Rapid Effects of Environmental Disturbance on Rat Plasma Unesterified Fatty Acid and Tryptophan Concentrations and Their Prevention by Antilipolytic Drugs

Curzon, G.; Knott, P. J.

doi:10.1111/j.1476-5381.1975.tb07580.x

Cited by 39 publications

(10 citation statements)

References 22 publications

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“…Total and free tryptophan concentrations were determined in serum as described by Bloxham & Warren (1974). Albumin-bound tryptophan was separated from free tryptophan by ultrafiltration, without pH control, by using CF25 Amicon Diaflo membrane cones (Curzon & Knott, 1975).…”

Section: Determination Oftrvptophan Concentrationsmentioning

confidence: 99%

Effects of chronic modification of dietary fat and carbohydrate in rats. The activities of some enzymes of hepatic glycerolipid synthesis and the effects of corticotropin injection

Lawson¹,

Jennings²,

Pollard³

et al. 1981

Biochemical Journal

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1. Rats were fed on diets enriched with starch, sucrose, corn oil or beef tallow for 3 weeks and the activities of various enzymes in the liver were measured. 2. The mitochondrial glycerol phosphate acyltransferase activity was lower in rats fed on the starch diet than on the two high-fat diets. 3. The non-microsomal (presumably peroxisomal) dihydroxyacetone phosphate acyltransferase activity was higher in rats fed on the starch diet and corn-oil diets than in those fed on the sucrose and beef-tallow diets. Urate oxidase activity was higher in rats fed on the starch diet than in the three other groups. There were no significant differences in the activity of acyl-CoA oxidase among the groups. 4. The activity of soluble phosphatidate phosphohydrolase was not significantly different among the dietary groups. There were increases of 3.3--4.3-fold in this activity in the dietary groups 6h after injection of corticotropin. The equivalent increases for the mitochondrial glycerol phosphate acyltransferase were 1.4--1.6 fold. 5. The corticosterone responses to the corticotropin injection were not significantly different between dietary groups. However, the corticosterone response of the rats fed on the two high-fat diets was prolonged when the rats were given an acute load of fructose [Brindley, Cooling, Glenny, Burditt & McKechnie (1981) Biochem. J. 200. 275--283]. 6. Rats fed on the high-fat diets had higher concentrations of circulating cholesterol than those fed on the starch and sucrose diets. Serum triacylglycerol concentrations were lower in the rats fed on the starch diet than in the three other groups. 7. The results are discussed in terms of the relationship between diet, hormonal balance and hepatic glycerolipid metabolism.

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Section: Determination Oftrvptophan Concentrationsmentioning

confidence: 99%

Effects of chronic modification of dietary fat and carbohydrate in rats. The activities of some enzymes of hepatic glycerolipid synthesis and the effects of corticotropin injection

Lawson¹,

Jennings²,

Pollard³

et al. 1981

Biochemical Journal

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“…under normal conditions, L-TRP circu-lates in the blood with a minor fraction free, whereas 70°/4, to 90'½, of L-TRP is loosely bound to serum albumin (Rao 1987;Curzon and Sarna 1984;Fernstrom 1984;Yuwiler et al 1977;McMenamy and Oncley 1958). This explains that the availability of circulating L-TRP is generally influenced by its binding to albumin (Curzon and Knott 1975). Moreover, the extraction of plasma L-TRP by the brain is, in part, related to competition of the brain transport site with plasma albumin, that is, it is proposed that the blood-brain barrier (BBB) transport site of L-TRP and its competing amino acids strips off albumin as it passes through the brain capillaries (Pardridge 1979;Smith et al 1990).…”

mentioning

confidence: 99%

Lower Serum L-Tryptophan Availability in Depression as a Marker of a More Generalized Disorder in Protein Metabolism

