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E Mezey

Publications and source records attributed to E Mezey.

At least 145 records · Page 8Linked to original sources
PubMed1989

Phenylethanolamine N-methyltransferase-containing neurons in the limbic system of the young rat.

Fifteen years ago epinephrine cells were shown to be present in the medulla oblongata of the rat. These cell groups (C1 and C2) were thought to supply the epinephrine innervation in the rest of the central nervous system. In this study I demonstrate the presence of epinephrine-producing neurons in the forebrain of the young rat. Neurons that are immunopositive for phenylethanolamine N-methyltransferase (S-adenosyl-L-methionine:phenylethanolamine N-methyltransferase, EC 2.1.1.29) are present in the central nucleus of the amygdala as well as in the bed nucleus of the stria terminalis. Neurons in the same location are also immunopositive for tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine, tetrahydrobiopterine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2]. The phenylethanolamine N-methyltransferase immunopositivity disappears by day 35, while a small amount of tyrosine hydroxylase-positive cells still can be found in the adult. In situ hybridization reveals tyrosine hydroxylase mRNA in the above nuclei in both young and adult animals. The number of the positive cells decreases in adulthood. RNA blot-hybridization analysis showed the presence of phenylethanolamine N-methyltransferase mRNA in the amygdala and the bed nucleus of the stria terminalis in the young and in the adult rat brain. Neurons that are immunopositive for phenylethanolamine N-methyltransferase are also present in the human amygdala.

Aging↗
PubMed1989

More rapid elimination of alcohol in women as compared to their male siblings.

Sex differences in rates of ethanol elimination were investigated in natural siblings to reduce genetic variability as compared to subjects chosen at random. Ethanol was infused intravenously in a dose of 0.6 g/kg of body weight over 45 to 60 min and serial blood samples obtained for 5 hr. The mean rate of ethanol elimination was higher in seven women, not different in one, and lower in one compared with their male siblings. The mean rate of ethanol elimination for all nine women was higher at 1.93 +/- 0.12 as compared with the value of 1.69 +/- 0.17 mmoles/kg body weight/hr in the men (p less than 0.05). Higher rates of ethanol metabolism in women as compared to men may be important in the increased susceptibility of women to liver injury caused by alcohol consumption.

Acetates↗
PubMed1988

Influence of epinephrine on alcohol dehydrogenase activity in rat hepatocyte culture.

The effects of epinephrine on alcohol dehydrogenase activity and on rates of ethanol elimination were determined in rat hepatocyte culture. Continuous exposure of the hepatocytes to epinephrine (10 microM) in combination with dexamethasone (0.1 microM) enhanced alcohol dehydrogenase activity on days 4-7 of culture, whereas neither hormone alone had an effect. The increased alcohol dehydrogenase activity was associated with an increased rate of ethanol elimination. Acute addition of 10 microM epinephrine to hepatocytes maintained in culture with 0.1 microM dexamethasone did not change alcohol dehydrogenase activity, but resulted in an immediate marked, but transitory, increase in ethanol elimination within the first 5 min after the addition of the hormone. Prazosin, an alpha 1-adrenergic blocker, and antimycin, an inhibitor of mitochondrial respiration, were powerful inhibitors of the transient increase in ethanol elimination, whereas 4-methylpyrazole was only partially inhibitory. These observations indicate that epinephrine has a chronic effect in increasing alcohol dehydrogenase activity and ethanol elimination and, also, an acute transient effect of increasing ethanol elimination which is not limited by alcohol dehydrogenase activity.

Alcohol Dehydrogenase↗
PubMed1988

Galanin coexists with vasopressin in the normal rat hypothalamus and galanin's synthesis is increased in the Brattleboro (diabetes insipidus) rat.

Galanin is a peptide containing 29 amino acid residues, that is present in the median eminence, in the magnocellular neurons of the supraoptic (SON) and paraventricular nuclei (PVN) of the rat hypothalamus and in the posterior pituitary. We report here that: (1) immunoreactivity for galanin (GAL) and vasopressin coexist in the SON of normal rats, (2) levels of mRNA encoding preprogalanin are markedly elevated in the PVN and SON of Brattleboro (diabetes insipidus) rats, as determined by in situ hybridization histochemistry but (3) levels of GAL-like immunoreactivity (GAL-LI) are significantly reduced in the posterior pituitary of these rats, as determined by radioimmunoassay. We suggest that production and possibly secretion of the peptide GAL may be increased in the Brattleboro rat.

