An Ex Vivo Method for Evaluating Prostaglandin Synthetase Activity in Cortical Slices of Mouse Brain

Shohami, Esther; Gross, Joshua

doi:10.1111/j.1471-4159.1985.tb05484.x

Cited by 33 publications

(20 citation statements)

References 12 publications

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“…Our present results agree with this report regarding the effect of both drugs on water content (SG in our measurements). However, we show here, as we did before (Shohami et aI., 1982;Shohami and Gross, 1985) and as others have re ported (e.g., Gaudet and Levine, 1979;Pappius and Wolfe, 1983), that indomethacin does significantly reduce PG synthesis in the brain, although the cel lular source of PG synthesis is not yet fully clear. Thus, the role of PGs in the development of vaso genic brain edema needs to be further explored.…”

Section: Discussionsupporting

confidence: 82%

“…Tissue samples of �20 mg each were hand cut on an ice-cold plate from an area just next to the zone of maximal macroscopic damage in the left hemisphere and from the corresponding contralateral area of the right hemisphere. The slices were incubated at 37°C in oxy genated Krebs-Ringer solution for I h for determination of endogenous production of PGs (Shohami and Gross, 1985). Brain production of PGE2, 6-keto-PGF1a (the stable metabolite of PGI2), and thromboxane (TX) B2 (the stable metabolite of TXA2) was determined by radioim munoassay using 3H-PGs (100-200 Ci/mmol; New En- gland Nuclear) and specific rat antibodies (Dr. L. Levine, Brandeis Univ., Waltham, MA, U.S.A.) that had <0.1% cross-reactivity with all major PGs.…”

Section: Methodsmentioning

confidence: 99%

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Dexamethasone and Indomethacin Do Not Affect Brain Edema following Head Injury in Rats

Shapira

Davidson

Weidenfeld³

et al. 1988

J Cereb Blood Flow Metab

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Summary: Head trauma was induced in rats by a weight drop device, falling over the exposed skull over the left hemisphere. The neurological state of the rats was evalu ated by a neurological severity score at 1 h and 18 h post head trauma. At 18 h post head trauma, rats were decapi tated and tissue from the vicinity of the injury and from a corresponding area in the contralateral hemisphere was taken for specific gravity (SO) determination using linear gradient columns. Slices were taken from the same sites for incubation in Krebs-Ringer solution, and the concen trations of prostaglandin (PO)E2, 6-keto-POF1a, and thromboxane B2 accumulated in the medium during 1 h were measured by radioimmunoassay. In one experi mental group, rats were pretreated with intraperitoneal dexamethasone sodium phosphate (4 mg/kg) 18 and 2 h before head trauma, and a third dose was given 8 h post head trauma. Another group was treated with intraperi toneal indomethacin (10 mg/kg) I h before and 7 h after head trauma. Other groups were treated immediately and Various cerebral insults trigger the release of ara chidonic acid from phospholipids of the cell mem branes, and the free acid is further metabolized by both cyclooxygenase and lipoxygenase (Bazan, 1970; Samuelsson et ai., 1979;Wolfe and Coceani, 1979;Wolfe, 1982 A preliminary report of this study was presented at the Israeli Trauma Research Meeting, November 1985.Abbreviations used: PO, prostaglandin; SO, specific gravity; TX, thromboxane. 3958 h after head trauma with 4, 8, 15, or 30 mg/kg of dexa methasone sodium phosphate. Another group of rats was treated with free dexamethasone (10 mg/kg) right after head trauma and 8 h later. Head trauma induced edema, as expressed by decreased SO, in the left hemisphere of all traumatized rats. Neither treatment protocol affected the neurological severity score of the injured rats or the SO of the contused hemisphere. PO synthesis, on the other hand, was significantly reduced following indo methacin or free dexamethasone, both in sham and trau matized rats, but not in dexamethasone sodium phos phate-treated rats. We conclude that pretreatment with indomethacin, dexamethasone sodium phosphate, or dexamathasone, used in the present protocols, does not affect posttraumatic cerebral edema. Thus, the role of POs as mediators of edema formation remains unclear.

