Autonomic dysfunction of gastric motility in major depression

Smooth muscle contraction of the fundus of stomach, duodenum and bladder from mice exposed to a stress-based model of depression

Several reports have demonstrated that depressive disorder is related to somatic symptoms including gastrointestinal or genitourinary alterations. The pathophysiological mechanisms underlying the gastrointestinal or genitourinary alterations associated with the depression are still not fully understood. Therefore, this study aimed to evaluate the motor activity of gastrointestinal (fundus of stomach and duodenum) and genitourinary tract (bladder) in a stress-based animal model of depression. Adult male mice were submitted to uncontrollable and unpredictable stress (learned helplessness model), controllable stress and non-stressful situations (control). Then, animals were euthanized and the fundus of stomach, duodenum segments or whole bladder were isolated and mounted in a standard organ bath preparation. We evaluated the contractile effects induced by KCl 80 mM for 5 min or carbachol (acetylcholine receptor agonist). The relaxant effects of isoproterenol (β-adrenoceptor agonist) were also checked. Animals submitted to the learned helplessness model developed a helpless (depressive-like behavior) or resilient (does not exhibit depressive-like behavior) phenotype. The contractions induced by carbachol were diminished in fundus of stomach isolated from helpless and resilient animals. The isoproterenol-induced fundus of stomach relaxation was reduced in resilient but not helpless mice. The contractions/relaxation of duodenum segments isolated from helpless or resilient animals were not altered. Both helpless and resilient animals showed an increase in the bladder contractions induced by carbachol while the relaxant effects of isoproterenol were reduced when compared to control. Conversely, mice underwent a controllable stress situation did not exhibit alterations in the fundus of stomach or duodenum contraction/relaxation induced by pharmacological agents although a decrease in the bladder contraction induced by carbachol was found. In conclusion, incontrollable and unpredictable stress and not depressive phenotype (helpless animals) or controllable stress could be related to the alterations in motor activity of the fundus of stomach and bladder.

Zuojin pill improves chronic unpredictable stress-induced depression-like behavior and gastrointestinal dysfunction in mice via the theTPH2/5-HT pathway

BACKGROUND

The complex bidirectional communication between the gastrointestinal tract and the brain is associated with mental disorders such as depression; serotonin, as a crucial neurotransmitter in the communication system between the central nervous system and the gastrointestinal tract, has effects on regulating gastrointestinal motility and sensation and improving psychosomatic status. Zuojin pill is used as a traditional Chinese medicine formula for the treatment of gastrointestinal disorders. This study explored the effects of Zuojin pill on the improvement of depression and gastrointestinal function in CUMS mice via TPH2 and its mechanism.

PURPOSE

The aim of this study was to investigate whether Zuojin pill could improve depression and concomitant gastrointestinal dysfunction, and to reveal whether Zuojin pill could work through the regulation of the tryptophan hydroxylase 2 (TPH2) pathway.

METHODS

The CUMS model was established to observe the effects of Zuojin pill on depression-like behavior and gastrointestinal function in mice. Nissler staining and HE staining were used to observe the structure of hippocampal neurons and intestinal mucosa respectively. 5-HT levels in serum, hippocampus, and intestinal tissues were measured by ELISA, and TPH2 expression in hippocampus and intestinal nerves was observed by WB and immunofluorescence. In order to investigate the protective effect and mechanism of Zuojin pill on PC12 cells, CORT used an in vitro model to produce PC12 cell damage.

RESULTS

Our study showed that Zuojin pill ameliorated depression-like behavior and gastrointestinal dysfunction in CUMS mice, elevated BDNF, 5-HT, and TPH2 expression in the hippocampus, and restored the ratio of dopaminergic and GABAergic neurons between intestinal muscles. In vitro experiments showed that Zuojin pill exerted a protective effect on neurons by regulating TPH2 ubiquitination and thus inhibiting CORT-induced apoptosis of PC12 cells.

CONCLUSION

Zuojin pill improves chronic unpredictable stress-induced depression-like behavior and gastrointestinal dysfunction in mice via the TPH2/5-HT pathway. Therefore, TPH2 may be a potential therapeutic target for depression with gastrointestinal dysfunction.

