Effect Of Endogenous Prostaglandins Research Articles

Production of interleukin-11 and interleukin-6 in cultured human gingival fibroblasts with the stimulation of lipopolysaccharides

To observe the effects of Porphyromonas gingivalis (Pg), Actinobacillus actinomycetemcomitans (Aa), Escherichia coli (Ec) lipopolysaccharides (LPS) on the production of IL-11 and IL-6 from healthy human gingival fibroblasts (HGF), and the effects of endogenous prostaglandin on HGF IL-11 and IL-6 production stimulated with the above LPS. HGF were stimulated with Pg-, Aa-, Ec-LPS of different concentrations (0.1, 1, 10 mg/L) for 24 h. And HGF were also stimulated with the combinations of 10 mg/L Pg-, Aa-, Ec-LPS and 10(-6) mol/L indomethacin respectively for 24 h. Levels of IL-11 and IL-6 in the supernatants were quantitated by ELISA. LPS from Aa, Ec, at the concentration of 10 mg/L and from Pg at the concentrations 1, 10 mg/L significantly augmented IL-11 production by HGF. IL-6 production was also significantly increased by stimulation with Aa-LPS at concentrations 1, 10 mg/L and with Ec-, Pg-LPS at concentrations 0.1, 1, 10 mg/L. In addition, IL-11 production was lower than IL-6 production by HGF stimulated with LPS. Indomethacin significantly inhibited IL-6 and IL-11 production in LPS-stimulated HGF. Aa-, Pg-, Ec-LPS may significantly increase IL-11 and IL-6 level in the supernatants of HGF, and endogenous prostaglandin may upregulate IL-11 and IL-6 production in LPS-stimulated HGF.

Cyclooxygenase-2-derived endogenous prostacyclin enhances mouse embryo hatching

The role of prostaglandins (PGs) in embryo hatching remains controversial. In addition, there is no direct evidence that mouse embryos synthesize PGs. The effects of endogenous PG on mouse embryo hatching were evaluated by blocking endogenous PG synthesis with indomethacin. Specific cyclooxygenase (COX) inhibitors were used to identify the role of COX-1- and COX-2-derived PGs. An eicosanoid profile was generated by incubating blastocysts with [3H]arachidonic acid and analysing the metabolites by high performance liquid chromatography. The expression and the localization of COX-1, COX-2 and prostacyclin synthase (PGIS) were examined by western blot analysis and immunohistochemistry. The hatching of embryos cultured in 30 microl of protein-free medium was blocked by indomethacin (P = 0.007) or a selective COX-2 inhibitor (P = 0.004). Adding back iloprost, a prostacyclin analogue, abolished the effects of the COX-2 inhibitor. Prostacyclin was the most abundant PG produced by mouse blastocysts, which expressed COX-1, COX-2 and PGIS. COX-1, COX-2 and PGIS were expressed in 4-cell stage embryos and beyond; they were present in the inner cell mass and the trophectoderm of the blastocysts. Mouse embryos express COX-1, COX-2 and PGIS which catalyse the formation of PGI2; COX-2-derived PGI2 plays a critical role in embryo hatching.

Effect of combined administration of lansoprazole and sofalcone on microvascular and connective tissue regeneration after ethanol-induced gastric mucosal damage.

We undertook the present study to clarify the alteration of localization of basic fibroblast growth factor (bFGF), endothelial cells, and myofibroblasts in the healing of ethanol-induced gastric mucosal damage by the combined administration of lansoprazole and sofalcone. Wistar strain male rats were used. Ethanol 50% was given through orogastric intubation. Thirty minutes later, an aqueous solution of lansoprazole, sofalcone, a combination of lansoprazole and sofalcone, or physiologic saline was given orally. The stomach was removed and the localization of bFGF, myofibroblast, and endothelial cells was examined using monoclonal antibodies. Some rats were pretreated with indomethacin to rule out the effect of endogenous prostaglandin. The combined administration of lansoprazole and sofalcone brought about increased concentrations and immunoreactive areas of bFGF and a greater number of endothelial cells, compared with the ethanol-alone treatment. The number of myofibroblasts increased more significantly in the group treated with a combination of agents than in that treated with ethanol alone, ethanol plus sofalcone, or ethanol plus lansoprazole. Indomethacin pretreatment partly abolished the effects of single and combined administration of these agents. In conclusion, the mixed administration of lansoprazole and sofalcone accelerated the microvascular and connective tissue regeneration during the healing of ethanol-induced gastric mucosal damage.

Effect of endogenous prostaglandins on acetylcholine release from dog trachealis muscle.

