Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Cultured rat hepatoma cells accumulate 2-aminoisobutyrate to high concentrations by a transport mechanism probably of the A type mediation. 2. Transport is enhanced by the presence of serum. When cells are deprived of serum the rate of transport declines over a period of hours; conversely addition of serum leads over a period of hours to increase in transport activity. In the presence of serum the apparent Km for aminoisobutyrate uptake is about 8 mM. In cells deprived of serum the Km is much higher. 3. Addition of insulin produces both an immediate increase in the rate of aminoisobutyrate uptake and a time-dependent rise. 4. The presence of alanine diminished aminoisobutyrate uptake in a concentration-dependent fashion. Competition is seen both in the presence and absence of serum but not when cells are incubated at 4 degrees C. 5. Preincubation with alanine for 1 h also diminishes aminoisobutyrate uptake when the alanine is removed. Cells take a period of several hours to recover from the depression of transport induced by alanine. 6. Transport of aminoisobutyrate rapidly declines in the presence of cycloheximide. Actinomycin had no effect for at least 8 h.
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PMID:Influence of serum and insulin on the accumulation of aminoisobutyrate by rat hepatoma cells. 6 Jan 38

Chronic ammonia toxicity in experimental mice was induced by exposing them for 2 and 5 days to 5 % (v/v) ammonia solution. The enzymes concerned with glutamate metabolism (aspartate-, alanine- and tyrosine aminotransferases, glutamate dehydrogenase and glutamine synthetase) and (Na+ + K+)-ATPase were estimated in the three regions of brain (cerebellum, cerebral cortex and brain stem) and in liver. Glutamate, aspartate, alanine, glutamine and GABA, RNA and protein were also estimated in the three regions of brain and liver. A significant rise in the activity of (Na+ + K+)-ATPase in all the three regions of brain along with a fall in the activity of alanine aminotransferase was noticed. Changes in the activities of other enzymes were also observed. A significant increase in alanine and a decrease in glutamic acid was observed while no change was observed in the content of other amino acids belonging to the glutamate family. As a result of this, changes in the ratios of glutamate/glutamine and glutamate + aspartate/GABA was observed. The results indicated that the brain was in a state of more depression and less of excitation. Under these conditions the liver tissue was showing a profound rise in the activity of the enzymes of glutamate metabolism. The results are further discussed.
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PMID:Chronic metabolic effects of ammonia in mouse brain. 9 19

C-fiber reflex were recorded from an ipsilateral S1 ventral root in the acute decerebrate spinal (T10) cat after stimulation of the superficial peroneal nerve. L-Tryptophan, infused in a dose of 150 mg/kg, increased the C-fiber reflex to 210% (S.E.M. +/- 30.1%) of control. This effect was antagonized by cyproheptadine, 0.5 mg/kg. L-Tryptophan increased the C-fiber reflex to 176% (S.E.M. +/- 13.0%) of control after p-chlorophenylalanine pretreatment. Pretreatment of the cats with the decarboxylase inhibitor alpha-methyldopa, 100 mg/kg, 30 minutes before infusion, antagonized the facilitatory effects of L-Tryptophan. L-Tryptophan, 150 mg/kg, had no effect on the monosynaptic or short latency polysynaptic reflexes. 5-Hydroxytryptophan, 20 mg/kg, had erratic effects on the C-fiber reflex producing both facilitation and depression which were not statistically significant. The recovery of tryptamine from brain perfusates, after perfusion of the anterior cerebellum and pons, with a modified Gaddum push-pull cannula, decreased across time. L-Tryptophan caused a slight increase in tryptamine release which was not statistically significant, whereas in cats pretreated with p-chlorophenyl alanine, a significant increase in tryptamine release was seen.
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PMID:The effect of L-tryptophan on spinal cord C-fiber reflexes. 13 Apr 82