Brain regulation of gastric dysfunction induced by stress

Psychological and physical stressors have been implicated in gastric disorders in humans. The mechanism coupling the brain to the stomach underlying stress-induced gastric dysfunction has remained elusive. Here, we show that the stomach directly receives acetylcholinergic inputs from the dorsal motor nucleus of the vagus (AChDMV), which are innervated by serotonergic neurons in the dorsal raphe nucleus (5-HTDRN). Microendoscopic calcium imaging and multi-tetrode electrophysiological recordings reveal that the 5-HTDRN → AChDMV → stomach circuit is inhibited with chronic stress accompanied by hypoactivate gastric function. Artificial activation of this circuit reverses the gastric dysfunction induced by chronic stress in both male and female mice. Our study demonstrates that this 5-HTDRN → AChDMV → stomach axis drives gastric dysfunction associated with stress, thus providing insights into the circuit basis for brain regulation of the stomach.

Depression and 24 gastrointestinal diseases: a Mendelian randomization study

The causality of the association between depression and gastrointestinal diseases is undetermined. We conducted Mendelian randomization (MR) analyses to systematically explore the associations of depression with 24 gastrointestinal diseases. Independent genetic variants associated with depression at the genome-wide significance level were selected as instrumental variables. Genetic associations with 24 gastrointestinal diseases were obtained from the UK Biobank study, the FinnGen study, and large consortia. Multivariable MR analysis was conducted to explore the mediation effects of body mass index, cigarette smoking, and type 2 diabetes. After multiple-testing corrections, genetic liability to depression was associated with an increased risk of irritable bowel syndrome, non-alcohol fatty liver disease, alcoholic liver disease, gastroesophageal reflux, chronic pancreatitis, duodenal ulcer, chronic gastritis, gastric ulcer, diverticular disease, cholelithiasis, acute pancreatitis, and ulcerative colitis. For the causal effect of genetic liability to depression on non-alcoholic fatty liver disease, a substantial proportion was mediated by body mass index. Genetic predisposition to smoking initiation mediated half of effect of depression on acute pancreatitis. This MR study suggests that depression may play a causal role in many gastrointestinal diseases.

Abnormal cortical-striatal-thalamic-cortical circuit centered on the thalamus in MDD patients with somatic symptoms: Evidence from the REST-meta-MDD project

OBJECTIVE

Somatic symptoms are common comorbidities of major depressive disorder (MDD), and negatively impact the course and severity of the disease. In order to enrich the understanding of the pathological mechanism and clarify the neurobiological basis of somatic symptoms in depression, we attempted to explore the changes of brain structure and function in a large sample between depression with and without somatic symptoms.

METHODS

Structure magnetic resonance imaging (MRI) data were collected from 342 patients with somatic symptoms (SD), 208 patients without somatic symptoms (NSD), and 510 healthy controls (HCs) based on the REST-meta-MDD project. We analyzed the whole brain VBM maps of the three groups, and combined with weight degree centrality (DC) index, we investigated whether the brain regions with gray matter volume (GMV) and gray matter density (GMD) abnormalities in MDD patients with somatic symptoms had corresponding brain functional abnormalities.

RESULTS

Between depression with and without somatic symptoms, we found that there are extensive GMV and GMD differences involving cortical regions such as the temporal lobe, occipital lobe, and insula, as well as subcortical brain regions such as thalamus and striatum. The comparison results of weight DC signals of GMV and GMD abnormal clusters between the SD and NSD groups were basically consistent with the GMV and GMD abnormal clusters.

CONCLUSION

The results indicate that the structure and function of cortical-striatal-thalamic-cortical (CSTC) circuit centered on the thalamus were abnormal in MDD patients with somatic symptoms. This may be the neurobiological basis of somatic symptoms in MDD.

Protective effect of valerian extract capsule (VEC) on ethanol- and indomethacin-induced gastric mucosa injury and ameliorative effect of VEC on gastrointestinal motility disorder

CONTEXT

Valerian extract capsule (VEC) is an effective Chinese patent medicine used for gastrointestinal (GI) diseases.

OBJECTIVE

To investigate the detailed pharmacological activity for VEC clinical effects in GI diseases.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into six groups: control, model, and drug-treated (VEC-L, VEC-M, VEC-H, and teprenone). Rats were orally administered VEC (124, 248, 496 mg/kg) and teprenone (21.43 mg/kg) for 3 consecutive days. After 1 h, the five groups (except the control group) were orally given ethanol (10 mL/kg) for 1 h or indomethacin (80 mg/kg) for 7 h. The spasmolytic activity of VEC (0.01-1 mg/mL) on ACh/BaCl₂-induced New Zealand rabbit smooth muscle contraction was performed. The C57BL/6 mice carbon propelling test evaluated the effects of VEC (248-992 mg/kg) on intestinal motility in normal and neostigmine/adrenaline-induced mice.

