Metabolite Levels in Brain Following Experimental Seizures: The Effects of Maximal Electroshock and Phenytoin in Cerebellar Layers

Abstract

Abstract— The effects of maximal electroshock (MES) and phenytoin on metabolites and cyclic nucleotides in layers of frozen‐dried cerebellum have been investigated. The four layers (molecular, Purkinje‐cell rich, granular and white matter) had remarkably homogeneous distributions of P‐creatine, ATP, glucose, glycogen, lactate, GABA and the cyclic nucleotides. MES caused dramatic decreases in P‐creatine, ATP, and glucose at 10 s after treatment, followed by a decrease in glycogen at 30 s. Lactate levels were elevated, and GABA was unchanged. Cyclic AMP concentrations were increased at 10s and cyclic GMP at 30 s. Phenytoin modified most of the MES induced changes in all the layers, although white matter was less affected by MES and/or phenytoin. Lactate concentrations were increased by MES and these effects were not altered when phenytoin was administered. The most dramatic effects of phenytoin were on the changes in cyclic nucleotides. Cyclic AMP concentrations were elevated after MES but the values returned to normal more rapidly when phenytoin was present. The drug almost obliterated the MES induced changes in cyclic GMP. The possible relationship of cyclic nucleotide concentrations and the modulation of seizure activity is discussed.

Sparing of metabolic stress in Purkinje cells after maximal electroshock

“…The minimal levels were observed 30 sec after MES, while at 10 min glucose increased to greater than normal values. The "overshoot" of glucose had been observed previously in both the cerebellum and cerebral cortex (3,5), and may be attributed to a stress-induced hyperglycemia. The increase in glucose was somewhat greater in the neuropil than in the cell bodies.…”

“…Coincidental with the tonic extension is a reduction of high-energy phosphate compounds in both the cerebellum and cerebral cortex (1-3). Analyses of freeze-dried sections have shown that the changes in energy status are not localized to any one region of the cerebellum, but are comparable in all four layers examined: molecular, Purkinje cell-rich, granular, and white (4). Similarly, the effects of seizures induced by the convulsant isoniazid were comparable in all the cerebral cortical layers examined (5).…”

“…Analyses of freeze-dried sections have shown that the changes in energy status are not localized to any one region of the cerebellum, but are comparable in all four layers examined: molecular, Purkinje cell-rich, granular, and white (4). Similarly, the effects of seizures induced by the convulsant isoniazid were comparable in all the cerebral cortical layers examined (5). The excessive stimulation of MES or of the drug-induced seizure apparently causes massive depolarization in the regions examined, resulting in an imbalance between energy production and consumption.…”

Subcellular Biochemical Investigation of Purkinje Neurons Using Synchrotron Radiation Fourier Transform Infrared Spectroscopic Imaging with a Focal Plane Array Detector

“…[16][17][18]22 Previous studies with microdissection and biochemical assay have revealed increased lactate in microdissected tissue within which Purkinje neurons were the dominant cell type, however, the Purkinje cell layer is too small to isolate without contamination from surrounding tissue (i.e., molecular and granular layer tissue). 22 Therefore, a technique capable of directly imaging the relative lactate concentration at the cellular level (<10 μm spatial resolution) would be of great benefit to this field.…”

Role for gamma-aminobutyric acid in selective vulnerability in gerbils.

“…Quantitative assessment of neuronal loss was confirmed in the pentobarbital experiments by measuring glycogen concentration in the cell body layer (i.e., stratum pyramidale) of the CA1 region. Sections of lyophilized cortex and the CA1 and CA3 cell body layers were dissected, and microquantitative analysis of glycogen content was performed on l-fxg pieces of tissue, as described by McCandless et al 24 …”