Animals↗
PubMed1988

Characteristics of alcohol dehydrogenase in fat-storing (Ito) cells of rat liver.

Fat storing (Ito) cells, located in the perisinusoidal spaces of the liver and the main storage site of vitamin A, have been associated with fibrogenesis. The mechanisms of alcoholic liver disease, although mostly unknown, do involve ethanol metabolism. This study examined the ability of fat-storing cells to metabolize ethanol. Alcohol dehydrogenase activity was detected in fat-storing cells of the rat liver. The enzyme was demonstrated also by enzyme-linked immunosorbent assay and immunohistochemical staining. The enzyme in fat-storing cells is similar to the hepatocyte enzyme in its Michaelis-Menten constants for substrates and coenzymes and in the competitive inhibition by ethanol of retinol oxidation. It differs from the hepatocyte enzyme by its greater susceptibility to inhibition by 4-methylpyrazole and by having a single isoelectric point of 9.5 as compared with multiple isoelectric points in the hepatocyte ranging from 6.9 to 8.8. The ability of the fat-storing cell to oxidize ethanol and the inhibitory effect of ethanol on retinol oxidation may be important in the pathogenesis of alcoholic liver disease.

Alcohol Dehydrogenase↗
PubMed1988

Alcohol and dietary intake in the development of chronic pancreatitis and liver disease in alcoholism.

Alcohol and dietary intake were determined in alcoholic patients with chronic pancreatitis and alcoholic liver disease. Patients with chronic pancreatitis, alcoholic hepatitis, and cirrhosis ingested approximately 50% of their calories as alcohol, and all had low mean intakes of protein, carbohydrate, and fat as compared with control subjects. Patients with severe alcoholic hepatitis had the lowest intake of nonalcohol calories and protein. Women with chronic pancreatitis had ingested alcohol for a shorter period of time than men whereas women with alcoholic hepatitis and cirrhosis had ingested less alcohol per kilogram body weight per day as compared with men. This study does not support the hypothesis that consumption of a high-protein and high-fat diet is a factor in the development of chronic pancreatitis in the alcoholic patient. The increased susceptibility of women as compared with men to alcoholic liver disease is established.

Alcohol Drinking↗
PubMed1988

Detection and localization of immunoreactive alcohol dehydrogenase protein in the rat testis.

Alcohol dehydrogenase in the testis metabolizes ethanol and a variety of physiological substrates such as dihydrotestosterone and vitamin A. Studies of the localization of enzyme activity in the testis have revealed its presence in either interstitial cells or seminiferous tubules alone or in both places. The purpose of this study was to detect and localize immunoreactive alcohol dehydrogenase in the testis. The testis enzyme had similar antigenicity than the liver enzyme as demonstrated by double immunodiffusion and inhibition titration using antibody to the liver enzyme. The concentration of immunoreactive enzyme protein was 1.7 +/- 0.1 micrograms/mg of cytosol protein in the testis as compared with 9.3 +/- 0.3 micrograms/mg of cytosol protein in the liver. Isoelectric focusing revealed eight isoenzyme bands. Only the three bands with the highest isoelectric points precipitated with antibody to liver alcohol dehydrogenase. By immunohistochemistry using this antibody, the enzyme was localized principally to the Leydig cells which are also the site of steroidogenesis. The presence in the seminiferous tubules of isoenzymes of lower isoelectric point, which do not react with the antibody to the liver enzyme, can not be excluded.

Alcohol Dehydrogenase↗
PubMed1988

Changes in erythrocyte enzyme activities during erythrocyte aging in alcoholism.

Aldehyde dehydrogenase, glucose-6-phosphate dehydrogenase, and pyruvate kinase activities were determined in erythrocytes of various ages, separated by Percoll gradient centrifugation, in 13 alcoholic patients and eight control subjects. The total erythrocyte activities of all three enzymes were not affected by alcoholism, however, the youngest cells of alcoholics had a decreased aldehyde dehydrogenase activity, while both glucose-6-phosphate dehydrogenase and pyruvate kinase activities were increased. The depression of aldehyde dehydrogenase activity not only persisted, but became more marked after 2 weeks of abstinence, while the enhanced activities of the two other enzymes returned to normal. These observations suggest that chronic alcohol ingestion suppresses aldehyde dehydrogenase in the bone marrow, while it enhances other erythrocytic enzymes.