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Section: Discussionsupporting

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Dexamethasone and Indomethacin Do Not Affect Brain Edema following Head Injury in Rats

Shapira

Davidson

Weidenfeld³

et al. 1988

J Cereb Blood Flow Metab

Self Cite

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“…The brains were rapidly removed (within 1 min) and placed on an ice-cold petri dish; slices of 15-20 mg were cut from both hemispheres and each placed in 1 ml of ice-cold ox ygenated Krebs solution, pH 7.4, as previously described (Shohami and Gross, 1985). This solution was replaced within 1-2 min with fresh Krebs solution and reoxygen ated, and the tubes were tightly closed and placed for 1 h in a shaking water bath at 37°C.…”

Section: Methodsmentioning

confidence: 99%

“…The role of PGs, particu larly that of PGE2, as mediators of inflammation has been well established (Bonta and Parnham, 1982a It is well documented that thromboxane (TXA2) and prostacyclin (PGI2), which are the products of the same precursor (arachidonic acid), have op posing biological effects: Namely, the first en hances platelet aggregation and is a vasocon strictor, while the latter inhibits aggregation and di lates blood vessels (Moncada and Vane, 1979). followed by a study of the synthetic capacity of the contused and the contralateral hemispheres to pro duce and release PGs by the method described by Shohami and Gross (1985).…”

mentioning

confidence: 99%

Head Injury Induces Increased Prostaglandin Synthesis in Rat Brain

Shohami

Shapira

Sidi

et al. 1987

J Cereb Blood Flow Metab

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123

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Summary: Head injury was induced in the left hemi sphere of rats, The rats were killed at various time in tervals after trauma (immediately, 15 min, 1 and 18 h, and 4 and 10 days), and the rates of synthesis and release of prostaglandin PGE2, 6-keto-PGF I", and thromboxane TXB2 from cortical slices of both hemispheres were studied. The rate of synthesis of PGE2 after 18 h was six and four times higher than control in the contused and contralateral hemispheres, respectively. By 10 days post trauma, both hemispheres had normal rate of PGE2 re lease. TXB2 and 6-keto-PGFI" synthetases were affected already 15 min after the injury, and a similarly elevated rate of synthesis was found in both hemispheres. The maximal effect was detected after 1 or 18 h with return to

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“…4,5 An elevated production of NO secondary to an increase in iNOS expression has been suggested to play an important role in the hyperemic effect of LPS in many vascular beds, including that of the brain. 6,7 An isoform of prostaglandin synthase (cyclooxygenase), PGS-2 (COX-2), is also induced 8,9 in fibroblasts, 10 neurons, 11 and astrocytes 12 after administration of LPS, and studies using enzyme inhibitors have suggested that induction of both iNOS and COX-2 may contribute to LPS-induced increases in CBF. Most of the previous studies have utilized systemic administration of LPS.…”

mentioning

confidence: 99%

Role of Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in Endotoxin-Induced Cerebral Hyperemia

Okamoto

Itoh

Roman

et al. 1998

Stroke

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Background and Purpose-Bacterial lipopolysaccharide (LPS), an endotoxin, has been reported to induce the expression of inducible isoforms of both nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in various cell types. LPS is also known to dilate systemic vasculature, including cerebral vessels. This study aimed to determine to what extent LPS induces iNOS and COX-2 expression in the brain and whether NO and/or cyclooxygenase metabolites derived from iNOS and/or COX-2 contribute to the LPS-induced cerebral hyperemia. Methods-Regional cerebral blood flow (rCBF) was measured by laser-Doppler flowmetry in halothane-anesthetized, artificially ventilated rats for 4 hours after intracerebroventricular administration of LPS. Results-LPS at doses of 0.01 mg/kg to 1 mg/kg caused dose-dependent, progressive increases in rCBF at 1 to 4 hours after administration. The increase in rCBF was attenuated by systemic administration of the selective iNOS inhibitor aminoguanidine (100 mg/kg IP) or the selective COX-2 inhibitor NS-398 (5 mg/kg IP), and it was abolished by preventing induction of these isoforms with dexamethasone (4 mg/kg IP). LPS significantly increased iNOS and COX-2 mRNA, iNOS protein, and iNOS and cyclooxygenase enzyme activity. The increases in iNOS and cyclooxygenase enzyme activity were eliminated by aminoguanidine and NS-398, respectively. Dexamethasone also prevented the increase in iNOS and cyclooxygenase activity. Conclusions-These results indicate that induction of iNOS and COX-2 expression and the increased production of NO and vasodilator prostanoids in the brain contribute to the elevation in CBF after intracerebroventricular administration of LPS. (Stroke. 1998;29:1209-1218.)

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An Ex Vivo Method for Evaluating Prostaglandin Synthetase Activity in Cortical Slices of Mouse Brain

Cited by 33 publications

References 12 publications

Dexamethasone and Indomethacin Do Not Affect Brain Edema following Head Injury in Rats

Dexamethasone and Indomethacin Do Not Affect Brain Edema following Head Injury in Rats

Head Injury Induces Increased Prostaglandin Synthesis in Rat Brain

Role of Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in Endotoxin-Induced Cerebral Hyperemia

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