Changes in glutamate-related enzyme activities in the striatum of the rat following lesion of corticostriatal fibres

The behaviour of enzymes putatively involved in glutamate/aspartate transmitter metabolism (glutamate dehydrogenase, aspartate amino-transferase, alanine aminotransferase, gamma-glutamyl-transpeptidase) was studied in the striatum 3, 7, 14 days and 7 weeks after mechanical destruction of corticostriatal fibres. For a period of up to seven days after unilateral lesion, enzyme activities were significantly diminished (by up to 13% based on protein) in the ipsilateral striatum as compared to the striatum of the intact side. Later, the enzyme activities in the ipsilateral striatum recovered. After seven weeks, an increase was observed for glutamate dehydrogenase activity, whereas the activity of alanine aminotransferase showed a transient rise enzyme levels is interpreted as being attributable to the destruction of nerve endings which are considered to be glutamatergic, interfering with various compensating processes (e.g. glial cell proliferation) which occur with advancing times after lesion.     

Changes in 3β-OH-steroid dehydrogenase activity in the adrenals of rat fetuses decapitatedin utero

Activity of 3-OH-steroid dehydrogenase in the adrenal cortex of 21-day rat fetuses in the control and 3 days after decapitationin utero was estimated quantitatively by microspectrophotometry. Activity of the enzyme, calculated per conventional cell in the zona fasciculata was considerably higher than in the developing zona glomerulosa. After hypophysectomy the 3-OH-steroid dehydrogenase activity was reduced in both zones of the adrenal.Laboratory of Hormonal Regulation and Laboratory of Cytology, Institute of Developmental Biology, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1317–1320, November, 1976.     

Β-Glucuronidase activity in trained red and white skeletal muscle of mice

Summary We studied the effects of prolonged running exercise (5 days a week, 1.5 h per day at a speed of 17.6 m/min) on the activity of some acid hydrolases (-glucuronidase, -N-acetylglucosaminidase, acid phosphatase and cathepsin D) and three enzymes of energy metabolism (cytochrome c oxidase, lactate dehydrogenase and creatine kinase) in the distal and in the proximal, the predominantly white and red parts, respectively, of the vastus lateralis-muscle from mice. The acid hydrolase activity levels were 1.24–1.69 higher in untrained red muscle compared to untrained white muscle. The light training applied increased the activity of -glucuronidase in both red and white muscle. No other significant training effects were observed in the enzyme activities measured.     

An iontophoretic study of the effects of α-amino-hydroxy-5-methyl-4-isoxazole propionic acid lesions of the nucleus basalis magnocellularis on cholinergic and GABAergic influences on frontal cortex neurones of rats

Unilateral lesions of the nucleus basalis magnocellularis (NBM) produced by -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid in rats caused, 8–10 weeks after the lesion, a 94% reduction in cortical acetylcholinesterase fibres and reduced activities of acetylcholinesterase and choline acetyltransferase by 70–80% in the frontal cortex ipsilateral to the lesion. In anaesthetized unlesioned control rats, iontophoretic administration of acetylcholine and carbachol produced atropine-sensitive inhibition and excitation of frontal cortical neurones, effects similar to those produced by electrically stimulating the NBM. The lesion reduced cortical neuronal firing rates but increased the percentage and sensitivity of neurones responding to acetylcholine, the predominant response changing from inhibition to excitation; response duration increased but latency was unaffected. The size of the response of individual neurones to carbachol, but not the percentage of sensitive neurones, was also increased in lesioned animals. The proportion of neurones responding to bicuculline and their individual sensitivities were increased by the lesion, suggesting that the lesion increased GABAergic tone; responses to glutamate were unchanged. The lesion did not affect the proportion of neurones in which acetylcholine modulated neuronal responses but reversed the nature of the modulation to predominantly excitatory; excitation was the predominant response to electrical forepaw stimulation in unlesioned control animals. This suggests a possible interaction between GABAergic and cholinergic mechanisms in selective attention and processing of cognitive information. Acute administration of di-isopropyl fluorophosphate to unlesioned animals significantly increased the number of frontal cortical neurones responding to acetylcholine, without affecting individual neuronal sensitivity or responses to carbachol and glutamate. The similarity of these effects to those of acetylcholine in lesioned animals suggests that the increased sensitivity to acetylcholine in the latter was due to loss of acetylcholinesterase, enabling diffusion of acetylcholine to more distant neurones. However, acetylcholinesterase does not hydrolyse carbachol and therefore it is necessary to postulate a different post-synaptic mechanism to explain the lesion-induced increases in the sensitivities of individual neurones to carbachol and to acetylcholine; interpretation of experimental findings should take these two mechanisms into account.     

