PGF2alpha Analogue Research Articles

Stimulation of release of beta-endorphin and oxytocin by prostaglandin F2 alpha in cattle at parturition.

Concentrations of beta-endorphin and oxytocin were measured in plasma of cows before, during and after parturition. The effect of the PGF2 alpha analogue cloprostenol on beta-endorphin and oxytocin release was investigated. During parturition, there were marked, parallel increases in beta-endorphin and oxytocin concentrations. Both hormones were released in an episodic manner in conjunction with uterine and abdominal contractions. It is therefore likely that factors stimulating oxytocin release also enhance beta-endorphin secretion. This suggests a role of labour or labour-associated hormones in stimulating peripheral beta-endorphin release. Cloprostenol caused an immediate, pronounced increase in plasma beta-endorphin and oxytocin concentrations.

16,16-dimethyl prostaglandin E2 modulates aflatoxin B1-induced injury of rat hepatocytes in primary culture: possible role of cAMP.

The hepatocellular cytoprotective effects of 16,16-dimethyl prostaglandin E2 (dmPGE2), an analogue of PGE2, were investigated using primary cultures of rat hepatocytes and aflatoxin B1 as the hepatotoxin. Lactic dehydrogenase (LDH) release by hepatocytes was used as an index of hepatotoxicity. When aflatoxin-treated hepatocytes were co-cultured with 16,16-dmPGE2 (0.01-0.5 micrograms/mL) LDH release was significantly reduced and ultrastructural changes of hepatocellular injury were markedly diminished. The magnitude of the cytoprotective effect was not dependent on the concentration of the prostaglandin over the range tested. A significant cytoprotective effect was also induced when hepatocellular cyclic AMP (cAMP) levels were increased by the addition of dibutyl-cAMP. In contrast to 16,16-dmPGE2, PGF2 alpha Tromethamine, an analogue of PGF2 alpha, which does not stimulate cAMP, induced insignificant changes in cytoprotection. These findings indicate that only a low concentration of 16,16-dmPGE2 (> or = 0.01 micrograms/mL) is necessary to induce a maximal hepatocellular cytoprotective effect and suggest that this effect may be dependent on activation of cAMP.

Effect of a Prostaglandin F2α Analogue Prostinfenem (15-Methyl-PGF2α), to Induce Luteolysis and Oestrus in Heifers

Different doses of 15-methyl-PGF2 alpha (0.125-10 mg) were used to induce luteolysis and oestrus in 7 heifers with 28 treatments on day 8-12 of the oestrous cycle. Twenty-three out of 28 treatments gave the desired response and the animals showed signs of oestrus within 5 days post-injection. The doses of 0.25-10 mg can be used to induce luteolysis and oestrus. The dose of 0.125 mg was not effective to induce luteolysis and only 1 out of 4 treatments responded. When higher doses were given (1-10 mg), progesterone levels decreased more rapidly and reached 1 nmol/l 16.2 h earlier than in animals which responded to doses less than 1 mg. The minimum effective dose was considered to be 0.25 mg. Clinical signs of oestrus, regression of corpus luteum and variation in the interval to oestrus were similar as for PGF2 alpha or its other analogues. By measurement of the main circulating prostaglandin F2 alpha metabolite, it was found that an endogenous PGF2 alpha release occurred 1-3 days post-injection of 15-methyl-PGF2 alpha. Furthermore in cases of post-oestrous bleedings an endogenous PGF2 alpha release was also seen concomitantly with the bleeding. This prostaglandin analogue seems to be useful for farm management and can be an alternative to other PGF2 alpha analogues.

Apparent decline in fertility in heifers after repeated oestrus synchronisation with cloprostenol

Over several years groups of heifers which were repeatedly treated with the PGF2 alpha analogue, cloprostenol, to synchronise oestrus were artificially inseminated. When sperm treatment was optimised, a reduction in conception rate was observed which was related to the number of synchronisation treatments the animals had received. Although factors such as a seasonal reduction in fertility may have contributed to the effect, there appeared to be a decrease in the proportion of animals becoming pregnant after successive synchronisations. Possible explanations for this observation are suggested.

Phorbol ester-induced expression of the common, low-affinity binding site for primary prostanoids in vascular smooth muscle cells.