The release of endogenous taurine, GABA, glycine, aspartate, glutamate, glutamine and alanine from the rat visual cortex was measured using a cortical cup technique. The electrocorticogram (ECoG) was monitored throughout most experiments. 2. Spreading depression, evoked by the dropwise placement of 10% KCl solution on to the brain outside the cup was associated with a significant increase in the release of GABA and glutamine but a marked fall in that of glutamate. The evoked release of GABA and glutamate but not of glutamine was Ca2+ dependent. 3. A solution containing 50 mM-K+ placed within the cup elicited a significant increase in the release of taurine and GABA, whereas 100 mM-K+ additionally released aspartate and glutamate. The K+-evoked release of these amino acids with the exceptions of taurine and glutamine was Ca2+-dependent. 4. Three series of experiments were carried out in which the preparations were stimulated electrically. Bipolar stimulation (100 Hz, 1 msec pulse width, 2-5 mA for 5 min) with the electrode within the cup was followed by significant increases in taurine, GABA and glutamate release; using a 5 mA current, there was an additional release of aspartate and alanine. Only the evoked release of GABA and glutamate was Ca2+ dependent. 5. In the second and third series of experiments, the electrode was sited adjacent to the cup or on the contralateral cortex respectively. Following stimulation (100 Hz, 1 msec pulse width, 2-5 mA for 5 min) there was a significant increase in taurine and GABA release and a significant fall in the release of aspartate and glutamate. With the exception of taurine, these changes in release were Ca2+ dependent. Reducing the stimulus current to 1-5 mA or the period of stimulation to 2-5 min initiated similar but statistically insignificant changes in release. A range (10-100 Hz) of stimulation frequencies was examined: the evoked release of GABA was linearly related to frequency whereas that of taurine was frequency-independent. The fall in aspartate and glutamate release was maximal at a frequency of about 50 Hz. 6. The results are discussed in relation to (a) the possible sites of release of the amino acids and (b) the proposed neurotransmitter roles of the physiologically active amino acids.
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PMID:The release of endogenous amino acids from the rat visual cortex. 18 88

Kinetics of the transport systems common for entry of L-isoleucine, L-leucine, and L-valine in Salmonella typhimurium LT2 have been analyzed as a function of substrateconcentration in the range of 0.5 to 45 muM. The systems of transport mutants, KA203 (ilvT3) and KA204 (ilvT4), are composed of two components; apparent Km values for uptake of isoleucine, leucine, and valine by the low Km component are 2 muM, 2 to 3 muM, and 1 muM, respectively, and by the high Km component 30 muM, 20 to 40 muM, and 0.1 mM, respectively. The transport system(s) of the wild type has not been separated into components but rather displays single Km values of 9 muM for isoleucine, 10 muM for leucine, and 30 muM for valine. The transport activity of the wild type was repressed by L-leucine, alpha ketoisocaproate, glycyl-L-isoleucine, glycyl-L-leucine, and glycyl-L-methionine. That for the transport mutants was repressed by L-alanine, L-isoleucine, L-methionine, L-valine, alpha-ketoisovalerate, alpha-keto-beta-methylvalerate, glycyl-L-alanine, glycyl-L-threonine, and glycyl-L-valine, in addition to the compounds described above. Repression of the mutant transport systems resulted in disappearance of the low Km component for valine uptake, together with a decrease in Vmax of the high Km component; the kinetic analysis with isoleucine and leucine as substrates was not possible because of poor uptake. The maximum reduction of the transport activity for isoleucine was obtained after growing cells for two to three generations in a medium supplemented with repressor, and for the depression, protein synthesis was essential after removal of the repressor. The transport activity for labeled isoleucine in the transport mutant and wild-type strains was inhibited by unlabeled L-alanine, L-cysteine, L-isoleucine, L-leucine, L-methionine, L-threonine, and L-valine. D-Amino acids neither repressed nor inhibited the transport activity of cells for entry of isoleucine.
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PMID:Repression and inhibition of transport systems for branched-chain amino acids in Salmonella typhimurium. 32 Jan 86

ATP-Mg++ (10 mumoles/100 g, iv) increased the LD50 for Salmonella enteritidis lipopolysaccharide (endotoxin) in male Holtzman rats (300 +/- 10 g) from 1.3 to 6.0 mg/rat. While endotoxin at 3 mg/rat iv 5 hr previously induced hypoglycemia to 12 +/- 4 mg/dl, ATP cotreatment blunted the hypoglycemia; i.e., plasma glucose values were 78 +/- 6 mg/dl. ATP treatment prevented the depression in gluconeogenesis induced by endotoxin as evaluated in vivo by the conversion of 14C-alanine to 14C-glucose. ATP treatment also reduced the hypercatabolism of U-14 C-glucose to 14CO2 in vivo and by epididymal fat pads in vitro. A role for ATP in preventing disruption of glucose homeostasis and development of endotoxin shock via counteracting insulin is suggested.
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PMID:Protection against endotoxin shock and impaired glucose homeostasis with ATP. 33 38

