Vitamin D treatment ameliorates memory function through downregulation of BAX and upregulation of SOD2 mRNA expression in transient global brain ischaemic injury in rats.

INTRODUCTION: Ischaemic stroke induces oxidative stress with SOD2 downregulation, and BAX upregulation producing apoptosis. Vitamin D is a fat-soluble hormone that has a neuroprotective effect. The aim of this study is to elucidate the role of vitamin D in memory function, oxidative stress and apoptosis in transient global brain schaemic injury (TGBII) model. MATERIALS AND METHODS: TGBII was performed in male Wistar rats (3 to 5 months, 150 to 300 g) which underwent bilateral common carotid artery occlusion (BCCAO) for 20 minutes, then reperfused for 10 days (BCCAO group, n = 6). Two groups of BCCAO were treated with intraperitoneal injection of calcitriol 0.125 µg/kgBW (VD1 group) and 0.5 µg/kgBW (VD2 group). The spatial memory function was tested using a probe test with Morris water maze (MWM). mRNA expression of BAX and SOD2 were assessed by the RT-PCR method. Meanwhile, immunohistochemical staining was used for identification of SOD2 protein. Statistical analysis is tested using one-way ANOVA followed by post-hoc LSD. RESULTS: MWM showed a shorter duration in target quadrant of BCCAO group than the SO group, which is associated with BAX upregulation and SOD2 downregulation. The VDtreated groups had longer duration probe test compared to BCCAO. Furthermore, VD-treated groups had a longer duration in probe test with lower mRNA expression of BAX and higher expression of SOD2. However, there was no significant difference in VD1 and VD2. Immunostaining showed a reduced SOD2 signal in pyramidal cell of CA1 area in BCCAO group and ameliorated in VD1 and VD2 groups. CONCLUSION: Vitamin D ameliorates memory function and attenuates oxidative stress and apoptosis in the TGBII model.

Vitamin D ameliorates memory function in association with reducing senescence and upregulating neurotrophin mRNA expression in transient global cerebral ischemic injury model in rats.

INTRODUCTION: Ischaemic stroke induces oxidative stress, mitochondrial damage, inflammation and senescence and the decrease of cognitive function. Vitamin D is a fat-soluble vitamin that has a neuroprotective effect to repair the function of the nervous system. The aim of this study is to investigate the effect of vitamin D on memory function, p16, p21 (senescence), and nerve growth factor (NGF) mRNA expression on the hippocampus after transient global cerebral ischemic. MATERIALS AND METHODS: The study was designed as quasiexperimental with a control group that only received posttests. We performed in vivo study with an induction bilateral common carotid artery occlusion (BCCAO) model and vitamin D injection for 10 days. A total of 24 rats were divided into four groups (n = 6): Sham operation (SO [control]), BCCAO (transient global cerebral ischemic model not given vitamin D), VD1 (BCCAO + vitamin D 0.125 µg/kgBW), and VD2 (BCCAO + vitamin D 0.5 µg/kgBW). The spatial memory function was tested with the Morris water maze. We performed immunohistochemistry to localise p16 expression. p16, p21 and NGF mRNA expression were assessed by reverse transcriptase (RT-PCR) method. RESULTS: The vitamin D treatment group required shorter mileage to find the platform and probe test. The total time spent was longer in the target quadrant than in non-target. The Vitamin D-treated group had lower p16 and p21 mRNA expression and higher NGF mRNA expression than the BCCAO group. Immunostaining showed p16 signal in the pyramidal cell of CA1 area in the BCCAO group. CONCLUSION: Vitamin D repairs memory function, senescence expression was lower and NGF was higher in the BCCAO model.