White light emitting diode suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial cytochrome c oxydase‐mediated IGF‐1 and TNF‐α pathways

Abstract

Light emitting diode (LED) light has been used in the treatment of traumatic brain injury, neural degenerative diseases and psychiatric disorders. A growing number of studies indicate that blue LED light affects cell proliferation and apoptosis in photosensitive cells and cancer cells, yet it remains unknown whether white LED light exposure impacts hippocampal neural cell proliferation and apoptosis. The present study was aimed to demonstrate the effect of white LED light exposure on viability of hippocampal neural cells and to reveal the underlying mechanisms. Cells exposed to white LED light for 24 h showed reduced viability, with higher apoptotic rate and a cell cycle arrest at G0/G1 phase. White LED light activated mitochondrial cytochrome c oxidase (Cco), in association with enhanced ATP synthase activity and elevated intracellular ATP concentration. Also, reactive oxygen species (ROS) and nitric oxide (NO) production were increased, accompanied by higher calcium concentration and lower mitochondrial membrane potential. Concurrently, the mRNA expression and the concentration of IGF‐1 were decreased, while that of TNF‐α were increased, in light‐exposed cells, which was supported by the luciferase activity of both gene promoters. The down‐stream mitogen‐activated protein kinase (MAPK), AKT/mTOR pathways were inhibited, in association with an activation of apoptotic caspase 3. N‐Acetylcysteine, a ROS scavenger, protected the cells from LED light‐induced cellular damage, with rescued cell viability and restored mRNA expression of IGF‐1 and TNF‐α. Our data demonstrate that white LED light suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial Cco/ROS‐mediated IGF‐1 and TNF‐α pathways.Support or Funding InformationThe National Basic Research Program of China (2012CB124703), the Special Fund for Agro‐scientific Research in the Public Interest (201003011), the Fundamental Research Funds for the Central Universities (KYZ201212) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.