Maes

Wauters

Verkerk

et al. 1996

Neuropsychopharmacology

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Recently, it has been reported that major and melancholic depression are accompanied by a lower availability of total L-tryptophan (L-TRP) to the brain and by significant changes in electrophoretically separated protein fractions, such as albumin and alpha 2-globulin. The aim of this study was to examine the relationships between serum L-TRP availability and total serum protein, albumin, and alpha 2-globulin in 42 depressed and 24 normal subjects. In depressed and normal subjects, alone and together, there were significant and positive correlations between serum L-TRP and total serum protein or albumin concentrations. In the depressed subjects, but not in normal controls, there were significant inverse relationships between the L-TRP/competing amino acid ratio and the alpha 2-globulin fraction. Serum L-TRP and albumin were significantly lower in melancholic subjects than in normal and minor depressed subjects. Depressed subjects had a significantly lower L-TRP/competing amino acid ratio and significantly higher serum alpha 2-globulin than normal controls. Total serum protein was significantly lower in major depressed subjects than in normal controls. The results suggest that lower L-TRP availability to the brain in depression is related to lower serum albumin and to increased alpha 2-globulin fraction, which are both hallmarks of the acute phase response in depression. the results further corroborate the hypothesis that lowered L-TRP availability in depression is related to the acute phase response in that illness.

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“…p < 0.001; p < 0.02. Faller, 1978), stress (Knott and Curzon, 1972;Curzon and Knott, 1975), disease (Mans et al, 1979~1, b), and drug treatments (Curzon and Fernando, 1976).…”

mentioning

confidence: 99%

Effect of Age on Variables Influencing the Supply of Tryptophan to the Brain

Sarna¹,

Tricklebank²,

Kantamaneni³

et al. 1982

Journal of Neurochemistry

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The relations of plasma concentrations of substances claimed to influence brain tryptophan concentration (total tryptophan, free tryptophan, large neutral amino acids) with the concentrations of tryptophan, 5‐hydroxytryptamine (5‐HT), and 5‐hydroxyindoleacetic acid (5‐HIAA) in the forebrain were investigated in rats of different ages (from 8 days to 16 months after birth). In brain, tryptophan fell by 46%, whereas 5‐HT rose by 20% between 8 and 40/42 days after birth. Thereafter, the levels of both tryptophan and 5‐HT remained essentially constant. Brain 5‐HIAA showed a more complex pattern, rising by 63% between 8 and 19 days, falling between 19 and 40/42 days, and then gradually rising until values at 16 months were significantly higher than those at 40/42 days. In plasma, the concentrations of free fatty acids, free and total tryptophan, and large neutral amino acids all decreased between 8 and 19 days and thereafter either remained constant or increased slowly, the exception being total tryptophan values, which showed large increases between 28/30 and 60/70 days. Also, the unidirectional uptake of tryptophan from blood to brain was determined using a carotid artery injection technique. Uptake values obtained using a tracer concentration of tryptophan in the injection solution decreased progressively with age. Kinetic analysis of the data in terms of the Michaelis‐Menten equation for carrier‐mediated transport indicated significantly lower values for Vmax and KD (a component for nonsaturable transport) in 6‐month‐old rats as compared to 19‐day‐old suckling rats, whereas Km values were the same at both ages. Detailed analysis of these results indicated that the age‐related changes in brain tryptophan were largely explicable in terms of plasma free tryptophan in association with blood‐brain transport characteristics; moderate differences in concentration of amino acids competing for transport were without apparent effect between 19 days and 16 months. The larger differences between 8 and 19 days after birth could be important.

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Rapid Effects of Environmental Disturbance on Rat Plasma Unesterified Fatty Acid and Tryptophan Concentrations and Their Prevention by Antilipolytic Drugs

Cited by 39 publications

References 22 publications

Effects of chronic modification of dietary fat and carbohydrate in rats. The activities of some enzymes of hepatic glycerolipid synthesis and the effects of corticotropin injection

Effects of chronic modification of dietary fat and carbohydrate in rats. The activities of some enzymes of hepatic glycerolipid synthesis and the effects of corticotropin injection

Lower Serum L-Tryptophan Availability in Depression as a Marker of a More Generalized Disorder in Protein Metabolism

Effect of Age on Variables Influencing the Supply of Tryptophan to the Brain

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