Prostaglandins, leukotrienes, and medicine最新文献

A high performance liquid chromatographic (HPLC) method was developed to measure thromboxane B₂ (TxB₂) levels in human serum. Serum samples (2 mL) were extracted using solid phase extraction columns in a C18/silica mode sequencing approach. The internal standard, 6-ketoprostaglandin F_1α was added to the serum extracts. The eicosanoids were doubly derivatized, first with panacyl bromide, then with methoxyamine to form methoxime-panacyl ester derivatives. The eicosanoid derivatives were chromatographed using a reverse phase HPLC system with UV detection (254 nm). Assay linearity was demonstrated with fortified TxB₂ standards in 3% bovine serum albumin over a range of 25 to 500 ng/ml (r$\text{>}$0.994). There was no significant interday difference or bias in assay results for pooled standards at 75, 226 and 376 ng/mL concentrations (p > 0.05). Pooled estimates of precision at these levels indicate an assay relative standard deviation 6–9%. The HPLC assay was used to quantitate TxB2 levels in human serum. Results were consistent with previously published values when drug-free serum was analyzed to assess $\text{ex vivo}$ TxB₂ formation.

Dietary supplementation with a marine lipid concentrate rich in n-3 fatty acids and pure ethyl ester of dihomo-gamma-linolenic acid (DHLA) resulted in inhibition of the chronic phase of inflammation in Salmonella-associated arthritis. The anti-inflammatory effect of DHLA was much stronger than that of two n-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid) present in marine oil. Fatty acid profiles in phosphoglyceride fractions of red blood cells showed incorporation of the respective supplemented fatty acids. Concentrations of 4 cyclookygenase products in femoral vein plasma were smaller in the fatty acid supplemented rats. These studies suggest that DHLA and marine n-3 fatty acids may have useful anti-inflammatory effects in Salmonella-associated arthritis.

The mechanism by which progesterone inhibits PG production is not clear. In systems using isolated human endometrial fragments, progesterone has been shown to inhibit PG production markedly. We have used such a system to test the action of two antiprogesterone steroids RU486 (Roussell-Uclaf) and ZK98734 (Schering) on isolated human endometrial and decidual tissue, with and without added progesterone. Progesterone (200nM) reduced PGF_2α production by the secretory phase endometrium from 10.9ng/mg tissue/24 hr to1.9 ng/mg/24hr on the third day of culture (p<01) and this effect was antagonised by the addition of either 200nM RU486 or 200nM ZK98734 (6.3 and 7.2 ng/mg /24 hr respectively). The antiprogestins on their own showed a slight inhibitory effect on day 3 and RU486 treatment resulted in a significant (p<.05) decrease in PG production from control. PGE and the main 13,14-dihydro-15-keto metabolites of E and F were also significantly decreased by progesterone and restored by the aMiprogestins. The PG production by decidua increased on days 2 and 3 in response to progesterone + antiprogestins but this was not significant. This data shows that the inhibition of PG production shown by progesterone, acting on secretory phase endometrium cultured as tissue fragments, is reversible by the receptor blocking antiprogestins.

The role of prostaglandins (PGs) and leukotrienes (LTs) in the induction of decidualization in the rat uterus was investigated. In the hypophysectomized progesterone (P4) primed rat, intraluminal infusion for four days by osmotic minipump, of PGE2 (lug/h), LTC4 (long/h) or 0.15M saline (1u1/h) significantly elevated uterine weight when compared to the noninfused horn: all were equally effective. In contrast, simultaneous infusion of PGE2 and LTC4 produced an increase in uterine weight which was markedly higher than any other conditions and the reaction was elicited along the entire length of the uterine horn. Infusion of PGE2, LTC4, a combination of the two or vehicle, into one uterine horn of day-5 pseudopregnant rats elicited a huge decidual response. Infusion of indomethacin, an inhibitor of PG synthesis, FPL 55712 (FPL), an antagonist of LTs, or a combination of these inhibitors evoked a minimal decidual response. In addition, FPL infused along with PGE2 or LTC4 markedly reduced the response that could be induced by these arachidonate metabolites alone. Furthermore, infusion of indomethacin along with LTC4 resulted in a far smaller response than that obtained with LTC4 alone. These results are interpreted to indicate that there is an interaction between LTs and PGs in the induction of the uterine decidual response.

$\text{In vivo}$ prostaglandin E2 (PGE2) levels were measured in esophageal mucosa excised from 9 normal subjects, 11 patients with gastroesophageal reflux without esophagitis (GER) and 8 patients with reflux esophagitis (RE). Severity of GER was quantified by postcibal pH monitoring. A manometric study was also performed. No difference was found in PGE2 levels between healthy mucosa in controls (41.7 ± 9.3 ng/g of wet tissue, at 15 cm above the lower esophageal sphincter (LES))and healthy mucosa in GER (37.8 ± 11.2 ng/g) or in RE 34.3 ± 9.0 ng/1). However, PGE2 levels were significantly enhanced within the inflammatory mucosa in RE (290.4 ± 45.7 ng/g). No difference was found in basal LES pressure between the 3 groups. These results suggest that PGE2 in the esophagus may be involved in pathogenesis of inflammation. Therefore PGE2 might not have the same cytoprotective function as in stomach or duodenum. No correlation was found between PGE2 levels in the esophagitis lesion or basal LES pressure. These data are not consistent with a possible relationship between LES pressure and the PGE2 content of the distal esophagus.

