Academic journal article Alcoholism and Psychiatry Research

Serum Concentration of N-Acetyl-[Beta]-D-Glucosaminidase in Alcohol Addicts

Academic journal article Alcoholism and Psychiatry Research

Serum Concentration of N-Acetyl-[Beta]-D-Glucosaminidase in Alcohol Addicts

Article excerpt


One of the priorities in medical research, as well as in mental disorders' research, is the identification of biological markers. Alcohol dependence is a complex condition and very often, when we try to diagnose it, we are faced with certain difficulties despite our experience and available diagnostic methods. In order to make an objective diagnosis, markers which would be characteristic of certain entities are tried to be identified. A trait marker represents the characteristics of pathophysiological processes which precede the clinical expression of the disorder, and possibly causes the disorder itself. It is also specific to certain conditions even without a clinical picture. In contrast, a state marker reflects a clinically manifested cluster of symptoms and signs. 1,2

Extensive alcohol consumption impairs liver cells, which leads to cell enzyme liberation. Besides this, alcohol causes the microsomal enzyme induction, which leads to the increase in the catalytic concentration of membrane-associated enzymes in serums. This is why defining these enzymes' catalytic concentrations (aminotransferase, gamma - glutamyltransferase, glutamate dehydrogenase, monoaminoxidase) is one of the indicators of alcoholism.3-5

N-acetyl-β-D-glucosaminidase (NAGA) is a lysosome hydrolase that can be found in low catalytic concentrations in healthy people's serum.6 It is composed of a group of glycoprotein isoenzymes which are divided into two main forms based on the difference in the molecular charge: NAGA-A and NAGA-B, and a few additional forms (NAGA-S, NAGA-P, NAGA-Il, NAGA-12).7

Isoenzymes NAGA-A and NAGA-B can be found in tissues and serum. They are made of a and β subunits: NAGA-A consists of an a and a β subunit, while NAGA-B of two β subunits. NAGA' s metabolism was examined in vitro and in vivo in rats. It was found that the tissue forms of NAGA-A and NAGA-B are eliminated quickly from the circulation (t V2 < 2 min). In contrast, serum forms of NAGA-A, NAGA-B and NAGA-P are eliminated much more slowly (t V2 = 2-4 hours).8

It was determined that on the surface of endothelium and mononuclear macrophages there are glycoprotein receptors which mediate the entrance of lysosome enzyme tissue forms into the endothelium cells, recognizing the terminal residue of oligosaccharide chains which end in mannose or N-acetylglucosamine. This is how tissue forms are eliminated from the circulation, mainly through liver and spleen.

The increase of the catalytic concentration of serum NAGA occurs secondarily due to a disarranged entrance (increased synthesis or release from tissue) and/or the enzymes' exit from the circulation. The increased catalytic NAGA concentrations in alcohol addicts, pregnant women and patients suffering from liver diseases can be attributed primarily to the growth of catalytic concentrations of NAGA-P isoenzymes. It is probably a consequence of increased synthesis of the β -subunit which dimerizes into the NAGA-P form. Macrophages are considered to be the cell source of the increased NAGA-P synthesis.9,10

Alcohol causes the function depression of the reticuloendothelial system of liver, decreasing in this manner the elimination of lysosome enzymes. So, the main cause of the catalytic concentration change is thought to be liver dysfunction induced by alcohol, and not the direct alcohol activity. Measuring the catalytic NAGA concentrations maintains the function of non-parenchymal liver cells because they are responsible for the eHmination of NAGA from plasma. 1 1 Considering the fact that data from the literature consider N-acetyl-ß-D-glucosaminidase to be one of the indicators of excessive alcohol intake, the aim of the present paper was to determine the catalytic concentration of enzymes in the subjects' serum and to examine its value as a marker for alcoholism.12


The research was conducted as a retrospective study. It included three groups of subjects. …

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