Neuropharmacology of S-adenosyl methionine

A review of nutrient treatments for paediatric depression

Paediatric depression is estimated to affect 15-20% of youths prior to adulthood and is associated with significant social, educational and physical impairment. Current treatments comprise moderately efficacious psychological therapies and pharmaceutical antidepressants. However, nutritional therapies are also available and are regularly sought by people with depressive illnesses and parents of depressed youths. In this narrative review, studies examining the antidepressant effects of individual nutritional supplements in child and adolescent populations are appraised. Epidemiological studies examining the relationship between nutritional status and paediatric depression, or depressive symptoms are also reviewed. Nutrients covered in this article include: omega-3 polyunsaturated fatty acids, s-adenosylmethionine, vitamin C, vitamin D, zinc, iron and B-vitamins. Although several of these nutrients present as promising treatments for paediatric depression, there is a lack of high-quality studies examining the antidepressant effects of all the aforementioned ingredients. Before nutritional treatments are accepted as validated treatments for paediatric depression, further high-quality studies are required.

Double-blind, placebo-controlled pharmacodynamic studies with a nutraceutical and a pharmaceutical dose of ademetionine (SAMe) in elderly subjects, utilizing EEG mapping and psychometry

In a double-blind, placebo-controlled crossover study, the effects of S-adenosyl-l-methionine (SAMe) on brain function measures of 12 normal elderly volunteers (6 m/6 f, aged 57-73 years, mean: 61 years) were investigated by means of EEG mapping and psychometry. In random order, the subjects were orally administered a pharmaceutical dose of 1600 mg SAMe, a nutraceutical dose of 400 mg SAMe and placebo, each over a period of 15 days, with wash-out periods of 2 weeks in between. EEG recordings, psychometric tests and evaluations of tolerability and side effects were carried out 0, 1, 3 and 6 h after drug administration on days 1 and 15. Multivariate analysis based on MANOVA/Hotelling T2 tests of quantitative EEG data demonstrated significant central effects of SAMe as compared with placebo after acute, subacute and superimposed drug administration of both the nutraceutical and the pharmaceutical dose. EEG changes induced by SAMe were characterized by an increase in total power, a decrease in absolute and relative power in the delta/theta and slow alpha frequencies, an increase in absolute and relative power in the alpha-2 and beta frequencies as well as an acceleration of the alpha centroid and the centroid of the total power spectrum. The delta/theta and the beta centroid showed variable changes over time. The dominant alpha frequency was accelerated, the absolute and relative power in the dominant alpha frequency attenuated after SAMe as compared with placebo. These acute and subacute pharmaco-EEG findings in elderly subjects are typical of activating antidepressants. Time-efficacy calculations showed that acute oral administration of SAMe in both the nutraceutical and the pharmaceutical dose induced the pharmacodynamic peak effect in the first hour with a subsequent decline. The 3rd and 6th hours still showed a significant encephalotropic effect after the 1600 mg dose. The maximum EEG effect was noted after 2 weeks of oral administration of both 1600 mg/die and 400 mg/die. The superimposed dose induced significant encephalotropic effects in the 3rd hour after 400 mg and in the 3rd and 6th hours after 1600 mg as compared with pre-treatment. Dose-efficacy calculations showed that the pharmaceutical dose of 1600 mg had a more pronounced effect on the CNS than the nutraceutical dose of 400 mg, with both doses being superior to placebo. Psychometric tests concerning noopsychic and thymopsychic measures as well as critical flicker fusion frequency generally demonstrated a lack of differences between SAMe and placebo, which reflects a good tolerability of the drug in elderly subjects. This was corroborated by the findings on side effects, pulse and blood pressure.

Serum folate and homocysteine levels in patients with obsessive-compulsive disorder

Previous studies have shown that folate deficiency, increased homocysteine, impaired metylation have been identified in depressive disorder. Recently, growing research has resulted in the biological association between obsessive-compulsive disorder (OCD) and affective disorders. Therefore, in the present study it was evaluated whether or not folate and homocysteine levels changed. Serum folate and homocysteine concentrations were measured in 23 patients with OCD and in same number of controls. In addition, all patients were assessed by Yale-Brown Obsession Compulsion Scale (Y-BOCS). Serum folate values were significantly lower in OCD patients than in controls, while homocysteine concentrations were higher in patients compared with controls. Serum folate values were significantly and negatively related to Y-BOCS scores. Total serum homocysteine concentrations were positively correlated to Y-BOCS scores and the duration of illness. There was a trend toward a negative correlation between the concentrations of serum folate and homocysteine. In conclusion, we identified that a group of patients with OCD might have folate deficiency, higher homocysteine levels and probable impaired metylation and monoamine metabolism.

