the first 2 h following administration of 175 micrograms CLO. The temporal pattern of prepartum activity, however, was affected by both prostaglandins. In control sows, most prepartum activity came during Hours 16-0 before delivery of first piglet (delivery). After CLO, sows engaged in nest-building more during Hours 32-17 and less during Hours 16-0. In another experiment, sows in farrowing crates were injected with saline, 175 micrograms CLO, or 10 mg PGF2 alpha on Day 112 and blood was collected 0, 15, 30, 60, and 90 min later. Another sample was collected when spontaneous prepartum activity was first observed. For approximately 90 min after PGF2 alpha treatment, sows rooted, pawed, and bit and rubbed faces on crate bars; after saline and CLO, this behavior was rarely observed. After prostaglandin treatment, plasma progesterone tended to decline, a 10-fold rise in relaxin came within 15 min, but estrone did not change. Plasma prolactin rose 10-fold within 30 min after PGF2 alpha treatment, and rose more gradually after CLO treatment. When sows exhibited spontaneous prepartum activity (approximately 7 h before delivery), endocrine status was characterized by low progesterone, high estrone:progesterone ratio, and high prolactin.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of pre- and post-ovulatory insemination on sperm distribution in the oviduct,accessory sperm to the zona pellucida,fertilisation rate and embryo development in sows

The aim of present study was to investigate the influence of pre-compared with post-ovulatory insemination, on the distribution of spermatozoa in the oviduct, the accessory sperm counts on the zona pellucida and early embryonic development. Thirty-six crossbred multiparous sows (Swedish Landrace x Swedish Yorkshire) were artificially inseminated once either at 20-15 h before (group AIB) or at 15-20 h after (group AIA) ovulation by using a pooled semen of two boars. Thereafter, they were randomly allocated to one of five groups: slaughter at 5-6h after AI (group I-AIB), at 20-25 h after ovulation (groups II-AIB and II-AIA), at 70 h after ovulation (groups III-AIB and III-AIA), on day 11 (groups IV-AIB and IV-AIA, first day of standing oestrus=day 1) and on day 19 (groups V-AIB and V-AIA).The plasma levels of oestradiol-17beta and progesterone differed significantly (P相似文献   

Progesterone levels and litter performance of sows following postpartum administration of prostaglandin F(2alpha)

A total of 101 sows was used to examine postpartum progesterone levels and litter performance following administration of 15 mg prostaglandins F(2alpha) (PGF(2alpha) n = 48) given within 12 h after farrowing. Daily blood samples and rectal temperatures were taken from all sows during the first 3 d post partum. Plasma progesterone (P(4)) concentrations were determined by radioimmunoassay (RIA). Regardless of treatment, plasma P(4) levels for all sows decreased in a similar fashion over the 3 d sampled. Mean (+/- SEM) P(4) on Day 2 (0.55 +/- 0.06 ng/ml) and Day 3 (0.38 +/- 0.04 ng/ml) were lower (P<0.01) than on Day 1 (0.98 +/- 0.08 ng/ml). Rectal temperature did not differ between PGF(2alpha) treated and nontreated sows nor was it different over the days measured. Litter characteristics, including survival rates on Day 7 and at weaning, and body weight on Days 3 and 35, were not affected by treatment. It was concluded that PGF(2alpha) administration to sows within 12 h post farrowing had no affect on the rate of luteal regression, as determined by P(4) concentration, nor on subsequent litter performance.     

The effect of prostaglandin F2 alpha administration on progesterone after hysterectomy of guinea-pigs

It is believed that in guinea-pigs the main luteolytic agent is prostaglandin F2 alpha (PGF2a)_and that it is synthesised in the uterus. In this study non-pregnant guinea-pigs were hysterectomised at Day 5 of the estrous cycle. Peripheral progesterone levels in animals from which the uterus had been removed remained elevated for an extended time. The results suggested the corpora lutea (CL) had an inherent life span in excess of the length of the estrous cycle. However after a time the levels of circulating progesterone declined, suggesting there might have been a reduction of a stimulating factor or the appearance of a non-uterine luteolysin. If after hysterectomy PGF2a was administered 4 and 5 days later then there was a reduction in the mean progesterone level but the decline did not continue. The CL at the stage of the experimental procedure were sensitive to luteolysin but they had retained their capability to resist endocrinological insult. The study provided further support for the contention that control of PGF2a activity is vital for progesterone maintenance. Additionally, the cells of the CL have the potential to be the site of some of the PGF2a control.     