We showed in an earlier study (Hanasaki, K., and Arita, H. (1989) Biochim. Biophys. Acta 1013, 28-35) that there is a common, low-affinity binding site for primary prostanoids in cultured vascular smooth muscle cells (VSMC). This site, called the "primary prostaglandin (PG) site," can be evaluated by radioreceptor assay using [3H]PGF2 alpha and [3H]PGE1. Comparison of the capacity of several PGF2 alpha analogs to displace both radioligand bindings indicated strict requirements of the 15-hydroxy group as well as the 13,14-double bond in the omega-side chain of prostaglandins for recognition of this site. Treatment of VSMC with phorbol 12-myristate 13-acetate (PMA), a known protein kinase C activator, led to concentration- and time-dependent increases in the binding activities of [3H] PGF2 alpha as well as [3H]PGE1, which could be completely suppressed by the addition of protein kinase C inhibitor, H-7. The PMA effects could be mimicked by phorbol 12,13-dibutylate, but not by inactive phorbol ester. Scatchard analyses revealed an approximately 8-fold increase in the binding density with unaltered binding affinity after PMA treatment. This expression of the primary PG site was blocked by the addition of cycloheximide and actinomycin D. In contrast, PMA did not affect the binding activity for the thromboxane A2/prostaglandin H2 receptor in VSMC. These results suggest that the expression of the primary PG site is regulated by a protein kinase C-dependent mechanism in VSMC.

Suppression par la lutectomie de l'accroissement simultané de la pression intramammaire et de l'ocytocinémie, induit par l'injection de PGF2α, chez la brebis

Seven lactating Lacaune ewes underwent either a total luteectomy on day 19 of pregnancy (D19) (compensated from that stage by a daily progesterone supplementation of 25 mg to ensure embryonic survival; group 1:4 animals) or a control laparotomy (group 2: 3 animals). Intra-jugular injection of 200 micrograms of a synthetic PGF2 alpha analogue (Dinolytic, Upjohn) caused an increase in the intramammary pressure (IMP) and a concomitant rise in oxytocinaemia only in the presence of a corpus luteum, ie in all ewes of groups 1 and 2 before D19 and only in those of group 2 after that stage. These experiments confirm that the corpus luteum, and not the other ovarian compartments, releases oxytocin when prostaglandin F2 alpha is administered.

Relationship between pre-partum relaxin concentrations and farrowing intervals in the pig.

Gilts were treated on Day 112 of gestation with saline or a prostaglandin (PG) F-2 alpha analogue. In control gilts there was a rise in the relaxin concentration from 48 h before the onset of delivery, peaking between 12 and 28 h pre partum followed by a steep fall. The relaxin concentrations at each 1-h time interval were analysed in relation to the farrowing interval for each gilt using correlation analysis. There was a significant (at least P less than 0.05) positive correlation between the relaxin concentration and the farrowing interval at every time period from 14 to 2 h before delivery. In contrast there was little relationship between concentrations of progesterone, oestrone and oestradiol-17 beta and farrowing intervals. The gilts treated with PGF-2 alpha analogues had steroid profiles indistinguishable from those in controls but differing relaxin secretion patterns. Relaxin concentrations peaked at 1-2 h after PGF-2 alpha injection and this was followed by a second smaller increase closer to the time of delivery in 7 out of 12 gilts. The 'two-peak' gilts had significantly higher relaxin concentrations at farrowing and took significantly longer to farrow than did the 'one-peak' gilts (P less than 0.005). These results suggest that high relaxin concentrations during the last 14 h before the onset of parturition are associated with increased farrowing times, but are not associated with any increase in neonatal mortality.

Effects of prostaglandin F2 alpha-analogue administration on luteal function, implantation of embryos and maintenance of pregnancy in bitches.

