beraprost and Edema

The role of prostaglandin pathways has been suggested in some toxicological responses to dioxins. Cyclooxygenase type 2b (COX2b), thromboxane synthase, and the thromboxane receptor (TP) pathway have been implicated in mediating 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced pre-cardiac edema in developing zebrafish at 55 h post fertilization (hpf). Pre-cardiac edema refers to edema located in a small cavity between the heart and body wall of zebrafish eleutheroembryos. In the present study, we assessed the role of prostacyclin, which counteracts some biological effects of thromboxane, in TCDD-induced pre-cardiac edema. Pre-cardiac edema induced by TCDD exposure (0.5 and 1 ppb) beginning at 24 hpf was markedly inhibited by exposure to beraprost (5 and 10 μM), a prostacyclin receptor (IP) agonist, beginning at 33 hpf. The preventive effect of beraprost was reduced by exposure to CAY10441 (10 μM), an IP antagonist starting at 33 hpf. Knockdowns of the IP receptor (IP-KD) with two different morpholinos caused edema by themselves and enhanced pre-cardiac edema caused by the low concentration of TCDD (0.5 ppb). On the other hand, short exposure beginning at 48 hpf to U46619 (7.5-30 μM), a thromboxane receptor agonist caused pre-cardiac edema, which was inhibited by exposure beginning at 48 hpf to both ICI-192,605 (24 μM), a TP antagonist, and beraprost. Expression of prostacyclin synthase was increased from fertilization, plateaued by 48 hpf, and was maintained until at least 96 hpf. Overall, the results demonstrate a preventive effect of prostacyclin on TCDD-induced pre-cardiac edema in developing zebrafish.

Topics: Animals; Antihypertensive Agents; Cyclooxygenase 2; Cytochrome P-450 Enzyme System; Edema; Edema, Cardiac; Embryo, Nonmammalian; Environmental Pollutants; Epoprostenol; Intramolecular Oxidoreductases; Platelet Aggregation Inhibitors; Polychlorinated Dibenzodioxins; Receptors, Thromboxane; Zebrafish; Zebrafish Proteins

The inhibition of prostaglandin (PG) synthesis is at the center of current anti-inflammatory therapies. Because cyclooxygenase-2 (COX-2) inhibitors and nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the formation of multiple PGs, there is currently a strong focus on characterizing the role of the different PGs in the inflammation process and development of arthritis. Evidence to date suggests that both PGE(2) and PGI(2) act as mediators of pain and inflammation. Most of the data indicating a role for PGI(2) in this context have been generated in animal models of acute pain. Herein, we describe the role of PGI(2) in models of osteoarthritis (OA) and rheumatoid arthritis using a highly selective PGI(2) receptor (IP, Ptgir) antagonist and IP receptor-deficient mice. In the rat OA model using monoiodoacetate injection into the knee joint, the IP antagonist reduced pain with an efficacy approaching that of the NSAID diclofenac. In a chronic model of inflammatory arthritis, collagen-antibody induced arthritis model in mice, IP receptor-deficient mice displayed a 91% reduction in arthritis score. Interestingly, pretreatment with the IP [N-[4-(imidazolidin-2-ylideneamino)-benzyl]-4-methoxy-benzamide] antagonist in this model also caused a significant reduction of the symptoms, whereas administration of the compound after the initiation of arthritis had no detectable effect. Our data indicate that, in addition to its role in acute inflammation, PGI(2) is involved in the development of chronic inflammation. The results also suggest that the inhibition of PGI(2) synthesis by NSAIDs and COX-2 inhibitors, in addition to that of PGE(2), contributes to their efficacy in treating the signs of arthritis.

Topics: Animals; Arthritis, Experimental; Carrageenan; Chromatography, High Pressure Liquid; Chronic Disease; Collagen; Cyclooxygenase 2 Inhibitors; Edema; Epoprostenol; Hot Temperature; Hyperalgesia; Inflammation; Iodoacetates; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Osteoarthritis; Ovalbumin; Pain; Prostaglandins I; Rats; Rats, Sprague-Dawley; Receptors, Epoprostenol

We examined whether beraprost sodium (beraprost), a stable analogue of PGI2, has an anti-inflammatory effect on the permeability barrier through endothelial cells in vivo. The injection of collagen (5 micrograms/head) plus epinephrine (0.6 microgram/head) showed time-dependently the increased Evans blue dye leakage of the lung in mice for 60 min. Beraprost significantly suppressed this leakage dose-dependently (control; 11.26 +/- 1.64 micrograms/lung, beraprost 10 micrograms/kg; 7.49 +/- 1.36 micrograms/lung, 30 micrograms/kg; 5.33 +/- 0.71 micrograms/lung, 100 micrograms/kg; 5.52 +/- 0.79 micrograms/lung). Pulmonary thromboembolism-induced Evans blue dye leakage was also reduced significantly by aspirin (5 mg/kg), but PGE1 (170 micrograms/kg) showed a tendency to potentiate the edematogenic response. One week after the injection of same dosage of collagen plus epinephrine in mice, pulmonary thromboembolism showed the increase of wet-to-dry weight ratio of the lung (normal; 3.84 +/- 0.01, control; 3.96 +/- 0.04) and right ventricular hypertrophy (normal; 28.2 +/- 0.9%, control; 32.3 +/- 0.9%) compared to normal mice. Beraprost significantly suppressed lung edema and hypertrophy dose-dependently, and over 30 micrograms/kg/day of beraprost, the effects were statistically significant (beraprost 30 micrograms/kg/day; 3.85 +/- 0.02 and 27.8 +/- 1.4%, 100 micrograms/kg/day; 3.85 +/- 0.02 and 27.3 +/- 1.1%). Beraprost significantly reduced 5-hydroxytryptamine (5-HT; 17 nmol/paw)-induced rat paw edema dose-dependently (5-HT alone; 100%, beraprost 10(-13) mol/paw; 91.19 +/- 2.22%, 10(-12) mol/paw; 85.79 +/- 4.85%, 10(-11) mol/paw; 78.49 +/- 3.95%). 5-HT-induced edema was also suppressed significantly by the co-injection of (-)-isoproterenol (10(-12) mol/paw), but PGE1 (10(-11) mol/paw) significantly potentiated the edematogenic response. From these results, we propose that the anti-inflammatory effect of beraprost may be contributed, in part, to the permeability barrier through end othelial cells in vivo.

Topics: Alprostadil; Animals; Anti-Inflammatory Agents; Aspirin; Cell Membrane Permeability; Collagen; Dose-Response Relationship, Drug; Edema; Endothelium, Vascular; Epinephrine; Epoprostenol; Lung; Male; Mice; Organ Size; Pulmonary Embolism; Rats; Rats, Wistar; Serotonin