Does photobiomodulation require glucose to work effectively?

A main requirement for cells to function normally is the availability of glucose.Glucose,available either direct from circulation or storage,is converted to the essential energy that cells need to drive critical intrinsic functions.If cells are deprived of glucose,they become dysfunctional and suffer distress.Photobiomodulation,the use of specific wavelengths of light on body tissues,has been shown to promote,through small organelles called mitochondria,the metabolism of glucose to make energy for cells;this energy can be used to improve cell function and survival.In this perspective,we hypothesize that the availability of glucose is central to the core mechanism of photobiomodulation;that photobiomodulation is at its most efficient in stimulating mitochondrial activity and improving cell function when there is glucose readily available.

A spotlight on dosage and subject selection for effective neuroprotection: exploring the central role of mitochondria

Neurons are notoriously vulnerable cell types.Even the slightest change in their internal and/or external environments will cause much distress and dysfunction,leading often to their death.A range of pathological conditions,including stroke,head trauma,and neurodegenerative disease,can generate stress in neurons,affecting their survival and proper function.In most neural pathologies,mitochondria become dysfunctional and this plays a pivotal role in the process of cell death.The challenge over the last few decades has been to develop effective interventions that improve neuronal homeostasis under pathological conditions.Such interventions,often referred to as disease-modifying or neuroprotective,have,however,proved frustratingly elusive,at both preclinical and,in particular,clinical levels.In this perspective,we highlight two factors that we feel are key to the development of effective neuroprotective treatments.These are:firstly,the choice of dose of intervention and method of application,and secondly,the selection of subjects,whether they be patients or the animal model.

Do astrocytes respond to light,sound,or electrical stimulation?

Astrocytes are not only the most populous cell type in the human brain,but they also have the most extensive and dive rse sets of connections,across synapses,axons,blood vessels,as well as having their own internal network.Unsurprisingly,they are associated with many brain functions;from the synaptic transmission to energy metabolism and fluid homeostasis,and from cerebral blood flow and blood-brain barrier maintenance to neuroprotection,memory,immune defenses and detoxification,slee p,and early development.And yet,notwithstanding these key roles,so many current therapeutic approaches to a range of brain disorders have largely neglected their potential involvement.In this review,we consider the role of astrocytes in three brain therapies;two are emerging treatments(photobiomodulation and ultrasound),while the other is well-established(deep brain stimulation).In essence,we explore the issue of whether external sources,such as light,sound,or electricity,can influence the function of astrocytes,as they do neurons.We find that,when taken all together,each of these external sources can influence many,if not,all of the functions associated with astrocytes.These include influencing neuronal activity,prompting neuroprotection,reducing inflammation(astrogliosis) and potentially increasing cerebral blood flow and stimulating the glymphatic system.We suggest that astrocytes,just like neurons,can respond positively to each of these external applications and that their activation co uld each impart many beneficial outcomes on brain function;they are likely to be key playe rs underpinning the mechanisms behind many therapeutic strategies.

Lights at night:does photobiomodulation improve sleep?

Sleep is a critical part of our daily routine.It impacts every organ and system of our body,from the brain to the heart and from cellular metabolism to immune function.A consistent daily schedule of quality of sleep makes a world of difference to our health and well-being.Despite its importance,so many individuals have trouble sleeping well.Poor quality sleep has such a detrimental impact on many aspects of our lives;it affects our thinking,learning,memory,and movements.Further,and most poignantly,poor quality sleep over time increases the risk of developing a serious medical condition,including neurodegenerative disease.In this review,we focus on a potentially new non-pharmacological treatment that improves the quality of sleep.This treatment,called photobiomodulation,involves the application of very specific wavelengths of light to body tissues.In animal models,these wavelengths,when applied at night,have been reported to stimulate the removal of fluid and toxic waste-products from the brain;that is,they improve the brain’s inbuilt house-keeping function.We suggest that transcranial nocturnal photobiomodulation,by improving brain function at night,will help improve the health and well-being of many individuals,by enhancing the quality of their sleep.