The effect of prostaglandin F2 alpha administration on progesterone after hysterectomy of guinea-pigs

It is believed that in guinea-pigs the main luteolytic agent is prostaglandin F2 alpha (PGF2a) and that it is synthesised in the uterus. In this study non-pregnant guinea-pigs were hysterectomised at Day 5 of the estrous cycle. Peripheral progesterone levels in animals from which the uterus had been removed remained elevated for an extended time. The results suggested the corpora lutea (CL) had an inherent life span in excess of the length of the estrous cycle. However after a time the levels of circulating progesterone declined, suggesting there might have been a reduction of a stimulating factor or the appearance of a non-uterine luteolysin. If after hysterectomy PGF2a was administered 4 and 5 days later then there was a reduction in the mean progesterone level but the decline did not continue. The CL at the stage of the experimental procedure were sensitive to luteolysin but they had retained their capability to resist endocrinological insult. The study provided further support for the contention that control of PGF2a activity is vital for progesterone maintenance. Additionally, the cells of the CL have the potential to be the site of some of the PGF2a control.     

Boar spermatozoa and prostaglandin F2alpha. Quality of boar sperm after the addition of prostaglandin F2alpha to the short-term extender over cooling time

Prostaglandin F(2alpha) (PGF(2alpha)) has been used to improve reproductive performance in swine. The goal of the present work was to determine how the addition of PGF(2alpha) affects boar sperm quality. Eleven different treatments were evaluated: eight with only PGF(2alpha) (0.625, 1.25, 2.50, 5, 10, 12.50, 25 and 50mg PGF(2alpha)/100ml) and three binary treatments (0.625mg PGF(2alpha)/100ml+200mug/ml hyaluronic acid (HA), 1.25mg PGF(2alpha)/100ml+200mug/ml HA, 0.625mg PGF(2alpha)/100ml+7.5muM caffeine (Caf)). All these substances were added to 16 ejaculates from 16 healthy and sexually mature boars (n=16), and each ejaculate was considered as a replicate. Our study also assessed the effects of these 11 treatments over different periods of preservation. Sperm quality was tested immediately after the addition of treatments (time 0), and after 1, 3, 6 and 10 days of cooling at 15 degrees C. To evaluate sperm quality, five parameters were analysed: (1) sperm viability, acrosome and mitochondrial sheath integrity (using a multiple fluorochrome-staining test), (2) sperm motility, (3) sperm morphology and (4) agglutination (using a computer assisted system) and (5) osmotic resistance (using the ORT). Parametric (analysis of variance for repeated measures) and non-parametric tests (Friedman test) were used as statistical analyses. Treatments with PGF(2alpha) concentrations higher than 12.5mg/100ml were cytotoxic while the others did not damage boar spermatozoa. Thus, the other treatments may be used to produce profitable effects without adverse effects. Moreover, the addition of PGF(2alpha) at 5mg/100ml to sperm diluted in BTS may maintain sperm viability and motility better after 6 days of cooling, because significant differences were observed (P<0.05) compared with control at the same time.     

The effect of prostaglandin F2 alpha treatments in superovulated cattle on estrus response and embryo production

Approximately 10% of cows in a commercial embryo transfer center that were superovulated for embryo production did not show estrus at the right time and therefore did not produce embryos. This problem was investigated by studying the effects of prostaglandin F2 alpha (PGF) treatment regime and dose rate on the superovulatory process. The cows in estrus following superovulation (96% vs. 86.6%), the % cleaved (62% vs. 51%) and the transferable embryo production (5.4 vs. 3.8) was increased when 50 mg. PGF was administered in three divided doses rather than in two doses. In a second experiment doses of 15 mg., 30 mg. and 45 mg. (each administered as three divided doses 6 hours apart) all produced the same estrus response (95.6, 97.9 and 95%) and production of transferable embryos (4.9, 3.6 and 4.6). Three-times-a-day PGF reduced the time interval from treatment to the onset of estrus, but the time from PGF to estrus was not correlated with embryo production.     

Stimulatory effect of prostaglandin F(2alpha) on Na-dependent phosphate transport in osteoblast-like cells

