Effects of fasting and diabetes on some enzymes and transport of glutamate in cortex slices or synaptosomes from rat brain

Neurochemical Research
E GalanopoulosG Palaiologos

Abstract

Phosphate-activated glutaminase (PAG) and glutamic acid decarboxylase (GAD) were assayed in homogenates and synaptosomes obtained from starved (48 hr or 120 hr) and diabetic (streptozotocin) rat brain cortex. Glutamine synthetase (GS) was assayed in homogenates, microsomal and soluble fractions, from brain cortex of similarly treated rats. L-Glutamate uptake and exit rates were determined in cortex slices and synaptosomes under the same conditions. The specific activity (s.a.) of PAG, a glutamate producing enzyme, decreased (50%) in the homogenate after 120-hr starvation. In synaptosomes it decreased (25%) only after 48-hr starvation. The s.a. of GAD and GS, which are glutamate-consuming enzymes, were progressively increased with time of starvation, reaching 39% and 55% respectively after 120 hr. GS in the microsomes or the soluble fraction and GAD in the synaptosomes showed no change in s.a. under these conditions. Diabetes increased (40%) microsomal GS s.a. and decreased GAD s.a. (18%) in the homogenate. The L-glutamate uptake rate was decreased (48%) by diabetes in slices but no in synaptosomes. It is suggested that a) enzymes of the glutamate system respond differently in different subcellular fractions towards diabetes or ...Continue Reading

References

Jul 1, 1975·Biochemical Medicine·C Dierks-VentlingS P Bessman
Mar 25, 1977·Science·A Martinez-HernandezM D Norenberg
Feb 2, 1979·Brain Research·M D Norenberg, A Martinez-Hernandez
Jul 1, 1979·Journal of Neurochemistry·H K Ward, H F Bradford
Jun 1, 1978·Journal of Neurochemistry·H F BradfordA J Thomas
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Mar 1, 1983·Journal of Neurochemistry·H K WardH F Bradford
Jun 11, 1984·FEBS Letters·M B TroegerM Erecińska

Citations

Mar 26, 2010·International Journal of Diabetes in Developing Countries·Nayeemunnisa Ahmed, Suraiya Tarannum
Jan 1, 1991·Neurochemical Research·V LellosG Palaiologos
Apr 29, 2010·Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism·Helle M SickmannStephan D Bouman
Oct 2, 2015·Aging and Disease·João M N Duarte
Aug 28, 2016·Chemico-biological Interactions·Nadia M S ArafaSara Abdullah Mubarak AlAzimi
Jul 12, 2017·Neural Plasticity·Jens Velde AndersenHelle S Waagepetersen
Apr 29, 2014·Metabolic Brain Disease·Helle M Sickmann, Helle S Waagepetersen

Related Concepts

Metazoa
Insula of Reil
Streptozotocin Diabetes
Fasting
Glutamate Decarboxylase
Glutamic Acids
Phosphate-Activated Glutaminase
Glutamate-Ammonia Ligase
August Rats
Synaptosomes

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