Oral choline administration to patients with tardive dyskinesia

Influence of Phosphatidylcholine on Lymphatic Absorption during Peritoneal Dialysis in the Rat

The mechanism whereby i.p. administration of phosphatidylcholine increases net ultrafiltration and solute clearances after long-dwell exchanges is not established. We performed 4-h exchanges in rats using 4.25% dextrose dialysis solution with and without the addition of 50 mgl L phosphatidylcholine. Net ultrafiltration was enhanced in the treated rats (p < 0.005) by a reduction in cumulative lymphatic absorption (p < 0.01) and without a concurrent increase in total net transcapillary ultrafiltration during the dwell time. Likewise, urea and phosphate clearances with i.p. phosphatidylcholine were enhanced mainly by the increase in the drain volume since serum to dialysate solute concentration ratios did not differ significantly between the treated and control rats. Thus, phosphatidylcholine increases net ultrafiltration and solute clearances in the rat by decreasing lymphatic absorption and without increasing transperitoneal transport of water and solutes into the peritoneal cavity. The uptake of the india ink by the lymphatics of rats who received dialysis exchanges without phosphatidylcholine and the lack of uptake in rats treated with phosphatidylcholine are supported by this observation. Reduction in lymphatic absorption with the addition of phosphatidylcholine to the infused dialysis solution offers an alternative means of enhancing the efficiency of long-dwell peritoneal dialysis.

Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics

Mood disorders are highly prevalent and are the leading cause of disability worldwide. The neurobiological mechanisms underlying depression remain poorly understood, although theories regarding dysfunction within various neurotransmitter systems have been postulated. Over 50 years ago, clinical studies suggested that increases in central acetylcholine could lead to depressed mood. Evidence has continued to accumulate suggesting that the cholinergic system has a important role in mood regulation. In particular, the finding that the antimuscarinic agent, scopolamine, exerts fast-onset and sustained antidepressant effects in depressed humans has led to a renewal of interest in the cholinergic system as an important player in the neurochemistry of major depression and bipolar disorder. Here, we synthesize current knowledge regarding the modulation of mood by the central cholinergic system, drawing upon studies from human postmortem brain, neuroimaging, and drug challenge investigations, as well as animal model studies. First, we describe an illustrative series of early discoveries which suggest a role for acetylcholine in the pathophysiology of mood disorders. Then, we discuss more recent studies conducted in humans and/or animals which have identified roles for both acetylcholinergic muscarinic and nicotinic receptors in different mood states, and as targets for novel therapies.

Phospholipase D and Choline Metabolism

Phospholipases D (PLDs) catalyze hydrolysis of the diester bond of phospholipids to generate phosphatidic acid and the free lipid headgroup. In mammals, PLD enzymes comprise the intracellular enzymes PLD1 and PLD2 and possibly the proteins encoded by related genes, as well as a class of cell surface and secreted enzymes with structural homology to ectonucleotide phosphatases/phosphodiesterases as typified by autotaxin (ENPP2) that have lysoPLD activities. Genetic and pharmacological loss-of-function approaches implicate these enzymes in intra- and intercellular signaling mediated by the lipid products phosphatidic acid, lysophosphatidic acid, and their metabolites, while the possibility that the water-soluble product of their reactions is biologically relevant has received far less attention. PLD1 and PLD2 are highly selective for phosphatidylcholine (PC), whereas autotaxin has broader substrate specificity for lysophospholipids but by virtue of the high abundance of lysophosphatidylcholine (LPC) in extracellular fluids predominantly hydrolyses this substrate. In all cases, the water-soluble product of these PLD activities is choline. Although choline can be formed de novo by methylation of phosphatidylethanolamine, this activity is absent in most tissues, so mammals are effectively auxotrophic for choline. Dietary consumption of choline in both free and esterified forms is substantial. Choline is necessary for synthesis of the neurotransmitter acetylcholine and of the choline-containing phospholipids PC and sphingomyelin (SM) and also plays a recently appreciated important role as a methyl donor in the pathways of "one-carbon (1C)" metabolism. This review discusses emerging evidence that some of the biological functions of these intra- and extracellular PLD enzymes involve generation of choline with a particular focus on the possibility that these choline and PLD dependent processes are dysregulated in cancer.

