Enzyme Histochemistry of the Rat Hippocampus During Experimental Status Epilepticus

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Abstract
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 h with the enzyme histochemical tests for succinic dehydrogenase (SDH), lactic dehydrogenase (LDH), thiaminopyrophosphatase (TPPase), acid phosphatase (AcPase), Mg2+ ATPase, and with general and neurohistological stains. In a 1st group of animals (1 1/2 to 10 h 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 2nd group (> 10 h of HSE), SDH 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 3rd group (> 18 h of HSE), SDH activity was low. No AcPase granules were observed in some pyramidal neurons and TPPase was negative in some areas of the pyramidal layer. Mg2+ ATPase reaction showed scarce 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.