RESULTS

Compared with the model group, VEC treatment reduced the gastric lesion index and mucosal damage. Further experiments showed that the pathological ameliorative effect of VEC was accompanied by augmentation of the enzymatic antioxidant system and cytoprotective marker (COX-1, p < 0.01; PGI2 p < 0.05;), along with the alleviation of the levels of MPO (ethanol: 15.56 ± 0.82 vs. 12.15 ± 2.60, p < 0.01; indomethacin: 9.65 ± 3.06 vs. 6.36 ± 2.43, p < 0.05), MDA (ethanol: 1.66 ± 0.44 vs. 0.81 ± 0.58, p < 0.01; indomethacin: 1.71 ± 0.87 vs. 1.09 ± 0.43, p < 0.05), and inflammatory mediators. VEC decreased the high tone induced by ACh/BaCl₂ and promoted intestinal transit in normal and neostigmine/adrenaline-induced mice.

DISCUSSION AND CONCLUSIONS

VEC showed a potential gastroprotective effect, suggesting that VEC is a promising phytomedicine for the treatment of GI diseases.

Altered Metabolomics in Bipolar Depression With Gastrointestinal Symptoms

OBJECTIVE

Although gastrointestinal (GI) symptoms are very common in patients with bipolar disorder (BD), Few studies have researched the pathomechanism behind these symptoms. In the present study, we aim at elucidate the pathomechanism of GI symptoms in BD through metabolomic analysis.

METHOD

BD patients were recruited from Shanxi Bethune Hospital that divided into two groups, each group assessed with the 24-item Hamilton Depression Rating Scale (HAMD-24) according to the presence or absence of GI symptoms. Healthy controls were recruited from the medical examination center of the same hospital. Differential metabolites were identified and further analyzed using Metabo Analyst 3.0 to identify associated metabolic pathways.

RESULTS

There were significantly higher HAMD-24 scores in the GI symptoms group than that of non-GI symptoms group (p = 0.007). Based on metabolomic analysis results, we found that the common disturbances metabolic pathway of both two patients groups was ketone body metabolism, and the unique disturbances metabolic pathways of BD with GI symptoms were fatty acid biosynthesis and tyrosine metabolism, and these changes were independent of dietary habits.

CONCLUSION

BD patients with GI symptoms exhibited disturbances in fatty acid and tyrosine metabolism, perhaps suggesting that the GI symptoms in BD patients are related to disturbances of the gut microbiome. Both groups of patients jointly exhibit disturbances of ketone body metabolism, which may serve as a biomarker for the pathogenesis of BD patients.

Brain structural alterations in MDD patients with gastrointestinal symptoms: Evidence from the REST-meta-MDD project

OBJECTIVE

While gastrointestinal (GI) symptoms are very common in patients with major depressive disorder (MDD), few studies have investigated the neural basis behind these symptoms. In this study, we sought to elucidate the neural basis of GI symptoms in MDD patients by analyzing the changes in regional gray matter volume (GMV) and gray matter density (GMD) in brain structure.

METHOD

Subjects were recruited from 13 clinical centers and categorized into three groups, each of which is based on the presence or absence of GI symptoms: the GI symptoms group (MDD patients with at least one GI symptom), the non-GI symptoms group (MDD patients without any GI symptoms), and the healthy control group (HCs). Structural magnetic resonance images (MRI) were collected of 335 patients in the GI symptoms group, 149 patients in the non-GI symptoms group, and 446 patients in the healthy control group. The 17-item Hamilton Depression Rating Scale (HAMD-17) was administered to all patients. Correlation analysis and logistic regression analysis were used to determine if there was a correlation between the altered brain regions and the clinical symptoms.

RESULTS

There were significantly higher HAMD-17 scores in the GI symptoms group than that of the non-GI symptoms group (P < 0.001). Both GMV and GMD were significant different among the three groups for the bilateral superior temporal gyrus, bilateral middle temporal gyrus, left lingual gyrus, bilateral caudate nucleus, right Fusiform gyrus and bilateral Thalamus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the HC group, the GI symptoms group demonstrated increased GMV and GMD in the bilateral superior temporal gyrus, and the non-GI symptoms group demonstrated an increased GMV and GMD in the right superior temporal gyrus, right fusiform gyrus and decreased GMV in the right Caudate nucleus (GRF correction, cluster-P < 0.01, voxel-P < 0.001). Compared to the non-GI symptoms group, the GI symptoms group demonstrated significantly increased GMV and GMD in the bilateral thalamus, as well as decreased GMV in the bilateral superior temporal gyrus and bilateral insula lobe (GRF correction, cluster-P < 0.01, voxel-P < 0.001). While these changed brain areas had significantly association with GI symptoms (P < 0.001), they were not correlated with depressive symptoms (P > 0.05). Risk factors for gastrointestinal symptoms in MDD patients (p < 0.05) included age, increased GMD in the right thalamus, and decreased GMV in the bilateral superior temporal gyrus and left Insula lobe.

