Nicotinic acid in the prevention and treatment of methionine-induced exacerbation of psychopathology in schizophrenics

Metabolomic and transcriptomic signatures of prenatal excessive methionine support nature rather than nurture in schizophrenia pathogenesis

The imbalance of prenatal micronutrients may perturb one-carbon (C1) metabolism and increase the risk for neuropsychiatric disorders. Prenatal excessive methionine (MET) produces in mice behavioral phenotypes reminiscent of human schizophrenia. Whether in-utero programming or early life caregiving mediate these effects is, however, unknown. Here, we show that the behavioral deficits of MET are independent of the early life mother-infant interaction. We also show that MET produces in early life profound changes in the brain C1 pathway components as well as glutamate transmission, mitochondrial function, and lipid metabolism. Bioinformatics analysis integrating metabolomics and transcriptomic data reveal dysregulations of glutamate transmission and lipid metabolism, and identify perturbed pathways of methylation and redox reactions. Our transcriptomics Linkage analysis of MET mice and schizophrenia subjects reveals master genes involved in inflammation and myelination. Finally, we identify potential metabolites as early biomarkers for neurodevelopmental defects and suggest therapeutic targets for schizophrenia.

Chen, Alhassen et al. show that schizophrenia-like behavioral deficits induced by excessive prenatal methionine administration are due to in-uterus aberrations rather than through early life mother-infant interaction in mice. This study identifies the brain metabolites and transcriptomic signatures, which potentially serve as early biomarkers for schizophrenia-like behaviors.

A Methionine-Induced Animal Model of Schizophrenia: Face and Predictive Validity

BACKGROUND

Modulating the methylation process induces broad biochemical changes, some of which may be involved in schizophrenia. Methylation is in particular central to epigenesis, which is also recognized as a factor in the etiology of schizophrenia. Because methionine administration to patients with schizophrenia has been reported to exacerbate their psychotic symptoms and because mice treated with methionine exhibited social deficits and prepulse inhibition impairment, we investigated whether methionine administration could lead to behavioral changes that reflect schizophrenic symptoms in mice.

METHODS

l-Methionine was administered to mice twice a day for 7 days.

RESULTS

We found that this treatment induces behavioral responses that reflect the 3 types of schizophrenia-like symptoms (positive, negative, or cognitive deficits) as monitored in a battery of behavioral assays (locomotion, stereotypy, social interaction, forced swimming, prepulse inhibition, novel object recognition, and inhibitory avoidance). Moreover, these responses were differentially reversed by typical haloperidol and atypical clozapine antipsychotics in ways that parallel their effects in schizophrenics.

CONCLUSION

We thus propose the l-methionine treatment as an animal model recapitulating several symptoms of schizophrenia. We have established the face and predictive validity for this model. Our model relies on an essential natural amino acid and on an intervention that is relatively simple and time effective and may offer an additional tool for assessing novel antipsychotics.

No gross abnormality of plasma homocysteine after acute methionine loading in clinically stabilized patients with schizophrenia

Homocysteine is reported to be a risk factor for schizophrenia. The methionine loading test evaluates the summation of a multitude of enzymatic pathways associated with homocysteine metabolism. Using a challenge paradigm, we measured homocysteine levels in 10 chronic schizophrenia patients and five controls at baseline and 3h after 100mg/kg oral methionine. This pilot study failed to detect a gross abnormality of plasma homocysteine level after acute methionine load in patients with schizophrenia. Elevations in plasma homocysteine reported in schizophrenia do not derive from a dynamic abnormality in methionine metabolism in this challenge paradigm.

Niacin and vitamin B6 in mental functioning: a review of controlled trials in humans

Fifty-three controlled trials of the effects of niacin, vitamin B6, and multivitamins on mental functions are reviewed. The results are interpreted with emphasis on the methodological quality of the trials. It turns out that virtually all trials show serious short-comings: in the number of participants, the presentation of baseline characteristics and outcomes, and the description of changes in concomitant treatments. Only in autistic children are some positive results are found with very high dosages of vitamin B6 combined with magnesium, but further evidence is needed before more definitive conclusions can be drawn. For many other indications (hyperactive children, children with Down's syndrome, IQ changes in healthy schoolchildren, schizophrenia, psychological functions in healthy adults and geriatric patients) there is no adequate support from controlled trials in favor of vitamin supplementation.

A metabolic basis for drug dependence

In man, incessant, compulsive sexual activity may follow an increase in brain serotonin simultaneously with a decrease in brain noradrenalin. In animals a similar compulsive aphrodisiac effect on behaviour can occur with the use of an antiserotonin drug permitting a relative increase in noradrenalin.

Five commonly used drugs of dependence, including morphine, have been shown to increase brain serotonin, thus disturbing the ratio of this monoamine, to noradrenalin.

It is argued that drug dependence is a phenomenon of learning and that this learning depends upon stimulation of the reward system of the lateral hypothalamus, medial forebrain bundle and midbrain reticular formation. Drug dependence could follow if the balance of brain serotonin and noradrenalin were seriously disturbed by the drug in either direction. It is suggested that normalization of this metabolic balance might be a logical goal for treatment in drug addiction.