Lecithin consumption increases acetylcholine concentrations in rat brain and adrenal gland

Lecithin's Roles in Oleogelation

This manuscript analyzes the research considering the exploitation of lecithin in oleogelation. The main objective of the work was to gather, analyze, and extract from the existing research data the information that enables us to identify lecithin-dependent roles. Oleogelation is still under research, while using various oleogelators and structurants provides changes on different physico-chemical levels. Multivariable formulations do not facilitate the elucidation of the specific role of any of them. Lecithin, due to its complex structure, big molecule, and amphiphilic nature, can provide different functionalities in complex matrices like oleogels. Therefore, this review identifies and categorizes the functionality of lecithin in oleogelation into four main roles: 1. oleogelation facilitator; 2. structure-forming impact; 3. texturing agent; and 4. functionality provider. Also, the origin and structure-forming characteristics of lecithin, as well as a short summary of the oleogelation process itself, are presented. Our critical analysis allowed us to identify the roles of lecithin in the oleogelation process and categorized them as follows: oleogelator, emulsifier, structural organization facilitator, structural modifier, crystal characteristics modifier, self-assembly promoter, thermal behavior changer, hydrogen-bonded networks promoter, hydrogel structure modifier, texture and structural modifier, gel-like state promoter, oil capacity enhancer, functionality provider, shelf life extender, and bioavailability and bioaccessibility enhancer. Lecithin came out as an important and multifunctional compound whose applications in oleogelation need to be thoroughly pre-considered. It is crucial to grasp all the possible roles of used compounds to be able to predict the final functionality and characteristics of formed oleogel matrices.

Circulating metabolites modulated by diet are associated with depression

Metabolome reflects the interplay of genome and exposome at molecular level and thus can provide deep insights into the pathogenesis of a complex disease like major depression. To identify metabolites associated with depression we performed a metabolome-wide association analysis in 13,596 participants from five European population-based cohorts characterized for depression, and circulating metabolites using ultra high-performance liquid chromatography/tandem accurate mass spectrometry (UHPLC/MS/MS) based Metabolon platform. We tested 806 metabolites covering a wide range of biochemical processes including those involved in lipid, amino-acid, energy, carbohydrate, xenobiotic and vitamin metabolism for their association with depression. In a conservative model adjusting for life style factors and cardiovascular and antidepressant medication use we identified 8 metabolites, including 6 novel, significantly associated with depression. In individuals with depression, increased levels of retinol (vitamin A), 1-palmitoyl-2-palmitoleoyl-GPC (16:0/16:1) (lecithin) and mannitol/sorbitol and lower levels of hippurate, 4-hydroxycoumarin, 2-aminooctanoate (alpha-aminocaprylic acid), 10-undecenoate (11:1n1) (undecylenic acid), 1-linoleoyl-GPA (18:2) (lysophosphatidic acid; LPA 18:2) are observed. These metabolites are either directly food derived or are products of host and gut microbial metabolism of food-derived products. Our Mendelian randomization analysis suggests that low hippurate levels may be in the causal pathway leading towards depression. Our findings highlight putative actionable targets for depression prevention that are easily modifiable through diet interventions.

Oral Administration of Egg- and Soy-Derived Lysophosphatidylcholine Mitigated Acetylcholine Depletion in the Brain of Scopolamine-Treated Rats

Enzyme-modified lecithin that contains lysophosphatidylcholine (LPC) is generally recognized as safe. However, its potential as a functional ingredient has been less investigated than other choline (Ch)-containing compounds, such as glycerophosphocholine (GPC). Reports on the possibility of LPC functioning as a cholinergic precursor in vivo and on its kinetics are limited to docosahexaenoic acid-bound LPC. Herein, three experiments were performed to investigate these processes in scopolamine (SCO)-treated rats. First, an egg-derived LPC reagent was orally administered to rats, and brain acetylcholine (ACh), Ch, plasma Ch, and LPC were measured. Second, soy- and rapeseed-derived enzyme-modified lecithins and GPC were administered for comparison. Third, soy-derived enzyme-modified lecithins with different fat contents were administered for comparison. The LPC reagent mitigated SCO-induced ACh depletion at 500 mg/kg body weight and increased plasma Ch, but not LPC, concentrations. Additionally, soy-derived LPC-containing food additive counteracted brain ACh depletion similarly to GPC. Interestingly, plasma Ch and linoleoyl-LPC levels were higher when soy-derived LPC with a higher fat content was administered, whereas the plasma levels of palmitoyl-LPC decreased and those of total LPC remained constant. In conclusion, egg- and soy-derived LPC species function as cholinergic precursors in vivo, and future studies should explore this potential.

