Retrograde mitochondrial signaling: This is a key factor where mitochondria in the cells communicate with the nucleus of the cell about what is going on, thus affecting what genes get expressed in the DNA-containing nucleus of our cells.
Cytochrome c oxidase: This is a photoreceptor located on mitochondria in our cells that “accepts” light photons and then triggers events in the mitochondria.
Adenosine triphosphate (ATP): This is cellular energy produced by mitochondria. One of the more notable findings from many studies is that exposure to red light increases levels of ATP production.
Light-sensitive ion channels: There are channels in our cells that control the flow of various ions (e.g. calcium, potassium, sodium, etc.). Some of these are affected by light and then are involved with triggering further events in the cell or between cells.
Reactive oxygen species (ROS): These are also commonly called “free radicals.” While commonly associated with bad things (e.g. cell damage, oxidation, etc.), they also play vital roles in our bodies as signaling molecules. For example, ROS are produced from physical exercise and signal many of the positive adaptations that our body makes to exercise.
Nitric oxide (NO): It is known that NO levels rise after red light exposure. NO is well known by most people for its role in blood vessel dilation, but it also acts in many other signaling pathways.
Cyclic AMP: This is involved with opposing inflammatory pathways, among other functions in the cell.
Calcium:Red light can affect calcium levels in the cell, which in turn act as a signal for numerous cellular processes.
RANKL: A protein involved in bone regeneration/remodeling.
Nuclear factor kappa B: This is a signaling compound that regulates many genes involved in inflammation and cell survival to stressors.
Akt/GSK3b/b-catenin pathway: This pathway relates to cell survival and apoptosis (programmed cell death).
Hypoxia-inducible factor: A protein involved in cellular adaptation to low oxygen levels.
ERK/FOXM1: Involved in regulating cell division.
Akt/mTOR/CyclinD1 pathway: Involved in cell growth signaling.
PPARy: Involved in the inflammatory response.
RUNX2: Involved in bone cell differentiation.
Transforming growth factor: Stimulator of collagen production (e.g. in the skin).
Vascular endothelial growth factor: Involved in angiogenesis, the formation of new blood vessels.
Pro- and anti-inflammatory cytokines: Many pro- and anti-inflammatory cytokines and mediators have been shown to have their levels altered by red light exposure.
Hepatocyte growth factor: Involved in liver cell health.
Heat-shock proteins: Involved in inflammation, wound healing, and cellular survival against many types of stressors (e.g. exercise, sauna/heat stress, etc.).
Basic fibroblast growth factor and keratinocyte growth factor: Involved in the wound healing process.
Melatonin: Interestingly, red light therapy has been shown to increase the “extra-pineal” production of melatonin outside of the pineal gland. Melatonin is much more than just a sleep-inducing hormone as most people know it, melatonin has critical roles in protecting the mitochondria from damage and supporting glutathione levels, which is one of our body’s most powerful and important antioxidants and detoxifying compounds. Some researchers have suggested that this increased melatonin may be a significant factor in the effects of red light.
Brain-derived neurotrophic factor: Involved in neuron/brain cell growth and regeneration.