Differential changes in CNS phosphatase activities during seizures

Neutral and alkaline phosphatase activities were studied in small synaptosomes isolated from rat brain and cerebellum after administration of the convulsant 3-mercaptopropionic acid (MP). Cerebral cortex phosphatase activity assayed at pH 7.2 in the presence of K+ increased both during and after seizures; when it was assayed at pH 7.2 in the absence of K+ it decreased at both stages. The enzyme activity determined in cortical fractions at pH 9.0 with or without K+ decreased in seizure and postseizure states. After MP treatment, cerebellum enzyme activity assay at pH 7.2 was higher than in controls throughout; phosphatase activity assayed at pH 9.0 decreased following MP administration except during seizures when the enzyme was assayed in the presence of K+. Such changes following MP treatment may well be related to seizure-induced alteration of phosphate ester levels or protein-kinase activities.