Regional distribution of prostanoids in rat brain: effect of insulin and 2-deoxyglucose

Prostaglandin synthesis in the brain has been suggested as a component in the control mechanism of the cerebral circulation. During insulininduced hypoglycemia there is a significant increase in local cerebral blood flow in various brain regions, however, regional loss of autoregulation occurs under these conditions. In the present study the regional distribution of PGE₂, TXB₂ (the stable metabolite of thromboxane) and 6-keto-PGF_1α (the stable metabolite of prostacyclin) was determined in rat brain following decapitation. Three groups of rats were treated with either saline, insulin or 2-deoxyglucose and their brains were rapidly removed one hour later. Samples from the cortex hypothalamus, hippocampus, striatum, nucleus accumbens and cerebellum were assayed by RIA for the content of PGE₂, TXB₂ and 6-keto-PGF_1α The levels of all three compounds in control rats were the lowest in the striatum and cerebellum, while in the cortex and hippocampus their levels were 4-6 times higher. Insulin had selective effect on the post decapitation levels of prostanoids. It increased PGE₂ in the n. accumbens and TXB₂ in the hippocampus, and reduced 6-keto-PGF_1α and TXB₂ in the cortex. 2-DG reduced all PGs in the cortex and 6-keto-PGF_1α in the hypothalamus and hippocampus. The results demonstrate that discrete brain areas have a differential capacity to accumulate PGs following decapitation. This capacity is selectively affected by insulin and 2-DG.