Choline supplements: An update

In this comprehensive review, we examine the main preclinical and clinical investigations assessing the effects of different forms of choline supplementation currently available, including choline alfoscerate (C₈H₂₀NO₆P), also known as alpha-glycerophosphocholine (α-GPC, or GPC), choline bitartrate, lecithin, and citicoline, which are cholinergic compounds and precursors of acetylcholine. Extensively used as food supplements, they have been shown to represent an effective strategy for boosting memory and enhancing cognitive function.

Dietary choline supplementation in adult rats improves performance on a test of recognition memory

In two experiments adult rats (aged at least 6 months at the start of the procedure) received a diet enriched with added choline for a period of 10 weeks; control subjects were maintained on a standard diet during this time. All rats then underwent the spontaneous object recognition (SOR) procedure in which they were exposed to a pair of objects and then tested, after a retention interval, to a display with one object changed. Exploration of the changed object indicates retention and use of information acquired during the exposure phase. All subjects showed retention with a 24-h interval (Experiments 1 and 2) and when retested after a further 24 h (Experiment 1). But when tested for the first time after a 48-h interval (Experiment 2), control subjects showed no evidence of retention, exploring both objects equally, whereas those given the dietary supplement continued to show a preference for the changed object. This supports the conclusion that dietary choline supplementation can enhance performance on a task regarded as a test of declarative memory, and will do so even when the supplementations is given in adulthood.

No Acute Effects of Choline Bitartrate Food Supplements on Memory in Healthy, Young, Human Adults

Choline is a dietary component and precursor of acetylcholine, a crucial neurotransmitter for memory-related brain functions. In two double-blind, placebo-controlled cross-over experiments, we investigated whether the food supplement choline bitartrate improved declarative memory and working memory in healthy, young students one to two hours after supplementation. In experiment 1, 28 participants performed a visuospatial working memory task. In experiment 2, 26 participants performed a declarative picture memorization task. In experiment 3, 40 participants performed a verbal working memory task in addition to the visuospatial working memory and declarative picture task. All tasks were conducted approximately 60 minutes after the ingestion of 2.0–2.5g of either choline bitartrate or placebo. We found that choline did not significantly enhance memory performance during any of the tasks. The null hypothesis that choline does not improve memory performance as compared to placebo was strongly supported by Bayesian statistics. These results are in contrast with animal studies suggesting that choline supplementation boosts memory performance and learning. We conclude that choline likely has no acute effects on cholinergic memory functions in healthy human participants.

Chronic dietary choline supplementation modulates attentional change in adult rats

In two experiments adult rats were maintained on a diet enriched with added choline for 12 weeks prior to behavioral testing; control rats remained on the standard diet during this time. In Experiment 1 all rats received training in the Hall-Pearce negative transfer paradigm in which prior training with a conditioned stimulus (CS) paired with a small reinforcer retards further learning when the size of the reinforcer is increased. This effect, which has been attributed to a loss of associability by the CS, was obtained in control subjects but not in those given the supplement. Experiment 2 investigated the effect of prior nonreinforced exposure of the to-be-CS (latent inhibition). Such exposure retarded subsequent learning in control subjects, but latent inhibition was not obtained in those given the supplement. We conclude that the mechanism that reduces the attention paid to a stimulus that accurately predicts its consequences does not operate effectively after choline supplementation. These results are consistent with a role for the cholinergic system of the basal forebrain in modulation of attention.

Neurotransmitter-precursor-supplement intervention for detoxified heroin addicts

This study examined the effects of combined administration of tyrosine, lecithin, L-glutamine and L-5-hydroxytryptophan (5-HTP) on heroin withdrawal syndromes and mental symptoms in detoxified heroin addicts. In the cluster-randomized placebo-controlled trial, 83 detoxified heroin addicts were recruited from a detoxification treatment center in Wuhan, China. Patients in the intervention group (n=41) were given the combined treatment with tyrosine, lecithin, L-glutamine and 5-HTP and those in the control group (n=42) were administered the placebo. The sleep status and the withdrawal symptoms were observed daily throughout the study, and the mood states were monitored pre- and post-intervention. The results showed that the insomnia and withdrawal scores were significantly improved over time in participants in the intervention group as compared with those in the control group. A greater reduction in tension-anxiety, depression-dejection, anger-hostility, fatigue-inertia and total mood disturbance, and a greater increase in their vigor-activity symptoms were found at day 6 in the intervention group than in the control group (all P<0.05). It was concluded that the neurotransmitter-precursor-supplement intervention is effective in alleviating the withdrawal and mood symptoms and it may become a supplementary method for patients' recovery from heroin addiction.

