http://www.sciencedirect.com/science/article/pii/S0006291X12008364
Abstract
Objective
We
previously reported that 710nm Light-emitting Diode (LED) has a
protective effect through cellular immunity activation in the stroke
animal model. However, whether LED directly protects neurons suffering
from neurodegeneration was entirely unknown. Therefore, we sought to
determine the effects of 710nm visible light irradiation on neuronal
protection and neuronal outgrowth in an in vitro stroke model.
Materials &methods
Primary
cultured rat cortical neurons were exposed to oxygen-glucose
deprivation (OGD) and reoxygenation and normal conditions. An LED array
with a peak wavelength of 710 nm was placed beneath the covered culture
dishes with the room light turned off and were irradiated accordingly.
LED treatments (4 min at 4 J/cm2 and 50 mW/cm2)
were given once to four times within 8 hours at 2 hr intervals for 7
days. Mean neurite density, mean neurite diameter, and total fiber
length were also measured after microtubule associated protein 2 (MAP2)
immunostaining using the Axiovision program. Synaptic marker expression
and MAPK activation were confirmed by Western blotting.
Results
Images captured after MAP2 immunocytochemistry showed significant (p<0.05) enhancement of post-ischemic neurite outgrowth with LED treatment once and twice a day. MAPK activation was enhanced by LED treatment in both OGD-exposed and normal cells.
The levels of synaptic markers such as PSD 95, GAP 43, and
synaptophysin significantly increased with LED treatment in both
OGD-exposed and normal cells (p < 0.05).
Conclusion
Our
data suggest that LED treatment may promote synaptogenesis through MAPK
activation and subsequently protect cell death in the in vitro stroke model.
Highlights
►
710nm wavelength light (LED) has a protective effect in the stroke
animal model. ► We determined the effects of LED irradiation in vitro
stroke model. ► LED treatment promotes the neurite outgrowth through
MAPK activation. ► The level of synaptic markers significantly increased
with LED treatment. ► LED treatment protects cell death in the in vitro stroke model.
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