Increase in brain prostaglandins during convulsions is due to increased neuronal activity and not to hypoxia

The levels of prostaglandin D2 (PGD2) and prostaglandin F2 alpha (PGF2 alpha), being the major prostaglandins formed in mouse brain in vivo were determined using a radioimmunological technique. Under basal conditions, they were less than 8.49 ng/g for PGD2 and less than 3.76 ng/g for PGF2 alpha. During seizures, induced by the centrally acting convulsant pentylenetetrazol, cerebral concentrations of both prostaglandins were markedly enhanced as compared to basal conditions. The seizure evoked increase in brain prostaglandins could be attributed to the enhanced neuronal activity. If convulsions were induced with the spinal cord convulsant strychnine no increase in brain prostaglandins was seen although the occurring hypoxia was probably very similar. Therefore, hypoxia does not seem to play a significant role in the prostaglandin increase. The effect of pentylenetetrazol on cerebral prostaglandins was independent of the mechanical convulsions induced by the drug. Muscle relaxed mice showed the same increase in cerebral prostaglandins as convulsing mice. Muscle relaxation alone had no influence on prostaglandin formation in brain. These data indicate that the increased neuronal activity induced by centrally acting convulsants is likely to be the sole cause for the rise in cerebral prostaglandins. Brain hypoxia, another known stimulus of prostaglandin synthesis, does not seem to play an important role during convulsions.