Dietary restriction of choline reduces hippocampal acetylcholine release in rats: in vivo microdialysis study

We fed rats with a diet deficient in choline for 12 weeks and studied how dietary choline deficiency affected their behavior and their ability to release acetylcholine in discrete regions of rat brain using step-through passive avoidance task and in vivo microdialysis. In comparison with the control, rats fed the choline-deficient diet showed poorer retention of nociceptive memory in the passive avoidance task. Average choline level in cerebrospinal fluid in the choline-deficient group was significantly less (33.1%) than that of control rats. In vivo microdialysis showed no difference in the pattern of acetylcholine release enhanced by intraperitoneal administration of scopolamine hydrochloride (2 mg/kg) in the striatum between the two groups, whereas in the hippocampus, the maximum and subsequent increase of acetylcholine from the baseline by scopolamine injection was significantly lower in the choline-deficient group than in the control. From the results of our study, we speculate that long-term dietary restriction of choline can affect extra- and intracellular sources of substrates required for acetylcholine synthesis, and eventually limit the ability to release acetylcholine in the hippocampus. Reduced capacity to release acetylcholine in the hippocampus implies that the mechanism, maintaining acetylcholine synthesis on increased neuronal demand, may vary in discrete regions of the brain in response to dietary manipulation. The vulnerability of the mechanism in the hippocampus to dietary choline restriction is indicated by impaired mnemonic performance we observed.

1-Methyl-4-phenyl-pyridinium increases S-adenosyl-L-methionine dependent phospholipid methylation

1-Methyl-4-phenyl-pyridinium (MPP(+)) and S-adenosyl-L-methionine (SAM) cause Parkinson's disease (PD)-like changes. SAM and MPP(+) require their charged S-methyl and N-methyl groups, so the PD-like symptoms may be related to their ability to modulate the methylation process. The SAM-dependent methylation of phosphatidylethanolamine (PTE) to produce phosphatidylcholine (PTC), via phosphatidylethanolamine-N-methyltransferase (PEMT), and the hydrolysis of PTC to form lyso-PTC, a cytotoxic agent, are potential loci for the action of MPP(+). In this study, the effects of MPP(+) on the methylation of PTE to PTC and the production of lyso-PTC were determined. The results showed that SAM increased PTC and lyso-PTC. The rat striatum showed the highest PEMT activity and lyso-PTC formation, which substantiate with the fact that the striatum is the major structure that is affected in PD. MPP(+) significantly enhanced PEMT activity and the formation of lyso-PTC in the rat liver and brain. MPP(+) increased the affinity and the V(max) of PEMT for SAM. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) effect was lesser and inhibited by deprenyl (MAO-B inhibitor). The nor-methyl analogs of MPP(+) were inactive, but some of the charged analogs of MPP(+) showed comparable effects to those of MPP(+). Lyso-PTC that can be increased by SAM and MPP(+) caused severe impairments of locomotor activities in rats. These results indicate that SAM and MPP(+) have complementary effects on phospholipid methylation. Thus, SAM-induced hypermethylation could be involved in the etiology of PD and an increase of phospholipid methylation could be one of the mechanisms by which MPP(+) causes parkinsonism.

Learning behaviour and cerebral protein kinase C, antioxidant status, lipid composition in senescence-accelerated mouse: influence of a phosphatidylcholine-vitamin B12 diet

Our objective was to determine whether dietary supplementation with phosphatidylcholine (PC) plus vitamin B12 could afford beneficial effects on biochemical and biophysical events in the brain of senescence-accelerated mouse (SAM) substrain SAMP8. We measured learning behaviour, hippocampal protein kinase C (PKC) activity, cerebral antioxidant status, phospholipid composition and fatty acid composition in 6-month-old SAMP8 and in age-matched controls (SAM substrain SAMR1). In comparison with SAMR1, SAMP8 showed a significant elevation in total grading score of senescence and a significant decline in acquisition SAMP8 had a lower hippocampal PKC activity and cerebral PKC-beta mRNA abundance than SAMR1. SAMP8 had increased cerebral lipid peroxide levels and proportion of sphingomyelin, and a lower proportion of 20 : 4n-6 and 22 : 6n-3 in cerebral phosphtidylethanolamine than SAMR1. SAMP8 fed the PC combined with vitamin B12 diet had an increased PKC activity and a higher proportion of 22 : 6n-3 than SAMP8 fed the control diet. These results indicate the potential benefit of PC combined with vitamin B12 as a dietary supplement.

