Increase of brain endogenous monoamine oxidase inhibitory activity (tribulin) in experimental audiogenic seizures in rats: evidence for a monoamine oxidase A inhibiting component of tribulin.

Brain tribulin activity in rats with an inherited predisposition to audiogenic epilepsy was studied after seizures of different intensity were induced by an electric bell. Weak seizures (from 0 to 2 arbitrary units) did not produce any changes in endogenous inhibitory activity towards either monoamine oxidase (MAO) A or B. Moderate seizures were characterized by increases in both MAO A and MAO B inhibitory activity (up to 1.9-fold). Complete tonic epileptiform seizures with total areflexia (4 arbitrary units) induced further augmentation (up to 2.5-fold) of MAO A but not of MAO B inhibitory activity. This dissociation between the two inhibitory activities points to the existence of a separate MAO A-inhibiting component of brain tribulin which is different from isatin.

Monoamine oxidase inhibition by novel antidepressant tetrindole.

The novel antidepressant tetrindole (2,3,3a,4,5,6-hexahydro-8-cyclohexyl-1H[3,2,1-j,k] carbazole) was found to be a selective inhibitor of monoamine oxidase A (MAO A). In vitro it inhibited rat brain mitochondrial MAO A in a competitive manner with Ki value of 0.4 microM. A 60 min preincubation did not change the competitive mode of interaction between enzyme and tetrindole (Ki value was 0.27 microM). The inhibition of rat brain mitochondrial MAO B was of mixed type with Ki value of 110 microM. Dilution or dialysis of mitochondrial suspension did not restore MAO A activity after inhibition by tetrindole both in vitro and in vivo, whereas inhibition of MAO B in vitro was completely reversible. Oral administration of tetrindole inhibited rat brain and liver mitochondrial MAO A by 80% within 0.5-1 hr and the onset of recovery of enzyme activity became evident after 24 hr. A small inhibition of MAO B (-20-30%) was observed in isolated brain and liver mitochondria within 1-6 hr and enzyme activity had completely recovered after 16 hr. The data obtained indicate that antidepressant activity of tetrindole may be explained by selective inhibition of MAO A, however an apparent discrepancy between competitive manner of MAO A inhibition in vitro and poor recovery of enzyme activity in vivo does not allow us to decide whether tetrindole is a "tight-binding" reversible inhibitor or a selective irreversible inhibitor of MAO A.

Endogenous stimulation of lipid peroxidation in brain increases proteolytic inactivation of mitochondrial monoamine oxidases.

Stimulation of lipid peroxidation in vivo (in experimental epilepsy and closed cranio-cerebral injury, as models for endogenous stimulation of lipid peroxidation) affects catalytic activity, substrate specificity of mitochondrial monoamine oxidases and increases their susceptibility to trypsinolysis. It is suggested that increased susceptibility to trypsinolysis reflects an appearance of new hydrophilic site(s) in monoamine oxidase molecules which may be responsible for an involvement of the modified enzymes in the deamination of other important nitrogenous compounds (such as gamma-aminobutyric acid) with subsequent impairment of a ratio between inhibition and excitation processes in the brain.

Enzyme transformations.

The paper briefly discusses the current theories on the processes underlying the transformation of the catalytic activity of a number of enzymes. The phenomenon of transformation, which is induced by mild chemical effects acting on a protein, is of interest both from the point of view of the investigation of its molecular mechanisms and from the point of view of the study of several pathological states under which this phenomenon is observed. Gorkin's own data are presented.

[Medico-biological aspects of biochemistry of amines and other nitrogen bases]. / Mediko-biologicheskie aspekty biokhimii aminov i drugikh azotistykh osnovanii.

The art-of-the-state and possible perspectives for studies of the properties of amine oxidases which are medically significant are briefly outlined. Due to the studies conducted at the Research Institute of Biomedical Chemistry of the Russian Academy of Medical Sciences, the authors discuss the results of studies of the following three problems: 1) modified catalytic properties of amine oxidases in experimental intoxications and abnormalities; 2) natural modulators of amine oxidases; 3) synthetic modulators of amine oxidases.