Cholinergic medication for antipsychotic-induced tardive dyskinesia

BACKGROUND

Tardive dyskinesia (TD) remains a troublesome adverse effect of conventional antipsychotic (neuroleptic) medication. It has been proposed that TD could have a component of central cholinergic deficiency. Cholinergic drugs have been used to treat TD.

OBJECTIVES

To determine the effects of cholinergic drugs (arecoline, choline, deanol, lecithin, meclofenoxate, physostigmine, RS 86, tacrine, metoxytacrine, galantamine, ipidacrine, donepezil, rivastigmine, eptastigmine, metrifonate, xanomeline, cevimeline) for treating antipsychotic-induced TD in people with schizophrenia or other chronic mental illness.

SEARCH METHODS

An electronic search of the Cochrane Schizophrenia Group's Study-Based Register of Trials (16 July 2015 and April 2017) was undertaken. This register is assembled by extensive searches for randomised controlled trials in many electronic databases, registers of trials, conference proceedings and dissertations. References of all identified studies were searched for further trial citations.

SELECTION CRITERIA

We included reports identified by the search if they were of controlled trials involving people with antipsychotic-induced TD and chronic mental illness, who had been randomly allocated to either a cholinergic agent or to a placebo or no intervention. Two review authors independently assessed the methodological quality of the trials.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data and, where possible, estimated risk ratios (RR) or mean differences (MD), with 95% confidence intervals (CI). We analysed data on an intention-to-treat basis, with the assumption that people who left early had no improvement. We assessed risk of bias and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

We included 14 studies investigating the use of cholinergic drugs compared with placebo published between 1976 and 2014. All studies involved small numbers of participants (five to 60 people). Three studies that investigated the new cholinergic Alzheimer drugs for the treatment of TD are new to this update. Overall, the risk of bias in the included studies was unclear, mainly due to poor reporting; allocation concealment was not described, generation of the sequence was not explicit, studies were not clearly blinded, we are unsure if data are incomplete, and data were often poorly or selectively reported.We are uncertain about the effect of new or old cholinergic drugs on no clinically important improvement in TD symptoms when compared with placebo; the quality of evidence was very low (RR 0.89, 95% CI 0.65 to 1.23; 27 people, 4 RCTs). Eight trials found that cholinergic drugs may make little or no difference to deterioration of TD symptoms (low-quality evidence, RR 1.11, 95% CI 0.55 to 2.24; 147 people). Again, due to very low-quality evidence, we are uncertain about the effects on mental state (RR 0.50, 95% CI 0.10 to 2.61; 77 people, 5 RCTs), adverse events (RR 0.56, 95% CI 0.15 to 2.14; 106 people, 4 RCTs), and leaving the study early (RR 1.09,95% CI 0.56 to 2.10; 288 people 12 RCTs). No study reported on social confidence, social inclusion, social networks, or personalised quality of life.

AUTHORS' CONCLUSIONS

TD remains a major public health problem. The clinical effects of both older cholinergic drugs and new cholinergic agents, now used for treating Alzheimer's disease, are unclear, as too few, too small studies leave many questions unanswered. Cholinergic drugs should remain of interest to researchers and currently have little place in routine clinical work. However, with the advent of new cholinergic agents now used for treating Alzheimer's disease, scope exists for more informative trials. If these new cholinergic agents are to be investigated for treating people with TD, their effects should be demonstrated in large well-designed, conducted and reported randomised trials.

