Changes in glutamine synthetase activity and glutamate uptake in hippocampus and frontal cerebral cortex in portal hypertensive rats.

GB ACOSTA; MA FERNANDEZ; DM ROSELLO; ML TOMARO; K BALLESTRESE; A LEMBERG

World Journal of Gastroenterology

The WJG Press

Lugar: Beijing, China; Año: 2009 vol. 15 p. 2893 - 2899

1007-9327

AIM: To study the activity of the enzyme glutamine synthetase and the glutamate uptake in two brain areas: hippocampus (Hic) and frontal cortex (FC) extracted from prehepatic portal vein of hypertensive rat model. METHODS: Male Wistar rats were divided in two groups (G): G1: sham operated rats and G2: portal hypertensive rats (PH) with a reglated stricture of the portal vein. Animals were sacrificed by decapitation the fourteen day after portal vein stricture.  Glutamine synthetase activity was determinated in Hic and FC. Specific uptake of radiolabeled L-glutamate was studied using synaptosomes-enriched fractions freshly prepared from both brain areas. RESULTS: We observed that the activity of glutamine synthetase increased in Hic, as compared to operated animals, and decreased in the FC. A significant decreased in the glutamate uptake was found in both brain areas, more marked in the hippocampal area. The decrement in glutamate uptake might be due to a deficient transport function, significantly and persistent increase in this excitatory neurotransmitter activity.   CONCLUSION: The presence of moderate ammonia blood levels may add its toxicity to excitotoxic glutamate in the brain, producing alterations to brain functions. Interesting, the portal vein stricture producing portal hypertension with normal levels, is capable to modify the normal function in some brain regions.