The ability of low protein diets containing small neutral, dispensable amino acids to induce threonine imbalance has been examined. Diets containing amino acids which compete for threonine transport in vitro (serine, alanine, alpha-amino-n-butyrate) caused depressions of growth and food intake which could be corrected to varying degrees by adding threonine to the diet. Large neutral, indispensable amino acids, moderately inhibitory of threonine transport, also induced the imbalance. Some amino acids that had little or no effect on threonine transport in vitro (acidic amino acids and proline) did not cause growth and food intake depressions. Other non-inhibitory amino acids (arginine and lysine) caused growth depressions which were not satisfactorily corrected by additional threonine alone, but were prevented by supplements of all the indispensable amino acids including threonine. Ornithine which was also not inhibitory of threonine transport was an exception. It induced a moderate growth depression which was corrected by additional threonine. Similar studies showed that histidine or tryptophan imbalance could be induced by feeding diets containing only those large neutral amino acids which compete for histidine or tryptophan transport in vitro. These experiments show that, based on the results of transport competition experiments, it is generally possible to devise amino acid supplements which can induce a dietary imbalance of a given amino acid.
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PMID:Induction of threonine imbalance by dispensable amino acids: relation to competition for amino acid transport into brain. 43 Feb 32

Young male rats (100-130 g) were fed diets of equal energy content containing o.5, 1,2,3,5, and 18% lactalbumin consumed either freely or in restricted amounts. The rats receiving low protein diets failed to grow and mature. Those consuming the 0.5 and1% protein diets given freely developed the characteristic features of kwashiorkor including edema, while those receiving the diets in restricted amounts developed the characteristic features of marasmus. The rats fed low protein diets had low plasma levels of essential amino acids; however, the lysine level was well maintained. The plasma levels of nonessential amino acids, especially glycine, alanine, and aspartic and glutamic acids were raised in marasmic rats but were reduced in rats fed low protein diets ad libitum. Young and severly malnourished rats appeared to have limited ability to synthesize urea. Therefore, they excreted more ammonia and other nitrogenous substances such as ethanolamine, and when given an amino acid load, intermediary metabolites of the ingested amino acids. Rats fed low protein diets showed diminution of total liver DNA, RNA, and protein. In addition to the reduction of protein synthesis resulting from decreased cellular RNA, ribosomes from the livers of protein-deficient rats had reduced ability to synthesize proteins. This defect was associated with the detatchment of the ribosomes from endoplasmic reticulum membrane and the elevation of the proportion of monosomes to polyribosomes. Malnutrition did not produce any change in the turnover rate of liver RNA. Protein deficiency caused significant depression of serum insulin, thyroxine, and corticosterone levels. Theoverall conclusion is that mammalian metabolism is well adapted to dietary intake and that this adaptation is achieved through dietary control of synthesis and release of key metabolic hormones.
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PMID:Experimental protein and energy in the rat. 80 70

Experiments on Wistar male rats revealed depression of labeled amino acid incorporation into the tissue proteins as a result of swimming. When prolonged swimming was accompanied by an enhanced adrenocortical activity the block of the protein synthesis in the liver proved to disappear. Adrenalectomy excluded the activation of alanine-aminotranspherase and a drop of the free amino acids in the liver during physical exercise: corticosterone administration to adrenalectomized animals restored these shifts.
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PMID:[Adrenocortical regulation of protein metabolism during prolonged physical stress]. 102 68

A quasi-elastic light-scattering technique was used to study the hydrodynamic conformations of antifreeze glycoproteins from an Antarctic fish. Antifreeze glycoprotein is composed of repeating units of Ala-Ala-Thr, with each threonine O-linked to a disaccharide, and it exists as several polymers of different numbers of this repeating unit. Molecular weights of the two major active polymers are 10,500 and 17,500 by such methods as centrifugation and osmotic pressure, but smaller than 20 by freezing-point depression. Translational diffusion coefficients at 20 degrees were 8.35 times 10-7 cm2 s-1 and 6.15 times 10-7 cm2 s-1 for the M-r-10,500 and 17,500 polymers, respectively. Measurements at -0.2 degrees in the presence of ice crystals did not indicate any conformational changes that might be related to the lowering of the freezing temperature. Lowering the temperature of these glycoprotein solutions close to temperatures of freezing caused a decrease in the effective hydrodynamic radius of both active and inactive glycoprotein components.
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PMID:Antifreeze glycoproteins from an Antarctic fish. Quasi-elastic light scattering studies of the hydrodynamic conformations of antifreeze glycoproteins. 116 94


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