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Treatment of brain disease with dietary precursors of neurotransmitters.

A growing number of brain diseases are characterized by decreased levels of one or more of the neurotransmitters. Recent experimental evidence indicates that nutritional factors strongly influence the regulation of two of these neurotransmitters, serotonin and acetylcholine. As a result, attempts are now being made to treat diseases associated with low levels of serotonin or acetylcholine by administering their dietary precursors, tryptophan and choline, respectively. This treatment may increase the amount of the deficient neurotransmitter at synapses and produce clinical benefit. Such efforts to elevate brain neurotransmitter levels with a naturally occurring precursor represent a new approach in medical therapeutics and will probably continue. We review the scientific basis for such treatment and show that brain levels of serotonin and acetylcholine depend upon the amounts of tryptophan and choline available to the brain; these, in turn, fluctuate according to dietary factors.

Acetylcholine↗

[The neurochemistry and neuropharmacology of diffuse Lewy body disease].

INTRODUCTION AND DEVELOPMENT: The main neurochemical alteration in diffuse Lewy body disease (DLBD) is the cholinergic deficit in the cerebral cortex, which involves mainly cholin-acetyl-transferase. There have been also described dopamine deficiency and alterations affecting other neurotransmitters and neuromodulators, such as serotonin, noradrenaline, neuropeptides, etc. Cerebral perfusion and glucose metabolism studies usually show diffuse hypoperfusion or hypometabolism, with higher alteration of associative cortex, including occipital involvement. Several studies have shown increased markers of oxidative stress in brain and other tissues, suggesting its possible role in the pathogenesis of DLBD. CONCLUSIONS: Acetylcholinesterase inhibitors seem to improve cognitive and conductual symptoms, although their usefulness according evidence-based medicine criteria is weak. Some patients need atypical neuroleptics at low doses to get the symptomatic control of conductual alterations.

Acetylcholine↗

[Effects of iodine and thyroid hormone deficiency during brain development on activities of cholinergic neurone-related enzymes in central nervous system of rats].

To study the effects of iodine and thyroid hormone deficiency during brain development on activities of enzymes of central acetyl choline metabolism, activities of choline acetylcholinetransferase (CHAT) and acetylcholinesterase (AChE) in hippocampus and cerebral cortex, basal forebrain and cerebellum in 20-day-old rats were determined. Results showed that CHAT and AChE activities in hippocampus, cerebral cortex and basal forebrain in iodine deficiency and hypothyroid rats were significantly lower than those in controls. A ratio of membranebound AChE to soluble AChE, activities of inextractable AChE, and percentage of its activities in the four sections of the brain in the trial rats were significantly lower, and activities of soluble AChE and its percentage of activities were significantly higher than those in controls. It suggests iodine and thyroid hormone deficiency could affect maturation of CHAT and disturb transformation and maturation of various molecular types of AChE and delay distinctly the development of cholinergic neurone during the critical period of brain development in rats.

Acetylcholinesterase↗

Chronic alcoholism enhances hepatocarcinogenicity of diethylnitrosamine in rats fed a marginally methyl-deficient diet.

To determine whether the chronic consumption of ethanol was capable of enhancing the hepatocarcinogenic activity of diethylnitrosamine per se, or through the accentuation of a methyl deficiency, two groups (A and B) of Sprague-Dawley female rats were fed for 10 months either a 20% casein basal diet marginally deficient in methyl, or the same diet supplemented with choline (1 gm per 100 gm) and folic acid (0.54 mg per 100 gm). Both groups were offered a drinking ethanol solution, while two other nonalcohol control groups (C and D) were isocalorically pair-fed to Groups A and B, and received diets in which the alcohol consumed by the corresponding groups was replaced by isocaloric amounts of sucrose. A baseline nonalcohol Group E, isocalorically pair-fed to Group A, received the intact basal diet of Group A and water. One day before the initiation of the experiment, and again 2 months later, all rats from the five groups were injected with a single i.p. dose of diethylnitrosamine (100 mg per kg). The growth attained by all groups was statistically similar. Hepatic triglycerides in Group A were significantly higher than in all the other groups. While in Group A primary hepatocellular carcinomas and renal tumors were encountered at the end of the experiment in 3 of 6 and in 2 of 6 rats, respectively, no malignancies were observed in any of the other groups. These results indicate that chronic ethanol consumption enhances the hepatocarcinogenic and renal tumorigenic activity of diethylnitrosamine, and strongly suggest that this action is mediated through the accentuation of methyl deficiency.