[Sorbent for purification of diamine oxidase by the method of affinity chromatography]. / Sorbent dlia ochistki diaminooksidazy metodom affinnoi khromatografii

A substrate of diamine oxidase hexamethylene diamine was covalently bound through adipinic acid dihydrazide to Sepharose 4B in order to prepare a sorbent for the purification of diamine oxidase by means of biospecific (affinity) chromatography. A method was developed to purify diamine oxidase from pig kidney cortex using the sorbent. The method, comprising three steps, yielded enzyme preparations with specific activity 2 000-fold higher than that of kidney homogenate.

[Use of bacterial luciferase for determining monoamine oxidase activity]. / Ispol'zovanie bakterial'noi liutsiferazy dlia opredeleniia monoaminooksidaznoi aktivnosti.

A bioluminescence assay is proposed for measuring monoamine oxidase activity in different biological specimens (platelets, mitochondria). The assay is based on the bioluminescent reaction catalysed by bacterial luciferase and coupled to monoamine oxidase. Two modifications of the bioluminescence assay were used. In the first case, the bioluminescent system was added to monoamine oxidase preincubated with the substrates, while in the second case, all the components of the coupled enzymatic systems were directly mixed in a cell. The proposed bioluminescence assay is simple, highly sensitive and rapid, and could be especially useful for biomedical examinations.

[Monoamine oxidase activity and effect of clorgyline on the polyamine level during hyperoxia in rats]. / Monoaminoksidaznaia aktivnost' i vliianie khlorgilina na uroven' poliaminov pri giperoksii u krys.

During hyperoxia monoamine oxidase type A acquires the ability to deaminate polyamines and histamine. A preliminary injection of clorgyline (a monoamine oxidase type A inhibitor) before hyperoxic exposure leads to a significant removal of oxygen seizures and prevents changes in the cerebral spermidine and histamine content observed in the unprotected animals. The data confirm the important role of modification of catalytic properties in monoamine oxidase in the mechanism of oxygen intoxication.

[The role of monoamine oxidase in the regulation of mitochondrial energy functions]. / Rol' monoaminoksidaz v reguliatsii énergeticheskikh funktsii mitokhondrii.

Incubation of aldehyde dehydrogenase-free mitochondrial preparations with biogenic amines serotonin, tyramine, 2-phenylethylamine and 5-methoxytryptamine resulted in inhibition of enzymes activity of both outer (rotenone-insensitive NADH-cytochrome c reductase) and inner (succinate dehydrogenase, succinate cytochrome c reductase) mitochondrial membranes. Solubilization of mitochondria after the incubation did not influence the amine-induced alteration of succinate dehydrogenase activity. Pretreatment of the organelles with a mixture containing chlorgyline and deprenyl completely inhibited monoamine oxidase (MAO) activity and prevented the effects of all the amines studied on mitochondrial enzymes. MAO-dependent effects of 5-methoxytryptamine were fully reproduced by 5-methoxyindolyl-3-acetaldehyde (one of probable products of 5-methoxytryptamine deamination). The effect of the aldehyde was not prevented by chlorgyline and deprenyl. After selective inhibition of MAO-A by chlorgyline the order of MAO-B-dependent effects of biogenic amines on mitochondrial enzymes studied was as follows: tyramine greater than or equal to 2-phenylethylamine much greater than serotonin. In deprenyl pretreated mitochondria the potency of MAO-A-dependent effects of these amines was: serotonin greater than tyramine much greater than much greater than 2-phenylethylamine. The data obtained suggest that the product(s) of oxidative deamination of biogenic amines (probably the aldehydes) catalyzed by both types of MAO (MAO-A and MAO-B) are able to regulate the energy functions of mitochondria.

[Characteristics of lipid peroxidation in alcoholic intoxication]. / Ob osobennostiakh perekisnogo okisleniia lipidov pri alkogol'noi intoksikatsii.

