Uptake and metabolism of L-(/sup 3/H)glutamate and L-(/sup 3/H)glutamine in adult rat cerebellar slices
Using very low concentrations (1 mumol range) of L-2-3-(/sup 3/H)glutamate, (/sup 3/H-Glu) or L-2-3-(/sup 3/H)glutamine (/sup 3/H-Gln), the authors have previously shown by autoradiography that these amino acids were preferentially taken up in the molecular layer of the cerebellar cortex. Furthermore, the accumulation of /sup 3/H-Glu was essentially glial in these conditions. Uptake and metabolism of either (/sup 3/H-Glu) or (/sup 3/H-Gln) were studied in adult rat cerebellar slices. Both amino acids were rapidly converted into other metabolic compounds: after seven minutes of incubation in the presence of exogenous /sup 3/H-Glu, 70% of the tissue accumulated radioactivity was found to be in compounds other than glutamate. The main metabolites were Gln (42%), alpha-ketoglutarate (25%) and GABA (1,4%). In the presence of exogenous /sup 3/H-Gln the rate of metabolism was slightly slower (50% after seven minutes of incubation) and the metabolites were also Glu (29%), alpha-ketoglutarate (15%) and GABA (5%). Using depolarizing conditions (56 mM KCl) with either exogenous /sup 3/H-Glu or /sup 3/H-Gln, the radioactivity was preferentially accumulated in glutamate compared to control. From these results we conclude: i) there are two cellular compartments for the neurotransmission-glutamate-glutamine cycle; one is glial, the other neuronal; ii) these two cellular compartments contain both Gln and Glu; iii) transmitter glutamate is always in equilibrium with the so-called ''metabolic'' pool of glutamate; iv) the regulation of the glutamate-glutamine cycle occurs at least at two different levels: the uptake of glutamate and the enzymatic activity of the neuronal glutaminase.
- Research Organization:
- Centre de Neurochimie du CNRS, Strasbourg, France
- OSTI ID:
- 6541487
- Journal Information:
- Neurochem. Res.; (United States), Vol. 8:10
- Country of Publication:
- United States
- Language:
- English
Similar Records
Developmental features of rat cerebellar neural cells cultured in a chemically defined medium
Metabolism of glutamine and glutamate in monkey lenses
Related Subjects
BRAIN
RADIOBIOLOGY
GLUTAMIC ACID
METABOLISM
GLUTAMINE
TRITIUM COMPOUNDS
UPTAKE
BIOLOGICAL PATHWAYS
ENZYME ACTIVITY
LIQUID COLUMN CHROMATOGRAPHY
MOLECULAR BIOLOGY
TRACER TECHNIQUES
AMIDES
AMINO ACIDS
BIOLOGY
BODY
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
CHROMATOGRAPHY
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
NERVOUS SYSTEM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
SEPARATION PROCESSES
550501* - Metabolism- Tracer Techniques