Can nutrient supplements modify brain function?

Over the past 40 y, several lines of investigation have shown that the chemistry and function of both the developing and the mature brain are influenced by diet. Examples are the effect of folate deficiency on neural tube development during early gestation, the influence of essential fatty acid deficiency during gestation and postnatal life on the development of visual function in infants, and the effects of tryptophan or tyrosine intake (alone or as a constituent of dietary protein) on the production of the brain neurotransmitters derived from them (serotonin and the catecholamines, respectively). Sometimes the functional effects are clear and the underlying biochemical mechanisms are not (as with folate and essential fatty acids); in other cases (such as the amino acids tyrosine and tryptophan), the biochemical effects are well understood, whereas the effect on brain function is not. Despite the incomplete knowledge base on the effects of such nutrients, investigators, physicians, and regulatory bodies have promoted the use of these nutrients in the treatment of disease. Typically, these nutrients have been given in doses above those believed to be required for normal health; after they have been given in pure form, unanticipated adverse effects have occasionally occurred. If this pharmacologic practice is to continue, it is important from a public safety standpoint that each nutrient be examined for potential toxicities so that appropriate purity standards can be developed and the risks weighed against the benefits when considering their use.

EGG phosphatidylcholine combined with vitamin B12 improved memory impairment following lesioning of nucleus basalis in rats

We investigated the effects of egg phosphatidylcholine (PC) combined with vitamin B12 on memory in the Morris water maze task, and on choline and acetylcholine (ACh) concentrations in the brain of rats. Animals with nucleus basalis Magnocellularis (NBM) lesion received intragastric administration of egg PC or vitamin B12, or both for 18 days. Memory acquisition and retention were remarkably impaired in NBM lesioned rats compared with in sham-operated control. NBM lesioned group had lower choline and ACh concentrations than control group in the frontal cortex. High dose of egg PC alone significantly increased choline concentration, but did not change ACh concentration in the frontal cortex. High dose of vitamin B12 alone did not change choline and ACh concentrations in the brain. Either egg PC or vitamin B12 did not improve memory acquisition and retention. However, low dose of egg PC combined with vitamin B12 significantly increased ACh concentration and improved memory acquisition and retention in the NBM lesioned rats. We concluded that egg PC combined with vitamin B12 improved the memory impairment of NBM lesioned rats through the action on the cholinergic neurons.

Muscarinic agonists in Alzheimer's disease

As therapeutic agents, M1 agonists in the short-term may palliate symptoms of AD and improve memory function. In the long-term, M1 agonists have the potential to modify the underlying pathophysiology of AD, and thereby prevent or retard the course of dementia.

Choline enhances scopolamine-induced acetylcholine release in dorsal hippocampus of conscious, freely-moving rats

We examined the effects of exogenous choline (30, 60, 120 mg/kg, i.p.) on basal and scopolamine-evoked acetylcholine (ACh) release in awake animals, using in vivo microdialysis. After collection of 3-4 baseline dialysate samples (15 min each), rats received either saline or choline chloride and 4 additional samples were collected. All animals then received scopolamine hydrochloride (0.5 mg/kg, i.p.) and 6 additional samples were collected. Basal ACh release in animals receiving choline did not differ from that in rats given saline, nor from ACh release prior to choline administration. Scopolamine alone increased average ACh levels in dialysates from 1.22 +/- 0.54 to 11.18 +/- 3.07 pmol/15 min (mean +/- SD; p = 0.001); administration of 60 mg/kg or 120 mg/kg of choline chloride significantly enhanced maximal scopolamine responses by about 55%. These results suggest that supplemental choline enhances evoked ACh release in hippocampus of freely-moving rats.

