Probiotics for Mental Health: A Review of Recent Clinical Trials

The digestive system is involved in providing both regulatory and biochemical signaling to the nervous system via the gut–brain axis. Major brain neurotransmitters within the enteric nervous system include acetylcholine, serotonin, and norepinephrine, which are triggered by various stimuli within the digestive system, including the microbiota. Associations between the gut microbiome and activation of neuroreceptors and neurotransmitters are related to factors such as appetite control, mood, and memory. This column presents the results of a brief review of recently published clinical trials related to gut microbiome interventions (n = 11) that aimed to address a variety of mental health outcomes. The impacts of probiotics on mental health and other clinical outcomes vary by the health of study participants. Continuing research on the mental health benefits of probiotics in healthy individuals is necessary.

Performance, Carcass Yield, Muscle Amino Acid Profile, and Levels of Brain Neurotransmitters in Aged Laying Hens Fed Diets Supplemented with Guanidinoacetic Acid

Guanidinoacetic acid (GA) is a natural precursor of creatine in the body and is usually used to improve the feed conversion and cellular energy metabolism of broiler chickens. The objective was to elucidate the effect of dietary supplementation of GA on carcass yield, muscle amino acid profile, and concentrations of brain neurotransmitters in laying hens. In total, 128 72-week-old ISA Brown laying hens were assigned to four equal groups (32 birds, eight replicates per group). The control group (T1) was fed a basal diet with no supplements, while the other experimental groups were fed a basal diet supplemented with 0.5 (T2), 1.0 (T3), and 1.5 (T4) g GA kg−1 diet. The T3 and T4 groups showed higher hen-day egg production and carcass yield compared to the control group (p = 0.016 and 0.039, respectively). The serum creatine level increased linearly with the increased level of dietary GA (p = 0.007). Among the essential amino acids of breast muscle, a GA-supplemented diet linearly increased the levels of leucine, isoleucine, phenylalanine, methionine, and threonine in the breast (p = 0.003, 0.047, 0.001, 0.001, and 0.015, respectively) and thigh (p = 0.026, 0.001, 0.020, 0.009, and 0.028, respectively) muscles. GA supplementation linearly reduced the level of brain serotonin compared to the control group (p = 0.010). Furthermore, supplementation of GA in the diet of laying hens linearly increased the level of brain dopamine (p = 0.011), but reduced the level of brain Gamma-aminobutyric acid (p = 0.027). Meanwhile, the concentration of brain nitric oxide did not differ between the experimental groups (p = 0.080). In conclusion, the dietary supplementation of GA may improve the carcass yield and levels of essential amino acids in the breast muscles, as well as the brain neurotransmitters in aged laying hens.

The Impact of Aerobic Training on Some Brain Neurotransmitters and Brain-Derived Neurotrophic Factor in Addicted Women

Introduction. Addiction is a chronic disease that needs time-consuming treatment. The medicines used to stop or reduce the tendency have not been successful so far. The purpose of this study was to investigate the effect of six weeks of aerobic training (morning and afternoon) on some brain neurotransmitters, brain-derived neurotrophic factor and quality of life in addicted females. Material and Methods. Thirty subjects were selected and divided into intervention (n = 15) and control (n = 15) groups. The aerobic training program consisted of six weeks of aerobic training, 3 sessions per week, and each session lasted for 45 to 60 minutes with a maximum intensity of 50-70% of the maximum heart rate. Paired sample t-test and ANCOVA were used to compare between- and within-group variance changes. Results. Weight levels, body mass index and body fat percentage significantly decreased (p < 0.05), while the serum levels of serotonin, dopamine and brain-derived neurotrophic factor (BDNF) increased significantly. The maximum oxygen consumption and quality of life increased significantly at the end of the period. Changes in intra-group mean in weight, body mass index, body fat percentage, dopamine, BDNF, maximum oxygen consumption, physical limitation, general health, vitality, social activity, physical and emotional function and life satisfaction are significantly different between experimental and control groups (p < 0.05). Conclusions. Six-week aerobic training performed in the morning and afternoon reduces body composition indicators and increases brain neurotransmitters, quality of life and maximum oxygen consumption in addicted females. Therefore, it can be effective in improving physical and mental health.

Perceptions of violence based on genetics: the influence of monoamine oxidase A in the origin of violent behavior

Objective: To gather scientific literature regarding the influence of the low activity of the enzyme Monoaminoxidase A, responsible for the regulation of brain neurotransmitters, on criminal and / or violent behavior. Methods: Searches were performed in the PubMed and SCOPUS databases using “genes”, “crime” and “monoaminoxidase”, selecting articles published between 2009 and 2019. Results: The selected sample, after applying the inclusion criteria and exclusion, was composed of 14 articles. Discussion: A relationship was found between low levels of activity of Monoaminoxidase A, when associated with socio-environmental factors, with a greater tendency to commit criminal and / or violent acts. Among the socio-environmental factors, the most cited is the experience of trauma in childhood. However, there were copyright disagreements, which demonstrates the need for further investigation and development of studies on the subject. Final considerations: It was found that individuals with low Monoaminoxidase A activity and who experienced stressful socioenvironmental factors are more prone to aggressive and / or violent behavior.

Lactobacillus plantarum DR7 Modulated Bowel Movement and Gut Microbiota Associated with Dopamine and Serotonin Pathways in Stressed Adults

We have previously reported that the administration of Lactobacillus plantarum DR7 for 12 weeks reduced stress and anxiety in stressed adults as compared to the placebo group, in association with changes along the brain neurotransmitters pathways of serotonin and dopamine-norepinephrine. We now aim to evaluate the effects of DR7 on gut functions, gut microbiota compositional changes, and determine the correlations between microbiota changes and the pathways of brain neurotransmitters. The administration of DR7 prevented an increase of defecation frequency over 12 weeks as compared to the placebo (p = 0.044), modulating the increase of stress-induced bowel movement. Over 12 weeks, alpha diversity of gut microbiota was higher in DR7 than the placebo group across class (p = 0.005) and order (p = 0.018) levels, while beta diversity differed between groups at class and order levels (p < 0.001). Differences in specific bacterial groups were identified, showing consistency at different taxonomic levels that survived multiplicity correction, along the phyla of Bacteroides and Firmicutes and along the classes of Deltaproteobacteria and Actinobacteria. Bacteroidetes, Bacteroidia, and Bacteroidales which were reduced in abundance in the placebo group showed opposing correlation with gene expression of dopamine beta hydrolase (DBH, dopamine pathway; p < 0.001), while Bacteroidia and Bacteroidales showed correlation with tryptophan hydroxylase-II (TPH2, serotonin pathway; p = 0.001). A correlation was observed between DBH and Firmicutes (p = 0.002), Clostridia (p < 0.001), Clostridiales (p = 0.001), Blautia (p < 0.001), and Romboutsia (p < 0.001), which were increased in abundance in the placebo group. Blautia was also associated with TDO (p = 0.001), whereas Romboutsia had an opposing correlation with TPH2 (p < 0.001). Deltaproteobacteria and Desulfovibrionales which were decreased in abundance in the placebo group showed opposing correlation with DBH (p = 0.001), whereas Bilophila was associated with TPH2 (p = 0.001). Our present data showed that physiological changes induced by L. plantarum DR7 could be associated with changes in specific taxa of the gut microbiota along the serotonin and dopamine pathways.