Electron microscopical demonstration of acid phosphatase activity in the central nervous system

Enzyme cytochemistry of the cerebral microvessel wall

The cytochemical localisation of five hydrolytic enzymes has been studied in the brain capillaries of laboratory animals. Acid phosphatase is present in primary lysosomes of endothelial cells; alkaline phosphatase activity is seen mainly on the plasma membrane of the luminal side but also in the basal lamina. The latter is also active concerning 5'nucleotidase. Butyrylcholinesterase is an enzyme synthesized by most brain capillary endothelial cells, as can be seen by intensive staining of endoplasmic reticulum cisternae. In contrast acetylcholinesterase activity at the capillaries presumably is of neuronal origin. Local neurons appear to secrete this enzyme, which then reaches the endothelial basal lamina via the extracellular spaces. From these cytochemical observations it is concluded that pinocytotic traffic in brain endothelial cells is predominantly from the brain tissue side to the luminal side.

The biochemical and morphological response of hydrolytic enzymes in the developing brain to hypocholesterolemic agents

Administration of hypocholesterolemic agents to developing rats has been found to selectively induce brain hydrolases. Certain regimes also caused an appreciable increase in total brain protein content. The hypocholesterolemic agents AY-9944 and zuclomiphene were tested individually and in combination. A fourth type of treatment utilized the above drugs in combination with Triparanol. Whenever AY-9944 was used, singly or in combination with other compounds, the beta-glucuronidase activity of developing brain was increased. Acid phosphatase and total brain protein were increased in animals treated with AY-9944 plus zuclomiphene or AY-9944 plus zuclomiphene and Triparanol. Neither AY-9944 nor zuclomiphene alone significantly affected brain total protein or acid phosphatase. Electron microscopic examination of tissue specifically reacted for acid phsophatase demonstrated that the increased enzyme activity was localized in cells in the perivascular spaces. Alkaline phosphatase and N-acetyl-beta-glucosaminidase, two other hydrolytic enzymes assayed, seemed to be much less influenced by the drug treatments.

Enzyme histochemistry of the rat hippocampus during experimental status epilepticus

EEG registered hippocampal status epilepticus (HSE) was provoked in 41 adult albino rats by intraseptal injection of ouabain, and the hippocampus was studied from 1 1/2 to 24 hr with the enzyme histochemical tests for succinic dehydrogenase (SDH), lactic dehydrogenase (LDH), thiaminopyrophosphatase (TPPase), acid phosphatase (AcPase), Mg2+ adenosine triphosphatase (Mg2++ ATPase), and with general and neurohistological stains. In a first group of animals (1 1/2 to 10 hr of HSE), a stage of general increase in enzymatic activity was detected in the pyramidal neurons (SDH, LDH, AcPase, and TPPase). Mg2+ ATPase showed a marked increase in astrocytes. In a second group (more than 10 hr of HSE), SDH was found decreased in the dendritic fields. LDH activity persisted in neuronal bodies, and AcPase and TPPase showed diffuse activity in the cytoplasm of some pyramidal neurons. In a third group (more than 18 hr of HSE), SDH activity was low. No AcPase granules were observed in some pyramidal neurons and TPPase was negative in some areas of pyramidal layer. Mg2+ ATPase reaction showed scare and retracted astroglial processes. These changes were coincident with "cellular ghosts" observed with hematoxylin-eosin techniques of the same samples in the pyramidal field and were interpreted as cellular death, attributed to relative anoxia following neuronal discharge.