Alcoholism↗

Effect of lipoprotein-X on lipid metabolism in rat kidney.

Lipoprotein-X (Lp-X) is found in the plasma of patients with familial lecithin: cholesterol acyltransferase (LCAT) deficiency syndromes. The majority of the patients with this disorder develop progressive glomerulosclerosis. In this study, the effect of Lp-X on lipid metabolism in perfused rat kidney was investigated. Lp-X was isolated from plasma of patients with familial LCAT deficiency by sequential ultracentrifugation and gel filtration column chromatography. Rat kidneys were perfused for 1-2 h with Krebs-Henseleit buffer containing 20 microM [1-(14)C]acetate or 20 microM [Me-3H]choline. In the presence of Lp-X, no significant difference in the incorporation of radioactivity into triglycerides, cholesterol, phosphocholine, CDP-choline and sphingomyelin was observed. However, incorporation of radioactivity into cholesteryl esters and phosphatidylcholine was significantly elevated in Lp-X perfused kidneys. The contents of cholesterol, cholesteryl esters and phosphatidylcholine were also significantly increased in Lp-X perfused kidneys. The increase in lipid content in the Lp-X perfused kidney is attributed to the direct deposition of Lp-X lipids into the organ. The increase in the labelling of cholesteryl esters was attributed to the increase of available substrate (cholesterol) for the acyl-CoA:cholesterol acyltransferase (ACAT) reaction. The increase in phosphatidylcholine labelling was caused by a reduced turnover of the newly synthesized labelled phosphatidylcholine during Lp-X perfusion.

1-Acylglycerophosphocholine O-Acyltransferase↗

Post-weaning diet affects genomic imprinting at the insulin-like growth factor 2 (Igf2) locus.

IGF2 loss of imprinting (LOI) is fairly prevalent and implicated in the pathogenesis of human cancer and developmental disease; however, the causes of this phenomenon are largely unknown. We determined whether the post-weaning diet of mice affects allelic expression and CpG methylation of Igf2. C57BL/6JxCast/EiJ F1 hybrid mice were weaned onto (1) a standard natural ingredient control diet, (2) a synthetic control diet or (3) a synthetic methyl-donor-deficient diet lacking folic acid, vitamin B(12), methionine and choline. Maternal Igf2 expression in kidney was negligible at birth, but increased to approximately 10% of total expression after 60 days on the natural control diet. By 60 days post-weaning, both synthetic diets caused significant LOI of Igf2 relative to animals weaned onto the natural control diet. Total Igf2 expression was significantly reduced in these groups, however, indicating that the increase in relative maternal Igf2 expression was caused by specific down-regulation of the paternal allele. The LOI induced by the synthetic-deficient diet persisted during a subsequent 100-day 'recuperation' period on natural ingredient diet. There were no group differences in overall or allele-specific CpG methylation in the H19 differentially methylated region (DMR), Igf2 DMR0 or Igf2 DMR1. At 30 and 60 days post-weaning, however, the paternal allele of Igf2 DMR2 was hypermethylated in the kidneys of mice on the control synthetic diet. These results indicate that post-weaning diet can permanently affect expression of Igf2, suggesting that childhood diet could contribute to IGF2 LOI in humans.

Alleles↗

Mechanism of calcium efflux from isolated bovine adrenal chromaffin cells.