Short-term feeding of a diet enriched in phospholipids increases bile formation and the bile acid transport maximum in rats

Earlier studies suggested that the secretory rate maximum (SRm) of bile acid and the cholestasis which occurs after the SRm is reached may be determined by the hepatic or extrahepatic biliary phospholipid pool. We therefore investigated whether bile formation and the bile acid SRm could be influenced by feeding a diet enriched in phospholipids. Male rats were fed phospholipid (PLD) or triacylglycerol (TgD)-enriched diet for 3 days, and bile formation as well as biliary lipid output were measured on the 4th day. In other similarly fed groups, cholic acid was infused in stepwise increasing doses to determine the effect of PLD on the SRm of cholic acid. The plasma lipid levels were significantly lower in PLD and TgD diets compared to basal diet. But, while the levels of total cholesterol (CH), HDL-CH, and phospholipid (PH) were not significantly altered by PLD compared to TgD, the triacylglycerol levels were markedly increased by PLD. In the liver of PLD fed rats, triacylglycerol and CH ester contents decreased by 39 and 62%, respectively, while free CH and PH contents were not significantly changed. The PLD significantly augmented spontaneous bile flow, bile acid, PH and CH secretion rates compared to TgD diet (65, 124, 164 and 654%, respectively). The enhanced biliary secretory function was associated with an increase in pericanalicular vacuoles and diverticuli in centrilobular hepatocytes. Compared to TgD fed rats, PLD rats showed a 2-fold decrease in the ratio of cholic acid/chenodeoxycholic acid in bile and a significant decrease in the % contribution of taurine conjugated BA. The PH fatty acids in bile were similar in both groups except that in PLD group the % contribution of C18:2 was higher than in TgD group. No differences were found in plasma membrane CH/PH content or total fatty acid composition. During bile acid infusion, the SRm and the total cholic acid secreted were significantly higher in the PLD than in the TgD rats. Moreover, the cholestatic response observed after high bile acid dose was markedly reduced by PLD. The results show that short-term feeding of PLD induces changes in CH and bile acid metabolism which result in enhanced biliary output of CH and PH. The enhanced pool of biliary lipid may protect plasma membranes from the deleterious effects of high bile acid concentrations.

Action of chronic choline administration on behavior and on cholinergic and noradrenergic systems

Chronic administration of low doses (0.2-0.8 g/kg/day) of choline caused in the rat an increase of errors evaluated in the staircase maze after 20 days of interruption of daily training. An analogous pharmacological treatment caused no modification of the acetylcholine (ACh) and norepinephrine (NE) levels and no consistent modification of the density of muscarinic and alpha 1-adrenergic receptors. Only at higher doses (2.5 g/kg/day) did chronic administration (20 days) of choline cause in several sections of the CNS, an increase of ACh and NE levels and of the muscarinic receptor density. These observations indicate that only at high doses of choline are there consistent modifications of the central cholinergic systems, suggesting that the behavioral modifications observed at low doses of choline are not determined by an upregulation of the central cholinergic system.

Caffeine potentiates the enhancement by choline of striatal acetylcholine release

We investigated the effect of peripherally administered caffeine (50 mg/kg), choline (30, 60, or 120 mg/kg) or combinations of both drugs on the spontaneous release of acetylcholine (ACh) from the corpus striatum of anesthetized rats using in vivo microdialysis. Caffeine alone or choline in the 30 or 60 mg/kg dose failed to increase ACh in microdialysis samples; the 120 mg/kg choline dose significantly enhanced ACh during the 80 min following drug administration. Coadministration of caffeine with choline significantly increased ACh release after each of the choline doses tested. Peak microdialysate levels with the 120 mg/kg dose were increased 112% when caffeine was additionally administered, as compared with 54% without caffeine. These results indicate that choline administration can enhance spontaneous ACh release from neurons, and that caffeine, a drug known to block adenosine receptors on these neurons, can amplify the choline effect.

Age-related changes in memory and their pharmacologic modulation

A passive avoidance procedure was used to measure the ability to learn and remember to avoid a noxious stimulus in 13-month-old mice and to test the effects that treatment with cytidine(5')-diphosphocholine (CDP-choline) had on these processes. Half of the mice received 500 mg/kg per day CDP-choline orally for 4 months, and the two groups were compared with a third group of younger animals (4-month-old mice). The older mice showed marked impairment in the execution of these tests; however, those treated with CDP-choline had significant improvement in their performance 24 hours after learning the task.