Adult↗
PubMed1987

Pro-opiomelanocortin-derived peptides (ACTH/beta-endorphin/alpha-MSH) in brainstem baroreceptor areas of the rat.

Relatively high concentrations of adrenocorticotropic hormone (ACTH), beta-endorphin and alpha-melanocyte-stimulating hormone (alpha-MSH) were determined by radioimmunoassay in the nucleus of the solitary tract (NTS) of rats. Dense networks of immunoreactive fibers for these peptides were most prominent in the commissural part of the nucleus, where immunostained perikarya (8-15 per section) were also seen in colchicine-treated rats. Moderate peptide levels and moderately dense immunoreactive networks of these peptides were found in the lateral reticular nucleus (including the A1 and A5-C1 catecholaminergic cell groups) and the nucleus ambiguus. Ten different types of surgical lesions or transections were performed in the hypothalamus and the lower brainstem to determine the origin of ACTH, beta-endorphin and alpha-MSH in the brainstem baroreceptor centers. Except the commissural part of the NTS, the baroreceptor areas receive ACTH, beta-endorphin and alpha-MSH innervations from both the hypothalamic arcuate cells and local neurons in the NTS. Fibers in the commissural part of the NTS seem to be of local origin. Hypothalamic fibers to the rostral part of the NTS and the vasomotor A5-C1 cell groups descend in both a medial (through the periaqueductal central gray) and a lateral (ventrolateral tegmental fibers) pathway, whereas fibers to the caudal lateral reticular nucleus (A1 cell group) and the nucleus ambiguus may run only in the lateral pathway. The descending fibers may decussate somewhere in the caudal hypothalamus-rostral midbrain, but caudal to that level they run and terminate ipsilaterally. Fibers from the ACTH-, beta-endorphin- and alpha-MSH-containing cells in the NTS form a bundle arching between the NTS and the ventrolateral medulla and partially (40-55%) innervate the vasomotor and the vasodepressor areas, as well as the nucleus ambiguus.

Adrenocorticotropic Hormone↗
PubMed1987

Characterization of human erythrocyte aldehyde dehydrogenase.

Human erythrocyte aldehyde dehydrogenase was purified to homogeneity. The enzyme exhibited a single band of activity on starch gel electrophoresis and on isoelectric focusing. It was a tetramer with an estimated molecular weight of 230,000 daltons and an isoelectric point of 5.0. Its pH optimum of 8.5, Michaelis-Menten constant for acetaldehyde of 46 microM, and high sensitivity to noncompetitive inhibition by disulfiram resembled human liver cytosolic aldehyde dehydrogenase. Low concentrations of magnesium (5-10 microM) resulted in enhancement of erythrocyte aldehyde dehydrogenase activity, whereas higher physiological concentrations of magnesium resulted in uncompetitive inhibition of enzyme activity. Magnesium inhibited the enzyme activity by increasing the binding of NADH to the enzyme as had been found to be the case for the inhibitory effect of magnesium on the human liver cytosolic enzyme. Erythrocyte aldehyde dehydrogenase may metabolize small amounts of acetaldehyde escaping the liver during ethanol metabolism and protect extrahepatic tissues from acetaldehyde toxicity.

Acetaldehyde↗
PubMed1987

Pyridoxine deficiency and ethanol-induced liver injury.

It has been suggested that pyridoxine deficiency may potentiate ethanol-induced liver injury. Our purpose was to clarify the effect of pyridoxine deficiency on ethanol-associated liver injury by comparing liver histology, serum liver enzymes, and the viability of cultured hepatocytes from pyridoxine-deficient and pyridoxine-sufficient rats that had been chronically fed ethanol-enriched diets. Our data fail to substantiate that pyridoxine-deficient animals are more susceptible to the hepatotoxic effects of ethanol than pair-fed pyridoxine-sufficient controls. Furthermore, the addition of pyridoxine to hepatocyte cultures fails to prevent in vitro cytotoxicity of added ethanol. Pyridoxine deficiency may augment ethanol-induced enhancement of hepatic urea synthesis. These data suggest that pyridoxine deficiency may contribute to the abnormal plasma amino acid profiles and nitrogen balance of chronic alcoholics, but that it does not potentiate ethanol-induced liver injury.

Animals↗
PubMed1987

Dexamethasone inhibits corticotropin-releasing factor gene expression in the rat paraventricular nucleus.

