Thiamine deficiency contributes to synapse and neural circuit defects

BACKGROUND

The previous studies have demonstrated the reduction of thiamine diphosphate is specific to Alzheimer's disease (AD) and causal factor of brain glucose hypometabolism, which is considered as a neurodegenerative index of AD and closely correlates with the degree of cognitive impairment. The reduction of thiamine diphosphate may contribute to the dysfunction of synapses and neural circuits, finally leading to cognitive decline.

RESULTS

To demonstrate this hypothesis, we established abnormalities in the glucose metabolism utilizing thiamine deficiency in vitro and in vivo, and we found dramatically reduced dendrite spine density. We further detected lowered excitatory neurotransmission and impaired hippocampal long-term potentiation, which are induced by TPK RNAi in vitro. Importantly, via treatment with benfotiamine, Aβ induced spines density decrease was considerably ameliorated.

CONCLUSIONS

These results revealed that thiamine deficiency contributed to synaptic dysfunction which strongly related to AD pathogenesis. Our results provide new insights into pathogenesis of synaptic and neuronal dysfunction in AD.

Knockout of Slc25a19 causes mitochondrial thiamine pyrophosphate depletion, embryonic lethality, CNS malformations, and anemia

SLC25A19 mutations cause Amish lethal microcephaly (MCPHA), which markedly retards brain development and leads to alpha-ketoglutaric aciduria. Previous data suggested that SLC25A19, also called DNC, is a mitochondrial deoxyribonucleotide transporter. We generated a knockout mouse model of Slc25a19. These animals had 100% prenatal lethality by embryonic day 12. Affected embryos at embryonic day 10.5 have a neural-tube closure defect with ruffling of the neural fold ridges, a yolk sac erythropoietic failure, and elevated alpha-ketoglutarate in the amniotic fluid. We found that these animals have normal mitochondrial ribo- and deoxyribonucleoside triphosphate levels, suggesting that transport of these molecules is not the primary role of SLC25A19. We identified thiamine pyrophosphate (ThPP) transport as a candidate function of SLC25A19 through homology searching and confirmed it by using transport assays of the recombinant reconstituted protein. The mitochondria of Slc25a19(-/-) and MCPHA cells have undetectable and markedly reduced ThPP content, respectively. The reduction of ThPP levels causes dysfunction of the alpha-ketoglutarate dehydrogenase complex, which explains the high levels of this organic acid in MCPHA and suggests that mitochondrial ThPP transport is important for CNS development.

No difference in blood thiamine diphosphate levels between Swedish Caucasian patients with congestive heart failure treated with furosemide and patients without heart failure

OBJECTIVES

To determine whether furosemide treatment in congestive heart failure (CHF) patients is associated with thiamine deficiency.

DESIGN

Patients without heart failure and without diuretic treatment were included to compare with patients with CHF belonging to New York Heart Association (NYHA) functional class II and III-IV, respectively, and receiving furosemide therapy.

SETTING

All patients were recruited from the emergency ward of the cardiology section. Huddinge University Hospital, where they were admitted due to CHF or acute myocardial infarction.

SUBJECTS

Ninety-nine patients were included from whom a blood sample was taken, as well as routine admission blood samples for the analysis of thiamine diphosphate (TPP) concentrations. Patients taking vitamin preparations were excluded.

MAIN OUTCOME MEASURES

Blood TPP concentrations were measured by high performance liquid chromatography (HPLC) and compared between the patient groups by the use of ANOVA.

RESULTS

No significant difference was found between the groups in blood TPP concentrations.

CONCLUSIONS

Thiamine deficiency may not be a complication of furosemide treatment in the studied Swedish patient population.

Thiamin and thiamin phosphate ester deficiency assessed by high performance liquid chromatography in four clinical cases of Wernicke encephalopathy

The concentrations of thiamin and thiamin phosphate esters were determined by high performance liquid chromatography in four patients with clinical Wernicke encephalopathy. Three were alcohol abusers, and one had prolonged vomiting and anorexia. Thiamin and thiamin monophosphate were assessed in plasma and whole blood (four patients) and in cerebrospinal fluid (two patients) before and during thiamin treatment. Thiamin diphosphate was also assessed in whole blood in the four patients. Before treatment, thiamin monophosphate was significantly decreased in all patients, and thiamin diphosphate in three. A poor increase in thiamin mono- and diphosphate was paralleled by a slow clinical improvement in one patient, while an increase in all thiamin compounds was observed in two patients with a rapid recovery. Thiamin monophosphate was a more sensitive marker of deficiency than thiamin diphosphate and unphosphorylated thiamin.

Red cell transketolase studies in a private practice specializing in nutritional correction

Erythrocyte transketolase (TKA) and thiamin pyrophosphate percentage uptake, or effect (TPPE) were performed on 1011 patients between 1983 and 1986. The subjects were drawn from a private practice specializing in nutritional correction as a major therapeutic thrust. Either TKA or TPPE or both were abnormal in 283 (28%). Out of the total number of patients with these abnormal studies 36 have been selected as representative. Their clinical presentation is correlated with subsequent laboratory testing in order to draw attention to the practical value of the test in a clinical setting. These data are presented because of the surprisingly high incidence of abnormal tests, that strongly suggests that there is widespread marginal nutritional deficiency in the United States and that it represents a clinical problem that deserves far more attention than it is presently receiving.

The role of thiamine in nervous tissue

The possibility that thiamine (vitamin B1) has a role in nervous tissue that is independent of its well-documented coenzyme function is discussed. After reviewing the localization and metabolism of the vitamin and its phosphate esters, the effects of either thiamine deprivation or antimetabolites of thiamine on conduction and transmission, and the relationship between thiamine triphosphate and the genetic, neurological disease, subacute necrotizing encephalomyelopathy (Leigh's disease), it is suggested that despite the lack of hard evidence, it is likely that the vitamin possesses this alternate function.