Prostaglandin F(2alpha) (PGF(2alpha)) has been reported to activate protein kinase C (PKC) through both phospholipase (PL) C and D, resulting in the proliferation of osteoblast-like cells. In addition, it has also been reported that Erk mitogen-activated protein kinase is also involved in the mechanism of PGF(2alpha)-induced proliferation of these cells. Recently, we have reported that several growth factors stimulate Na-dependent phosphate transport (Pi transport) activity of osteoblast-like cells, which has been recognized to play an important role in their mineralization. In the present study, we investigated the effect of PGF(2alpha) on Pi transport in MC3T3-E1 osteoblast-like cells. PGF(2alpha) stimulated Na-dependent Pi transport dose dependently in the range between 1nM and 10 micro M in MC3T3-E1 cells. The effect was time dependent up to 24h. Kinetic analysis revealed that PGF(2alpha) induces newly synthesized Pi transporter. Pretreatment with actinomycin D and cycloheximide suppressed PGF(2alpha)-induced enhancement of Pi transport. Combined effect of PMA and PGF(2alpha) was not additive in Pi transport. Calphostin C, a PKC inhibitor, dose-dependently suppressed Pi transport induced by PGF(2alpha). On the contrary, U0126, which inhibits an upstream kinase of Erk (MEK), did not affect PGF(2alpha)-induced enhancement of Pi transport. In conclusion, PGF(2alpha) stimulates Pi transport through activation of PKC in osteoblast-like cells.     

An unexpected negative inotropic effect of prostaglandin F2alpha in the rat heart

Prostaglandin F(2alpha) (PGF(2alpha)) is produced during myocardial inflammation and many of the insults that trigger contractile dysfunction also activate prostaglandin synthesis and production. However, although PGF(2alpha) plays a significant role in the cardiac response to inflammation, the effect of this particular compound on the heart was largely studied at the cellular level and probably no due attention was paid to the effect of PGF(2alpha) on the whole heart contractility. Therefore, in the present study we have investigated the effect of PGF(2alpha) on isolated right ventricle of the rat heart. PGF(2alpha) (1nM-1microM) induced concentration-dependent decrease of the amplitude of contractions of the ventricular muscle. Real time RT-PCR has revealed that prostaglandin FP receptors are expressed in the rat myocardium and the level of expression was similar to those of creatine kinase and adenylate kinase, which are proteins abundantly present in the heart. An antagonist of FP receptors, PGF(2alpha) dimetilamide (10nM), abolished negative inotropic effect induced by PGF(2alpha). To examine the possibility that PGF(2alpha) could activate non-FP prostaglandin receptor, we have measured the level of expression of all known prostaglandin receptors in the rat heart. These experiments have shown that the order of expression of prostaglandin receptors in the rat heart is FP>EP1=TP>EP4>EP3>DP=IP. Based on the obtained results we conclude that PGF(2alpha) induces negative inotropic effect on rat heart by activating FP prostaglandin receptors. This effect of PGF(2alpha) could contribute to cardiac dysfunction in conditions of systemic and myocardial inflammation.     

The effect of prostaglandin F2alpha on the activator calcium of the uterus.

The mechanism through which PGF2_α exerts its oxytocic action was studied in 150 uterine strips, 48 excised from 25 days pregnant and 102 from post partum rabbits. PGF2_α delayed the loss of excitability upon exposure of the uterus to Ca-free Krebs Ringer Bicarbonate (KRB) solution and accelerated recovery when half (1.25 mM) of the normal CaCl₂ was replaced in the KRB. This effect of PGF2_α was more pronounced in the post partum than the pregnant uterus, which resisted Ca-deficiency by high affinity binding in its plasma membrane of the activator-Ca (A-Ca).The Ca-ionophore A23187 simulated the action of PGF2_α but only during stimulation with 12 V/5 cm and not with 60 V/5 cm. This finding suggests that while the effect of PGF2_α is limited to a control of the movement of the extracellular and membrane-bound Ca, A23187 affects the distribution of Ca liberated by the strong (60 V/5 cm) electric field from internal stores of the myometrial cells. In the presence of Ruthenium-red (a Ca-influx inhibitor) and only 1.25 mM CaCl₂, PGF2_α restored excitability slowly, indicating that PGF2_α is an oxytocic agent because it promotes Ca-influx. However, knowing that Ca-efflux is in part dependent upon Ca-influx the most informative present finding was the observation that PGF2_α did not promote ⁴⁵Ca-efflux when ⁴⁰Ca-influx was inhibited by Verapamil. This demonstration provided more direct evidence that PGF2_α promotes the influx of the A-Ca and thus explained the mechanism of action of this key regulator at the molecular level.     

Analysis of the abortive action induced by prostaglandin F2 alpha in the mouse. Study of ova and their transplantation]

In mice PGF2 alpha injections (120 mg/kg from first to the 4th day) determines a high proportion of early abortions. The mechanism of this action has been investigated by transplantation of blastocysts removed from PGF2 alpha treated mice to pseudopregnant mice. The results of transplantation experiments indicate that the percentage of implantation is the same whether the eggs are taken from PFG2alpha treated or control mice. The number of eggs present in the uterine horns 84 hours after fertilization is 40 % lower than in control animals. At an earlier stage, 60 hours after fertilization, the uterus of PGF2 alpha treated females contains 85 % of eggs as compared to 20 % in controls. This proportion is reversed in the fallopian tubes. It can therefore be concluded that the high abortion rate of PGF 2 alpha treated mice is not due to an embryotoxic effect but to a faster transport of the fertilized eggs which reach therefore the uterus before implantation can take place.     

