PGE1) And E2 Research Articles

Cutaneous vascular and sweating responses to intradermal administration of prostaglandin E1 and E2 in young and older adults: a role for nitric oxide?

Cyclooxygenase (COX) contributes to cutaneous vasodilation and sweating responses; however, the mechanisms underpinning these responses remain unknown. We hypothesized that prostaglandin E1 (PGE1) and E2 (PGE2) (COX-derived vasodilator products) directly mediate cutaneous vasodilation and sweating through nitric oxide synthase (NOS)-dependent mechanisms in young adults. Furthermore, we hypothesized that this response is diminished in older adults, since aging attenuates COX-dependent cutaneous vasodilation and sweating. In 9 young (22 ± 5 yr) and 10 older (61 ± 6 yr) adults, cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites receiving incremental doses (0.05, 0.5, 5, 50, 500 μM each for 25 min) of PGE1 or PGE2 with and without coadministration of 10 mM N(ω)-nitro-l-arginine, a nonspecific NOS inhibitor. N(ω)-nitro-l-arginine attenuated PGE1-mediated increases in CVC at all concentrations in young adults, whereas it reduced PGE2-mediated increases in CVC at lower concentrations (0.05-0.5 μM) in older adults (all P < 0.05). However, the magnitude of the PGE1- and PGE2-mediated increases in CVC did not differ between groups (all P > 0.05). Neither PGE1 nor PGE2 increased sweat rate at any of the administered concentrations for either the young or older adults (all P > 0.05). We show that although cutaneous vascular responsiveness to PGE1 and PGE2 is similar between young and older adults, the cutaneous vasodilator response is partially mediated through NOS albeit via low-to-high concentrations of PGE1 in young adults and low concentrations of PGE2 in older adults, respectively. We also show that in both young and older adults, PGE1 and PGE2 do not increase sweat rate under normothermic conditions.

Does Preincubation with Prostaglandin E1 or Prostaglandin E2 Enhance Oxytocin-Induced Myometrial Contractility In Vitro?

To determine if preincubation with prostaglandin E1 (PGE1) and E2 (PGE2) enhances oxytocin-induced myometrial contractility in vitro. Myometrial strips from 13 women were incubated with PGE1 (10-5 mol/L or 10-6 mol/L), PGE2 (10-5 mol/L or 10-6 mol/L) or solvent before adding cumulative concentrations of oxytocin (10-10 to 10-6 mol/L). The area under the contraction curve was calculated after addition of each agent. One- and two-way analysis of variance was used for comparison (significance p < 0.05). PGE2 10-5 mol/L reduced response to oxytocin 10-9 to 10-6 mol/L (p < 0.05). PGE2 reduced spontaneous myometrial contractility as compared with PGE1 (p < 0.05). A dose-dependent negative effect of prostaglandins was detected on oxytocin 10-8 mol/L (10-5 mol/L > 10-6 mol/L; p < 0.05). Contrary to the hypothesis, neither PGE1 nor PGE2 enhanced oxytocin-induced myometrial contractility; in fact, PGE2 decreased contractility.

The Effects of Prostaglandin E1 and Prostaglandin E2 on in vitro Myometrial Contractility and Uterine Structure

To estimate the effects of prostaglandin E1 (PGE1) and E2 (PGE2) on myometrial contractility and structure in vitro. Myometrial strips from 18 women were incubated with PGE1 (10-5 mol/L), PGE2 (10-5 mol/L), or solvent (CTR) for up to 360 minutes in organ chambers for isometric tension recording. The area under the contraction curve, total collagen content, and percentage of the area covered by connective tissue were calculated at various time periods. PGE1 significantly increased in vitro myometrial contractility up to 90 minutes when compared with PGE2 and CTR (p < 0.01) and up to 180 minutes as compared with PGE2 (p < 0.05). After 360 minutes, CTR and PGE1 samples had lower total collagen content and area covered by connective tissue than PGE2 (p < 0.01). The effects of prostaglandins on the uterus cannot be solely explained by contractility. Treatment with PGE1 significantly increased myometrial contractions and decreased both total collagen content and the area covered by connective tissue. Such findings may explain the higher rates of vaginal delivery, tachysystole, and uterine rupture associated with PGE1 use.