Extracellular levels of amino acids in striatum and globus pallidus of 6-hydroxydopamine-lesioned rats measured with microdialysis

Extracellular aspartate, glutamate, glutamine, taurine and GABA concentrations were measured by microdialysis in the rat striatum and globus pallidus after a unilateral 6-hydroxydopamine lesion of the dopamine system. The basal and potassium-evoked overflow of GABA was increased in the ipsilateral striatum, but the evoked overflow was decreased in both contralateral striatum and pallidum. Both basal and evoked overflow of glutamate was increased in ipsilateral striatum. The basal overflow of aspartate was significantly increased in the ipsilateral side. Basal glutamine on the other hand was decreased in the ipsilateral side. Taurine remained unchanged in both regions. These results suggest that dopamine is involved in the regulation of transmission by GABA and glutamate. Since glutamine might be the precursor to glutamate, the change in glutamate might affect the glutamine level. The changed aspartate level has no obvious explanation.     

Differential response of enzymes of glutamate metabolism in neuronal perikarya and synaptosomes in acute hyperammonemia in rat

Activity levels of the enzymes of glutamate metabolism were determined in the neuronal perikarya and synaptosomes isolated from the cerebral cortex of normal and hyperammonemic rats. In neuronal perikarya, the activities of glutamate dehydrogenase, aspartate, alanine aminotransferases and glutamine synthetase were elevated in hyperammonemic states. In synaptosomes, glutamate dehydrogenase and aspartate aminotransferase were suppressed, while glutamine synthetase and glutaminase were elevated. These results suggested the involvement of neuronal perikarya in ammonia detoxification at least in acute hyperammonemic states.     

Change in biochemical profile of pregnant camels (Camelus dromedarius) at term

Results for biochemical determinations on serum of 28 pregnant camels (Camelus dromedarius) at term were compared with those of 32 non-pregnant camels (C. dromedarius). Sera from pregnant group had higher mean alkaline phosphatase activity and lower mean albumin, blood urea nitrogen, calcium, cholesterol, iron, phosphorus, total protein concentrations, γ-glutamyl transferase, and lactate dehydrogenase activities. All the differences are significant. Globulin, creatinine concentrations, alanine aminotransferase, aspartate aminotransferase, and creatinine kinase activities did not differ significantly.     

Aspartate, glutamate and GABA levels in pallidum, substantia nigra, center median and dorsal raphe nuclei after cylindric lesion of caudate nucleus in cat

Aspartate, glutamate and GABA levels were determined in afferent and efferent projection nuclei of the striatum after unilateral cylindric lesion in the head of the caudate nucleus in cats. Two and four weeks after operation, GABA content was significantly reduced in substantia nigra and pallidum ipsilateral to the lesion. Glutamate (GLU) level was decreased in substantia nigra and pallidum only 4 weeks after lesion, whereas aspartate content in substantia nigra decreased significantly already after 2 weeks. No changes in the contents of these amino acids were detected in the dorsal raphe nucleus, which receives a projection from the caudate, as well as in the center median nucleus, which projects to the striatum. These experiments using longer survival times substantiate the role of GABA in caudato-pallidal and caudatonigral projections. The possibility is discussed that aspartate (ASP) could function as transmitter of cortico-nigral fibers.     