Role of Choline in the Modulation of Degenerative Processes: In Vivo and In Vitro Studies

The purpose of the present study was to examine the nutraceutical potential of choline as an added value to its well-known brain nutrient role. Several toxicity, antitoxicity, genotoxicity, antigenotoxicity, and longevity endpoints were checked in the somatic mutation and recombination test in in vivo Drosophila animal model. Cytotoxicity in human leukemia-60 cell line (HL-60) promyelocytic and NIH3T3 mouse fibroblast cells, proapoptotic DNA fragmentation, comet assay, methylation status, and macroautophagy (MA) activity were tested in in vitro assays. Choline is not only safe but it is also able to protect against the DNA damage caused by an oxidative genotoxin. Moreover, it improves the life extension in the animal model. The in vitro results show that it is able to exhibit genetic damage against leukemia HL-60 cells. Single-strand breaks in DNA are observed at the molecular level in treatments with choline, although only a significant hypermethylation on the long interspersed elements-1 and a hypomethylation on the satellite-alpha DNA repetitive DNA sequences of HL-60 cells at the lowest concentration (0.447 mM) were observed. Besides, choline decreased MA at the lower assayed concentration and the MA response to topoisomerase inhibitor (etoposide) is maintained in the presence of treatment with 0.22 mM choline. Taking into account the hopeful results obtained in the in vivo and in vitro assays, choline could be proposed as a substance with an important nutraceutical value for different purposes.

A brief history of choline

In 1850, Theodore Gobley, working in Paris, described a substance, 'lecithine', which he named after the Greek 'lekithos' for egg yolk. Adolph Strecker noted in 1862 that when lecithin from bile was heated, it generated a new nitrogenous chemical that he named 'choline'. Three years later, Oscar Liebreich identified a new substance, 'neurine', in the brain. After a period of confusion, neurine and choline were found to be the same molecule, and the name choline was adapted. Lecithin was eventually characterized chemically as being phosphatidylcholine. In 1954, Eugene Kennedy described the cytidine 5-dihphosphocholine pathway by which choline is incorporated into phosphatidylcholine. A second route, the phosphatidylethanolamine-N-methyltransferase pathway, was identified by Jon Bremer and David Greenberg in 1960. The role of choline as part of the neurotransmitter acetylcholine was established by Otto Loewi and Henry Dale. Working in the 1930s at the University of Toronto, Charles Best showed that choline prevented fatty liver in dogs and rats. The importance of choline as an essential nutrient for human health was determined in the 1990s through controlled feeding studies in humans. Recently, an understanding of the role of genetic variation in setting the dietary requirement for choline in people is being unraveled.

Acute toxicity assessment of choline by inhalation, intraperitoneal and oral routes in Balb/c mice

Studies suggest that choline has potential to be used as a dietary supplement and a drug for immune inflammatory diseases like asthma and rhinitis. But there are apprehensions regarding adverse effects of choline when given orally in high doses. To address this knowledge gap, toxicity assessment of choline chloride was carried out by intranasal (i.n.), oral and intraperitoneal (i.p.) routes in Balb/c mice for 28days. Body weight, food and water consumption of mice were recorded daily. Hematology and clinical chemistry were assessed to check hepatocellular functions and morphological alterations of the cells. Splenocyte counts were analysed for evaluating cellular immunity. Liver function test was performed by assaying different enzyme systems in serum such as, urea, blood urea nitrogen (BUN), creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Body weight, food and water consumption did not differ between mice treated with choline and the saline control group. Hematologic and biochemical variables were not affected with any increase in serum toxicity marker enzymes indicating normal liver functioning. Choline administration did not affect total cholesterol and high density lipoprotein levels as compared to their respective controls. Urea and blood urea nitrogen levels in choline treated mice were not different than controls. Creatinine level was, however, higher than control in i.p. treatment group, but other parameters were normal. In conclusion, the repeated consumption of choline chloride via i.n. and oral or i.p. routes did not cause toxicity in mice in the toxicological endpoints examined.

Direct detection of brain acetylcholine synthesis by magnetic resonance spectroscopy

The cholinergic system is an important modulatory neurotransmitter system in the brain. Changes in acetylcholine concentration have been previously determined directly in animal models and human brain biopsy specimens, and indirectly, by the effects of drugs, in living humans. Here, we developed a method for direct determination of acetylcholine synthesis in living brain tissue. The method is based on administration of choline, enriched with carbon-13 (stable isotope) in the two methylene positions, and detection of labeled acetylcholine and all other metabolic fates of choline, by carbon-13 magnetic resonance spectroscopy. We tested this method in rat brain slices and found it to be specific for acetylcholine synthesis in both the cortex and hippocampus. This method is potentially useful as a research tool for exploring the cholinergic system role in cognitive processes and memory storage as well as in diseases in which the malfunction of the cholinergic system has been implicated.

