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[Study of the intracerebral connections after intracortical administration of glutamate]
Abstract:
Various microdoses of monosubstituted sodium L-glutamate (MSG) were injected into zone AI of the cat cerebral acoustic cortex. In 2 h--14 days, it was stated light optically that the place of injection was slightly stained, and most of neurons failed to stain. At the place of MSG injection, electron microscopic investigation revealed neurons with various degree of pathologic changes up to the lethal ones. Astroglia was edematous, oligodendrocytes and pericytes had normal appearance. In field 4 and in zone AII of the acoustic cortex, separate neural cells with sharply increasing number of ribosomes and polysomes were noted. Anterograde axonal degeneration in the lesioned neurons and their terminals was revealed in frontal sections impregnated after Wiitanen. In the cortical field 7, in zones AII, AIV, Ep of the acoustic cortex, in the head of the nucleus caudatus and in the internal geniculate body, terminal boutons degenerating after the dark type and at the same time as after surgical extirpation of zone AI were revealed. Owing to the fact that the lesions are of local character and the trauma is small, it is possible to use neuronal glutamate-induced degeneration as a method for investigating intracerebral connections.
Insights
Monosodium L-glutamate (MSG) injections in the cat auditory cortex caused localized neuronal damage. This glutamate-induced degeneration offers a precise method for mapping brain connections.
Area of Science:
- Neuroscience
- Cell Biology
Context:
- Investigating the effects of monosodium L-glutamate (MSG) on neuronal structures within the cat's cerebral acoustic cortex.
- Utilizing microdoses of MSG to induce localized neuronal degeneration for experimental purposes.
Purpose:
- To evaluate the pathological changes in neurons and surrounding glial cells following MSG injection.
- To identify and trace degenerating neuronal pathways originating from the injection site.
- To establish MSG-induced neuronal degeneration as a viable method for studying intracerebral connections.
Summary:
- Microinjections of monosodium L-glutamate (MSG) into the AI zone of the cat's auditory cortex resulted in localized neuronal damage, observed through light and electron microscopy.
- Pathological changes ranged from mild to lethal, with affected neurons showing increased ribosomes and polysomes, while surrounding glia (astroglia, oligodendrocytes, pericytes) exhibited varying states.
- Anterograde axonal degeneration was identified in lesioned neurons and their terminals, with degenerating boutons observed in various cortical fields and subcortical structures, mirroring effects of surgical ablation.
Impact:
- Demonstrates the potential of using precisely induced neuronal glutamate-induced degeneration as a novel and minimally invasive technique for mapping complex intracerebral neural circuits.
- Provides insights into the cellular and structural consequences of excitotoxicity in specific brain regions.
- Offers a valuable tool for neuroscientists studying brain connectivity and neuronal pathways.