The influences of thermal stress on serum biochemical parameters of Iranian fat-tailed sheep and their correlation with triiodothyronine (T3), thyroxine (T4) and cortisol concentrations

In order to study the influences of thermal stress on serum biochemical parameters of Iranian fat-tailed sheep and their correlation with triiodothyronine (T₃), thyroxine (T₄) and cortisol concentrations, an experiment was conducted using 45 clinically healthy Iranian fat-tailed sheep. These animals were divided into three experimental groups: group I, 15 sheep at 4 °C, group II 15 sheep at 21 °C and group III 15 sheep at 40 °C. Blood samples were taken from the jugular vein of all animals after 7 days exposure to the appropriate environmental temperature. The concentrations of total protein, glucose, cholesterol, total lipid, calcium, inorganic phosphorus, magnesium, creatine kinase, lactate dehydrogenase, triiodothyronine and thyroxine in cold stress conditions were higher than in heat stress; in contrast, the activities of aspartate aminotransferase and alanine aminotransferase were higher in heat stress conditions than in cold (p = <0.05). Although there were no significant differences in the concentrations of blood urea nitrogen, triglyceride, alkaline phosphatase and cortisol at either heat stress or cold stress, the first three assays were significantly lower than in animals kept at optimum temperatures, with cortisol having significantly higher values. These results revealed that very hot and very cold conditions had a profound effect on serum biochemical parameters.Abbreviations ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - LD lactate dehydrogenase - CK creatine kinase - ALP alkaline phosphatase     

Alteration of regulatory enzyme activities in fast-twitch and slow-twitch muscles and muscle fibres in low-intensity endurance-trained rats

The effect of progressive, low-intensity endurance training on regulatory enzyme activities in slow-twitch (ST) and fast-twitch (FT) muscle fibres was studied in 32 rats. Of those rats 16 were trained on a treadmill at a running speed of 10m · min^–1 5 days a week over an 8-week period. Running time was progressively increased from 15 min to 2 h · day^–1. Of the rats 4 trained and 4 sedentary rats were also subjected to acute exhausting exercise. Enzyme activities of phosphofructokinase 1 (PFKI) from glycolysis, -ketoglutarate dehydrogenase (-KGDH) from the Krebs cycle and carnitine palmitoyltransferase (CPT I and II) from fatty acid metabolism in soleus, tibialis anterior and gastrocnemius muscles were measured in trained and sedentary rats. Enzyme activities of individual ST and FT fibres were measured from the freeze-dried gastrocnemius muscle of 8 trained and 8 sedentary rats. In the sedentary rats the activity of PFK1 in tibialis anterior and soleus muscles was 141% and 41% of the activity in gastrocnemius muscle, respectively. The activity of -KGDH in tibialis anterior and soleus muscles was 164% and 278% of the activity in gastrocnemius muscle, respectively. The activity of CPT I in tibialis anterior and gastrocnemius muscles were at the same level, but in soleus muscle the activity was 127% of that in mixed muscle. Endurance training increased enzyme activities of -KGDH and CPT I significantly (P < 0.05) in gastrocnemius muscle but not in soleus or tibialis anterior muscle. After training both -KGDH and CPT II activities were elevated significantly (P < 0.05) in the ST fibres of gastrocnemius muscle, whereas in FT fibres only -KGDH was increased. For PFK1 activity no significant change was observed in ST or FT fibres. After acute exercise, activities of mitochondrial enzymes -KGDH and CPT I tended to be elevated in all muscles. Thus, low-intensity endurance training induced significant peripheral changes in regulatory enzyme activities in oxidative and fatty acid metabolism in individual ST or FT muscle fibres.     