We used a radioenzymatic technique to measure effects of the prostaglandin synthesis inhibitor indomethacin and of exogenous prostaglandin E2 (PGE2) and prostaglandin I2 (PGI2) on acetylcholine (ACh) efflux from canine tracheal smooth muscle (TSM) during sustained electrical field stimulation (EFS; 2 Hz, 2 ms pulse duration, 50 V for 15 min). ACh efflux from indomethacin (INDO, 10(-6) M)-pretreated and control TSM increased with consecutive stimulations. However, efflux of ACh was greater in INDO-treated than control muscles. INDO increased the tension produced by TSM in response to EFS. Neither PGE2 (10(-8) M) nor PGI2 (10(-6) M) had any effect on ACh efflux from INDO-pretreated TSM during the first of three periods of EFS. However, PGI2 and PGE2 prevented the progressive increase in ACh efflux observed on subsequent stimulations. PGE2 but not PGI2 decreased contractions of TSM caused by EFS. Our results demonstrate that endogenous prostaglandins, probably PGE2, do inhibit EFS-evoked ACh release from canine TSM in vitro, but suggest that these prostaglandins modulate EFS-evoked contractions predominantly by postsynaptic mechanisms.

Purification and quantification of arachidonate metabolites: critical evaluation of methods and interpretation of results.

S INCE THE INITIAL description of prostaglandins in 1935, a vast body of knowledge has accumulated on the physiology and chemistry of arachidonate metabolites and how they relate to perinatal medicine. In addition to contributing to the initiation of labor in the mother, arachidonate metabolites are involved in closure and/or maintenance of ductus arteriosus patency; they help effect changes in pulmonary vascular tone, and they act as mediators in lung injury. Moreover, a protective effect of endogenous prostaglandins in the gastrointestinal (GI) tract has been speculated on, and caveats have been raised regarding inhibition of their synthesis with indomethacin. Almost every organ system appears to be linked to the arachidonate acid pathway. While much has been learned about how arachidonic acid metabolism relates to perinatal medicine in the past two decades, difficulties in measuring prostaglandins and leukotrienes in tissues, blood, and other biological fluids have delayed the progress of research (see also chapter by Mitchell). Since radioimmunoassay (RIA) was introduced into the field of prostaglandin measurement in the early 197Os, a large amount of RIA work has been published in the perinatal area. The concentrations recorded in the same body fluids have varied enormously among the different reports. Some of the early studies that used RIA to analyze prostaglandins in the peripheral circulation reported concentrations in control subjects in the ng/mL range. More recent RIA studies have indicated much lower concentrations, ie, in the pg/mL range (Table 1). Even though RIA is a highly sensitive technique, its specificity has been questioned. For example, RIA studies by Seiss and Dray l l at the Pasteur Institute, using a range of sample preparation techniques, indicated marked decreases in plasma 6-keto-prostaglandin F,, (6-keto-PGF,,) concentrations in humans with increasing sample cleanup, even with corrections for recovery (Table 2). In our laboratory, we have also found that the prostaglandin concentrations in human milk measured by RIA are much lower after purification with octadecylsilyl extraction and high-performance liquid chromatography (HPLC) (Table 3). ‘* The decrease in reported concentrations of arachidonic acid metabolites over the past several years is presumably due to improved techniques that have increased the specificity of RIA, such as the use of more specific antibodies and improved chromatographic clean-up (eg, silicic acid chromatography, thin-layer chromatography [TLC], and HPLC). Other techniques such as those using gas chromatography/mass spectrometry (GUMS) have also been highly beneficial in accurately quantitating prostaglandin metabolites. However, only recently has GUMS been shown to be effective in the low pg/mL range, where many of the arachidonic acid metabolites are currently thought to exist in the peripheral circulation. In this report, we will review some of the major techniques that have been used to purify and quantitate arachidonic acid metabolites. Readers who are interested in more specific details are referred to references 13 and 14 and to those cited in the text following.

Role of prostaglandins in regulating gastric motility.

Muscles of the stomach possess the ability to synthesize several prostaglandins. These compounds function as local regulatory agents by influencing the motor performance of the muscle cells. In the distal stomach the dominant effect of endogenous prostaglandins is to decrease the amplitude of contractions and decrease the ability of the muscles to respond to excitatory stimuli. Prostaglandins also have a chronotropic role in the distal stomach, and they are responsible for the frequency effect of gastrin pentapeptide. In the proximal stomach prostaglandins have an opposite role; they promote tonic contraction. Because of the diverse effects of prostaglandins, they probably have complicated effects on gastric motility. In general, emptying of solids should be retarded by endogenous prostaglandins, whereas emptying of fluids may be facilitated by these compounds. Overproduction of prostaglandins may produce abnormal motility patterns and affect gastric emptying. A case of gastric pseudoobstruction apparently involving prostaglandins is discussed.