Ademetionine (S-adenosylmethionine) neuropharmacology: implications for drug therapies in psychiatric and neurological disorders

Ademetionine (S-adenosylmethionine; SAMe) is a ubiquitous metabolite present in all cells and biological fluids, and serves as a methyl donor in a multitude of different methylation reactions involving proteins, phospholipids, catecholamines and DNA. Pharmaceutical preparations of some stable salts of SAMe are available for parenteral and oral use in humans, and have been shown to increase plasma and cerebrospinal fluid SAMe concentrations. In experimental studies administration of SAMe is associated with increases in brain monoamine neurotransmitters and b-adrenergic and muscarinic receptor functions. These neuropharmacological effects are postulated to be involved in the antidepressant activity of SAMe which has been confirmed in numerous controlled studies. Preliminary studies indicate that SAMe has therapeutic potential in the treatment of other CNS disorders including dementia, acquired immune deficiency syndrome (AIDS)-associated myelopathy, and brain ischaemia. This review will focus on recent experimental and clinical aspects of SAMe in the central nervous system, and the therapeutic use in psychiatric and neurological disorders.

Electrophysiological neuroimaging of the central effects of S-adenosyl-L-methionine by mapping of electroencephalograms and event-related potentials and low-resolution brain electromagnetic tomography

BACKGROUND

S-Adenosyl-L-methionine (SAMe, or ademetionine) is a naturally occurring molecule used as both a nutraceutical and a pharmaceutical to treat depression.

OBJECTIVE

The central mode of action of SAMe was investigated in 20 healthy volunteers by mapping of electroencephalograms (EEGs) and event-related potentials (ERPs) and low-resolution brain electromagnetic tomography (LORETA).

DESIGN

In an acute and subacute, double-blind, placebo-controlled, crossover study, subjects received in random order infusions of 800 mg SAMe and placebo for 7 d, with a washout period of 3 wk between the 2 treatment periods. EEG recordings were made 0, 1, 3, and 6 h after and ERP recordings were made 0 and 1 h after the drug infusions on days 1 and 7.

RESULTS

Multivariate analyses of variance and Hotelling T2 tests showed significant acute and subacute encephalotropic effects of SAMe compared with placebo. Acute pharmaco-EEG changes were typical of classic antidepressants of the thymoleptic type; subacute alterations were typical of cognition enhancers. Regarding ERPs, standard N1 and P2 latencies were shortened, and target P300 latencies were lengthened. N1 amplitudes increased after subacute treatment, and temporooccipital P300 amplitudes increased after the acute dose. Similar changes were described for antidepressants. LORETA showed that the N2 source strength increased in both the left and the right temporal lobes, whereas the P300 source strength increased in the dorsolateral prefrontal regions and decreased in the ventral limbic regions.

CONCLUSION

EEG-ERP mapping identified SAMe as an antidepressant. LORETA targeted brain regions crucial in the therapeutic efficacy of antidepressants.

A comparative study of methionine adenosyltransferase activity and regional distribution in mammalian spinal cord

To provide a background for future studies on neurodegenerative changes in the spinal cord, the present study analysed the distribution of the activity of methionine adenosyltransferase (ATP:L-methionine S-adenosyltransferase, EC 2.5.1.6, MAT), an enzyme that catalyses the synthesis of the biological methyl group donor S-adenosylmethionine (AdoMet), in spinal cords from bovine and pig, and compared the results with those from human spinal cord. The enzyme activity was estimated by a radiochemical method measuring the rate of formation of [(3)H]AdoMet from L-[methyl-(3)H]methionine and ATP. The MAT activity (V(max)) was quite homogeneously distributed between spinal regions and species investigated (19-50 pmol [(3)H]AdoMet/mg protein/minute), with the highest level found in the male bovine group. The bovine group (both males and females) also presented a 20% higher enzymatic activity in the dorsal horn as compared to the ventral horn and white matter areas. In the pig spinal cord, the highest level of activity was found in the white matter. The lowest affinity for methionine (highest K(m)) was found in the human spinal cord. Whole spinal cords of one cat and one rhesus monkey were also analysed and the levels of MAT activity were similar to that of humans and bovine females, respectively. Studies of MAT stability in the rat spinal cord (post-mortem time 0-72 hr) showed a significant decrease in enzyme activity during the interval of 0-8 hr (23 degrees ). From this time point on and up to 72 hr (4 degrees ), the significant decrease in the activity remained at 60% of the initial value.