Long-term restoration of nigrostriatal system function by implanting GDNF genetically modified fibroblasts in a rat model of Parkinson’s disease

The motor behavior and levels of dopamine and its metabolites in the striatum were studied in rats that received a unilateral injection of 6-OHDA and underwent grafting of rat-derived primary fibroblasts that had been genetically modified to express lacZ and human glial cell line-derived neurotrophic factor (GDNF). Rotation behavior tests were performed each week and striatal levels of DA and its metabolites were measured every 4 weeks after grafting of fibroblasts that expressed lacZ, with or without additional transfection of the GDNF transgene. Rats grafted with GDNF-producing fibroblasts showed a significant improvement in motor behavior as determined by the rotation test, with a less pronounced reduction in the levels of dopamine and its metabolites in the striatum as compared with those in the control animals or brain parts. In addition, there was a lower decrease in the number of TH immunoreactive neurons in the substantia nigra ipsilateral to the lesion in rats with GDNF-producing fibroblasts than in rats with lacZ-expressing fibroblasts. These results support the notion that intracerebral grafting of fibroblasts that express GDNF is a potentially useful therapeutic strategy for treating Parkinsons disease.     

Corticosteroid metabolism in rat kidney in vitro

An attempt has been made to identify the subcellular localization of renal corticosteroid metabolism. Subcellular fractions were prepared by differential centrifugation, identified by marker enzymes and incubated under different conditions with corticosterone (B). The NADP⁺/NADPH dependent metabolism of B could be localized in the nuclear and microsomal fraction. The most prominent metabolite was 11-dehydro-B, which is formed by 11-hydroxysteroid dehydrogenase (EC 1.1.1.146). Enzyme kinetic studies of this enzyme with B as substrate revealed apparentK _m-values in the range of 10^–7 M for both the nuclear and microsomal fraction.Abbreviations B corticosterone - G-6-P glucose-6-phosphatase - SDH succinic dehydrogenase - 11-HSD 11-hydroxysteroid dehydrogenase - HPLC high pressure liquid chromatography - met metabolite - STM (STE and DTE) as explained in legend to Fig. 1 Dedicated to Prof. K. J. Ullrich on the occasion of his 60th birthday     

The effect of experimental streptococcus infection in myocarditis on some biochemical and inflammatory markers in albino rats

Background

Myocarditis is an uncommon disease that presents with a wide range of symptoms in children and adults. It is histologically characterized by varying degrees of myocardialnecrosis, edema and cellular infiltration myocardial inflammation is a nonspecificresponse to many triggers such as bacterial infection, cardio toxic agents, ormechanical injury.

Objective

This study was carried out to investigate the experimental Streptococcus faecalis induction of myocarditis and its effect on some blood parameters, inflammatory markers and histopathological changes in male albino rats.

Methods

Rats were infected by intraperitoneal injection of 10 8 CFU/ml of Streptococcus faecalis and sacrificed after one, two and seven days post infection. Biochemical analyses of blood were carried out to investigate the serum biomarkers of inflammation, liver function tests, cardiac enzymes & kidney function tests.

Results

All biochemical analyses showed statistically significant increase in the measured parameters due to bacterial infections except for blood urea which appear to be normal. A significant positive correlation was observed between lactate dehydrogenase enzyme (LDH) with creatinine (r =0.778, P<0.01). In the 7 days group, there were significant positive correlations between aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (r=0.675, P<0.05), erythrocyte sedimentation rate (ESR) with Urea (r=0.659, P<0.05) and alkaline phosphatase (ALP) with C-reactive protein (CRP) (r=0.765, p<0.01).

Conclusion

Many of these biomarkers will provide important new insights into pathophysiology and aid in the diagnosis and management of cardiovascular patients.     

Bile acids and their amidates inhibit 11β-hydroxysteroid dehydrogenase obtained from rat kidney