An agonist sensitive, quick and simple cell-based signaling assay for determination of ligands mimicking prostaglandin E2 or E1 activity through subtype EP1 receptor: Suitable for high throughput screening

BackgroundConventionally the active ingredients in herbal extracts are separated into individual components, by fractionation, desalting, and followed by high-performance liquid chromatography (HPLC). In this study we have tried to directly screen water-soluble fractions of herbs with potential active ingredients before purification or extraction. We propose that the herbal extracts mimicking prostaglandin E1 (PGE1) and E2 (PGE2) can be identified in the water-soluble non-purified fraction. PGE1 is a potent anti-inflammatory molecule used for treating peripheral vascular diseases while PGE2 is an inflammatory molecule.MethodsWe used cell-based assays (CytoFluor multi-well plate reader and fluorescence microscopy) in which a calcium signal was generated by the recombinant EP1 receptor stably expressed in HEK293 cells (human embryonic kidney). PGE1 and PGE2 were tested for their ability to generate a calcium signal. Ninety-six water soluble fractions of Treasures of the east (single Chinese herb dietary supplements) were screened.ResultsAfter screening, the top ten stimulators were identified. The identified herbs were then desalted and the calcium fluorescent signal reconfirmed using fluorescence microscopy. Among these top ten agonists identified, seven stimulated the calcium signaling (1-40 μM concentration) using fluorescence microscopy.ConclusionsFluorescence microscopy and multi-well plate readers can be used as a target specific method for screening water soluble fractions with active ingredients at a very early stage, before purification. Our future work consists of purifying and separating the active ingredients and repeating fluorescence microscopy. Under ordinary circumstances we would have to purify the compounds first and then test all the extracts from 96 herbs. Conventionally, for screening natural product libraries, the procedure followed is the automated separation of all constituents into individual components using fractionation and high performance liquid chromatography. We, however, demonstrated that the active ingredients of the herbal extracts can be tested before purification using an agonist sensitive, quick and simple cell-based signaling assay for ligands mimicking the agonists, PGE1 and PGE2.

Profile of prostaglandin E1 and E2 binding to four subtype prostaglandin E receptors

Prostaglandin E1 (PGE1) and E2 (PGE2) are ligands for prostaglandin E2 receptor (EP) family, which are designated as EP1, EP2, EP3 and EP4. Interestingly, PGE2 mediates inflammation whereas PGE1 is acting as an anti‐inflammatory factor. However the molecular basis of their opposite actions on the EP receptors is poorly understood. In this study, the PGE1 and PGE2 binding affinity and signaling on the human recombinant EPs expressed in the live HEK293 stable cell lines were determined by [3H]PGE2 binding and the calcium and cyclic AMP signaling, respectively. The Kd of [3H]PGE2 binding to the EP1, EP2, EP3 &amp; EP4 was 0.35 nM, 0.45 nM, 0.021 nM, and 0.047 nM, respectively. PGE2 showed higher affinity or preference for EP3 and EP4 as compared to that of EP1 and EP2. The IC50 thus calculated from [3H]PGE2 displacement experiments using cold PGE1 and PGE2 for the EPs is, EP1 ( PGE1 0.1mM, PGE2 5μM), EP2 ( PGE1 1μM, PGE2 1μM), EP3 ( PGE1 1μM,PGE2 100 nM) and EP4 ( PGE1 1μM, PGE2 100nM). PGE1 showed a higher calcium signal in EP1 as compared to that of PGE2. In addition, there was a one log concentration difference between PGE2 and PGE1 for generation of calcium signal in EP4. The calcium signal indicated that the EP1 is the likely dominant receptor in terms of signaling in tissues that co express the EPs. This study provides a molecular basis to understand the biological functions of PGE1 and PGE2 through their binding and signaling properties.

Inhibition of purinergic transmission by prostaglandin E1 and E2 in the guinea-pig vas deferens: an electrophysiological study.