Cholinergic medication for neuroleptic-induced tardive dyskinesia

BACKGROUND

Tardive dyskinesia remains a troublesome adverse effect of conventional antipsychotic (neuroleptic) medication. It has been proposed that tardive dyskinesia could have a component of central cholinergic deficiency. Cholinergic drugs have been used to treat tardive dyskinesia.

OBJECTIVES

To determine the effects of cholinergic drugs (arecoline, choline, deanol, lecithin, meclofenoxate, physostigmine, RS 86, tacrine, metoxytacrine, galantamine, ipidacrine, donepezil, rivastigmine, eptastigmine, metrifonate, xanomeline, cevimeline) for treating neuroleptic-induced tardive dyskinesia in people with schizophrenia or other chronic mental illness.

SEARCH STRATEGY

An electronic search of the Cochrane Schizophrenia Group's register (October 2001) was undertaken. This register is assembled by extensive searches for randomised controlled trials in many electronic databases, registers of conference proceedings and dissertations. References of all identified studies were searched for further trial citations. Principal authors of trials were contacted.

SELECTION CRITERIA

Reports identified by the search were included if they were of controlled trials dealing with people with neuroleptic-induced tardive dyskinesia and chronic mental illness, who had been randomly allocated to either a cholinergic agent or to a placebo or no intervention. Two reviewers independently assessed methodological quality of trials.

DATA COLLECTION AND ANALYSIS

Two researchers extracted data and, where possible, estimated relative risks (RR) or weighted mean differences (WMD), with 95% confidence intervals (CI). Data were analysed on an intention-to-treat basis, with the assumption that people who dropped out had no improvement.

MAIN RESULTS

We included eleven studies investigating the use of older cholinergic drugs compared with placebo. Most studies involved small numbers of participants (5-20 people). We found no completed trials of the new cholinergic Alzheimer drugs for the treatment of tardive dyskinesia. Cholinergic drugs did not result in any substantial improvement in tardive dyskinesia symptoms when compared with placebo (8 RCTs, 170 people, RR no important improvement 0.84 CI 0.68 to 1.04). Neither did tardive dyskinesia symptoms increase (7 RCTs, 137 people, RR deterioration in tardive dyskinesia 1.17 CI 0.55 to 2.50). Pooled results for endpoint AIMS scores were equivocal (4 RCTs, 86 people, WMD -0.19 CI -0.53 to 0.14). Deanol may cause gastric adverse effects (5 RCTs, 61 people, RR 9.00 CI 0.55-148) and other adverse effects such as sedation and peripheral cholinergic effects (6 RCTs, 94 people, RR 6.83 CI 0.99-47). One study reported on global outcome. Meclofenoxate was neither clearly helpful nor harmful when compared with placebo (1 RCT, 60 people, RR not of global benefit 0.89 CI 0.59 to 1.32). We found no difference between people allocated cholinergics and those given placebo for the outcome of leaving the study before completion (10 RCTs, 240 people, RR 0.52 CI 0.21 to 1.33).

REVIEWER'S CONCLUSIONS

Tardive dyskinesia remains a major public health problem. The clinical effects of older cholinergic drugs are unclear, as too few, too small studies leave many questions unanswered. Cholinergic drugs should remain of interest to researchers and currently have little place in routine clinical work. However, with the advent of new cholinergic agents now used for treating Alzheimer's disease, scope exists for more informative trials. If these new cholinergic agents are to be investigated for treating people with tardive dyskinesia, their effects should be demonstrated in well-designed, conducted and reported randomised trials.