The present experiment was carried out to clarify the effect of administration of the prostaglandin F2 alpha (PGF2 alpha)-analogue on the luteal function and the maintenance of pregnancy in bitches. Fifty-one bitches received a single inoculation of PGF2 alpha-analogue by intramuscular injection. The effect of this agent was observed by monitoring progesterone (P) levels and the state of the uterus by laparotomy, the occurrence of abortion, and the state of parturition. As a result, when bitches were administered with 100-400 micrograms at the beginning of the luteal phase, the decrease in the P level was temporary. In bitches inoculated with 100-800 micrograms of PGF2 alpha-analogue at the functional luteal stage, the P level began to decrease as early as on the following day after injection. In those treated with 100-200 micrograms of PGF2 alpha-analogue at 10-15 days of pregnancy, pregnancy was maintained in 3 of 5 bitches that had received the treatment at day 10, while in the remaining two, all embryos died after implantation. In those that had received the same treatment at day 15, only 2 of 7 maintained pregnancy. Pregnancy was interrupted in eight bitches treated with doses of 100-200 micrograms at days 25-45. In four bitches treated with doses of 100-200 micrograms at day 55, premature birth was induced after 30-44 hr. In conclusion, regression of the corpus luteum, abortion, and premature birth were induced in bitches treated with 100-200 micrograms at each stage, except the beginning of the luteal phase and of the pregnancy.

Effects of PGF2 alpha-analogue administration during the luteal phase on the next estrous cycle in the bitch.

[in Japanese]

Ejection du lait induite par PGF2α pendant les deux premiers mois qui suivent l'insémination des vaches. Applications à un diagnostic de gravidité

Milk ejection after intrajugular injection of 256 micrograms of a synthetic PGF2 alpha analogue (Dinolytic, Upjohn) was measured every 2 days until D60 in 7 pregnant cows and until D25 in 5 non pregnant inseminated cows (trial 1). There was a very close correlation (r around + 0.98) between the values of the 3 parameters used to characterize milk ejection, i.e. amplitude of intramammary pressure deflection, surface area under the pressure curve, alveolar milk volume collected by a teat probe. In the two groups of animals, these values behaved similarly until D15 with a sudden increase between D2 and D7. From D15 they decreased abruptly in females where insemination had failed while they still remained at a high level until D25 (then decreasing until D60) in those presumed to be pregnant (fig. 2). These responses were assumed to result from the release of luteal oxytocin and it is suggested that a single injection of 256 micrograms of Dinolytic on D20, together with milk ejection control using a teat probe, would be a rapid, little expensive method for the farmer (without risks of luteolysis) (trial 2 and fig. 3) to distinguish between pregnant and non pregnant cows.

Prostaglandin F2 alpha and oxytocin release during persistence of the corpus luteum in sheep.

Oxytocin (OT), progesterone and prostaglandin F2 alpha (PGF2 alpha) concentrations were measured in the utero-ovarian vein (UOV) of ewes which displayed persistence of the corpus luteum (CL). During the period of expected luteolysis, the frequency of OT and PGF2 alpha pulses in the UOV was significantly (P less than 0.005 for both) lower in ewes with persistent CLs, compared with ewes that underwent normal luteal regression. In contrast, the amplitude of both OT and PGF2 alpha pulses was similar in both groups of animals. It is suggested that persistence of the CL resulted from a decreased PGF2 alpha pulse frequency, which may have arisen from a decreased frequency of stimulation by OT. In two persistent CL ewes, however, it appeared that a failure at the level of the uterus may have contributed to the observed decrease in PGF2 alpha release. Although a PGF2 alpha analogue (Lutalyse) infusion into the uterine vein of two ewes with persistent CLs failed to induced luteolysis, it did stimulate a large release of OT into the UOV. This suggests that persistent CLs maybe more resistant to PGF2 alpha and, that at day 22 post-oestrus, these CLs are capable of releasing large quantities of OT into the UOV.

Distribution of estrus, interpretation of ovarian findings and cervical patency in bovine recipients synchronized with a PGF2 alpha analog (Delprostenate)