Influence of S-adenosyl-L-methionine on chronic mild stress-induced anhedonia in castrated rats

1. S-adenosyl-L-methionine (SAMe) is the most important methyl donor in the brain and is essential for polyamine synthesis. Methyl group deficiency in the brain has been implicated in depression; on the other hand, polyamines enhance phosphorylation processes, and phosphorylation of functional proteins in neurons in involved in the therapeutic mechanisms of antidepressants. 2. The effect of SAMe in an animal model of 'depression', the chronic mild stress-induced anhedonia, was studied using long-term castrated male and female Lister hooded rats. 3. Chronic daily exposure to an unpredictable sequence of mild stressors produced, within 3 weeks, a significant reduction of the consumption of a sucrose solution. SAMe (100, 200 or 300 mg kg-1 daily i.m.) while having no influence on sucrose intake in non-stressed animals, dose-dependently reinstated sucrose consumption within the first week of treatment, both in male and in female stressed rats. Imipramine (10 mg kg-1 daily i.p.) produced a similar effect after a 3 week treatment. 4. Similarly, a palatable food reward-induced place preference conditioning was developed in SAMe (200 or 300 mg kg-1 daily i.m.)--and in imipramine (10 mg kg-1 daily i.p.)--treated chronically stressed animals (males and females), whilst it could not be obtained in vehicle-treated rats. 5. Moreover, the same doses of SAMe (but not of imipramine) restored the exploratory activity and curiosity for the environment (rearing), in the open-field test. 6. While imipramine caused a blockade of the growth throughout the treatment, SAMe produced only a transient growth arrest during the first week of treatment. 7. These results show that SAMe reverses an experimental condition of 'depression-like' behaviour in rats, the effect being more rapid and complete than that of imipramine, and without apparent side effects.

Pharmacokinetic-pharmacodynamic interaction between the COMT inhibitor tolcapone and single-dose levodopa

1. Single oral doses of the catechol-O-methyltransferase (COMT) inhibitor tolcapone (10-800 mg) or placebo were administered simultaneously with a dose of levodopa/benserazide 100/25 mg to seven sequential groups of six healthy male subjects in a two-way crossover study. 2. Plasma concentrations of tolcapone, its metabolite 3-O-methyltolcapone, levodopa and 3-O-methyldopa (3-OMD) were determined in conjunction with COMT activity in erythrocytes. 3. The drug combination was well tolerated at all dose levels and there were no signs indicative of an increase in dopaminergic stimulation. 4. Tolcapone caused a rapid and reversible inhibition of COMT activity in erythrocytes in parallel with a dose-dependent decrease in the formation of 3-OMD. Tolcapone increased the area under the concentration-time curve and elimination half-life of levodopa. The maximum effects were obtained at a dose of about 200 mg when both parameters increased approximately twofold. The drug had no influence on the maximum concentration of levodopa. 5. Tolcapone was rapidly absorbed and eliminated with, on average, a tmax of 1.5 h and a t1/2 of 2.3 h. The drug showed dose-proportional pharmacokinetics, in contrast to 3-O-methyltolcapone whose formation was relatively decreased at higher doses. 6. Plasma concentrations of tolcapone correlated with inhibition of COMT activity in erythrocytes and suppression of 3-OMD levels, but not with changes in levodopa pharmacokinetics.

Change in folate status with antidepressant treatment

Ninety-nine consecutive unmedicated outpatients with a major depressive illness had blood drawn for measurement of serum folate (SF), red cell folate (RCF), and vitamin B12 within 24 hours of completion of ratings of severity of depression at the beginning and ending of a 5-week trial of desmethylimipramine (mean dose = 149.2 mg/day, range = 75-225 mg). As compared with nonresponders, responders had a significantly higher mean SF at baseline (nonresponders = 13.8 nmol/l; responders = 17.7 nmol/l) and RCF showed a significant inverse correlation with severity of depression and a significant positive correlation with age of onset of illness. At week 5, change in severity of depression was significantly correlated with change in RCF, and significantly more responders than nonresponders had an increase in RCF. The possible role of folate status in the regulation of mood and response to treatment is discussed.

