The effect of probiotics on signaling pathways of genes involved in depression: review article

Depression is the psychological disorder which caused by chronic stress and extensive communication network between the gastrointestinal system via the “gut–brain-microbiota axis”. Depression can systematically activate/deactivate many genes and signaling molecules involved in the pathogenesis of the gastrointestinal disease. Whereas, most of the anti-depressant drugs suppress the depression symptoms by altering the neurotransmitters activity; studies on probiotics have shown the anti-depressant potential of them. Nutritional psychiatry is a field of psychiatry that investigates the relationship between dietary patterns and risk of mental disorders. The special type of probiotic has been identified to improve a number of diseases, such as diabetes, obesity, gastrointestinal infections, cancers, reduction of allergies and mood disorders such as depression. There is an evidence about therapeutic effects of probiotics in symptoms of depression, but because of the low number of samples, the limitation in use of different strains of bacteria and the limited laboratory equipment, it is difficult to make a definitive view about these results and need to more clinical study to determine the effective dose of probiotics in the treatment of depression. The articles related to this subject were collected from reliable database till the 2017 year, new studies and reviews articles which determine the effects of probiotics on the treatment of digestive and neurological diseases. The objective of this review is to study the current clinical research about the effects of probiotics in the treatment of symptoms of depression and discuss future directions in this field. Most of the studies demonstrated probiotics’ ability to improving mood, change behavior and improve the symptoms of stress and depression such as insomnia by increasing of serotonin and reducing of inflammation; and modulation of emotional behavior with effect on specific cytokines in brain. It has been discovered that probiotics have therapeutic effects extend beyond the gut and into the central nervous system by influence signaling pathways. In conclusion, it seems they have the potential to be used as a dietary supplement to optimize and enriched the food products and effective step in the prevention and treatment of various disorders in the nervous system instead of chemical drugs