On Day 3 of the estrous cycle (estrus = Day 0), dairy heifers were given either 10 mg i.m. FSH-P (FSH-P primed; n = 9) or a saline vehicle (saline primed; n = 9). On Day 10, all heifers were superovulated with FSH-P (total = 27.7 mg i.m.) in declining doses over 5 d. Heifers were inseminated artificially at estrus. From Day 2 until estrus, the number and size of follicles >2 mm were monitored daily by ultrasonography. The mean (± SEM) number of corpora lutea (CL) (6.2 ± 1.5 vs 10.7 ± 0.9; P<0.05) and the mean number of recovered embryos and unfertilized ova (3.6 ± 1.7 vs 8.4 ± 2.2; P<0.05) were lower in FSH-P-primed than in saline-primed heifers. Prior to initiation of superovulation, follicles >10 mm appeared on Days 6 to 7 in saline-primed heifers but only on Days 8 to 10 in FSH-P-primed heifers (P<0.05). Also, until Day 10, the mean number of follicles 4 to 6 mm and 7 to 10 mm was higher (P<0.05) in FSH-P-primed than in saline-primed heifers. After initiation of the superovulatory treatment (Day 10 to estrus), saline-primed heifers had a greater and faster increase in the mean number of follicles >10 mm (P<0.02) than FSH-P-primed heifers did. Depletion in the number of follicles 2 to 3 mm (P<0.001) between Day 10 and estrus and in the number of follicles 4 to 6 mm (P<0.05) between Day 12 and estrus occurred in both groups of heifers. Decreased superovulatory response and embryo recovery in FSH-P-primed heifers may have been due to the presence of large follicles (>10 mm) prior to the initiation of the superovulatory treatment which reduced the ability of small follicles to grow into larger size classes during superovulatory treatment.

Continuous infusion of oxytocin prevents induction of uterine oxytocin receptor and blocks luteal regression in cyclic ewes.

Continuous intravenous infusion of oxytocin (3 micrograms/h) between Days 13 and 21 after oestrus delayed return to oestrus by 7 days (length of cycle 23.3 +/- 0.6 days compared to 16.6 +/- 0.2 days in control ewes). At a lower infusion rate (0.3 micrograms/h) oxytocin delayed luteolysis in only 2 of 5 ewes. Treatment from Day 14, when luteolysis had already begun, was ineffective. Delay of luteal regression by oxytocin had no effect on the length of subsequent cycles. Measurement of circulating progesterone concentrations and luteal weight showed that prolongation of the oestrous cycle was due to prevention of luteal regression. Luteal regression and behavioural oestrus were induced during continuous oxytocin administration begun on Day 13 when cloprostenol was given on Day 15 (mean cycle length, 17.3 +/- 0.21 days). Continuous oxytocin infusion from Day 13 blocked the rise in uterine oxytocin receptor concentrations which normally precedes oestrus. Mean receptor concentrations in caruncular and intercaruncular endometrium and in myometrium were 76, 36 and 9 fmol/mg protein on Day 17 in ewes receiving continuous oxytocin (3 micrograms/h); in control ewes these values were 675, 638 and 130 fmol/mg protein respectively at oestrus. Receptor concentrations on the day of oestrus in ewes receiving oxytocin and cloprostenol were not significantly different from those in control ewes (649, 852, and 109 fmol/mg protein respectively). Since cloprostenol, a PGF-2 alpha analogue, overcame the antiluteolytic action of oxytocin, it is suggested that continuous oxytocin treatment may inhibit uterine production of PGF-2 alpha, possibly by down regulating the uterine oxytocin receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Ovarian production of progesterone and 20 alpha-dihydroprogesterone in vitro following prostaglandin F2 alpha induced luteolysis in the superluteinized rat.

Superluteinized rats were injected with the prostaglandin F2 alpha (PGF2 alpha) analogue cloprostenol to induce luteolysis. The treatment decreased progesterone production of ovarian homogenates from 8.9 +/- 0.5 to 4.0 +/- 0.7 nmol/ovary/10 min (mean +/- SEM) within 40 min. tochondrial fractions isolated from control and cloprostenol treated animals produced 4.7 +/- 0.4 and 2.8 +/- 0.3 nmol progesterone/ovary/10 min, respectively. Thus, the PGF2 alpha analogue treatment significantly reduced mitochondrial progesterone production. Addition of the 15 000 X g supernatant fraction did not influence the progesterone production rates of the mitochondrial fraction. The basal progesterone secretion from quartered ovaries decreased from 1.50 +/- 0.15 to 0.38 +/- 0.05 nmol/ovary during the initial 15 min of incubation following cloprostenol administration. hCG and N6,O2'-dibutyryladenosine 3':5'-cyclic monophosphate (DBC) stimulated the progesterone secretion from quartered ovaries, but the response was delayed in ovaries obtained from cloprostenol treated animals. Although the response was delayed, the progesterone secretion following cloprostenol treatment was re-activated with cAMP either directly or via hCG. The increment in progesterone secretion above unstimulated controls in response to DBC was not influenced by the cloprostenol treatment while the increment caused by hCG was decreased. Our data suggest that: 1) PGF2 alpha deactivates mitochondrial progesterone production, 2) this deactivation may be overcome by cAMP, and 3) PGF2 alpha decreases gonadotrophin responsive adenylyl cyclase.