Endogenous prostaglandin (PG) concentrations (6oxo PGF_1α, PGE, PGF_2α) have been measured by radioimmunoassay in the endaeetrium of women with objectively assessed menstrual blood loss (MBL). The concentration of PGE and “total” PG (6oxo PGF_1α+PGE+PGF _2a) was greater in the endometrium of those women with heavy menses (median MBL 152ml (range 86,432) n=16) than in those individuals with a normal menstrual loss (MBL 59m1 (18,78) n=18). The concentrations of PGE and PGF_2α were similar in each group, but the concentration of 6oxo PGF_1α was significantly less than that of both PGE and- PGF _2α. In 19 individuals, specimens of endometrium were incubated or I and 2 hours in modified 199 medium to assess PG release. There was a direct correlation between endogenous PG content and the production of 6oxo PGF_1α, PGE, PGF_2α and “total” PG in the first tour, which persisted for the second hour with PGF_2α and “total” PG. Endometrial PGs may play a role in the mechanism underlying menstruation; however the observed relationship between the prostanoids and MBL will vary with different experimental methods.

Prostanoid synthesis was investigated in suspensions of isolated mouse hepatocytes and nonparenchymal liver cells. A stable metabolite of thromboxane A₂ (TXB₂) of prostacyclin (6-keto PGF_1∝) and one of the prostaglandins (PGF_2∝) was detected by radio-immuno-assay (RIA). Hepatocytes synthesized mainly TXB₂, while smaller amounts of 6-keto PGF_1∝ and PGF_2∝ were detected during 60 min incubation. Homogenization of hepatocytes caused a slight increase in TXB₂ production and provoked the synthesis of PGF_2∝ and 6-keto PGF_1∝. Theaddition ofarachidonate to hepatocytes did not influence prostanoid production at concentrations below 10⁻⁵ M. Higher concentrations further increased TXB₂ production and also increased the synthesis of 6-keto PGF_1∝ and PGF_2∝. Nonparenchymal cells synthesized all the three types of prostanoids and homogenization of these cells did not result in a marked change. The addition of 10⁻⁷−10⁻⁵M arachidonate increased the TXB₂, 6-keto PGF_1∝ and PGF_2∝ synthesis in nonparenchymal cells. No further increase was found at higher concentrations.

The role of G proteins and protein kinase C in mediating muscarine receptor-linked prostanoid synthesis by the rat urinary bladder was investigated using the G protein activator, sodium fluoride (NaF); the protein kinase C activators, phorbol myristate (PMA) and phorbol dibutyrate (PDBU); the protein kinase C inhibitor, H7, and the parasympathomimetic, carbachol. NaF stimulated in vitro rat urinary bladder prostacyclin (PGI₂) synthesis (EC₅₀ = 6 mmol. ⁻¹), an action inhibited by the presence of EDTA (10 mmol. 1⁻¹). Carbachol potentiated the stimulatory action of NaF. NaF (10 mmol.l⁻¹)-stimulated PGI₂ synthesis was inhibited by the calcium channel blockers verapamil, nifedipine and the protein kinase C inhibitor, H7, in concentrationdependent manners. Carbachol-stimulated PGI₂ synthesis was also inhibited by H7. PDBU and PMA were without effect on de novo, NaF-or carbachol-stimulated urinary bladder PGI₂ synthesis. Other prostanoids (PGE₂ and PGF_2α) were stimulated to the same degree as PGI₂ by NaF, and inhibited equally by H7 and calcium channel blockers. Dibutyryl adenosine 3′:5′-cyclic monophosphate was without effect on de novo or NaF-stimulated prostanoid synthesis. Since fluoride activates G proteins, these data indicate that: (1) muscarine receptorprostanoid synthesis coupling is mediated by G proteins in the rat urinary bladder; (2) fluoride action is mediated by protein kinase C and not adenyl cyclase, probably through activation of phospholipase C and therefore the generation of the protein kinase C activator diacyl glycerol; (3) activated protein kinase C may initiate Ca²⁺⁺ mobilisation linked to prostanoid synthesis; and (4) the lack of effect of the phorbol esters on urinary bladder PGI₂ synthesis, in contrast to that on other smooth muscle, indicates that in different smooth muscle tissues there are varying forms of protein kinase C.

Oral administration of two nonsteroidal anti-inflammatory drugs, ibuprofen and flurbiprofen, can suppress the Salmonella-induced arthritis in rats. The joint swelling index of arthritic paws showed suppression of arthritis in animals treated with the drugs, this effect being greater with flurbiprofen. Measurement of 5 eicosanoids in femoral vein plasma showed increase of arachidonic acid products in Salmonella-treated rats. Inhibition of joint inflammation resulting from treatment with ibuprofen and flurbiprofen is reflected by a decrease in concentration of all 5 eicosanoids which were found in the order: PGE₂ > TXB₂ > 6-keto-PGF_1α > PGE₁ > PGF_2α. These studies indicate that flurbiprofen is a more powerful anti-inflammatory agent than ibuprofen. However, since the joint disease was not completely cured, optimal intervention is quite likely to require modulation of the lipoxygenase pathway.