Effect of oral CDP-choline on plasma choline and uridine levels in humans

Twelve mildly hypertensive but otherwise normal fasting subjects received each of four treatments in random order: CDP-choline (citicoline; 500, 2000, and 4000 mg) or a placebo orally at 8:00 a.m. on four different treatment days. Eleven plasma samples from each subject, obtained just prior to treatment (8:00 a.m.) and 1-12 hr thereafter, were assayed for choline, cytidine, and uridine. Fasting terminated at noon with consumption of a light lunch that contained about 100 mg choline. Plasma choline exhibited dose-related increases in peak values and areas under the curves (AUCs), remaining significantly elevated, after each of the three doses, for 5, 8, and 10 hr, respectively. Plasma uridine was elevated significantly for 5-6 hr after all three doses, increasing by as much as 70-90% after the 500 mg dose, and by 100-120% after the 2000 mg dose. No further increase was noted when the dose was raised from 2000 to 4000 mg. Plasma cytidine was not reliably detectable, since it was less than twice blank, or less than 100 nM, at all of the doses. Uridine is known to enter the brain and to be converted to UTP; moreover, we found that uridine was converted directly to CTP in neuron-derived PC-12 cells. Hence, it seems likely that the circulating substrates through which oral citicoline increases membrane phosphatide synthesis in the brains of humans involve uridine and choline, and not cytidine and choline as in rats.

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.

Decreased serum choline concentrations in humans after surgery, childbirth, and traumatic head injury

The serum levels of choline decreased by approximately 50% in patients having a surgery under general as well as epidural anesthesia. The decrease is lasts for two days after surgery. Intravenous administration of succinylcholine, either by a single bolus injection or by a slow continuous infusion, increased the serum choline levels several folds during surgery. In these patients, a significant decrease in the serum choline levels was observed one and two days after surgery. In 16 pregnant women at the term, serum choline levels were higher than the value observed in 19 nonpregnant women. The serum choline levels decreased by about 40% or 60% after having a childbirth either by vaginal delivery or caesarean section, respectively. Serum choline levels in blood obtained from 9 patients with traumatic head injury were significantly lower than the observed levels in blood samples obtained from healthy volunteers. These observations show that serum choline levels increase during pregnancy and decrease during stressful situations in humans.

Intracerebroventricular injection of choline increases plasma oxytocin levels in conscious rats

In the present study, we examined the effect of intracerebroventricularly (i.c.v.) injected choline on both basal and stimulated oxytocin release in conscious rats. I.c.v. injection of choline (50-150 micrograms) caused time- and dose-dependent increases in plasma oxytocin levels under normal conditions. The increase in plasma oxytocin levels in response to i.c.v. choline (150 micrograms) was greatly attenuated by the pretreatment of rats with atropine (10 micrograms; i.c.v.), muscarinic receptor antagonist. Mecamylamine (50 micrograms; i.c.v.), a nicotinic receptor antagonist, failed to suppress the effect of 150 micrograms choline on oxytocin levels. Pretreatment of rats with 20 micrograms of hemicholinium-3 (HC-3), a specific inhibitor of choline uptake into nerve terminals, greatly attenuated the increase in plasma oxytocin levels in response to i.c.v. choline injection. Osmotic stimuli induced by either oral administration of 1 ml hypertonic saline (3 M) following 24-h dehydration of rats (type 1) or an i.c.v. injection of hypertonic saline (1 M) (type 2) increased plasma oxytocin levels significantly, but hemorrhage did not alter basal oxytocin concentrations. The i.c.v. injection of choline (50, 150 micrograms) under these conditions caused an additional and significant increase in plasma oxytocin concentrations beyond that produced by choline in normal conditions. These data show that choline can increase plasma oxytocin concentrations through the stimulation of central cholinergic muscarinic receptors by presynaptic mechanisms and enhance the stimulated oxytocin release.

Behavioral effects of dietary neurotransmitter precursors: basic and clinical aspects

The levels and possibly function of several neurotransmitters can be influenced by the supply of their dietary precursors. The neurotransmitters include serotonin, dopamine, noradrenaline, histamine, acetylcholine and glycine, which are formed from tryptophan, tyrosine, histidine, choline and threonine. Tryptophan has been tested more than the other precursors in clinical trials and is currently available in some countries for the treatment of depression. Other uses for tryptophan and the therapeutic potential of other neurotransmitter precursors have not been tested adequately. Given the relative lack of toxicity of dietary components, further clinical trials with neurotransmitter precursors should be carried out.