Chromaffin cells isolated from bovine adrenals and maintained in culture were loaded with 45Ca, and the mechanism of 45Ca efflux from these cells was investigated. During exposure to a Ca-deficient, Mg (1 mM)-containing medium, replacement of NaCl with sucrose, choline Cl, or Tris Cl reduced the rate of 45Ca efflux by approx. 30-40%, showing the presence of a Na-dependent 45Ca efflux mechanism. In contrast to the previous findings, however, Li can partially replace Na in maintaining 45Ca efflux. Reintroduction of Ca to a Ca-deficient medium increased the rate of 45Ca efflux depending on the concentrations of Ca, showing the presence of a Ca-dependent Ca efflux mechanism. The marked but transient rise in the rate of 45Ca efflux in response to Ca reintroduction was observed under conditions in which the concentration of internal Na was raised either by inhibiting Na pumping activity (ouabain or K removal) or by removal of Mg from the medium. The increased 45Ca efflux was further potentiated by simultaneous Na removal and was markedly inhibited by Ca channel blockers, suggesting that the transiently increased Ca influx in exchange for internal Na facilitated the rate of 45Ca efflux. However, other conditions which evoke catecholamine secretion by stimulating Ca influx also increased the rate of 45Ca efflux, suggesting that the increased Ca influx via any route increases 45Ca efflux. These results thus confirmed the presence of both Na-dependent and Ca-dependent Ca efflux mechanisms in chromaffin cells.

Adrenal Medulla↗

Identification of the nuclear localization signal of rat liver CTP:phosphocholine cytidylyltransferase.

CTP:phosphocholine cytidylyltransferase (CT) is a major regulatory enzyme in phosphatidylcholine synthesis in mammalian cells. CT is found in both soluble and particulate forms, both of which are nuclear. We report here the identification of a 21-residue sequence at the amino terminus of CT, 8KVNSRKRRKEVPGPNGATEED28, which was sufficient to direct beta-galactosidase into the cell nucleus. Further deletions from either end of this sequence greatly reduced the nuclear localization of beta-galactosidase. Deletions of amino acids within the nuclear localization signal or of the entire signal disrupted CT nuclear localization, but CT was not completely excluded from the nucleus. Clones of stable transfectants of the nuclear localization signal-deficient CT expressed in Chinese hamster ovary (CHO) 58 cells, which is temperature-sensitive for growth and CT activity, were isolated and characterized. The deletion mutants were active under the same conditions as the wild-type enzyme. Despite the difference in subcellular location from wild-type CT, the nuclear localization mutants were fully able to complement the CT-deficient cell line CHO 58 for both growth and choline incorporation into phosphatidylcholine at the nonpermissive temperature. The mobility of the mutant enzymes on SDS gels was altered relative to the mobility of wild-type CT; however, the extent of phosphorylation of the mutant enzymes was decreased only slightly. Thus, the distribution of CT in both cytoplasm and nucleus, rather than exclusively nucleus, has little effect on the ability of CT to function in growing CHO cells.

Amino Acid Sequence↗

[Neuropharmacological analysis of the compensatory-recovery processes in deficiency of the generalization function in lobectomized cats].

Compensatory-recovery abilities of the cat brain were studied in free behaviour under frontal deficiency by means of parenteral pharmacological influence on dopamin-, cholin- and GABA-ergic systems. Activation of dopaminergic structures in lobectomized cats restored complex forms of generalization, and GABA-ergic system stimulation improved simple forms of generalization. Excitation of cholinergic formations deepened decompensation of generalization function.

Adaptation, Physiological↗

Vitamin A deficiency enhances docosahexaenoic and osbond acids in liver of rats fed an alpha linolenic acid-adequate diet.

The synthesis of docosahexaenoic (DHA, 22:6n-3) and Osbond acid (OA, 22:5n-6) is regulated by the heterodimer of peroxisome proliferator-activated receptor and retinoid X receptor (RXR). 9-Cis retinoic acid, a metabolite of vitamin A, is the most potent ligand of RXR. We tested whether vitamin A deficiency impairs DHA and OA synthesis in rats fed a vitamin A- and alpha-linolenic acid (ALA)-sufficient (VASALAS), vitamin A-sufficient and ALA-deficient (VASALAD), vitamin A-deficient and ALA-sufficient (VADALAS), or vitamin A- and ALA-deficient (VADALAD) diet. After 7 wk of feeding, liver and colon choline (CPG) and ethanolamine (EPG) phosphoglyceride FA were analyzed. The VADALAS compared with the VASALAS rats had elevated levels of both DHA (P< 0.05) and OA (P < 0.005) in liver CPG and EPG. In contrast, the VADALAD group had a lower DHA (P < 0.01) and higher OA (P < 0.005) level in CPG and EPG of both tissues than their VASALAD counterparts. ALA deficiency reduced DHA and enhariced OA levels in liver and colon CPG and EPG in both the vitamin A-sufficient (VASALAS vs. VASALAD) and -deficient (VADALAS vs. VADALAD) rats (P < 0.005). The study demonstrates that ALA deficiency reduced DHA and enhanced OA levels in tissue membranes, and dietary vitamin A deficiency has a profound effect on membrane DHA and OA in rat tissues. Both vitamin A and DHA are involved in a myriad of vital physiological functions pertaining to growth and development and health. Hence, there is a need for a further study to unravel the mechanism by which vitamin A influences membrane DHA and OA.