Lights for epilepsy:can photobiomodulation reduce seizures and offer neuroprotection?

Epilepsy is synonymous with individuals suffering repeated“fits”or seizures.The seizures are triggered by bursts of abnormal neuronal activity,across either the cerebral cortex and/or the hippocampus.In addition,the seizure sites are characterized by considerable neuronal death.Although the factors that generate this abnormal activity and death are not entirely clear,recent evidence indicates that mitochondrial dysfunction plays a central role.Current treatment options include drug therapy,which aims to suppress the abnormal neuronal activity,or surgical intervention,which involves the removal of the brain region generating the seizure activity.However,~30%of patients are unresponsive to the drugs,while the surgery option is invasive and has a morbidity risk.Hence,there is a need for the development of an effective non-pharmacological and non-invasive treatment for this disorder,one that has few side effects.In this review,we consider the effectiveness of a potential new treatment for epilepsy,known as photobiomodulation,the use of red to near-infrared light on body tissues.Recent studies in animal models have shown that photobiomodulation reduces seizure-like activity and improves neuronal survival.Further,it has an excellent safety record,with little or no evidence of side effects,and it is non-invasive.Taken all together,this treatment appears to be an ideal treatment option for patients suffering from epilepsy,which is certainly worthy of further consideration.

How and why does photobiomodulation change brain activity?

The concept that certain wavelengths of light can change regional brain activity as well as influencing the functional connectivity between different brain centers,is rather striking.Such a concept goes beyond that of a function for light stimulating specialized retinal ganglion cells to entrain circadian rhythms but extends this to include light having a direct influence on all neurons to potentially influence a range of core higher-order brain activities.In this perspective,we explore how light may influence such core brain activities,together with why it should do so in the first place.

Exploring the use of transcranial photobiomodulation in Parkinson's disease patients

Parkinson＇s disease is a neurological disorder with distinct motor signs of resting tremor,akinesia and/or lead-pipe rigidity,together with non-motor symptoms of impaired smell,cognition and autonomic function.These manifest after a major degeneration of neurones mainly within the brainstem,particularly among the dopaminergic neurones.

Why and how does light therapy offer neuroprotection in Parkinson＇s disease？

Red and infrared light （X = 600-1,070 nm） therapy, known also as photobiomodulation, has been reported to offer neu-roprotection and to improve locomotor behaviour in animal models of Parkinson＇s disease, from rodents to non-human primates （Rojas and Gonzalez-Lima, 2011; Hamblin, 2016; Johnstone et al., 2016）. The neuroprotective aspect of this therapy is particularly relevant; the saving of neurons that would normally die as a result of the parkinsonian degeneration, is without doubt,

Targeting the body to protect the brain:inducing neuroprotection with remotely-applied near infrared light

The incidence of intractable age-related neurodegenerative conditions such as Alzheimer＇s and Parkinson＇s diseases and age-related macular degeneration is projected to increase substantially over the coming decades with the ageing of the global population. While the burden of disease associ- ated with other chronic conditions has decreased in recent times due to improved diagnosis and treatment, current therapies for neurodegenerative diseases still fall short in that they are only effective in treating signs and symptoms - they do little to slow or prevent disease progress. Thus, there is an urgent need for treatments that address disease progression.

The code of light:do neurons generate light to communicate and repair?

A great challenge in neuroscience has been to understand how neurons communicate.The neuroanatomists of the 19th Century could see neurons stretching processes to contact other neurons,but could not see the detail of the contact.Many thought that neurons formed a syncytium,with continuity of membranes from one to the next.Over the ensuing two hundred years or so,we have come to understand that the circuity of the brain is not formed by a syncytium of neurons;rather,individual neurons communicate with each other with a range of biological signals.Neurons are highly active cells,with their activity being electrical and their communication being either chemical,electrical or gaseous.