Choline ingestion increases the resonance of choline-containing compounds in human brain: an in vivo proton magnetic resonance study

Choline is a crucial intermediate in several clinically relevant neurochemical processes. In this study, choline-containing compounds in human brain (principally phosphocholine, glycero-phosphocholine, and choline) were measured by 1H-magnetic resonance spectroscopy, before and after the ingestion of 50 mg/kg choline in four normal control subjects. Substantial and remarkably similar increases in the brain choline resonance occurred in each subject, with a nearly two-fold rise in the choline resonance observed 3 hr following choline ingestion (p = 0.008 versus baseline). One subject also received a dose of 200 mg/kg choline, and exhibited a proportionally larger increase in the brain choline resonance. The results are consistent with animal data reporting a rise in choline-containing compounds following choline administration. This is the first study to our knowledge where an oral nutrient has been shown to produce a detectable change in human brain composition in vivo. Studying choline transport and biotransformation in human brain may have relevance to several neuropsychiatric disorders, including affective disorders and dementia.

Recognition and differential diagnosis of tardive dyskinesia

Tardive dyskinesia (TD) is a consequence of chronic neuroleptic therapy. It is an irregular stereotyped movement disorder that is usually choreic in appearance, and is subject to temporary volitional control. Dystonia, akathisia, and tics are uncommon variants of the classic tardive syndrome. Characteristic clinical features including amelioration by action, augementation by distraction, partial volitional suppressibility, and lack of subjective distress help differentiate TD from other movement disorders such as resting tremor, Huntington's disease, spontaneous dyskinesias, and abnormal movements accompanying psychiatric illnesses.

Masticatory muscle hyperactivity in temporomandibular disorders: is it an extrapyramidally expressed disorder?

Masticatory muscle hyperactivity appears to have an important role in temporomandibular disorders. A pathophysiological model for masticatory muscle hyperactivity is proposed that is centrally mediated, yet maintains support for present peripheral causes and therapies. In this hypothesis, masticatory muscle hyperactivity represents a mild extrapyramidal disorder distantly related to orofacial dyskinesias. Experimental evidence suggests a neurotransmitter imbalance in the basal ganglia, involving dopaminergic preponderance, or cholinergic and GABA-nergic hypofunction as the underlying cause.

Effects of cholinergic and anticholinergic drugs on ketamine-induced linguopharyngeal motor activity

Benztropine mesylate (Cogentin) and physostigmine salicylate (Antilirium), were tested for changes in tongue protrusions, retrusions, and swallowing acts in rats anesthetized with a 100 mg/kg IM injection of ketamine hydrochloride. These ketamine-induced linguopharyngeal events were monitored by means of a force displacement transducer fed onto a polygraph. Benztropine (0.05-1 mg/kg) caused mild to moderate reductions in the rate of these events for a short period of time, up to about 30 min. With physostigmine (5-25 micrograms/kg), linguopharyngeal activity was markedly increased, up to 50-fold by the highest dose within 5 min and returned almost to the baseline within 60 min. With lower doses, more moderate responses were obtained. If methscopolamine (1.4, 3, 6 mg/kg IM) preceded physostigmine, the physostigmine enhancement was preserved.

A time course and dose-response study of the regulation of brain nicotinic receptors by dietary choline

We have previously demonstrated that the administration of oral choline chloride to rats results in a significant increase in the concentration of putative nicotinic cholinergic receptors (nAChRs), as measured by alpha-bungarotoxin binding, in comparison with rats fed a choline-free diet. We have extended and elucidated these data in the studies reported here. The increase in the concentration of nAChRs was found to be dose-dependent and attributable to choline supplementation rather than choline deficiency. The increase in the concentration of nAChRs occurs rapidly (within 24 h) and is reversible (over a period of days) upon elimination of choline supplementation. The oral administration of choline chloride had been successful in some but not all neurological disorders associated with presumed cholinergic hypoactivity. Studies of dietary choline intake in animals may provide information with respect to the mechanism by which choline stimulates an increase in nAChRs and may suggest a treatment regime that maximizes the central effects of choline.

