Chronic stress is linked to changes in brain physiology and functioning, affects the central nervous system (CNS), and causes psychiatric diseases such as depression and anxiety. In this study, antidepressant effects of the probiotic bacterium Lactobacillus rhamnosus GG (ATCC 53103) (LGG) (15 × 10 ⁸ cfu/ml/day) on the mechanisms playing a role in the pathophysiology of depression were investigated, and the results were compared with the effects of bupropion (20 mg/kg/day) and venlafaxine (20 mg/kg/day). A total of 56 male Wistar Albino rats were used in control, stress, bupropion, venlafaxine, LGG, bupropion + stress, venlafaxine + stress, LGG + stress groups, n = 7 each. Changes in the body weight of the rats during the experiment were determined by weight measurement. Gene expression levels were determined by the RT-PCR method. Four different behavioral tests were performed to evaluate depressive behaviors (sucrose preference test, three-chamber sociability test (social interaction test), elevated plus maze test, forced swim test). LGG treatment was effective in reducing depressive-like behaviors, increased BDNF level, 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1 expression levels in the hippocampus and NOD1 receptor expression level in the small intestine ( p < 0.05), and also decreased neurodegeneration level, glial cell activity, and intestinal permeability in depressed rats. As a result, it was revealed in this study for the first time that the LGG probiotic bacterium has antidepressant properties and was found to be more effective than the antidepressant drugs bupropion and venlafaxine. Our results suggest that LGG is a potential psychobiotic bacterium and can be useful to treat depression. It may be an effective and useful option in combating depression.

Objectives: Interactions between neuropeptides and psychiatric disorders have been investigated for many years. The aim of this study was to evaluate oxytocin (OXT), arginine-vasopressin (AVP), and atrial natriuretic peptide (ANP) and assess their interactions with each other, as well as investigate these changes with the manifestations of schizophrenia. Participants and methods: Thirty-four individuals having acute schizophrenia and 24 healthy individuals as the control group were included in the study. Positive and Negative Syndrome Scales, Global Assessment of Functionality score, and Clinical Global Impression (CGI) scores were measured. Serum hormone levels were analyzed using enzyme-linked immunosorbent assay and were compared with the clinical findings. Results: OXT levels were significantly lower and AVP levels were significantly higher in patients having acute schizophrenia than the control group. OXT was negatively correlated with Positive and Negative Syndrome Scales positive score and CGI score, while it was positively correlated with Global Assessment of Functionality score. AVP was negatively correlated with CGI score. ANP levels of the patients having schizophrenia were lower than the control group; however, there was no significant correlation with clinical findings. Conclusion: The obtained data indicate that the AVP level was higher, but OXT and ANP levels were lower in the patients having acute schizophrenia. Specifically OXT is related with reduced disease severity and increased functionality.

Depression, a prevalent psychiatric disorder, exerts severe and debilitating impacts on an individual's mental and physical well-being, and it is considered a chronic mental illness. Chronic stress plays an important role in the pathophysiology of depression. Lactobacillus plantarum and Streptococcus thermophilus are psychobiotic bacteria and synthesize some neurotransmitters that play a role in the pathogenesis of depression. In this study, we aimed to investigate the therapeutic effects of Bactolac (Lactobacillus plantarum NBIMCC 8767 + Streptococcus thermophilus NBIMCC 8258) on chronic stress-induced depression in rats. Behavioral tests, including the sucrose preference test, elevated plus maze test, forced swim test, and three-chamber sociability test, were employed to assess depressive and anxiety-like behaviors. The expression level of the 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1, NLRP3 and MC4R; BDNF levels, glial activity and intestinal permeability were determined in chronic stress-induced depression in rats. In conclusions, chronic stress decreased the expression levels of 5-HT1A, DRD1, ADRA-2A, GABA-A α1, CNR1, NR3C2, NOD1 and BDNF level; increased the expression levels of NLRP3 and MC4R, caused neurodegeneration and glial activity, ultimately led to depressive effects. Bactolac was effective in reducing depressive-like behaviors according to the results of behavioral tests. Bactolac treatment provided high neuronal survival rate increasing BDNF level, prevented the excessive release of pro-inflammatory cytokines by reducing the expression levels of NLRP3 and MC4R, therefore, prevented the excessive activation of the hypothalamus–pituitary–adrenal (HPA) axis and accordingly, reduced neurodegeneration and glial cell activation in depressed rats. We can suggest that Bactolac supplementation may be beneficial in coping with stress, alleviate the effects of chronic stress and help to protect mental health.

Obesity is a growing global health concern that leads to metabolic imbalances and progressive cardiac remodelling. This study investigated whether semaglutide (SMG) can counteract the disruption to the gut-heart-metabolic axis and associated myocardial injury caused by obesity. Twenty-one male Wistar rats were assigned to control, obese (OB), and obese+semaglutide (OB + SMG) groups. The control group was fed a normal diet, while the obese groups were given a cafeteria diet for 16 weeks. In addition, the OB + SMG group received 150 mcg/kg of SMG subcutaneously once a week for the last four weeks. The following were measured alongside HOMA indices: Lipid profile, cardiac enzymes, leptin, insulin, TMAO and LPS levels. Myocardial and intestinal samples were assessed biochemically and histopathological for the levels of MMP-2/MMP-9, TIMP-1, TGF-β, IL-1β, HO-1, occludin, ZO-1 and claudin. Obesity markedly increased body weight, fasting glucose, leptin, insulin resistance, the atherogenic index and cardiac risk, while also increasing LPS, TMAO, TGF-β, IL-1β, MMP-2/MMP-9 activity and decreasing TIMP-1. Semaglutide significantly reversed these abnormalities, improving metabolic indices, restoring the balance between MMPs and TIMPs, and reducing inflammatory mediators. Histological analysis revealed reduced cardiomyocyte degeneration and enhanced intestinal epithelial architecture in the OB + SMG group. Semaglutide notably enhanced the expression of occludin, claudin, and ZO-1, supporting strengthened intestinal barrier integrity, and restored HO-1 expression, indicating improved antioxidant defenses. These findings suggest that semaglutide provides cardioprotection in obesity by restoring gut barrier function, reducing inflammation and normalizing extracellular matrix turnover. By stabilizing the gut-heart-metabolic axis and mitigating structural myocardial injury, semaglutide may interrupt the progression from metabolic dysfunction to cardiomyopathy. This highlights its therapeutic potential in the treatment of obesity-related cardiovascular disease, extending beyond glycemic control.