Neurotoxicity of folates: implications for vitamin B12 deficiency and Huntington's chorea

Vitamin B6, B12 and folate modulate deregulated pathways and protein aggregation in yeast model of Huntington disease

Huntington's disease (HD) is an incurable and progressive neurodegenerative disease affecting the basal ganglia of the brain. HD is caused due to expansion of the polyglutamine tract in the protein Huntingtin resulting in aggregates. The increased PolyQ length results in aggregation of protein Huntingtin leading to neuronal cell death. Vitamin B6, B12 and folate are deficient in many neurodegenerative diseases. We performed an integrated analysis of transcriptomic, metabolomic and cofactor-protein network of vitamin B6, B12 and folate was performed. Our results show considerable overlap of pathways modulated by Vitamin B6, B12 and folate with those obtained from transcriptomic and metabolomic data of HD patients and model systems. Further, in yeast model of HD we showed treatment of B6, B12 or folate either alone or in combination showed impaired aggregate formation. Transcriptomic analysis of yeast model treated with B6, B12 and folate showed upregulation of pathways like ubiquitin mediated proteolysis, autophagy, peroxisome, fatty acid, lipid and nitrogen metabolism. Metabolomic analysis of yeast model shows deregulation of pathways like aminoacyl-tRNA biosynthesis, metabolism of various amino acids, nitrogen metabolism and glutathione metabolism. Integrated transcriptomic and metabolomic analysis of yeast model showed concordance in the pathways obtained. Knockout of Peroxisomal (PXP1 and PEX7) and Autophagy (ATG5) genes in yeast increased aggregates which is mitigated by vitamin B6, B12 and folate treatment. Taken together our results show a role for Vitamin B6, B12 and folate mediated modulation of pathways important for preventing protein aggregation with potential implications for HD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03525-y.

Differentiation of Reversible Hemichorea Due to Vitamin B12 Deficiency From Huntington Disease Via FDG PET

ABSTRACT

Vitamin B12 deficiency may present with diverse symptoms, complicating the differential diagnosis. Extrapyramidal movement disorders, for instance, are a rare manifestation of vitamin B12 deficiency. MRI of the brain frequently remains without conclusive findings. However, 18 F-FDG PET/CT may reveal characteristic changes in the metabolism of the basal ganglia and thus contribute to an accurate diagnosis. We demonstrate the case of a woman with left-sided hemichoreatic movements due to vitamin B12 deficiency showing a contralateral putaminal hypermetabolism, which normalized after vitamin B12 supplementation, ruling out other deviating causes, particularly Huntington disease.

Relationship of normal serum vitamin B12 and folate levels to cognitive test performance in subtypes of geriatric major depression

This retrospective study evaluated the relationships between normal serum vitamin B12 and folate levels and neuropsychologic measures in a sample of 60 geriatric inpatients with psychotic depression, nonpsychotic depression, bipolar disorder, and dementia--all consecutively referred for cognitive testing. The psychotic depression subgroup demonstrated numerous significant positive correlations between B12 and cognitive subtests not seen in other diagnostic subgroups, especially those of IQ, and verbal and visual memory. Metabolic factors including vitamin B12 may play specific roles in the cognitive dysfunctions of different geropsychiatric disorders.

Folate induced-hypermotility response after bilateral injection into the nucleus accumbens of the rat. Possible mediation through dopaminergic mechanisms

Folic acid (FA) and certain of its reduced congeners produce excitatory effects when applied to neuronal tissue. Recent evidence has suggested that folates have other biological properties in common with the excitatory amino acids. The purpose of this study was to determine the activity of folate compounds in a system sensitive to excitatory amino acids. Bilateral injection of folic acid into the nucleus accumbens resulted in a marked increase in locomotor activity at doses of 2.5 and 5 micrograms. Larger doses resulted in behavioral responses, such as body tremor and labored breathing, which interfered with the locomotor response. Similarly, 5-formyltetrahydrofolic acid (FTHF) produced a marked hypermotility response after bilateral injection into the nucleus accumbens (2.5-25 micrograms), while dihydrofolic acid, tetrahydrofolic acid, and 5-methyltetrahydrofolic acid were ineffective. Pretreatment with reserpine (10 mg/kg, i.p.) markedly reduced the hypermotility response elicited by folic acid and FTHF as did pretreatment with haloperidol in both peripheral (0.8 mg/kg) and direct (5 micrograms) injection into the nucleus accumbens. In addition, injection of muscimol (30 ng), which depresses hypermotility induced by dopamine and amphetamine, produced a significant decrease in the hypermotility response produced by folic acid. In contrast, pretreatment with phentolamine (5 mg/kg, i.p.) or propranolol (4 mg/kg, i.p.) did not decrease folic acid or FTHF-induced responses. These results suggest that folic acid and FTHF produce an increase in locomotor activity by facilitating dopaminergic neurotransmission in the nucleus accumbens, possibly by inducing the release of dopamine from the nerve terminals. Thus, these folates have effects similar to those of the excitatory amino acids when injected into the nucleus accumbens.

Cobalamin inactivation by nitrous oxide produces severe neurological impairment in fruit bats : protection by methionine and aggravation by folates

Nitrous oxide, which inactivates cobalamin when administered to fruit bats, results in severe neurological impairment leading to ataxia, paralysis and death. This occurs after about 6 weeks in animals depleted of cobalamin by dietary restriction, and after about 10 weeks in cobalamin replete bats. Supplementation of the diet with pteroylglutamic acid caused acceleration of the neurological impairment - the first unequivocal demonstration of aggravation of the neurological lesion in cobalamin deficiency by pteroylglutamic acid. The administration of formyltetrahydropteroylglutamic acid produced similar aggravation of the neurological lesion. Supplementation of the diet with methionine protected the bats from neurological impairment, but failed to prevent death. Methionine supplementation protected against the exacerbating effect of folate, preventing the development of neurological changes. These findings lend support to the hypothesis that the neurological lesion in cobalamin deficiency may be related to a deficiency in the methyl donor S-adenosylmethionine which follows diminished synthesis of methionine.