Abstract

BACKGROUND
It is well documented that calcium ions perform a major role in neuronal degeneration in cerebrovascular disease and the other degenerative diseases, and that 1,25-dihydroxyvitamin D3 (D3) has the dose-dependent protective effects. This study was performed to examine the effects of different D3 dosages against delayed neuronal damage of the hippocampus.
METHODS
Mature mongolian gerbils were injected with either 0.8 microgram/kg/day (group 2) for 5 days or 1.0 microgram/kg/day for 8 days (group 3) prior to the 10 min ligation of the bilateral common carotid arteries. Immunohistochemical expression for the glial cell line-derived neurotrophic factor (GDNF), the basic fibroblast growth factor (bFGF) and the platelet-derived neurotrophic factor (PDNF) was observed in the D3-injected (0.8 microgram/kg/day for 5 days) group.
RESULTS
Group 2 showed a highly significant attenuation of delayed neuronal damage in the lateral CA1 region at 7 days after reperfusion. Group 3 showed unilateral or bilateral hemispheric infarcts 24 h after the onset of reperfusion. The D3-injected group showed a markedly increased bFGF expression level.
CONCLUSION
The dose-dependent effect of D3 suggests the importance of determining the appropriate D3 dose for clinical applications. Although the mechanism(s) of neuroprotection by D3 remains unclear, D3 may facilitate a reduction in ischemia-induced oxidative stress via the activation of the neurotrophic factors, including bFGF and GDNF.

• Keywords: Calcitriol;Cerebrovascular Disorders;Hypoxic;Ischemic Brain Injury