1. The effects of prostaglandin E1 (PGE1) and E2 (PGE2) on postjunctional electrical activity in the guinea-pig vas deferens evoked by sympathetic nerve stimulation were investigated using both intracellular and focal extracellular recording techniques in vitro. 2. Bath application of PGE1 (1-100 nM) or PGE2 (0.1-100 nM) concentration-dependently inhibited the amplitudes of all excitatory junction potentials (e.j.ps) evoked during short trains of stimuli (10 stimuli at 1 Hz). Increasing the duration of nerve stimulation (100 stimuli at 1 Hz) did not overcome this inhibitory effect. At these concentrations PGE1 and PGE2 were without any apparent inhibitory effect on the amplitudes of spontaneous e.j.ps. 3. Local application of PGE1 (10-100 nM) or PGE2 (10-30 nM) markedly reduced the frequency of occurrence of excitatory junction currents (e.j.cs) evoked by trains of 20-100 stimuli at 1 to 4 Hz without changing the amplitudes of spontaneous e.j.cs or the configuration of the nerve terminal impulse. 4. In the presence of PGE1 or PGE2, raising the frequency of stimulation (from 1 to 4 Hz), increased the likelihood of e.j.c. occurrence. 5. The postjunctional electrical activity recorded in the guinea-pig vas deferens is believed to be due to ATP released from the sympathetic nerve endings. Thus the present study demonstrates that both PGE1 and PGE2 powerfully inhibit quantal ATP release in the guinea-pig vas deferens.

Prostaglandin E2 is an inhibitor of adenylate cyclase in rabbit proximal tubule.

Prostaglandin E1 and E2 (PGE) antagonize the phosphaturic effect of parathyroid hormone (PTH), but do not alter the phosphaturia evoked by adenosine 3',5'-cyclic monophosphate (cAMP) analogues. These findings support the idea that PGE interfere with activation of adenylate cyclase in the renal proximal tubule. We tested this hypothesis in the rabbit renal proximal straight tubule (PST). In the PST, adenylate cyclase was activated by PTH (Km = 10(-9) M PTH), but not by PGE2, which attenuated the activation of adenylate cyclase by PTH. The inhibition by PGE2 of PTH action was prevented by pertussis toxin, which deactivates the regulatory aggregate, Ni. In the PST, PGE2 also attenuated the activation of adenylate cyclase by cholera toxin. The inhibitory effect of PGE2 was selective; PGE2 did not inhibit activation of adenylate cyclase in glomeruli, but it inhibited the enzyme in proximal convoluted tubules (PCT) and PST. We conclude that PGE2 inhibits adenylate cyclase in rabbit proximal tubule. We propose that this action may, in part, regulate transport function in vivo.

Biologically active prostaglandins from some new odd‐numbered essential fatty acids

AbstractAll‐cis 8,11,14‐octadecatrienoic‐(18:3 ω4), nonadecatrienoic‐(19:3 ω5), heneicosatrienoic‐(21:3 ω7), docosatrienoic‐(22:3 ω8) and 5,8,11,14‐nonadecatetraenoic‐(19:4 ω5) and heneicosatetraenoic‐(21:4 ω7) acid were synthesized. These fatty acids were used for a study of their enzymic conversion into homologues of prostaglandin E1 (PGE1) and E2 (PGE2) by a particulate fraction of sheep vesicular glands. Moreover, their essential fatty acid (EFA) activities in the rat were determined.18:3 ω4 and 22:3 ω8 could not be converted into prostaglandin‐like materials; 19:3 ω5, 19:4 ω5, 21:3 ω7 and 21:4 ω7 yielded ω nor PGE1, ω nor PGE2, ω homo PGE1 and ω homo PGE2 respectively, the biological activities of which were comparable with those of PGE1 and PGE2, when tested on guinea pig ileum, rat blood pressure and ADP‐induced platelet aggregation. The conversion rates were compared with those of arachidonic acid (20:4 ω6) and dihomo‐y‐linolenic acid (20:3 ω6) and appeared to be, in decreasing order: 20:4 ω6 &gt; 20:3 ω6 &gt; 21:4 ω7 &gt; 19:4 ω5 &gt; 21:3 ω7 &gt; 19:3 ω5.Only the fatty acids that yielded biologically active prostaglandins showed considerable EFA‐activities; 18:3 ω4, 20:3 ω7 and 22:3 ω8 had no EFA‐activity. The ratios of the EFA‐activities of the fatty acids correlate roughly with the ratios of their conversion rates into prostaglandins.The fatty acids obtained from the liver mitochondria of rats fed with the various fatty acids were analysed. A considerable incorporation was found for the C19 and C21 acids. The C19 and C21 trienoic acids were dehydrogenated for the greater part to their corresponding tetraenoic acids, whereas the C19 acids were partly chain‐lengthened and further dehydrogenated to 21:5 ω5. The conclusion is that all‐cis fatty acids with the structure:CH3(CH2)n(CHCH‐CH2)4(CH2)2COOH, in which n = 3, 4 or 5, and those which can be converted by the rat into them, have EFA‐activity.