Effect of choline administration on the release of acetylcholine from the striatum as determined by microdialysis in awake rats

The release of acetylcholine from the striatum was recorded by an on-line microdialysis method during intraperitoneal administration of high doses of choline (1 mmol/kg). The effect of choline administration was also studied in rats in which the striatal release of acetylcholine was stimulated by atropine infusion. The results did not support the idea that the release of acetylcholine in the striatum is under the control of precursor availability.

Effects of dipalmitoylphosphatidylcholine liposomes on high affinity transport of choline and synthesis of acetylcholine in cerebral cortical synaptosomes in the rat

The presynaptic cholinergic effects of the phospholipid dipalmitoylphosphatidylcholine were investigated in non-depolarized synaptosomes from the cerebral cortex of the rat. This naturally-occurring phospholipid, in the form of small unilamellar vesicles (3.0 mg/ml), inhibited both high affinity uptake of [3H] choline and the synthesis of [3H] acetylcholine. This lipid-induced inhibition was apparently competitive, since it was observed at 1 microM but not 20 microM extracellular concentration of choline. These results indicate that dipalmitoylphosphatidylcholine may reduce the synthesis of acetylcholine in resting nerve terminals.

A long-lasting cholinesterase inhibitor affecting neural and behavioral processes

A series of analogues of physostigmine were prepared with the aim of investigating their inhibitory effects on acetylcholinesterase in the treatment of Alzheimer's disease. One of the isomers prepared was evaluated for its anticholinesterase activity in vivo, acute toxicity, and some behavioral effects. This compound was a competitive inhibitor of the enzyme and was found to antagonize the stimulating effect produced by scopolamine on locomotor activity and to facilitate memory consolidation.

Effects of choline augmentation on acetylcholine synthesis and release in rat atrial minces

The uptake and acetylation of [3H]-choline, as well as the calcium-dependent release of a newly synthesized [3H]-ACh, was studied in a new rat atrial mince preparation. The hemicholinium-3-sensitive uptake and acetylation of [3H]-choline increased as [3H]-choline concentrations were elevated to 100 microM in atrial minces. In contrast, hemicholinium-3-sensitive [3H]-choline uptake was saturated with 15 microM [3H]-choline in brain synaptosomes. The increased atrial [3H]-ACh synthesized in the presence of [3H]-choline augmentation was releasable by 50 mM K+-depolarization in a 1 mM cobalt-sensitive manner. These results suggest that atrial parasympathetic activity may be more sensitive to circulating choline concentrations than brain cholinergic neurons are.

Action of arecoline on the levels of acetylcholine, norepinephrine and dopamine in the mouse central nervous system

Modifications caused by arecoline (2 mg/kg and 10 mg/kg injected subcutaneously) in the levels of acetylcholine (ACh), norepinephrine (NE) and dopamine (DA) in the mouse cortex and "subcortex" were studied. The animals were killed by microwave irradiation of the head 15 minutes after drug administration. Arecoline 10 mg/kg caused a reduction in levels of ACh in the cortex and "subcortex" at the limit of statistical significance (p 5-10%) and a statistically significant reduction in levels on NE. A statistically significant increase in DA was observed only in the cortex after 2 mg/kg and 10 mg/kg of arecoline.

Brain and serum levels of choline and lecithin resulting from long-term administration

Choline and phosphatidylcholine tissue concentrations were examined in mice treated with long-term (18-22 month) dietary choline enrichment, choline deficiency, or phosphatidylcholine enrichment. There were no significant differences found in choline levels among the dietary groups in any of the tissues examined: plasma, erythrocytes, cortex, hippocampus, and striatum. In contrast, the concentration of phosphatidylcholine in both the choline enriched and phosphatidylcholine enriched groups were significantly increased in the cortex, compared to the choline deficient group, and in the striatum, compared to control. No differences in phosphatidylcholine concentration were found in the hippocampus or plasma between any of the dietary groups. These results are in contrast to the reported effects of acute or short-term choline and phosphatidylcholine treatment and indicate that there may be differences between the effects of short-term and long-term administration on the blood and brain levels of choline and phosphatidylcholine.