Induced abortion with two prostaglandin F2 alpha analogues in mares: plasma progesterone changes.

Three experiments were conducted to test the abortifacient effects of PGF2 alpha analogues on mares during midgestation (average gestation length 141.5 days). The progesterone concentration was measured by radioimmunoassay. In experiment 1. five mares received an injection of PGF2 alpha analogue (fluprostenol: 500 micrograms intramuscularly) and a second injection either at 24, 48, of 72 h. Although the progesterone concentration decreased (P less than 0.05) an average of 44 per cent in 24 h, none of the pregnancies were terminated. In experiment 2, beginning at least 10 days after experiment 1, the same five mares were given PGF2 alpha analogue as follows: 250 micrograms intravaginally and 500 micrograms intramuscularly. The treatment was repeated 48 h later. Progesterone concentrations had not increased since experiment 1 and did not decrease during the 48 h following either injection. In experiment 3, six mares (average gestation length 162 days) were treated every 6 or 12 h with PGF2 alpha analogue (cloprostenol: 375 micrograms) until expulsion of the fetus occurred at 47 +/- 25 h after the initial injection; the mares received an average of 5 treatments. The progesterone concentration averaged 22 +/- 7 ng/ml before the initial PGF2 alpha treatment, decreased (P less than 0.05) to 8.4 +/- 2.7 ng/ml by 12 h before expulsion and 1-8 +/- 0.4 ng/ml 12 h after fetal expulsion. The progesterone concentration remained below 1.0 ng/ml for the next 4 days. However, only one of six mares exhibited estrual behavior after induced abortion.

Effects of prostaglandins and thromboxane analogues on bullock and dog iris sphincter preparations.

1 The bullock iris sphincter was contracted by low concentrations of prostaglandin E2 (PGE2), 16, 16-dimethyl PGE2 and 17,18,19,20-tetranor-16-p-chlorophenoxy PGE2. Other compounds with thromboxane-like actions, for example 11,9-epoxymethano PGH2, were also potent spasmogens, ZK 36374, a stable carbacyclin, was a partial agonist on the PGE-sensitive system of this tissue. 2 The thromboxane antagonist, EP 045, had little effect on the action of PGE2 and 16,16-dimethyl PGE2 on the bullock iris. 3 The dog iris sphincter was sensitive to PGF2 alpha but not to PGE2 and 11,9-epoxymethano PGH2. 4 16,16-dimethyl PGE2 had very low activity on the dog iris in contrast to its high activity on the bullock iris. The reverse was found with the 17,18,19,20-tetranor-16-m-trifluoromethylphenoxy analogue of PGF2 alpha (ICI 81008). This indicates a considerable selectivity of action of the two analogues. 5 The results are discussed in relation to the existing knowledge of prostanoid receptors.

Culture sensitization and inhibition of luteinizing hormone responsive production of cyclic AMP in luteal cells by luteinizing hormone, prostaglandin F2 alpha and [D-Trp6]-luteinizing hormone releasing hormone.