Red cell folate concentrations in psychiatric patients

Red cell folate and vitamin B12 estimations were performed on 243 successively admitted in-patients at a District General Hospital Psychiatric Unit and 42 out-patients (29 attending a lithium clinic). Patients were classified into five diagnostic groups. The mean ages of the manic and schizophrenic patients were lower than of the depressed or euthymic patients but age was not correlated with red cell folate or serum B12 levels in any group. There were 89 (31%) patients with red cell folate below 200 ng/ml and 35 (12%) with concentrations below 150 ng/ml. Significantly more of these low-folate patients were in-patients than out-patients. The mean red cell folate in the depressed patients was significantly lower than in the euthymic, manic and schizophrenic groups. Alcoholics had a similar mean red cell folate to depressed patients which was not quite significantly lower than the other groups. The mean serum B12 level in the alcoholics was, however, significantly raised. There were no significant differences in red cell folate or serum B12 between lithium-treated and untreated euthymic patients. The highest proportions of values below 200 ng/ml and 150 ng/ml were found in depressed and alcoholic patients. Endogenous depressives had the highest percentage of values below 150 ng/ml (folate-deficient) of all psychiatric groups and alcoholic patients. The significance of these findings is discussed.

L-3,4-dihydroxyphenylalanine (levodopa) lowers central nervous system S-adenosylmethionine concentrations in humans

To determine whether levodopa reduces the levels of S-adenosylmethionine in the human central nervous system, cerebrospinal fluid (CSF) concentrations of S-adenosylmethionine, methionine, 3-methoxytyrosine, levodopa and 5-methyltetrahydrofolate were measured in six children with dopamine deficiency before and after treatment. In four, the lack of dopamine was secondary to a reduction in concentration of levodopa and these were treated with levodopa together with a peripheral dopa-decarboxylase inhibitor. In the other two, levodopa in the central nervous system naturally accumulated due to a congenital deficiency of aromatic-L-amino acid decarboxylase and these were treated with pyridoxine (which in this condition lowers central levodopa concentrations). Raising levodopa concentrations in the central nervous system caused a fall in CSF S-adenosyl-methionine concentration and a rise in CSF 3-methoxytyrosine concentration. No change was observed in CSF methionine concentration and in all patients CSF 5-methyltetrahydrofolate concentration was normal. With one exclusion there was a linear relationship between CSF S-adenosylmethionine and 3-methoxytyrosine concentrations. This is the first demonstration of such effects in humans and the implications upon levodopa therapy are discussed.

S-adenosyl-L-methionine. A review of its pharmacological properties and therapeutic potential in liver dysfunction and affective disorders in relation to its physiological role in cell metabolism

S-Adenosyl-L-methionine (SAMe) is a naturally occurring molecule distributed to virtually all body tissues and fluids. It is of fundamental importance in a number of biochemical reactions involving enzymatic transmethylation, contributing to the synthesis, activation and/or metabolism of such compounds as hormones, neurotransmitters, nucleic acids, proteins, phospholipids and certain drugs. The administration of a stable salt of SAMe, either orally or parenterally, has been shown to restore normal hepatic function in the presence of various chronic liver diseases (including alcoholic and non-alcoholic cirrhosis, oestrogen-induced and other forms of cholestasis), to prevent or reverse hepatotoxicity due to several drugs and chemicals such as alcohol, paracetamol (acetaminophen), steroids and lead, and to have antidepressant properties. In all of these studies SAMe has been very well tolerated, a finding of great potential benefit given the well-known adverse effects of tricyclic antidepressants with which it has been compared in a few trials. Thus, with its novel mechanisms of action and good tolerability, SAMe is an interesting new therapeutic agent in several diverse disease conditions, but its relative value remains to be determined in appropriate comparisons with other treatment modalities in current use.