Animals↗

The AAPT1 gene of soybean complements a cholinephosphotransferase-deficient mutant of yeast.

Aminoalcoholphosphotransferases (AAPTases) utilize diacylglycerols and cytidine diphosphate (CDP)-aminoalcohols as substrates in the synthesis of the abundant membrane lipids phosphatidylcholine and phosphatidylethanolamine. A soybean cDNA encoding an AAPTase that demonstrates high levels of CDP-choline:sn-1,2-diacylglycerol cholinephosphotransferase activity was isolated by complementation of a yeast strain deficient in this function and was designated AAPT1. The deduced amino acid sequence of the soybean cDNA showed nearly equal similarity to each of the two characterized AAPTase sequences from yeast, cholinephosphotransferase and ethanolaminephosphotransferase (CDP-ethanolamine:sn-1,2-diacylglycerol ethanolaminephosphotransferase). Moreover, assays of soybean AAPT1-encoded enzyme activity in yeast microsomal membranes revealed that the addition of CDP-ethanolamine to the reaction inhibited incorporation of 14C-CDP-choline into phosphatidylcholine in a manner very similar to that observed using unlabeled CDP-choline. Although DNA gel blot analysis suggested that AAPT1-like sequences are represented in soybean as a small multigene family, the same AAPT1 isoform isolated from a young leaf cDNA library was also recovered from a developing seed cDNA library. Expression assays in yeast using soybean AAPT1 cDNAs that differed only in length suggested that sequences in the 5'leader of the transcript were responsible for the negative regulation of gene activity in this heterologous system. The inhibition of translation mediated by a short open reading frame located 124 bp upstream of the AAPT1 reading frame is one model proposed for the observed down-regulation of gene activity.

Amino Acid Sequence↗

A family with chronic haemolysis and selective accumulation of erythrocyte CDP-choline.

In this paper, we report a family with compensated chronic haemolysis where the only erythrocyte abnormality detected was an increased level of erythrocyte CDP-choline. Using 31P-NMR spectroscopy and enzymatic analysis the possibility of a pyrimidine 5'-nucleotidase deficiency was excluded. Thus, this family represents the first evidence for a hereditary haemolytic anaemia where the inferred enzymatic defect is located to choline phosphotransferase, the enzyme catalysing the final step in lecithin synthesis. The family history indicates an autosomal dominant mode of transmission with incomplete penetrance.

5'-Nucleotidase↗

Effect of feeding protein deficient diet on phospholipid turnover and protein kinase C mediated protein phosphorylation in rat brain.

Feeding of protein deficient diet is known to alter the transmembrane signalling in brain of rat by reducing total protein kinase C (PKC) activity. Phospholipid metabolism regulates the activation of PKC through generation of second messengers and the extent of PKC activation accordingly influences the magnitude of phosphorylation of its endogenous substrate proteins. Thus it was speculated that ingestion of protein deficient diet may modify the turnover rate of membrane phospholipids and magnitude of phosphorylation of endogenous substrate proteins of PKC. The experiments were conducted on rats fed on three different types of laboratory prepared diets viz. casein (20% casein), deficient (4% protein, rice flour as source of protein) and supplemented (deficient diet supplemented with L-lysine and DL-threonine) for 28 days. The metabolism of phosphoinositides (PIs) and phosphatidyl choline (PC) was studied by equilibrium labeling with [3H] myo inositol and [14C methyl] choline chloride respectively. The phosphorylation of endogenous substrate proteins of PKC was studied by using 32P-gamma-ATP followed by SDS-PAGE and autoradiography. The results suggest that in deficient group, there is an increased incorporation of [3H] myo inositol in PIs and inositol phosphate pool in comparison to the casein group. The phosphatidyl inositol (PI) turnover reduced, although there was a marginal increase in the phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bis phosphate (PIP2). Supplementation of diet showed a reversal of the pattern towards control to a considerable extent. In the deficient group, PC metabolism showed an increased incorporation of [14C methyl] choline in choline phospholipids but decreased incorporation in phosphoryl choline in comparison with the casein group. The increase in total PC contents was significant but marginal in residue contents. The turnover rate of PC increased only marginally and that of residue declined. Supplementation of diet reduced the total contents of PC and residue, but the turnover rate of PC and residue remained still higher. Phosphorylation of endogenous proteins showed four different proteins of 78, 46, 33 and 16 kDa to be the substrates of PKC in casein group. In deficient group, phosphorylation of these proteins increased markedly while supplementation of diet had a reversing effect rendering the values to be intermediate between casein and the supplemented group. The changes in phospholipid metabolism and in phosphorylation of endogenous substrate proteins of PKC suggest that dietary protein deficiency causes alterations in transmembrane signalling mechanism in rat brain. These effects are partially reversed by improving the quality of proteins in the diet.

