Postischemic production of eicosanoids in gerbil brain.

The postischemic production of PGE2, PGD2, 6-keto-PGF1 alpha, and TXB2 in brain tissue was studied in Mongolian gerbils using tissue extraction as well as a new ex vivo method. This new method permits the study of prostaglandin synthesis in slices from discrete areas of the brain (cortex, hippocampus, striatum, hypothalamus). Gerbils were sacrificed at 0, 5, and 30 minutes, and 4 and 24 hours after a 15-minute occlusion of both carotid arteries. Apart from 6-keto-PGF1 alpha, tissue prostaglandins determined by the extraction method were significantly increased 3 and 30 minutes after reperfusion. The most pronounced changes found by the ex vivo method were increased productions of PGD2 immediately after reperfusion (285% in cortex, 215% in hypothalamus) and PGE2 (350% in hippocampus, 320% in striatum) 4 hours after reperfusion. At 24 hours after reperfusion PGE2 and PGD2 synthesis were significantly decreased by 23-70% of the values obtained from sham-operated controls. Thromboxane increased slightly in all areas after recirculation and subsequently decreased to values below the control level in striatum. The results obtained by ex vivo incubation of tissue slices demonstrate that ischemia and subsequent recirculation cause site-, time-, and PG-specific changes of tissue eicosanoid production.