Lithium and lecithin in tardive dyskinesia: an update

Psychiatric inpatients with tardive dyskinesia (TD) were treated with either lithium alone (n = 9) or with a combination of lithium and lecithin (n = 9) for 5 weeks in a double-blind, placebo-controlled experiment. A statistically significant but clinically unimportant improvement of TD occurred during both treatments. The addition of lecithin to lithium had no effect.

Meclofenoxate therapy in tardive dyskinesia: a preliminary report

Tardive dyskinesia seems to occur as a result of diminished cholinergic and enhanced dopaminergic activity in the striatum. Meclofenoxate has been shown to increase cerebral cholinergic activity. To ameliorate the tardive dyskinesia, meclofenoxate was given orally, 600-1200 mg/day, for 6-12 weeks. The effects of the drug were evaluated by scoring the degree of involuntary movement. Among 11 subjects with tardive dyskinesia or dystonia, 4 improved markedly, 1 moderately, 2 slightly, and there was no improvement in 4. One patient with subacute oral dyskinesia, induced by administration of neuroleptics for 1 month, improved markedly. The possibility that meclofenoxate may be effective in dealing with dyskinesias that are induced by neuroleptics warrants further attention.

Tardive dyskinesia: nondopaminergic treatment approaches

The continuing concern about tardive dyskinesia (TD) has stimulated a broad search for therapies for this disorder. Since neuroleptic drugs are thought to be the etiological agents, acting presumably through dopamine receptor blockade, nondopaminergic drugs have been the focus of recent study. However, no uniformly safe and effective drug treatment has been identified. Augmentation of cholinergic function is theoretically attractive, but further research is needed to develop practical and effective compounds. GABA drugs do not consistently suppress TD. The effect of benzodiazepines in TD is unclear, but these agents may be of some temporary benefit in patients with distressing symptoms. Lithium, serotonergic compounds, and numerous neuropeptides all fail to have any consistent effect in TD. Early reports of benefit with alpha- and beta-noradrenergic agents are interesting but require further study. Many other drug types have been tried without benefit. For the majority of patients, it may be best to give no drug treatment. Any drug that is capable of suppressing TD may aggravate the disorder in the long term. The potential for a spontaneous gradual remission of TD is an argument in favor of a patient, nonaggressive, and cautiously optimistic approach to this disorder.

Variable clinical response to choline in tardive dyskinesia

Tardive dyskinesia is widely believed to be a state of relative hyperdopaminergic and hypocholinergic imbalance in the striatum of patients chronically treated with neuroleptics. However, not all patients with tardive dyskinesia respond to cholinergic drugs, which theoretically should restore the balance and improve the symptoms. We report a controlled, double-blind, crossover study of choline chloride in 11 patients with persistent tardive dyskinesia. Seven patients showed partial or minimal improvement, while two did not change and two deteriorated. The results are discussed in the light of other similar findings in the literature, and the implications for pharmacological subtypes of tardive dyskinesia using cholinergic probes are explored.

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.

Low concentrations of trifluoperazine affect striatal cells in culture

Primary monolayer cultures of the newborn rat corpus striatum were treated with the phenothiazine trifluoperazine after various times in culture. When the drug is added to cells at least 3 weeks old, concentrations of 10(-7) and 10(-8) M appear morphologically identical to controls but show significant changes in synthesis of acetylcholine and gamma-aminobutyric acid, particularly the former. The results with these very low concentrations suggest that the drug has a highly specific effect directly on striatal cells, and that it is not acting via calmodulin.

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).

Dopamine stimulation of phosphatidylcholine (lecithin) biosynthesis in rat brain neurons

Rat brain synaptosomes contain enzymes, phosphatidylethanolamine N-methyltransferase(s) (EC 2.1.1.17), that catalyze the methylation of endogenous phosphatidylethanolamine to form its mono-, di-, and trimethyl (i.e., phosphatidylcholine) derivatives. We observe that the activity of these enzymes is enhanced when synaptosomes are incubated with catecholamines: 0.1 mM dopamine increases incorporation of [3H]methyl groups into monomethylphosphatidylethanolamine, dimethylphosphatidylethanolamine, and phosphatidylcholine by factors of 1.7, 1.3, and 2.1, respectively, and 0.1 mM norepinephrine increases [3H]methyl incorporation into monomethylphosphatidylethanolamine and dimethylphosphatidylethanolamine by factors of 1.6 and 2.1, respectively. Stimulation by dopamine, which is observed at concentrations as low as 1 microM, is blocked by haloperidol.