Animals↗

Dietary regulation of dipalmitoyl phosphatidylcholine in the lung. Effects of essential fatty acid deficiency.

An essential fatty acid deficiency resulted in a significant decrease of saturated phosphatidylcholine in rat lung tissue, with the reduction being mainly due to that of dipalmitoyl species. This decrease was almost completely reversed by administration of a diet containing linoleate from seven days. The features of saturated phosphatidylcholine synthesis in the deficient rat lung slices were studied with labeled precursors in the presence of different concentrations of linoleate and oleate in the medium. Labeling patterns of saturated phosphatidylcholine using [2-3H]glycerol and [Me-14C]choline were unaffected in all ratios of linoleate to oleate examined. The incorporation rates of both [3H]acetate and [1-14C]palmitate into saturated phosphatidylcholine decreased in the deficient state, but that of the palmitate label increased markedly with increase in the concentration of linoleate in the medium. This stimulatory effect due to the increased linoleate concentration, however, was not found with the acetate label. While the utilization of 1-[1-14C]palmitoyl glycerophosphocholine by lung tissue was enhanced in the deficient state, in the presence of linoleate it showed almost the same level as that of the controls. The essential fatty acid deficiency resulted in an increase in the activity of liver choline kinase by 46%. However, other enzyme activities involved in phosphatidylcholine synthesis in the lung and liver were unaffected by the deficient state.

Acetates↗

[The dementias].

Statistics indicate that in Europe people over 65 years of age will be 23.5% at the beginning of the next century and prevalence of severe dementias is estimated to be 5% in this population group. Clinically, dementia is a syndrome characterized by memory loss, other cognitive dysfunctions and loss of ability for self-care. This organic syndrome, that can have many different causes, must be differentiated from other similar psychiatric disorders of the elderly such as the pseudo-dementias. The most important of these causes are Alzheimer's disease (AD) and vascular dementias. Other causes are infections, toxic and metabolic disorders, normal pressure hydrocephalus and head trauma. Many efforts are required in order to reach an accurate differential diagnosis, as 10-15% of the dementia syndromes are reversible if an appropriate therapy is applied. Because of its high frequency, AD is one of the most actively studied areas in dementia research. The specific causes of AD are still unknown, but recent case-control studies suggest the importance of risk factors such as familiarity and previous head trauma. Other hypotheses concern prion infections, aluminium toxicity and immunologic disorders. The most important findings of the last years however, concern biochemical alterations in Alzheimer's brains. After the first observations of Davies and Maloney (1976), who observed a reduction of choline acetyltransferase in cerebral cortex, many reports successively indicated the importance of deficiencies of the cholinergic systems in AD. Other neurotransmitter systems, such as the noradrenergic and the serotoninergic systems, were also found to be involved in AD. From these findings a rational therapeutic approach to the disease was proposed. Initially, the clinical trials employed physostigmin with uncertain results. Later, therapeutic attempts with choline, lecitine, acetylcarnitine and phosphatidilserine resulted more promising, at least in the initial phase. However, consistent data are not yet completely available. Finally, the management of AD also concerns problems of familiar education to the behavioural management of AD patients and the eventual possibilities of social assistance. Vascular dementia and Creutzfeldt-Jakob disease will also be discussed.