Recently it has ben demonstrated that interaction of corticosteroids with extraadrenal target cells can effectively be modulated by metabolic transformation of the steroid hormone. As far as 11-hydroxylated glucocorticoids are concerned 11-hydroxysteroid dehydrogenase (11-HSD) is the most important enzyme charged with target cell metabolism. Inhibition of 11-HSD function either by genetically transmitted deficiency or by exogenous enzyme inhibitors causes severe pathophysiological derangements, which result in a syndrome of apparent mineralocorticoid excess. In the present paper we have tested whether or not endogenous inhibitors of this enzyme system might exist. The effects of the main naturally occurring mono-, di-, and trihydroxylated bile acids in man on 11-HSD have been studied in in vitro experiments. Using rat renal microsomes it could be demonstrated that unconjugated bile acids of all three classes as well as the corresponding glycine and taurine amidates effectively inhibit oxidative as well as reductive activity of 11-HSD, with lithocholic acid and chenodeoxycholic acid being the most potent compounds. It is concluded that bile acids are potent endogenous inhibitors of 11-HSD and, therefore, could participate in abnormalities of cortisol metabolism observed in liver cirrhosis and extrahepatic biliary obstruction and, possibly, after ingestion of bile acids.Abbreviations CA cholic acid - CDCA chenodeoxycholic acid - DCA deoxycholic acid - GCA glycocholic acid - GCDCA glycochenodeoxycholic acid - GLCA glycolithocholic acid - 11-HSD 11-hydroxysteroid dehydrogenase (EC 1.1.1.146) - IC₅₀ molar concentration of bile acid at 50% inhibition of enzyme activity - LCA lithocholic acid - TDCA taurodeoxycholic acid - TLCA taurolithocholic acid - TUDCA tauroursodeoxycholic acid - UDCA ursodeoxycholic acid Supported by the Deutsche Forschungsgemeinschaft Hi 97/16 1-4. Parts of this study have been presented at the 21st meeting of the Gesellschaft für Nephrologie [23]     

Diagnostic enzyme profile in houbara bustard tissues ( Chlamydotis undulata macqueenii )

We have reported tissue profiles of diagnostic enzymes in heart, liver, kidney, duodenum, pancreas, pectoral muscle and quadriceps muscle from houbara bustards (Chlamydotis undulata macqueenii). Enzymes studied included aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), alkaline phosphatase (ALKP), lactate dehydrogenase (LDH) and creatine kinase (CK). The data from our studies suggest that the tissue enzymes which are commonly used as clinical diagnostic tools in other species may also be used to evaluate tissue integrity in houbara bustards. However, although tissue enzyme patterns in the bustard showed some similarities compared with other avian species, there were also important differences. GGT and ALKP activities were predominantly present in the bustard kidney. CK appeared to be a sensitive indicator of muscle cell damage in the bustard. Although ALT, LDH and AST appeared to be sensitive indicators of liver cell damage, they were non-specific for this organ, and consequently no enzyme studied was a specific indicator of liver cell damage in the bustard.     

The effect of starvation in the rat on metabolite concentrations in blood,liver and skeletal muscle

The effects of starvation on the concentration of blood and tissue metabolites was determined at different times in rats starved up to 6 days.The concentration of the hepatic gluconeogenic intermediates: pyruvate, phosphoenolpyruvate, 2-phosphoglycerate and 3-phosphoglycerate, decreased by 50% by the third day and then gradually increased to control levels by the sixth day of starvation. The change in the concentration of these metabolites correlates inversely with the plasma free fatty acid levels and the -hydroxybutyrate: acetoacetate (B/A) ratios, suggesting that the increased generation of reducing equivalents from free fatty acid oxidation stimulate glyceraldehyde-phosphate dehydrogenase. However, this apparent stimulation does not appear to control glyconeogenic flux. The concentration of hepatic oxaloacetate increased gradually during starvation and correlated closely with the increase in hepatic gluconeogenic flux suggesting that the hepatic concentration of oxaloacetate may be important in controlling the rate of hepatic gluconeogenesis.The calculated equilibrium expression: [alanine] [-ketoglutarate]/[pyruvate] [glutamate] and [aspartate] [-ketoglutarate]/[oxdaloacetate] [glutamate] for alanine aminotransferase and aspartate amino transferase respectively, remained fairly constant in all the tissues studied throughout the starvation period, despite large changes in the concentrations of the individual reactants, indicating that these reactions are near equilibrium.The -hydroxybutyrate: acetoacetate (B/A) ratios, taken to reflect the mitochondrial redox state, increased more than 4-fold in liver and muscle after the first day of starvation. It decreased after the third day of starvation and returned close to prefasting levels by the sixth day. The change in B/A ratios in blood was similar to those observed in the organs, except that the magnitude of the change was less. The changes observed in the mitochondrial redox state during starvation correlate closely with the changes in plasma free fatty acid concentrations and with the rate of fatty acid oxidation.     