Many cells are able to regulate their sensitivity to hormones. In order to investigate the mechanism(s) by which rat luteal cells regulate their sensitivity to LH, we have developed and characterized a cell culture model. Cultures of dispersed rat luteal cells were exposed to graded doses of bovine LH, an analogue of LH releasing hormone (LH-RH) ([D-Trp6]-LH-RH), and prostaglandin F2 alpha (PGF2 alpha) for 3 h. The media containing these hormones were then replaced with fresh hormone-free medium and the cells cultured for 24 h. In order to test the sensitivity of these cultures after 24 h, the medium was discarded and replaced by medium alone, or medium containing a standard dose of bovine LH for 1 h. The amount of cyclic AMP accumulated during this hour was used as an index of the sensitivity of the cells to LH. Control cultures became 'supersensitive' to LH with augmented production of cyclic AMP during culture but LH-receptor binding activity was not increased. During the first 2 h of culture, LH (100 ng/ml) increased accumulation of cyclic AMP by fourfold, but after 5 h of culture, stimulation of cyclic AMP accumulation by the same dose of LH was increased 32-fold, 299-fold at 13 h and 359-fold at 21 h of culture. The increase in LH-responsive accumulation of cyclic AMP with cultured was severely impaired by early exposure of cells to LH, LH-RH analogue or PGF2 alpha during the first 2 h of culture. Also, both LH-RH analogue and PGF2 alpha acutely inhibited LH-stimulated accumulation of cyclic AMP. Inhibition of culture-induced sensitization of LH responsiveness was not altered by the addition of 3-isobutyl-1-methylxanthine. Scatchard analysis of LH binding sites indicated that pretreatment of luteal cells with LH (or human chorionic gonadotrophin at an equivalent dose) reduced the number of free LH receptors when measured after 24 h of culture, but total receptor binding activity was not changed. However, a similar effect was not seen with cells treated with PGF2 alpha or LH-RH analogue. It is suggested that 'culture-induced' supersensitivity may represent either recovery of pre-isolation sensitivity or result from the loss of an endogenous factor(s) which retards the coupling of the LH receptor and adenylate cyclase. Although PGF2 alpha and LH-RH analogue have been shown to directly prevent the occupied LH receptor from activation of adenylate cyclase, the present observations have indicated that this inhibitory process was continued even when these agents were removed from the culture medium.

ChemInform Abstract: SYNTHESIS AND BIOLOGICAL ACTIVITY OF CARBOXYL‐TERMINUS MODIFIED PROSTAGLANDIN ANALOGS

AbstractGemäß dem Formelbild werden die Analoga (IV), (V) und (VII) dargestellt Die einzelnen Reaktionsschritte verlaufen mit 40 ‐ 80%iger Ausbeute.

Response of ewes to a single injection of an analogue of PGF-2 alpha given at different stages of the oestrous cycle.

Six groups of 4 ewes were given a single i.m. injection of 100 microgram ICI 80,996 on Days 3, 5, 8, 11, 14 or 16 of the oestrous cycle. On day 3 treatment was only partly effective in causing luteal regression, with only 2 of the 4 treated ewes returning to oestrus. Injection had no apparent effect when given on Day 16, at a time when luteal regression had already started naturally. However, treatment between Days 5 and 14 inclusive of the oestrous cycle evoked a rapid fall in progesterone concentrations to basal values of less than 0.5 ng/ml within 24 h with a high degree of synchrony in the return of oestrus (37.7 +/- 1.6 h) and the timing of the LH peak (45.3 +/- 3.2 h) after injection. We conclude that the corpus luteum of the ewe is responsive to ICI 80,996 only between Days 5 and 14 of the oestrous cycle.

Synthesis and biological activity of carboxyl-terminus modified prostaglandin analogues.

A series of PGE2, 16,16-dimethyl-PGE2, and PGF2 alpha analogues modified at the carboxyl terminus with tetrazole, amide, acylurea, imide, and sulfonimide functionalities was evaluated for uterine stimulant, bronchodilator, hypotensive, gastric antisecretory, and diarrheal activity. These compounds were prepared by modification of the Corey prostaglandin synthesis utilizing as a key step condensation of known hemiacetals with the ylide derived from the requisite substituted phosphonium salts. Structure--activity relationships suggest that a proton at the C-1 position appears necessary for agonist activity and the acidity of this proton has a relatively greater influence on activity than pendant steric bulk. Noteworthy are the tissue-selective bronchodilator activity of N-acetyl-PGE2-carboxamide and the selectivity for uterine tissue of N-methanesulfonyl-PGE2-carboxamide, 2-decarboxy-2-(tetrazol-5-yl)-16,16-dimethyl-PGE2, N-acetyl-16,16-dimethyl-PGE2-carboxamide, and N-methanesulfonyl-16,16-dimethyl-PGE2-carboxamide.