Topochemical Aspects of Nucleic Acid and Protein Metabolism Within the Neuron‐neuroglia Unit of the Spinal Cord Anterior Horn

Abstract

Abstract— Using a two‐wavelength modification of ultraviolet and visible cytospectro‐photometric methods, the content of nucleic acids per cell was determined in neuronal cytoplasm and glial satellite cell‐bodies from the spinal cord anterior horns in mice and rats. Mice which had been swimming for 3 and 4 h showed an increase in the content of RNA in the spinal motoneurons with no changes in the neuroglia. Stronger stimulation of the nervous system such as electrical skin irritation (20‐40 V, approx. 40 impulses/min) for 5 min resulted in an increase of RNA in the motoneurons of rat spinal cord and a decrease in the surrounding glia. Exhausting actions upon the nervous system (60 min irritation of rat paws by the electrical current, acute clonic convulsions in rats injected with cardiazol (pentamethylenetetrazol, metrazol) or initial free motor activity after 3 weeks of restraint of mice) induced a marked decrease of RNA content throughout the whole neuron‐neuroglia unit. After stimulation, return to normal amounts of RNA and protein was more rapid in glia than in neurons. After 1‐3 days rest the level of RNA was normal in motoneurons, but a decrease in glial RNA was shown. These trace changes in the glia are believed to reflect an adaptation mechanism in the nervous system at the cellular level. The relationship between neuronal and glial compartments within the neuron‐neuroglia unit is discussed; a supporting, homeostatic, secondary role of glial metabolism with respect to adequate reconstruction of neuronal metabolism is outlined.

Local Gene Expression in Axons and Nerve Endings: The Glia-Neuron Unit

“…VIIIB3). Comparable results were later obtained with different neurons and their corresponding glial cells analyzed with the same method (261). In agreement with previous data, these results suggested that an increment in neuronal RNA and protein was associated with the loss of glial RNA only if the stimulation was sufficiently intense and/or prolonged.…”

“…This early criticism appears to have been largely based on the lack of information on intercellular exchanges of materials, which is now well known to occur in eukaryotic cells, such as follicular cells and oocytes (217,238). The data supporting intercellular transport of glial RNA to the neuron soma have also been corroborated by cytospectrophotometric methods that may hardly be blamed for confusing a glial cell with a dendrite (260,261). As reviewed in this article, intercellular transport of newly synthesized RNA from periaxonal glia to the axon has been demonstrated in vertebrate (25,80,177,280) and invertebrate species (9,62,92,117,229,265), as well as between perisynaptic cells and squid nerve terminals (92,116).…”

“…85,126,260,261). True, it is surprising that randomly collected neurons of the same type displayed consistently similar biochemical changes when exposed to a certain experimental condition.…”

Topochemical aspects of nucleic‐acid and protein metabolism within the neuron‐neuroglia unit of the hypothalamic supraoptic nucleus

“…3). The latter type of reciprocal RNA change within the neuron-neuroglia unit has been occasionally seen in sympathetic ganglion (Pevzner, 1965) and spinal cord (Pevzner, 1971). Similar findings were reported in Deiters' neurons of the rabbit and their perineuronal glial capsule under effects of some neuroleptic drugs (HydBn, 1964;HydBn and Lange, 1966).…”

“…To evaluate macromolecular changes in neurons and glia, the same cytospectrophotometric methods were employed which had been applied in earlier studies on other kinds of the neuron-neuroglia unit (Pevzner, 1965(Pevzner, , 1971(Pevzner, , 1972. To determine RNA content (in all experimental series except for adrenalectomy), sections were stained with gallocyanin chrome alum (Einarson, 1951;Pearse, 1968) as modified by Berube et al (1966).…”