Content of malonic dialdehyde and dynamics of its accumulation in ascorbate-dependent lipid peroxidation (LP), content of diene conjugates, lipid hydroperoxides and lipofuscin-like pigments as well as activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathione transferase) were studied in homogenates of liver, lung, heart and kidney tissues of persons suffering from chronic alcoholism during life-time, of persons lost from acute alcohol intoxication as well as of persons not abusing with alcohol during life-time and lost from accidents (control). In chronic alcoholism the rate of ascorbate-dependent LP was distinctly increased in liver tissue as compared with controls or with acute mortal alcohol intoxication, while the rate of the patterns studied was increased in lung tissue of the latter group of patients. At the same time, increase in content of lipofuscin-like pigments and a decrease in the activity of antioxidant enzymes studied were noted.

[Oxidation of fatty-aromatic aldehydes in liver tissues]. / Ob okislenii zhirno-aromaticheskikh al'degidov v tkaniakh pecheni.

A protein fraction, which did not contain NADP [or NADPH]-dependent aldehyde reductase as well as NAD [or NADP]-dependent aldehyde dehydrogenases, but which catalyzed oxidation of fatty-aromatic aldehydes, was isolated from extract of rat liver tissue using ammonium sulfate fractionation combined with gradient syvorptive chromatography on DEAE-Sephadex A-25 [or Molselect DEAE-25], CM-Sephadex C-25 and gel-filtration on Sephadex G-200. Investigations of molecular weight and catalytic properties of the protein fraction obtained enabled to identify it with xanthine oxidase [EC 1.2.3.2]. Aldehyde dehydrogenases as well as xanthine oxidase are involved in oxidation of fatty-aromatic aldehydes to corresponding fatty acids, besides the reduction of the aldehydes to alcohols, catalyzed by aldehyde reductase and alcohol dehydrogenases.

[Biogenic amine deamination in experimental tuberculosis]. / Dezaminirovanie biogennykh aminov pri éksperimental'nom tuberkuleze.

Stimulation of lipid peroxidation /increase in content of conjugated dienes and of malone dialdehyde/, which was prevented by administration of isoniazid or sodium thiosulphate, was detected in mitochondrial fraction of liver tissue obtained from rats with tuberculosis of lungs. At the same time, in the mitochondrial fraction a significant decrease in tyramine and serotonin deamination rates and an increase in histamine, lysine and putrescine deamination rates were observed. The altered ratio of the deamination rates of the nitrogenous compounds may be prevented by administration of isoniazid and sodium thiosulphate into the animals. A hypothesis is discussed on the possible significance of qualitative alteration /transformation/ in catalytic properties of the mitochondrial monoamine oxidase induced by the stimulation of lipid peroxidation as a cause underlying the reversible impairments in ratios of rates of the nitrogenous compounds deamination in tuberculosis.

[Monoamine oxidase and adenylate deaminase activity of mitochondrial fractions of the rat liver in alcoholic intoxication]. / Monoaminoksidaznaia i adenilatdezaminaznaia aktivnost' mitokhondrialhnykh fraktsii pecheni krys pri alkogol'noí intoksikats ii

Decrease in monoamine oxidase and increase in diamine oxidase and adenylate deaminating activities were found in rat liver mitochondrial fractions after repeated injections of ethanol. A monoamine oxidase inhibitor pargyline and an inhibitor of phosphodiesterase theophylline prevented the increase in adenylate deaminating activity in a subfraction of mitochondrial membranes in the ethanol intoxicated rats. In a subfraction of soluble mitochondrial proteins pargyline did not affect but theophylline prevented completely the increase in adenylate deaminating activity. The stimulation of adenylate deaminating activity in mitochondrial fractions of rat liver in ethanol intoxication might be caused by: 1) transformation of mitochondrial monoamine oxidases (in the subfraction of mitochondrial membranes) and 2) activation (or increased biosynthesis) of the adenylate deaminase in the subfraction of soluble mitochondrial proteins. The adenylate cyclase system is probably involved in the latter process.

[Partial purification and properties of the adenylate deaminase from subfractions of soluble mitochondrial proteins of rat liver]. / Chastichnaia ochistka i svoistva adenilatdezaminazy iz subfraktsii rastvorimykh mitokhondrial'nykh belkov pecheni krys.