The effect of glucocorticoids on corticotropin-releasing factor (CRF) gene expression was studied by combination of in situ hybridization histochemistry and steroid implantation. Dexamethasone micropellets, implanted around the hypothalamic paraventricular nucleus (PVN), caused total inhibition of the hybridizable CRF mRNA signal above the parvocellular neurons of the PVN. Unilateral implantation of dexamethasone around the PVN resulted in a decrease of hybridizable CRF mRNA at the dexamethasone-implanted side. Dexamethasone implants into the cerebral cortex, dorsal hippocampus, ventral subiculum, lateral septum or amygdala were without any effect on the CRF expression in the PVN. Corticosterone did not result in any significant change in CRF mRNA, when implanted into the paraventricular region, dorsal hippocampus or ventral subiculum. When it was placed into the amygdala however, in a few cases it slightly inhibited the CRF mRNA levels in the ipsilateral PVN.

Adrenalectomy↗
PubMed1987

Tyrosine hydroxylase mRNA is increased by hyperosmotic stimuli in the paraventricular and supraoptic nuclei.

In situ hybridization histochemistry was used to locate cells containing tyrosine hydroxylase (TH) mRNA in the hypothalami of salt-loaded and Brattleboro rats. The hyperosmotic plasma conditions found in these animals, as compared to control animals, was associated with an increase in detectable TH mRNA-producing cells in the paraventricular and supraoptic nuclei. These results suggest that dopamine synthesized by neurons of those nuclei may participate in the regulation of neuropeptide synthesis and release within the nuclei and the posterior pituitary.

Animals↗
PubMed1986

Quantitative in situ hybridization histochemistry reveals increased levels of corticotropin-releasing factor mRNA after adrenalectomy in rats.

A 35S-labeled 48-base synthetic oligonucleotide complementary to a portion of the rat corticotropin-releasing factor (CRF) mRNA was used for in situ hybridization histochemistry. CRF-synthesizing cells were located in the paraventricular nucleus of the hypothalamus. These cells were observed in the medial parvocellular subdivision where there was a 90% increase in the amount of CRF mRNA per unit volume after adrenalectomy.

Adrenalectomy↗
PubMed1986

Innervation of the nucleus of the solitary tract and the dorsal vagal nucleus by thyrotropin-releasing hormone-containing raphe neurons.

The nucleus of the solitary tract and the dorsal vagal nucleus are richly innervated by thyrotropin-releasing hormone (TRH)-containing fibers arising from the caudal raphe nuclei. After transection of vertically oriented fibers by a horizontal knife-cut in the medulla oblongata, TRH-staining disappeared from the vagal nuclei while it increased in transected nerve fibers ventral to the knife-cut. TRH-containing cells are mainly located in the nucleus raphe pallidus and raphe obscurus. TRH-containing fibers run dorsally within the raphe and enter the dorsal vagal complex at its rostral tip. Then they turn caudally and send branches laterally. Immediately caudal to the level of the obex, several TRH-containing fibers cross over the central canal. Cells in regions other than the raphe (hypothalamus or other rostral areas, ventrolateral medulla, cranial nerves) must contribute little to the TRH innervation of the nucleus of the solitary tract and dorsal vagal nucleus, since various knife-cuts transecting all above possible connections did not alter the TRH innervation pattern or TRH concentrations of these vagal nuclei.

Animals↗
PubMed1986

Depression of alcohol dehydrogenase activity in rat hepatocyte culture by dihydrotestosterone.

Hepatocytes harvested from castrated rats retained a higher alcohol dehydrogenase (EC 1.1.1.1) activity than hepatocytes harvested from normal rats during 7 days of culture. Dihydrotestosterone (1 microM) decreased the enzyme activity, after 2 and 5 days of culture, in hepatocytes from castrated and control animals respectively. Dihydrotestosterone decreased the enzyme activity to similar values in both groups of hepatocytes by the end of 7 days of culture. Testosterone (1 microM) had no effect on the enzyme activity in normal hepatocytes and only a transitory effect in decreasing the enzyme activity in hepatocytes from castrated animals. The increases in alcohol dehydrogenase activity after castration and their suppression by dihydrotestosterone were associated with parallel changes in the rate of ethanol elimination. Additions of substrates of the malate-aspartate shuttle or dinitrophenol did not modify ethanol elimination. These observations indicate that dihydrotestosterone has a direct suppressant effect on hepatocyte alcohol dehydrogenase and that the enzyme activity is a major determinant of the rate of ethanol elimination.

Alcohol Dehydrogenase↗