Liver enzyme activity and histological changes in the liver of silver foxes (<Emphasis Type="Italic">Vulpes vulpes fulva</Emphasis>) experimentally infected with opisthorchiid liver flukes. A contribution to the pathogenesis of opisthorchiidosis

Blood samples from silver foxes experimentally infected with Opisthorchis felineus and Metorchis bilis, respectively, were examined for the activity of liver enzymes. The average activities of aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), alkaline phosphatase and alanine aminotransferase in uninfected control animals were 20, 1.8, 57 and 44 units/l, respectively. The liver enzymes in infected foxes reacted differently, depending on dose, species of flukes and individual peculiarities. The highest individual deviation of infected from control animals was registered in the case of GLDH, reaching increases of up to 200-fold. In contrast, AST showed the lowest deviation from control values (less than 10-fold). By the end of the study period, enzyme activities had declined. The prepatent periods for M. bilis and O. felineus in foxes were 2 weeks and 4 weeks, respectively. High egg per gram values were established at the beginning of the patent period. At necropsy, chronic inflammatory reactions were found in the bile ducts and in the wall of the gall bladder. The number of flukes at the end of the study was low.     

Biochemical and genetical studies of NADP-specific glutamate dehydrogenase in the fission yeast Schizosaccharomyces pombe

The initial velocity, pH and temperature optima, and Km values of Schizosaccharomyces pombe NADP-glutamate dehydrogenase (NADP-GDH: EC 1.4.1.4) have been determined. NADP-GDH was found to be specific for the substrates used in the reaction mixtures. NADP-GDH activity showed a sigmoidal response to changes in -ketoglutarate concentrations, following Hill kinetics with a coefficient n_H=2. A two-fold and a three-fold increase in activity was found in extracts of cells grown on a medium containing cytosine or histidine as a sole nitrogen source, respectively, relative to the activity found in cells grown on other sole nitrogen sources including ammonium, adenine, arginine, aspartate, asparagine, glutamate, glutamine, leucine, lysine, proline, uridine and urea. Five NADP-GDH-defective mutants were isolated on the basis of no growth on ammonium plus allantoin as sole nitrogen sources. The mutants also failed to grow on allantion alone but, in contrast, they were phenotypically indistinguishable from the wild-type growing on solid minimal medium with ammonium. Additionally, the mutants were found to grow as wild-type on minimal medium with alanine, arginine, asparagine, aspartate, glutamate, glutamine, leucine, ornithine and proline in the absence or presence of allantoin. In liquid minimal medium with ammonium as sole nitrogen source they had a slower growth than the wild-type. Normal growth was observed in cells grown on alanine, arginine, asparagine, aspartate, glutamate, glutamine, leucine, ornithine and proline. The mutants had undetectable levels of NADP-GDH activity, but retained wild-type levels of NAD-GDH, glutame synthase (GOGAT) and glutamine synthetase (GS). Mutants were found to map in two unlinked genetic loci by recombinational analysis. One locus was designated as gdh1 and was represented by four mutant alleles (gdh1-1, gdh1-2, gdh1-3 and gdh1-4), whilst the second locus, gdh2, had one mutant allele (gdh2-1). No differences were observed in growth tests or enzymic studies between these loci.     

Metabolic sequelae of experimental leptospirosis in grivet monkeys.

Leptospira interrogans serovars balcanica and tarassovi both induced mild subclinical infections in grivet monkeys. The activities in serum of lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and creatine phosphokinase and the level of alpha 1-antichymotrypsin increased in a few days after infection. Concomitant decreases in serum iron levels were observed in some cases. These changes occurred in the absence of any observable clinical signs though there were histopathological lesions in some organs. No haematological changes or alterations in other sreum components were detected.