Isolation and partial purification of AMP-deaminase from subfraction of soluble proteins of the mitochondrial fraction from rat liver is described. The enzyme preparations obtained deaminated AMP at the highest rate from pH 6.4 to 6.6. At the optimal pH value and in presence of optimal AMP concentrations the AMP-deaminase preparation was not activated by ATP or K+ and was inhibited by inorganic phosphate. Relationship was noted between both the content of protein in the enzyme preparations and length of the interval from composing the samples to monitoring the enzymatic activity and the following parameters of the AMP-deaminase: (a) shape of curves describing the rate of AMP deamination as a function of the nucleotide concentration, (b) reversible decrease in the AMP-deaminating activity after dialysis, (c) properties to deaminate, besides AMP, also some other nucleotides (ADP, NAD, FAD), (d) dynamics of inactivation of the enzyme preparations by controlled heating. The properties of the partially purified AMP-deaminase from the subfraction of rat liver soluble mitochondrial proteins were not identical with those described previously for other AMP-deaminases.

[Characteristics of changes in amine oxidase activity during pesticide poisoning]. / Ob osobennostiakh izmenenii aktivnosti aminoksidaz pri intoksikatsii pestitsidami.

In persons professionally contacting with pesticides for a long time activity of membrane-bound monoamine oxidases (MAO) was statistically distinctly higher (about 2-fold) in blood thrombocytes, while activity of soluble amine oxidase (AO) was considerably lower (about 5-fold) in blood serum and plasma as compared with persons who did not have prolonged contact with pesticides. These data suggest that estimation of MAO activity in thrombocytes and of AO activity in blood serum may be used for hygienic evaluation of criteria involved in the conception "normal state--prepathology".

[Adenylate deaminase of the liver mitochondria in normal state and in alcoholic intoxication]. / O mitokhondrial'nykh adenillatdezaminazakh pecheni v norme i pri alkogol'noi intoksikatsii

AMP-deaminases were isolated and partially purified from subfractions of soluble mitochondrial proteins of rat liver under normal conditions and in ethanol intoxication. Repeated freezing and thawing of the mitochondrial fractions from liver of rats, which were treated with ethanol (1 ml of 32% solution daily for 7 days, intraperitoneally), liberated into the subfraction of soluble mitochondrial proteins significantly less AMP-deaminases, as compared with the control animals. The enzyme preparations obtained from intoxicated and intact animals were quite similarly inactivated by controlled heating, deaminated at similar rates AMP, ADP, FAD and some other nitrogenous compounds (but did not deaminate adenosine and some structural analogues of AMP). However, an inhibitory effect of the structural analogues of AMP and of nucleosides was significantly higher towards the AMP-deaminase from healthy rats as compared with the corresponding enzyme preparations obtained from the ethanol-treated animals. The increase in velocity of enzymatic AMP deamination in the subfraction of soluble mitochondrial proteins apparently does not represent a suitable target for possible therapeutic approaches to control the phenomenon, observed in the experimental ethanol intoxication, of stimulation of the deaminating activity in total mitochondrial fraction of rat liver.

[Normalization of impairments in deamination of nitrogen compounds in experimental hypercholesterolemia]. / O putiakh normalizatsii narushenii dezaminirovaniia azotistykh soedinenii pri éksperimental'noi giperkholesterinemii.

Appearance of cadaverine deaminating activity in mitochondrial fractions of liver and kidney of rabbits with experimental alimentary hypercholesterolaemia was prevented by an antioxant diludin (2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine) which also decreased the abnormally elevated AMP-deaminating activity and elevated the decreased monoamine oxidase activity (substrates: serotonin, benzylamine, tyramine). In heart and brain tissues as compared with liver and kidney the impairments caused by hypercholesterolaemia and the normalizing effect of diludin were less distinct. The effects of diludin could be reproduced by nucleophylic reagents sodium thiosulphate or ascorbate. The normalization of impairments in deamination of nitrogenous compounds in hypercholesterolaemia was accompanied by improvement in morpho-physiological manifestations of atherosclerosis (injury of aortal intima, alteration in heart rhythm, changes in content of cholesterol, triglycerides and lipoproteins in blood serum). The data obtained are in agreement with the hypothesis on the significance of qualitative alteration (transformation) in catalytic properties of mitochondrial monoamine oxidases in the mechanism of impairments in deamination of nitrogenous compounds in atherosclerosis.