Affective disorders and S-adenosylmethionine: a new hypothesis

S-Adenosyl-L-methionine (AdoMet) is a safe and probably effective antidepressant agent in certain forms of clinical depression. This article presents a new hypothesis to account for the mechanism of action of S-adenosylmethionine in such illnesses, based upon the known biochemistry of this compound, and upon current knowledge of clinical and genetic aspects of affective disorders. Giulio Cantoni, S. Harvey Mudd and V. Andreoli postulate that at least some major mood disorders are due to abnormalities affecting the AdoMet-dependent methylation of a substance in the CNS. For convenience and without prejudging the chemical structure of this substance, they call it 'barinine'. The model requires that barinine be subject to AdoMet-dependent methylation and that methylbarinine be subject to metabolic demethylation to regenerate the original barinine. Methylbarinine should be mood elevating, whereas barinine itself should not be. Depression is a result of abnormalities lowering the normal steady-state concentration of methylbarinine, whereas mania results from an abnormal elevation of methylbarinine.

The switch mechanism and the bipolar/unipolar dichotomy

During open trials of intravenous and oral S-adenosyl methionine (SAM) and a placebo-controlled trial of intravenous SAM in 29 patients, 25 patients had SAM and four had placebo (27 courses of SAM, two of the patients receiving two trials a piece). Nine of 11 bipolar patients (all SAM-treated) switched into elevated mood state (hypomania, mania and euphoria) and two did not respond. Six endogenous unipolar patients improved and five did not. No non-endogenous patient or placebo patient responded for more than 14 days. No unipolar patient switched into elated mood. In eleven (38%) trials and nine (33%) patients there was a switch from depression to elation. Biochemical data from the cerebrospinal fluid of eight patients suggested that the role of the dopaminergic system should be further explored.

Folic acid and psychopathology

1. The incidence of folic acid deficiency is high in patients with various psychiatric disorders including depression, dementia and schizophrenia. 2. In epileptics on anticonvulsants, folate deficiency often occurs because anticonvulsants inhibit folate absorption. In these patients folate deficiency is often associated with psychiatric symptoms. 3. In medical patients psychiatric symptoms occur more frequently, and in psychiatric patients symptoms are more severe, in those with folate deficiency than in those with normal levels. 4. Many open studies have demonstrated therapeutic effects of folate administration on psychiatric symptoms in folate deficient patients. 5. Several placebo-controlled studies have not demonstrated therapeutic effects, possibly because the doses they used (15-20 mg/day) are known to be toxic and to cause mental symptoms. 6. Two placebo-controlled studies have demonstrated beneficial effects of folic acid administration, one in patients with a syndrome of psychiatric and neuropsychological changes associated with folate deficiency and the other in patients on long-term lithium therapy. In the latter study the dose was only 0.2 mg/day. 7. Folic acid deficiency is known to lower brain S-adenosylmethionine and 5-hydroxytryptamine. S-Adenosylmethionine, which has antidepressant properties, raises brain 5-hydroxytryptamine. Thus, depression associated with folate deficiency is probably related to low brain 5HT. 8. S-Adenosylmethionine is involved in many methylation reactions, including methylation of membrane phospholipids, which influences membrane properties. This may explain the wide variety of symptoms associated with folate deficiency. 9. Because the costs and risks associated with low doses of folic acid (up to 0.5 mg/day) are small, folic acid should be given as an adjunct in the treatment of patients with unipolar or bipolar affective disorders and anorexia, epileptics on anticonvulsants, geriatric patients with mental symptoms and patients with gastrointestinal disorders who exhibit psychiatric symptoms. 10. Although the majority of the patients listed above will probably not be helped by folic acid therapy, a significant minority are likely to have folate-responsive symptoms.

S-adenosylmethionine in the treatment of depression

The antidepressant property of S-adenosylmethionine (SAMe) has been supported by several uncontrolled and controlled studies. Compared to standard antidepressant agents, SAMe has fewer side-effects and shorter lag period. Future studies to delineate SAMe-responsive depression are warranted.

Clinical correlations of one-carbon metabolism abnormalities

1. Ninety psychiatric inpatients with a DSM III diagnosis of schizophrenia, mania, or major depression were studied. 2. Upon admission/transfer to the Clinical Studies Unit, and prior to discharge, measurements of symptom severity (BPRS, Ham-D, Young's Mania Scale) and blood samples were obtained. 3. Erythrocytes from these paired (admission and discharge) blood samples were assayed for methionine adenosyltransferase (MAT) activity and phosphatidylcholine (PC) content. 4. Comparisons were made between the changes in MAT Vmax, or % PC, and changes in symptom severity. 5. For the majority of the patients (79.3% of the schizophrenics; 84.6% of the depressives; and 93.8% of the manics), clinical improvement was associated with a "normalization" of enzyme activity. The association between changes in % PC and clinical response did not achieve significant correlation.