Lack of clinically significant improvement of patients with tardive dyskinesia following phosphatidylcholine therapy

A double-blind controlled study was undertaken to examine the value of phosphatidylcholine as a treatment for tardive dyskinesia (TD) in 19 psychiatric patients. All patients were maintained on their usual psychotropic medication throughout the entire study. In addition, they were given either phosphatidylcholine (30 g/day) or placebo for 6 weeks. Thirteen of the patients received the crossover treatment for 6 weeks, after which 10 of the 13 were continued on the crossover medication for an additional 6 weeks. At the end of the study, 5 patients had received phosphatidylcholine for 12 weeks and another 12 patients had received the drug for only 6 weeks. Plasma and red blood cell choline levels were monitored every 3 weeks as a measure of compliance. Although some patients showed clinical improvement of their TD, the results did not differ significantly between active drug and placebo. This was in spite of a marked elevation of plasma and red blood cell choline (up to 300% for the Lafayette Clinic patients and up to 400% for the patients from the Ypsilanti Regional Psychiatric Hospital) during treatment with phosphatidylcholine. Side effects of the drug included occasional gastrointestinal upsets and diarrhea but, in general, the medication was tolerated very well. The results indicate that large doses of phosphatidylcholine of soya origin are of no clinical value in treating symptoms of TD in spite of very large increases in blood choline.

Dietary tryptophan does not alter the function of brain serotonin neurons

The hypothesis that alterations in dietary tryptophan modify the functional activity of brain serotonin-containing neurons was tested by recording the electrophysiological activity of single serotonergic cells in awake, behaving cats after meal ingestion of diets containing varying proportions of tryptophan and the neutral amino acids that compete with tryptophan for uptake into the brain. The data revealed that while the various diets produced significant changes in brain serotonin and its major metabolite, 5-hydroxyindoleacetic acid, there was no change in the activity of serotonin-containing dorsal raphe cells following meal ingestion. Furthermore, a pulse injection of tritiated labeled tryptophan following the various diets produced no significant change in the release of tritiated serotonin into the lateral ventricles, while tritiated 5-hydroxyindoleacetic acid was significantly increased. These data suggest that dietary tryptophan does not alter the functional activity of central serotonergic neurons, in contrast with current popular beliefs that such dietary manipulations alter brain function.

Dopamine in manic depressive illness. A pharmacological synthesis

If the clinical symptoms of mania are a consequence of increased activity in central dopaminergic (DA) pathways in predisposed individuals, then drugs increasing DA neurotransmission should precipitate or exacerbate mania in such people, whereas drugs which reduce DA neurotransmission should ameliorate manic symptoms. Of the drugs which enhance DA neurotransmission, those which increase synthesis of DA (levodopa), those which promote DA release (amphetamine), and those which act directly as agonists or DA receptors (bromocriptine) have all been shown to precipitate mania. Conversely, drugs which reduce DA neurotransmission by inhibiting synthesis (alpha-methylparatyrosine) or by blocking DA receptors (pimozide) are effective in reducing manic symptoms. DA systems are not working in isolation; evidence is presented showing an influence on manic illness of central cholinergic and GABA-ergic processes. It is suggested that there is an interacting set of neurotransmitter pathways linking the limbic system and the ventral tegmental (A10) area involving DA, acetylcholine and GABA upon which drugs can act to influence the course of a manic illness.

Cytidine(5')diphosphocholine enhances the ability of haloperidol to increase dopamine metabolites in the striatum of the rat and to diminish stereotyped behavior induced by apomorphine

Experiments were performed to determine whether exogenous cytidine(5')diphosphocholine (CDP-choline) could modify release of dopamine in the striatum and behavior dependent on dopamine, perhaps by providing supplemental choline for synthesis of acetylcholine. Rats received water (control) or CDP-choline orally (100 mg/kg per day, for 5 days), either alone or before injection with haloperidol (1 mg/kg, i.p.), apomorphine (0.15 mg/kg, s.c.), or both. Stereotyped behavior was measured during the hour after administration of apomorphine; levels of the dopamine metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum were assessed at the end of this period (2 hr after administration of haloperidol). In rats receiving the CDP-choline, the stereotyped behavior observed after injection of apomorphine alone (P less than 0.01), or after haloperidol plus apomorphine (P less than 0.01), was attenuated. The pretreatment with CDP-choline also significantly increased levels of HVA (by 24%) and DOPAC (by 23%) in the striatum over appropriate controls in animals receiving haloperidol, or by 29 and 59% (averaging data for all time points), respectively, in animals receiving haloperidol plus apomorphine. One mechanism by which CDP-choline may affect behavior involves contributing choline to enhance synthesis of acetylcholine.