[Mechanism of disturbances in the deamination of nitrogenous compounds in experimental hypercholesterolemia and atherosclerosis]. / O mekhanizme narushenii dezaminirovaniia azotistykh soedinenii pri éksperimental'noi giperkholesterinemii i ateroskleroze.

Experimental alimentary hypercholesterolaemia in rabbits caused not only a decrease in deamination of monoamines (serotonin, benzylamine, tyramine) in liver, brain, kidney and heart mitochondrial fractions but also an appearance in these fractions of a qualitatively new reactions, namely that of cadaverine deamination, which was occasionally accompanied by stimulation of AMP deamination. In mitochondrial fractions from liver tissue obtained by autopsy in cases of ischemic heart disease accompanied by atherosclerosis, as compared with the corresponding fractions from the liver of persons who died in accidents and in whom no distinct morphological manifestations of atherosclerosis could be noted, there was observed a decrease in deamination of serotonin or tyramine (by 52% and 63%), appearance of cadaverine deamination (Vmax constitutes 35% of the Vmax value for serotonin deamination in the same fraction (and stimulation) 2-fold) of AMP deamination. The impairments in deamination of the nitrogenous compounds in experimental hypercholesterolaemia and in atherosclerosis are apparently due to qualitative alteration (transformation) in catalytic properties of mitochondrial monoamine oxidases. Implications of this hypothesis for future research on treatment of atherosclerosis are discussed.

[Features of the biochemical action of paraquat on oxidative deamination of biogenic amines and other nitrogen compounds]. / Osobennosti biokhimicheskogo deistviia parakvata na protsessy okislitel'nogo dezaminirovaniia biogennykh aminov i drugikh azotistykh soedinenii.

Intoxication of rats with the herbicide paraquat (1,1-dimethyl-4,4-bipyridilium dichloride) was accompanied by accumulation in lungs, brain, heart, liver or kidney of malonic dialdehyde (MDA) (the compounds reacting with 2-thiobarbituric acid), indicating that the intoxication stimulated lipid peroxidation (LPO) in biomembranes. Treatment of the intoxicated rats with the antioxidant diludin (2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine) or with the nucleophilic reagents sodium ascorbate or thiosulphate normalized the content of MDA in lungs, brain, heart, liver or kidney demonstrating the reversibility of the LPO stimulation caused by paraquat. On incubation of mitochondrial fractions of homogenates of lungs, brain, heart, liver or kidney of the intoxicated rats (as compared with the corresponding fractions from the intact animals) a decrease was noted in deamination of the substrates of monoamine oxidases serotonin, tryptamine, benzylamine, tyramine; at the same time, deamination of glucosamine and gamma-aminobutyric acid was increased and deamination of putrescine and L-lysine appeared. These impairments in deamination of nitrogenous compounds caused by paraquat were reversible. All the impairments were normalized by the treatment of the experimental animals with the antioxidative and nucleophilic reagents; a decrease was noted in the rate of development of the lethal paraquat intoxication and appearance of morphological manifestations of normalization. The data obtained suggest that the reversible, qualitative modification ("transformation") of the monoamine oxidases of the type A might explain the peculiarities of the alterations in deamination of nitrogenous compounds in paraquat intoxication.

[Changes in kinetics of deaminated biogenic amines in spontaneous hypertension]. / Izmemeniia kinetiki dezaminirovaniia biogennykh aminov pri spontannoi gipertenzii.

Rate of serotonin and benzylamine deamination was increased in liver tissue of rats with spontaneous hypertension. The increase was due to elevation in Vmax value for monoamine oxidases of the A and B types as compared with the corresponding values of control animals. The Vmax value was increased in kidney of hypertensive animals for MAO of the B type (benzylamine as a substrate). At the same time, Km for MAO of the B type was increased in liver tissue, while Km for MAO of the A type was decreased in brain of hypertensive animals. Titration of the MAO active sites exhibited their increased concentration in the B type MAO in liver mitochondria of experimental animals. The data obtained suggest an important role of alterations in the MAO catalytic activity in pathogenesis of spontaneous hypertension.