Vitamin D deficiency has been detected in epileptic patients. Vitamin D participates in neuroprotection, brain cell proliferation, and differentiation. Consequently, vitamin D supplementation has been suggested as an alternative treatment in epileptic patients. We aimed at assessment of vitamin D signaling pathway in epileptic patients. In the present study, we evaluated vitamin D serum concentration as well as expression of vitamin D receptor (VDR) gene and genes encoding for vitamin D activating enzyme 1-alpha-hydroxylase (CYP27B1) and deactivating enzyme 24-hyroxylase (CYP24A1) in epileptic patients compared with healthy individuals. We found significant lower levels of vitamin D in epileptic patients compared with healthy subjects. Expression analyses showed significant downregulation of VDR expression in peripheral blood of epileptic patients compared with healthy subjects (relative expression (REx) = 0.16, P < 0.001). However, there was no significant difference in CYP24A1 expression between epileptic patients and normal subjects. CYP27B1 expression analysis showed significant upregulation in male patients aged between 30 and 40 (REx = 5.43, P = 0.013). After using two-way ANCOVA for adjusting the effects of sex and age, there was a statistically significant difference in the VDR expression values between patient and control groups (P < 0.001). Spearman's correlation analysis showed no significant correlation between genes expression levels and patients' age or vitamin D serum concentrations. However, we found significant correlations between VDR expression levels and CYP24A1/ CYP27B1 expression levels in epileptic patients (r = 0.435 and P < 0.001; r = 0.26 and P = 0.02 respectively). There was also a significant correlation between the expression levels of CYP24A1 and CYP27B1 (r = 0.349 and P = 0.001). Our study shows a possible role for VDR in the pathogenesis of epilepsy.
Keywords: CYP24A1; CYP27B1; Epilepsy; VDR; Vitamin D.