Neuroprotective effect of exogenous vascular endothelial growth factor on rat spinal cord neurons in vitro hypoxia.
BACKGROUND
Vascular endothelial growth factor (VEGF) is well known as a hypoxia-induced protein. That it markedly increased expression of VEGF and improvement of rat motor function after spinal cord injury suggested that VEGF could play a neuroprotective role in ischaemic tolerance. This study investigated whether vascular endothelial growth factor has direct neuroprotective effects on rat spinal cord neurons.


METHODS
We employed primary cultures of embryonic rat spinal cord neurons, then administrated different concentrations of VEGF164 in the culture medium before hypoxia when the number of neurons was counted and the cell viability was detected by MTT. The neuronal apoptosis and expression of VEGF and its receptor genes were evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick-end labelling (TUNEL) and immunohistochemistry. The VEGFR2/FLK-1 inhibitor, SU1498, was used to confirm whether the neuroprotective effect of VEGF was mediated through VEGFR2/Flk-1 receptors.


RESULTS
In hypoxic conditions, the number and viability of neurons decreased progressively, while the number of TUNEL-positive cells increased along with the prolongation of hypoxic exposure. When the concentration of VEGF in cell culture medium reached 25 ng/ml, the cell viability increased 11% and neuronal apoptosis reduced to half, this effect was dose dependent and led to an approximately 25% increase in cell viability and about threefold decrease in TUNEL-positive cells at a maximally effective concentration of 100 ng/ml. In normal conditions, VEGF/Flk-1 but not VEGF/Flt-1 gene expressed at a low level: after hypoxia, the expression of VEGF/Flk-1, but not VEGF/Flt-1 was significantly increased. The protective effect of VEGF was blocked by the VEGFR2/Flk-1 receptor tyrosine kinase inhibitor, SU1498.


CONCLUSIONS
VEGF has direct neuroprotective effects on rat spinal cord neurons, which may be mediated in vitro through VEGFR2/Flk-1 receptors.
Ding
Xin-min
XM
Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu 610041, China.
Mao
Bo-yong
BY
Jiang
Shu
S
Li
Sheng-fu
SF
Deng
Yi-ling
YL
D000818:Animals; D015687:Cell Hypoxia; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D005260:Female; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000502:physiology
D002934:Cinnamates; D018696:Neuroprotective Agents; C483044:SU 1498; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2