The Effect of Flurbiprofen, a Potent Inhibitor of Prostaglandin Synthesis, on Insulin and Glucagon Release from Isolated Rat Pancreas*

The influence of different levels of inhibition of prostaglandin (PG) synthesis on the release of insulin and glucagon was investigated in the basal state (5.6 mM glucose) and in response to 30-min perfusion of 16.7 mM glucose using the isolated perfused rat pancreas model. Flurbiprofen (FLR), a potent and selective inhibitor of PG synthesis, was present in the perfusate during the entire experimental period at a concentration of 10(-8), 5 X 10(-8), or 10(-6) M; control experiments were performed without the drug. Levels of immunoreactive PGE2, PGF2 alpha, insulin, and glucagon were measured in the portal venous effluent. FLR inhibited PG synthesis in a dose-related manner; PGE2 was inhibited more than PGF2 alpha. Basal and glucose-induced secretion of insulin was augmented by FLR at 5 X 10(-8) M, but was inhibited at 10(-6) M. At 10(-6) M FLR, basal glucagon secretion was inhibited; glucose-induced suppression still occurred without any potentiation. We conclude that 1) endogenous PGs modulate the secretion of insulin and glucagon; 2) divergence of the effects of low and high levels of inhibition of PG biosynthesis on insulin release may be due to altered tissue proportions of various PGs and related autacoids; and 3) the predominant effect of endogenous PGs on glucagon release is tonic stimulation.

Effect of endogenous prostaglandin E on the vasoconstrictor response to noradrenaline.

The effect of the endogenous prostaglandin E (PGE) level in the vascular wall on the vasoconstrictor response to noradrenaline (NA) was examined using the perfused central artery of an isolated rabbit ear. The endogenous PGE level in the ear artery was estimated from that in the venous perfusate, which was measured by radioimmunoassay. Pretreatment with indomethacin, a cyclooxygenase inhibitor, was followed by a significant decrease in the PGE level and a significant increase in the vasoconstrictor response to exogenous NA. In addition, there was a significant correlation between the response to NA and the PGE level in the venous perfusate in combination with the results during perfusion of indomethacin and of PGE1 plus indomethacin, although the former did not correlate with the latter under the basal conditions alone. From these results, it seems possible to draw the conclusion that as far as vasoconstrictor responsiveness is concerned, there is some antagonism between NA and endogenous and/or exogenous PGE in the rabbit ear artery.

Effects of endogenous prostaglandin E on intestinal motility.

The role of endogenous prostaglandin E (PGE) in the regulation of intestinal motility in situ was studied in cats anesthetized with pentobarbital. The basal concentration of PGE in the ileum was found by radioimmunoassay to be 3.3 +/- 0.6 ng PGE per g wet wt (chi +/- SE, n = 12). Intramesenteric arterial infusion of acetylcholine (ACh) (100 microgram/min) increased intestinal motility, and PGE concentration rose to 6.7 +/- 0.8 ng/g. Intravenous infusion of indomethacin (4 mg/kg) enhanced spontaneous and ACh-induced motility and abolished the ACh-induced rise in ileal PGE concentration. We conclude that basal PGE synthesis limits the motility of the resting and ACh-stimulated cat ileum.

Endogenous prostaglandin E and contractile activity of isolated ileal smooth muscle.

The effects of endogenous prostaglandin E (PGE) on the contractile activity of isolated cat ileal muscle rings were studied. Force development in circularly oriented muscle fibers were recorded. The muscles contained a mean basal PGE concentration of 1 +/- 0.6 ng PGE per g wet wt (mean +/- SE) as measured by radioimmunoassay. Acetylcholine (ACh) or elevated potassium caused contractions and enhanced PGE concentration (P less than 0.05). Removing Ca2+ from high potassium solutions blocked contraction, but PGE concentration still increased (P less than 0.02). The prostaglandin synthetase inhibitors, indomethacin and 5,8,11,14-eicosatetraenoic acid (ETA) reduced PGE concentration in muscles (less than 50 pg PGE per g muscle) and increased the magnitude of contractions induced by either ACh or elevated potassium. Spontaneous contractions were observed in many tissues after inhibition of PGE synthesis. In conclusion, endogenous PGE limits spontaneous and depolarization-induced muscular activity in cat ileal circular muscle. Synthesis of PGE was increased by depolarizing stimuli whether or not contractions were blocked by the removal of external calcium.