25-Hydroxy Vitamin D Exhibits NGF-like Activity in PC12 Cells

Abstract

Background: In our previous study, 25-hydroxy vitamin D (25OHD) supplementation was associated with improved serum vitamin D levels and, possibly, improved cognitive function. In response to nerve growth factor, PC12 cells first undergo proliferation, followed by growth arrest and differentiation. We studied the effects of 25OHD on neurite elongation in PC12 cells. Methods: PC12 cells were treated with 10ng/mL NGF with or without 6 nmol/L of 25OHD for 9 days. Phase-contrast micrographs were recorded and cells with a neurite outgrowth longer than the diameter of their cell body were counted. To investigate the expression level of Akt protein, PC12 cells were preincubated with 10ng/mL NGF with or without 6 nmol/L of 25OHD for 4 days, and lysates were assayed using a commercially available AKT/AKT ELISA kit. Results: In the presence of NGF, 25OHD induced an increase in both the number of cells with extended neurites and the length of neurites. Expression of phosphorylated Akt was enhanced by 25OHD without NGF and 25OHD up-regulated NGF-induced phosphorylation. Conclusion: These findings show that 25OHD displays NGF-mimicking and NGF-enhancing neurogenic activity in PC12 cells, which potentially depended on activating P3K/AKT signaling pathways.