[Role of vitamin D in the physiopathology of neurodegenerative diseases]

Correlation Between Tic Disorders and Serum 25-Hydroxyvitamin D Levels in Chinese Children

OBJECTIVE

To explore the correlation between serum 25-hydroxyvitamin D levels and tic disorders (TDs) in Chinese children.

METHODS

We selected 2960 children with TD and 2665 healthy controls, aged 5-14 years, from the Department of Neurology of the Shanghai Children's Hospital. Serum 25-hydroxyvitamin D levels and degrees of vitamin D deficiency were compared between patients with TD and healthy children.

RESULTS

The mean serum 25-hydroxyvitamin D level in the TD group was significantly lower than that in the control group (P < 0.001). The proportion of patients with 25-hydroxyvitamin D deficiency in the TD group was significantly higher than that in the control group. However, there was no correlation between 25-hydroxyvitamin D deficiency and the severity of TD. In addition, for age-wise comparison, mean levels of 25-hydroxyvitamin D and its deficiency in the TD group were the most significant in children over 9 years of age.

CONCLUSION

There is a correlation between 25-hydroxyvitamin D deficiency and TD in Chinese children, but not between 25-hydroxyvitamin D deficiency and the severity of TD. There was a correlation between age and deficiency of 25-hydroxyvitamin D; this deficiency was most pronounced among those over the age of 9 years.

Effect of Vitamin D in HN9.10e Embryonic Hippocampal Cells and in Hippocampus from MPTP-Induced Parkinson's Disease Mouse Model

It has long been proven that neurogenesis continues in the adult brains of mammals in the dentatus gyrus of the hippocampus due to the presence of neural stem cells. Although a large number of studies have been carried out to highlight the localization of vitamin D receptor in hippocampus, the expression of vitamin D receptor in neurogenic dentatus gyrus of hippocampus in Parkinson's disease (PD) and the molecular mechanisms triggered by vitamin D underlying the production of differentiated neurons from embryonic cells remain unknown. Thus, we performed a preclinical in vivo study by inducing PD in mice with MPTP and showed a reduction of glial fibrillary acidic protein (GFAP) and vitamin D receptor in the dentatus gyrus of hippocampus. Then, we performed an in vitro study by inducing embryonic hippocampal cell differentiation with vitamin D. Interestingly, vitamin D stimulates the expression of its receptor. Vitamin D receptor is a transcription factor that probably is responsible for the upregulation of microtubule associated protein 2 and neurofilament heavy polypeptide genes. The latter increases heavy neurofilament protein expression, essential for neurofilament growth. Notably N-cadherin, implicated in activity for dendritic outgrowth, is upregulated by vitamin D.

Dietary Calcium Intake May Contribute to the HOMA-IR Score in Korean Females with Vitamin D Deficiency (2008-2012 Korea National Health and Nutrition Examination Survey)

Background

Vitamin D and calcium are important factors involved in the regulation of blood glucose and insulin secretion. The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) score is a useful variable for evaluating insulin resistance, and therefore we cross-sectionally compared HOMA-IR scores according to serum vitamin D levels and dietary calcium intake.

Methods

We selected data from healthy males (n=5,163) and females (n=7,506) analyzed over 5 years (2008–2012) via the Korea National Health and Nutrition Examination Survey (KNHANES). We calculated HOMA-IR scores and compared them according to serum 25-hydroxyvitamin D (25(OH)D) concentration classification (<20, 20–30, >30 ng/mL) and dietary calcium quintile after adjustment for relevant variables using complex sample analysis. Comparisons were done after data weighting.

Results

The mean dietary calcium intake in males and females was 558.1 mg/day and 445.9 mg/day, respectively. The mean serum 25(OH)D concentration in males and females was 19.4 ng/mL and 16.8 ng/mL, respectively. After adjustment for relevant variables, HOMA-IR score was significantly correlated with serum 25(OH)D concentration and dietary calcium intake in females, whereas it was only correlated with serum 25(OH)D concentration in males. HOMA-IR was significantly lower in the top quintile of dietary calcium intake (mean, 866 mg/day) within females with vitamin D deficiency (P=0.047).

Conclusion

Adequate dietary calcium intake may be important for normal HOMA-IR in females with vitamin D deficiency.