Cardiovascular effects of prostaglandin I2 and prostaglandin F2 alpha in the unanesthetized bullfrog, Rana catesbeiana

The cardiovascular effects of prostaglandin (PG)I2 and PGF2 alpha were compared in the unanesthetized American bullfrog (Rana catesbeiana). Control mean arterial pressure (MAP) and heart rate (HR) were 25.7 +/- 1.1 mm Hg and 35.1 +/- 1.1 beats/min, respectively. Intravenous injections of PGI2 decreased MAP and increased HR in a dose-dependent fashion over the range of concentrations tested (0.03, 0.3, 3, and 10 micrograms/kg-body weight [bw]. Neither atropine (1 mg/kg-bw) nor verapamil (1 mg/kg-bw) treatment altered the MAP or HR responses to PGI2 (3 micrograms/kg-bw). However, propranolol (5 mg/kg-bw) significantly blunted the hypotensive effects without affecting the increase in HR. Prostaglandin F2 alpha (tested at 0.3, 3, 30, and 100 micrograms/kg-bw) increased both MAP and HR. Mean arterial pressure increased with concentrations greater than 0.3 microgram/kg-bw and reached peak effects at 30 micrograms/kg-bw. Prostaglandin F2 alpha increased HR at doses greater than 0.3 microgram/kg-bw. Neither the pressor nor positive chronotropic effects of PGF2 alpha (30 micrograms/kg-bw) were affected by atropine or propranolol. However, verapamil significantly attenuated the pressor effects without affecting the increase in HR. These results demonstrate that both prostaglandins have qualitatively similar effects on HR, but opposite effects on MAP. Prostaglandin I2 is a hypotensive prostaglandin, while PGF2 alpha is hypertensive. The pressor effects of PGF2 alpha are partially dependent on calcium influx. The positive chronotropic effects of both prostaglandins are independent of the autonomic nervous system, suggesting a different mechanism of action.     

Synergistic effect of prostaglandin F2alpha and cyclic AMP on glucose transport in 3T3-L1 adipocytes

The combined effect of prostaglandin F2alpha (PGF2alpha) and cAMP on glucose transport in 3T3-L1 adipocytes was examined. In cells pretreated with PGF2alpha and 8-bromo cAMP for 8 h, a synergy between these two agents on glucose uptake was found. Insulin-stimulated glucose transport, on the other hand, was only slightly affected. The synergistic effect of these two agents was suppressed in the presence of cycloheximide and actinomycin D. In concord, immunoblot and Northern blot analyses revealed that GLUT1 protein and mRNA levels were both increased in cells pretreated with both PGF2alpha and 8-bromo cAMP, greater than the additive effect of each agent alone. The synergistic action of PGF2alpha with 8-bromo cAMP to enhance glucose transport was inhibited by GF109203X, a selective protein kinase C (PKC) inhibitor. In addition, in cells depleted of diacylglycerol-sensitive PKC by prolonged treatment with 4beta-phorbol 12beta-myristate 13alpha-acetate, a PKC activator, the synergistic effects of PGF2alpha and 8-bromo cAMP on glucose transport and GLUT1 mRNA accumulation were both abolished. Taken together, these results indicate that PGF2alpha may act with cAMP in a synergistic way to increase glucose transport, probably through enhanced GLUT1 expression by a PKC-dependent mechanism.     

Characteristics of the normal gluconeogenesis effect of prostaglandin F2 alpha and in myocardial infarct

The effect of PGF2 alpha on glucose synthesis de novo in a healthy rat organism and those with coronary occlusion-myocardial infarction was studied. There was observed prostaglandin's metabolic action simultaneously at one direction: there was increased the concentration of non-nitric precursors of gluconeogenesis in blood of animals of both groups, final disintegration product of tissue proteins, the gluconeogenic activity of key enzymes and therefore the concentration of newly formed glucose went up as so as glycogen in liver, cardiac and skeletal muscle. Seemingly, PGF2 alpha stimulates the intensity not only of gluco-, but glyconeogenesis having cardioprotective action. At the same time metabolic effect of PGF2 alpha is strongly marked in coronary occlusion rat with myocardial infarction.