Neonatal monosodium glutamate treatment modifies glutamic acid decarboxylase activity during rat brain postnatal development.
Monosodium glutamate (MSG) produces neurodegeneration in several brain regions when it is administered to neonatal rats. From an early embryonic age to adulthood, GABA neurons appear to have functional glutamatergic receptors, which could convert them in an important target for excitotoxic neurodegeneration. Changes in the activity of the GABA synthesizing enzyme, glutamic acid decarboxylase (GAD), have been shown after different neuronal insults. Therefore, this work evaluates the effect of neonatal MSG treatment on GAD activity and kinetics in the cerebral cortex, striatum, hippocampus and cerebellum of the rat brain during postnatal development. Neonatal MSG treatment decreased GAD activity in the cerebral cortex at 21 and 60 postnatal days (PD), mainly due to a reduction in the enzyme affinity (K(m)). In striatum, the GAD activity and the enzyme maximum velocity (V(max)) were increased at PD 60 after neonatal MSG treatment. Finally, in the hippocampus and cerebellum, the GAD activity and V(max) were increased, but the K(m) was found to be lower in the experimental group. The results could be related to compensatory mechanisms from the surviving GABAergic neurons, and suggest a putative adjustment in the GAD isoform expression throughout the development of the postnatal brain, since this enzyme is regulated by the synaptic activity under physiological and/or pathophysiological conditions.
Ureña-Guerrero
Mónica Elisa
ME
Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Jalisco, Mexico.
López-Pérez
Silvia Josefina
SJ
Beas-Zárate
Carlos
C
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D001921:Brain / Q000201:enzymology* / Q000254:growth & development*; D002531:Cerebellum / Q000201:enzymology / Q000254:growth & development; D005260:Female; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D006624:Hippocampus / Q000201:enzymology / Q000254:growth & development; D007700:Kinetics; D017072:Neostriatum / Q000201:enzymology / Q000254:growth & development; D009929:Organ Size / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D012970:Sodium Glutamate / Q000633:toxicity*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; D012970:Sodium Glutamate