Biochemical effects of phosphatidylcholine treatment in rats

We measured several biochemical effects of 10 days of intragastric administration of phosphatidylcholine (10 mmoles/kg) to rats because of the expanding clinical use of chronic phosphatidylcholine treatment for disorders involving impaired cholinergic neurotransmission. The plasma and erythrocyte choline concentrations were increased 3.5-fold, which was the same percent increase as found after an acute treatment with phosphatidylcholine. The lipid and fatty acid compositions of the plasma were also altered; free and total cholesterol levels increased, triglycerides increased, the monoene fatty acids generally decreased, and the diene and tetraene fatty acids generally increased. We found no effect of this treatment on the hepatic microsomal cytochrome P-450 activity or on the N-demethylation of benzphetamine or methamphetamine. Ten days of phosphatidylcholine treatment increased the concentration of choline in the brain but had no effect on the concentration of acetylcholine, the activity of choline acetyltransferase, cholinesterase activity, the apparent KD or Bmax of muscarinic receptors, or the fatty acid composition of rat brain lipids. These findings indicate that the largest effect caused by this treatment was an increase in the choline levels. No indication of altered cholinergic metabolism was observed. Further studies of the effects of chronic phosphatidylcholine treatment are required to clarify its therapeutic mechanism of action.

Nutrition and the neurosurgical patient

There has been a rapid expansion of knowledge in the field of nutrition and metabolism with regard to the general surgical patient. However, only recently has there been greater appreciation of the benefits of adequate nutrition and appropriate metabolic care of the neurosurgical patient. In this review, the authors attempt to outline 1) the metabolic response to stress in general, and how it applies to the neurosurgical patient; 2) how best to provide adequate nutritional support for the neurosurgical patient; 3) the effects of nutrition on neurotransmitters; and 4) the effect of diet and nutrition on patients with malignant brain tumors.

Choline and cholinergic neurons

Mammalian neurons can synthesize choline by methylating phosphatidylethanolamine and hydrolyzing the resulting phosphatidylcholine. This process is stimulated by catecholamines. The phosphatidylethanolamine is synthesized in part from phosphatidylserine; hence the amino acids methionine (acting after conversion to S-adenosylmethionine) and serine can be the ultimate precursors of choline. Brain choline concentrations are generally higher than plasma concentrations, but depend on plasma concentrations because of the kinetic characteristics of the blood-brain-barrier transport system. When cholinergic neurons are activated, acetylcholine release can be enhanced by treatments that increase plasma choline (for example, consumption of certain foods).

The presence of phospholipase D in rat central nervous system axolemma

An axolemma-enriched fraction prepared from a purified myelinated axon fraction isolated from rat CNS was found to contain phospholipase D at a specific activity similar to that of a microsomal fraction isolated from whole brain. There was a concomitant threefold enrichment in the specific activity of phospholipase D and acetylcholinesterase in the axolemma-enriched fraction compared with the specific activities of these enzymes in the starting white matter whole homogenate. This axonal phospholipase D may be involved in remodeling of phospholipid, which in turn may affect axonal functions such as ion translocation.

Choline administration: lack of effect on plasma catecholamines in rats

Choline chloride (35 or 70 mg/kg, IP) or saline was administered daily for 3 consecutive days to adult male Sprague-Dawley rats. Before and 30, 60 and 120 minutes after the third injection of choline chloride or saline, blood samples were collected from a chronic tail artery catheter and later analyzed for levels of norepinephrine (NE) and epinephrine (EPI). Plasma levels of both catecholamines did not differ between choline- and saline-injected rats at either of the four sampling points. When insulin (10 IU/kg, SC) was administered to stimulate the sympathetic-adrenal medullary system reflexly, plasma levels of NE and EPI increased significantly above basal values but were similar for choline- and saline-injected rats. These findings do not support a role for choline availability in the regulation of catecholamine secretion from the adrenal medulla.

The failing brain

In the elderly, loss of brain wet weight and reduction in neuronal populations may be related to declining cognitive function. In some brain areas there appear to be reduced dendritic arborization. In the aging brain, neurotransmitter metabolism is affected. Catecholamine concentration appears to be especially reduced. More marked loss of cells and synapses is seen in senile dementia of the Alzheimer's type, and there is a significant reduction in choline acetyltransferase activity and in the ability of isolated biopsy tissue to synthesise acetylcholine. The significance of these findings and the possibility of drug intervention is discussed.