Effects of short-term and prolonged aerogenic hypoxia on gamma-glutamyl transpeptidase activity in the brain, liver, and biological fluids of young rats

Šťastný, F; Lisý, V.; Tomášová, H; Trojan, S

doi:10.1007/bf00964539

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…GSH has been shown to protect the liver against ischemia reperfusion injury in animal models 16, 20, 21 . Hepatic ischemia can cause elevation of serum GGT with peak blood levels within 20 and 30 hours after restoration of hepatic arterial blood flow 18, 24 . Reperfusion is associated with a surge of ROS, which may overwhelm host natural antioxidant defenses 21 .…”

Section: Discussionmentioning

confidence: 99%

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Early elevated serum gamma glutamyl transpeptidase after liver transplantation is associated with better survival

et al. 2014

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Background: Gamma glutamyl transpeptidase (GGT) is a membrane bound enzyme that plays a key role in the synthesis of the antioxidant glutathione. Epidemiological studies have linked high GGT with an increased risk of morbidity and cardiovascular mortality. In contrast, GGT is usually elevated in liver transplant recipients that experience good outcomes. Aims: To study if and how GGT is correlated with mortality following liver transplantation. Methods: We analyzed the prognostic relevance of serum GGT levels during the early and late postoperative period after liver transplantation in 522 consecutive adults. We also studied alanine aminotransferase, aspartate aminotransferase, and total bilirubin levels. Results: Early after transplantation, the peak median (interquartile range) GGT levels were significantly higher in patients who survived more than 90 days compared to non-survivors: 293 (178-464) vs. 172 (84-239) U/l, p<0.0001. In contrast, late after transplantation, GGT levels were significantly lower in patients who survived more than 5 years than those who did not ( p<0.01). The pattern of GGT levels also differed from those of alanine aminotransferase, aspartate aminotransferase, and total bilirubin early after transplantation, while these patterns were congruent late after transplantation. Kaplan-Meier survival analysis showed that early after transplantation the higher the GGT levels, the better the 90-day survival ( p<0.001). In contrast, late after transplantation, higher GGT levels were associated with a lower 5-year survival ( p<0.001). Conclusions: These paradoxical findings may be explained by the time-dependent role of GGT in glutathione metabolism. Immediate postoperative elevation of GGT may indicate a physiological systemic response while chronic elevation reflects a pathological response.

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Section: Discussionmentioning

confidence: 99%

“…It will be important to understand the relationship of serum GGT and cellular GGT in the period immediately after surgery. Besides, cumulative evidence suggests that there is a relationship between the induction and release of ROS and ischemia reperfusion injury after other types of abdominal surgery 18, 21, 24 .…”

Section: Discussionmentioning

confidence: 99%

Early elevated serum gamma glutamyl transpeptidase after liver transplantation is associated with better survival

et al. 2014

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Biochemical characteristics of γ-glutamyl transpeptidase in capillaries from entorhinohippocampal complex of quinolinate-lesioned rat brain

Šťastný

Dvořáková

Lisý

1997

Molecular and Chemical Neuropathology

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Quinolinic acid (QUIN) is an endogenous excitotoxic agonist of the N-methyl-D-aspartate (NMDA) type of glutamate receptor, which causes slowly progressing degeneration of vulnerable neurons in some brain regions. Using changes in the activity of membrane-bound gamma-glutamyl transpeptidase (GGT) as a marker of cell damage, we found a significant decrease of this enzyme activity, which was preferentially located in the ipsilateral hippocampal formation and entorhinal cortex, 4 d after the unilateral intracerebroventricular (icv) injection of 0.5 mumol QUIN. The dose of QUIN divided into two half-doses injected bilaterally led to a symmetrical decline of GGT activity in hippocampal areas. The lesion was characterized by a suppression of GGT activity in hippocampal and entorhinal capillaries, corresponding to 60 and 81% of their initial value, respectively, but no significant changes were ascertained in synaptosomal membranes. The changes in the activity of capillary GGT were associated with the decrease of apparent maximal velocity Vmaxapp, whereas apparent Michaelis constant K(m)app (0.69-0.79 mM) remained unaffected. In the nonlesioned brain, concanavalin A (Con A) affinity chromatography revealed five glycoforms of synaptosomal GGT in contrast to only one found in hippocampal and entorhinal capillaries. The results document that neither the saccharide moiety of GGT nor the value of enzyme K(m)app is significantly affected by the QUIN-induced lesion of the rat brain. However, the suppression of GGT activity, which is accompanied by a decrease in the value of Vmaxapp in brain microvessels, may suggest dysfunction of the blood-brain barrier (BBB) in the QUIN-injured rat brain.

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The effect of acute and repeated hyperammonemia on γ-glutamyl transpedtidase in homogenates and capillaries of various rat brain regions

Hilgier

Albrecht

Lisý

et al. 1990

Molecular and Chemical Neuropathology

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The effect of hyperammonemia of varying degree and duration on the gamma-glutamyl-transpeptidase (GGT) activity was studied in the homogenates and capillaries of different brain regions of the rat. "Acute" hyperammonemia (750 and 600 mg of ammonium acetate per kg b.w. were injected i.p. at 30 min interval, and the animals were decapitated immediately), in which blood ammonia was increased 14-fold, and brain ammonia six-fold above the control level, produced a 20% increase of the enzyme activity in cerebellum, and a 17% decrease in gyrus dentatus, but had no effect in the frontal cortex and the CA1 and CA3 regions of hippocampus. "Subchronic" hyperammonemia (two injections of 600 mg ammonium acetate/kg were given at 24 h intervals, and tissue samples were removed 24 h later), that was accompanied by only a 60% increase of blood or brain ammonia, increased the activity in cerebellum to 38% above control, but produced no effect in the other brain regions. "Chronic" hyperammonemia (three injections of 600 mg ammonium acetate/kg at 24 h intervals and excision of tissue samples 30 min after the last injection), in which blood and brain ammonia were, respectively, 60 and 100% higher than in control animals, elevated the GGT activity in the cerebellum by 57%, in CA1 by 15%, and in CA3 by 21%, but produced no effect in the frontal cortex or gyrus dentatus. By contrast, "chronic" hyperammonemia produced a 30% increase of GGT activity in cerebral cortical capillaries, but only a 10% increase in hippocampal capillaries, and no change in cerebellar capillaries. The results suggest that, hyperammonemia of relatively long duration may contribute to the enhancement of brain GGT activity observed in chronic forms of hepatic encephalopathy. However, ammonia does not appear to activate the enzyme directly.

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Effects of short-term and prolonged aerogenic hypoxia on gamma-glutamyl transpeptidase activity in the brain, liver, and biological fluids of young rats

Cited by 7 publications

References 19 publications

Early elevated serum gamma glutamyl transpeptidase after liver transplantation is associated with better survival

Early elevated serum gamma glutamyl transpeptidase after liver transplantation is associated with better survival

Biochemical characteristics of γ-glutamyl transpeptidase in capillaries from entorhinohippocampal complex of quinolinate-lesioned rat brain

The effect of acute and repeated hyperammonemia on γ-glutamyl transpedtidase in homogenates and capillaries of various rat brain regions

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