A Kinetic Study of the Neuron-Glia Relationship

Abstract

Kinetic studies have been performed on the activity of the succinate oxidizing enzyme complex in living nerve cells and glial cells after increasing duration of stimulation. The nerve cells and glia of the lateral vestibular nucleus were used. The results show a clear difference between the neuron and its surrounding glia. The nerve cell reacted by highly increasing the capacity of the electron transporting system, reflecting an increased consumption of energy as a function of the stimulation. The glia, in contrast, did not change in this respect.Qualitative as well as quantitative biochemical differences have been shown to exist between the neuron and the glia immediately surrounding the neuron (1, 24). Differences were found even down to the base composition of RNA in the two types of cells (3). Physiological stimulation of the vestibular nerve was found to be followed by a significant increase of the amount of RNA, protein, and certain enzyme activities in the neuron. Inverse changes were found in the glia.The following investigation is a kinetic study of the behaviour of an enzyme reaction and its temperature dependence in the neuron and neighbouring glia, as a function of increased physiological stimulation.The comparison between the reactions in the neuron and in the glia could be made on a dry weight basis. Therefore, it was possible to study differences in energy requirement as the functional demand on the vestibular organ was changed. The activity of the succinate oxidizing enzyme complex (here called succinoxidase) was chosen because of the unique position of succinate in the Krebs cycle with direct transfer of electrons to the cytochrome system of the respiratory chain. MATERIAL AND EXPERIMENTALCONDITIONS 87 white rabbits weighing 1.6 to 1.8 kg were used. The vestibular nerve was stimulated by rotating the animal through 120 ° horizontally and 30 ° vertically with 30 turns per minute and for 25 minutes per day for 1 to 7 days. The animal was placed in a tightfitting box with the head away from the centre. Vestibular tests were used to check that the peripheral organ had not been damaged. The animals were killed by bleeding and the brain rapidly removed. The large nerve cells within the lateral vestibular nucleus, the so called Deiters' nerve cells, and the neuroglia immediately surrounding each nerve cell were used for the study. The brain material was immersed in 0.25 M sucrose solution. The cells were rapidly removed by freehand dissection under a stereomicroscope at X 100 magnification as described earlier (2, 5). The nerve cells were transferred to a clean solution of sucrose and cleaned from glia. The glia cells surrounding each nerve cell were collected in a dense cluster and trimmed down to a spheroid having a volume approximately equal to that of the nerve cell. This was checked as described earlier (2). The dry weight per unit volume of the nerve cell and the glia was determined by quantitative x-ray micro-

Role of Mitochondrial Metabolism in the Control of Early Lineage Progression and Aging Phenotypes in Adult Hippocampal Neurogenesis

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Effect of Norepinephrine on Glucose Metabolism in Glioblastoma and Neuroblastoma Cells in Cell Culture

“…A metabolic relationship existing between neurons and glia was suggested originally by Hyden and Lange (2) on the basis of whole animal studies and more recently by Gilman and Nirenberg (3) on the basis of the finding that the neurotransmitter, norepinephrine, causes an increase in 3': 5'-cyclic AMP (cAMP) in rat glioblastoma cells in cell culture. These findings were substantiated by Clark and Perkins (4), who also found a rapid increase in the concentration of cAMP of epinephrine and histamine, in addition to norepinephrine, in a tumor astrocyte cell-line derived from a primary culture of a human glioblastoma multiforme.…”

Neurochemistry

“…Whole isolated neurons had no adenosinetriphosphatase activity until the membrane was broken, indicating that the enzyme is inside the cell. A study of the succinoxidase activities on six successive days after the onset of stimulation showed a progressive increase in neurons but no change, whatsoever, in the glial cells (119). The nerve cells showed an increased content of RNA in the stimulated animals and a de crease in the peri neuronal glia.…”