A systematic review and meta-analysis of the associations of vitamin D receptor genetic variants with two types of most common neurodegenerative disorders.

BACKGROUND: Whether vitamin D receptor (VDR) genetic variants influence individual susceptibility to neurodegenerative disorders remains controversial. AIMS: This meta-analysis was conducted to analyze correlations of VDR genetic variants with two types of most common neurodegenerative disorders, Parkinson's disease (PD) and Alzheimer's disease (AD). METHODS: Systematic literature research of PubMed and Embase was performed to identify eligible articles. Q test and I2 statistic were employed to decide whether pooled analyses would be performed with random-effect models (REMs) or fixed-effect models (FEMs). All statistical analyses were conducted with Review Manager. RESULTS: Totally sixteen studies were enrolled for analyses. Among these eligible studies, ten studies were about PD (2356 cases and 2815 controls) and six studies were about AD (1256 cases and 1205 controls). Pooled overall analyses suggested that VDR rs7975232 (additive model: p = 0.03, OR = 1.19, 95% CI 1.01-1.39) and rs2228570 (recessive model: p < 0.008, OR = 1.26, 95% CI 1.06-1.50; allele model: p < 0.001, OR = 0.80, 95% CI 0.71-0.91) variants were significantly correlated with PD, and VDR rs731236 (dominant model: p = 0.003, OR = 0.70, 95% CI 0.56-0.89; additive model: p = 0.02, OR = 1.32, 95% CI 1.06-1.66; allele model: p = 0.02, OR = 0.82, 95% CI 0.69-0.96) variant was significantly correlated with AD. Further subgroup analyses by ethnicity revealed that the positive results were mainly driven by the Asians, whereas no significant associations were observed in Caucasians. CONCLUSION: Our meta-analysis suggested that VDR rs7975232 and rs2228570 variants might serve as genetic biomarkers of PD, whereas VDR rs731236 variant might serve as a genetic biomarker of AD.

Antinociceptive effects of Ginsenoside Rb1 in a rat model of cancer-induced bone pain.

Ginsenoside Rb1 (GRb1) is a major ingredient of ginseng, a traditional medicine that has been used for thousands of years. Previous studies have reported that GRb1 had anti-inflammatory, antioxidant and neuroprotective effects. The current study aimed to evaluate the antinociceptive effects of GRb1 in a rat model of cancer-induced bone pain (CIBP) established by intratibial injection of Walker 256 cells. Intraperitoneal injection (i.p.) of GRb1 (5 and 10 mg/kg, but not 1 mg/kg) partially and transiently reversed the mechanical allodynia and thermal hyperalgesia in CIBP rats at 14 days following surgery when the pain behavior is established. Furthermore, repeated administration of GRb1 demonstrated persistent analgesic effect. Additionally, the protein expression and immunoreactivity of iba1, which is the maker of microglia, was significantly suppressed in CIBP rats treated with GRb1 (i.p., 10 mg/kg) from day 12 for three consecutive days compared with CIBP rats treated with a vehicle. Furthermore, upregulation of spinal interleukin (IL)-1ß, IL-6 and tumor necrosis factor-α were also significantly inhibited by the treatment of GRb1 (i.p., 10 mg/kg) from day 12 for three consecutive days. Together, these results indicated that GRb1 may attenuate CIBP via inhibiting the activation of microglia and glial-derived proinflammatory cytokines.