Aged↗

Decompensation of hepatic and cerebral acyl-CoA metabolism in BALB/cByJ mice by chronic riboflavin deficiency: restoration by acetyl-L-carnitine.

BALB/cByJ mice have an autosomal recessive deficiency of short-chain acyl-CoA dehydrogenase (SCAD) and show elevated excretion of urinary butyrylglycine, ethylmalonate, and methylsuccinate, which resembles the SCAD deficiency disorder in children. These mice are clinically normal, perhaps because of an efficient acyl-CoA conjugation system. We attempted to decompensate the acyl-CoA metabolism in mutant mice by chronic treatment with a riboflavin-deficient diet for 3 weeks to potentiate the SCAD deficiency. We studied the urinary profiles of organic acids, acylglycines, hepatic and cerebral profiles of carnitines, and ammonia to assess the potentiation of this disorder. Cerebral activity of choline acetyltransferase (ChAT) was determined to study the effects of acyl-CoA accumulation on the cholinergic system. The results indicate that in riboflavin-deficient mutant mice, the excretion of ethylmalonate, methylsuccinate, butyrylglycine, and dicarboxylic acids was enhanced. Hepatic and cerebral free and esterified carnitines were reduced, indicating a potentiation of the secondary carnitine deficiency. Hepatic ammonia levels, but not cerebral ammonia or glutamine levels, were elevated, indicating a tendency towards secondary hyperammonemia. Brain choline acetyltransferase activity was significantly reduced in striatum, implying a reduced availability of cerebral acetyl-CoA or a decreased cerebral transport of choline: Most of these changes were partially or completely restored by a concomitant treatment with acetyl-L-carnitine (ALCAR). In summary, we conclude that BALB/cByJ mice with SCAD deficiency, but with a functional urea cycle, might have an adequate adaptive mechanism to adjust to an excessive acyl-CoA load without hyperammonemia at the cerebral level. However, any deficiency of vitamins or cofactors in the diet could disturb an adaptation to this disorder and produce an effect on the cholinergic system.

Acetylcarnitine↗

[Comparative analysis of potassium and sodium flux across a muscle fiber membrane in a saline medium deficient in alkali metal cations].

Sodium and potassium fluxes from frog sartorius in magnesium-, choline- and Tris-Ringer solutions free of sodium and potassium have been studied wih the flame-emission technique. In the media examined the rate constant of potassium loss appeared to decrease as much as by 100 times when the internal sodium increases from 10 to 60-130 mumol/g. d. w. At. high internal sodium concentration, ouabain (10(-4) M) significantly increases the loss of potassium, whereas at low sodium concentration there is no such effect. The role of potassium reabsorption in the phenomena observed has been analyzed. No constant stoichiometry between the changes in ouabain-sensitive sodium fluxes and "reabsorbed" potassium fluxes has been found. With ouabain applied the time-course of shifts of these two fluxes are different. It is suggested that the effect of the internal sodium concentration and ouabain on potassium loss in sodium, and potassium-free media may be due not only to the reabsorption of potassium, but also to the change of potassium efflux itself.

Animals↗

Fragmentation of the distal portion of Tomes' processes of secretory ameloblasts in the forming enamel of rat incisors.

In order to investigate enamel and dentin phospholipid metabolic pathways, two separate experiments were carried out. Firstly, rats were given chloroquine, a drug which induces a lipidosis-like disease. Extensive accumulation inside lysosomes was seen in all the groups of cells in the forming part of the rat incisor, except secretory ameloblasts which were unaffected by the drug. Secondly, the uptake and fate of 3H-choline were studied by radioautography on rats fed either normally or on an essential fatty acid deficient diet (EFAD). Four hours after the injection of the precursor, incorporation reached a maximum then decreased gradually. At 4 days the forming enamel displayed higher silver grain density than any other compartment. In EFAD rats 3H-choline incorporation was decreased drastically in each compartment except in the forming enamel which was not affected by the deficiency. The longer retention of the labeling in the forming enamel and the lack of lysosomal accumulation in chloroquine-treated secretory ameloblasts support the hypothesis that fragments of the distal Tomes' process are released during enamel formation. Disconnected from the cells, membrane remnants are neither reinternalized nor subjected to further degradation inside lysosomes.

Ameloblasts↗