Some neurological disorders can be improved with photobiomodulation, a non-invasive technique based on the application of low-intensity light to stimulate impaired functions in specific regions of the body. A study published in the Journal of Affective Disorders reveals the effectiveness of photobiomodulation applied to the brain-gut axis in correcting certain cognitive alterations and sequelae caused by chronic stress. This study opens up new prospects for the application of this technique to future therapies for the treatment of neurological diseases.
The article, based on the study of laboratory animal models, is led by Professor Albert Giralt, from the Faculty of Medicine and Health Sciences and the Institute of Neurosciences (UBneuro) at the University of Barcelona. Also taking part are teams from the Center for the Production and Validation of Advanced Therapies (CREATIO) at the UB and the University of Girona, as well as from the University of Montpellier and the REGEnLIFE company (France).
Low-intensity light to activate the gut-brain axis
In clinical practice, photobiomodulation uses light from lasers or other low-intensity sources to stimulate the activity of an organ whose physiology is altered. This new study applies, for the first time in the field of depression, the combined use of photobiomodulation to stimulate different organs, notably the brain and the intestine.
“This is one of the most innovative scientific contributions of the study: simultaneously stimulating the brain and gut in a coordinated manner, in other words the gut-brain axis. Today, research on this axis is attracting a great deal of scientific interest and represents a very promising field for the treatment of nervous system diseases.”
“The new therapeutic approach focuses on this now rediscovered scenario of intervention and manipulation of the gut-brain axis to treat neurological and psychiatric disorders,” explains Giralt. “Photobiomodulation is a non-invasive technology, very well tolerated by patients and devoid of the side effects of pharmacological treatments. What’s more, this advance could also be useful in the treatment of pathologies without clear or incomplete medical coverage, such as treatment-resistant depression,” adds the expert.
The photobiomodulation application devices developed by REGEnLIFE are the result of earlier studies carried out on Alzheimer’s patients. They combine several stimulation sources (laser, LED, etc.) with a magnetic ring to stabilize light emission in a pulsed – rather than continuous – manner, to avoid tissue overheating. They are suitable for clinical application in patients.
Psychiatric disorders: beyond the brain
Another scientific objective of the study is to demonstrate that psychiatric disorders are not only localized in the brain, “but that other tissues and organs also play a decisive role in their pathophysiology. If new therapies take all these factors into account, it’s highly likely that we’ll be able to achieve very satisfactory results in the future”, says the researcher.
But do these two photobiomodulation applications both act on the cerebrointestinal axis? Until now, only descriptive studies of the changes induced by photobiomodulation have been carried out. This study now explores the molecular mechanisms and reveals how photobiomodulation is able to reverse the cognitive effects of chronic stress by restoring the sirta1 pathway, “linked to neuronal senescence and death, modulation of the negative pyramid and normalization of gut microbiota diversity”, notes researcher Anna Sancho-Balcells (UB-UBneuro-CIBERNED), first author of the paper.
Other studies,” she continues, “knew that the SIRT1 pathway was altered in preclinical models of stress and depression. However, the mechanisms by which photobiomodulation exerts its beneficial effects remained a mystery. In our study, we found that the SIRT1 pathway is the most altered physiological pathway in certain chronically stressed brain regions, and that photobiomodulation has the ability to restore it.”
In the digestive system, photobiomodulation is said to activate changes in the intestinal microbiota, with greater effects in the case of double brain-gut stimulation than in the case of intestinal treatment alone. As Professor Xavier Xifró of the TargetsLab research group at the University of Girona’s Faculty of Medicine explains, “the associated cellular mechanisms seem to be linked to the improvement of neuro-inflammatory processes. Thus, the changes observed in the microbiota are strongly associated with certain changes in neuro-inflammation (for example, microgliosis and astrogliosis, which occur through inflammation of specific cells of the nervous system)”.
Combined photobiomodulation for patients suffering from depression
Photobiomodulation could become a potential adjunctive treatment, administered as a complement to pharmacological therapy, in cases of major depressive disorders. In future research, the team hopes to promote the design of clinical trials to test the efficacy of combined photobiomodulation in patients suffering from depression.
“Photobiomodulation is likely to be particularly suitable for certain forms of depression, such as treatment-resistant depression. We are also keen to explore the relationship with neuro-inflammatory processes: this is one of the parameters best preserved after photobiomodulation, and treatment-resistant depression is strongly associated with neuro-inflammation,” concludes the research team.
Source: University of Barcelona
Journal reference:
Sancho-Balsells, A., et al. (2024). Brain-gut photobiomodulation restores cognitive alterations in chronically stressed mice through the regulation of Sirt1 and neuroinflammation. Journal of Affective Disorders. doi.org/10.1016/j.jad.2024.03.075
