Ultrastructural localization of thiamine pyrophosphatase in plasma membranes of brain phagocytes long time after cardiac arrest.

Brain phagocytes are members of a heterogeneous family of microglial cells. In this study we investigated the membrane activity of the enzyme, thiamine pyrophosphatase (TPP-ase), in brain phagocytes. Studies were performed on rats subjected to a transient ischemia because ischemic incident precipitates proliferation of microglial cells in the brain. Brain tissue was sampled from animals that survived 12 months after experimentally evoked cardiac arrest. The product characteristic for TPP-ase activity was present in the Golgi cisterns of neurons, basement membranes of endothelia and capillary pericytes. TPP-ase activity was present on plasma membranes of brain phagocytes. The phagocyte TPP-ase activity did not depend on the anatomical localization of the cell in the brain (cortex, hippocampus, hypothalamus). Thus, TPP-ase activity can be considered as a marker of brain phagocytes.