Motion sickness: a modulatory role for the central cholinergic nervous system

The present review has extended the general theory of motion sickness proposed by Wood and Graybiel [135, 136] by identifying specific neurophysiological mechanisms that are involved in motion sickness and by interpreting the actions of both scopolamine and amphetamine as effective anti-motion sickness drugs within this neurophysiological context. The neurochemical and neurophysiological effects of scopolamine have been reviewed in relationship to central cholinergic pathways. Cholinergic pathways have been associated with both the perception and expression of normal and excessive levels of motion stimuli. New approaches to the problem of the prevention of motion sickness have been considered. Efferent nicotinic innervation at the primary sensory hair cells and the medial vestibular nucleus were identified as sites where modulation by cholinergic drugs might exert a beneficial influence. However, it was generally conceded that the complexity of the cholinergic system and the interaction of scopolamine with that system left open the possibility that pharmacological doses of drugs specific to the cholinergic system might exert significant modulatory influences at alternative sites, as well.

Intra-patient variability in the measurement of tardive dyskinesia

Intra-patient variability in the movements of tardive dyskinesia was examined through the analyses of 8-min frequency counts collected over a period of 11 weeks for six chronic schizophrenic patients. Weekly observation segments of 8 min, 4 min, 2 min, 1 min and 30 s showed considerable variation both across weeks and within sessions. Variations were of sufficient magnitude to contribute to the possibility of false negative tardive dyskinesia assessments and false positive treatment outcome designations. Measurement procedures taking this variability into account are urged for the study of tardive dyskinesia. Additionally, independently obtained rating scale scores showed no association to the collected frequency count data, suggesting fundamental differences between these two assessment procedures.

Effects of the diet on brain function

The rates of synthesis by brain neurons of the neurotransmitters serotonin, acetylcholine, and the catecholamines depend on the brain levels of the respective precursor molecules. Brain levels of each precursor are influenced by their blood concentration, and for the amino acid precursors, by the blood levels of other amino acids as well. Since diet readily alters blood concentrations of each of these precursors, it thereby also influences the brain formation of their neurotransmitter products.

Effect of choline on central dopaminergic function in normal subjects

Oral administration of choline (10 g) had no effect on basal serum growth hormone or prolactin concentrations in normal subjects (N = 5). Choline significantly enhanced the increase in growth hormone secretion induced by apomorphine HCl (0.5 mg s.c.). These data suggest that cholinergic mechanisms may enhance hypothalamic-pituitary dopaminergic function in man in contrast to their inhibitory effect on dopaminergic function in the basal ganglia.

Effect of increasing choline, in vivo and in vitro, on the synthesis of acetylcholine in a sympathetic ganglion

The experiments described in this paper were designed to test whether increasing choline availability over normal physiological levels increases acetylcholine synthesis in the cat's superior cervical ganglion. When ganglia were perfused with Krebs solution, an increase in the medium's choline concentration over physiological (10(-5)M) levels increased tissue choline but did not increase tissue acetylcholine or the release of acetylcholine from stimulated ganglia. However, increasing plasma choline in the whole animal increased ganglionic acetylcholine levels. The basis for this difference in the effects of in vivo and in vitro exposure to elevated choline levels on the tissue acetylcholine content was found to involve plasma factor(s), rather than indirect actions of choline, and the acetylcholine content of isolated ganglia was increased when the tissue was perfused with plasma, instead of Krebs solution, containing 10(-3)M-choline. The extra acetylcholine generated by this procedure was associated with a subsequent transient increase in transmitter release during short intervals of stimulation, but most of the extra acetylcholine was not readily available for release from stimulated ganglia. It is concluded that increasing choline available to sympathetic ganglia over physiological concentration does not have a sustained effect on the turnover of releasable transmitter under the conditions of these experiments.