Hippocampal Neuron Density and Seizures in the Mongolian Gerbil

Abstract

Mongolian gerbils of the seizure-sensitive strain exhibit epileptic seizures in relation to changes in the environment, a characteristic which was increased to about 100% by inbreeding. The seizures vary from animal to animal but are rather stable in the individual animal, which makes it possible to study neuron densities in the hippocampus of the gerbil in relation to seizure type and seizure intensity. Five groups of gerbils with seizures ranging from minor movements and motor arrest to intense generalized convulsions were investigated with a quantitative method including cell counting by light microscope, estimation of possible brain shrinkage and determination of nucleoli and nuclei diameters. Cell densities were determined in different areas of the pyramidal cells of the hippocampus (H-fields). The study discloses a reduction of cell densities in fields H2 and H3 in relation to intense generalized convulsions. The reduction in cell density in field H2 is probably a result of seizure activity, whereas the field H3 cell loss can be the result of both the hypoxia and the seizure activity.