CONCLUSION

MDD patients with GI symptoms have more severe depressive symptoms. MDD patients with GI symptoms exhibited larger GMV and GMD in the bilateral thalamus, and smaller GMV in the bilateral superior temporal gyrus and bilateral insula lobe that were correlated with GI symptoms, and some of them and age may contribute to the presence of GI symptoms in MDD patients.

Yeokwisan, a Standardized Herbal Formula, Enhances Gastric Emptying via Modulation of the Ghrelin Pathway in a Loperamide-induced Functional Dyspepsia Mouse Model

Background: Yeokwisan, a standardized herbal formula, has exhibited clinical benefit for patients suffering from refractory functional dyspepsia (FD) in Korea since 2016. However, data about the mechanism of action of this formula are yet not available. Aim of the study: To evaluate and explore the effects of Yeokwisan on gastric emptying, a major symptom of functional dyspepsia, and its underlying mechanisms of action using a mouse model. Materials and methods: BALB/C mice were pretreated with Yeokwisan (100, 200, and 400 mg/kg, po) or mosapride (3 mg/kg, po) for 5 days and then treated with loperamide (10 mg/kg, ip) after 20 h of fasting. A solution of 0.05% phenol red (500 μL) or diet of 5% charcoal (200 μL) was orally administered, followed by assessment of gastric emptying or intestinal transit. Plasma acyl-ghrelin (ELISA), C-kit (immunofluorescence and western blotting), nNOS (western blotting) and gastric contraction- and ghrelin-related gene/protein expression levels were examined in stomach and small intestine tissues. Results: Loperamide injection substantially delayed gastric emptying, while Yeokwisan pretreatment (especially 200 and 400 mg/kg Yeokwisan) significantly attenuated this peristaltic dysfunction, as evidenced by the quantity of phenol red retained in the stomach (p < 0.05 or 0.01) and stomach weight (p < 0.05 or 0.01). The levels of plasma acyl-ghrelin and expression of gastric ghrelin-related genes, such as growth hormone secretagogue receptor (GHSR), ghrelin-O-acyltransferase (GOAT), adrenergic receptor β1 (ADRB1) and somatostatin receptor (SSTR), were significantly normalized (p < 0.05 or 0.01) by Yeokwisan (400 mg/kg). Yeokwisan (400 mg/kg) significantly tempered the loperamide-induced alterations in the c-kit and nNOS levels (p < 0.01) as well as the expression of contraction- and ghrelin-related genes, such as 5-HT4 receptor (5-HT4R), anoctamin-1 (ANO1), ryanodine receptor 3 (RYR3) and smooth muscle myosin light chain kinase (smMLCK), in the stomach, but not in the small intestine. Conclusion: The present results showed the clinical relevance of Yeokwisan, in treating FD, especially in promoting gastric emptying but not small intestinal transit. The main mechanisms corresponding to these effects may involve the modulation of the ghrelin pathway and activation of interstitial cells of Cajal in stomach tissue.

Resveratrol Modulates the Gut-Brain Axis: Focus on Glucagon-Like Peptide-1, 5-HT, and Gut Microbiota

Resveratrol is a natural polyphenol that has anti-aging and anti-inflammatory properties against stress condition. It is reported that resveratrol has beneficial functions in various metabolic and central nervous system (CNS) diseases, such as obesity, diabetes, depression, and dementia. Recently, many researchers have emphasized the connection between the brain and gut, called the gut-brain axis, for treating both CNS neuropathologies and gastrointestinal diseases. Based on previous findings, resveratrol is involved in glucagon-like peptide 1 (GLP-1) secreted by intestine L cells, the patterns of microbiome in the intestine, the 5-hydroxytryptamine (5-HT) level, and CNS inflammation. Here, we review recent evidences concerning the relevance and regulatory function of resveratrol in the gut-brain axis from various perspectives. Here, we highlight the necessity for further study on resveratrol's specific mechanism in the gut-brain axis. We present the potential of resveratrol as a natural therapeutic substance for treating both neuropathology and gastrointestinal dysfunction.

Effects of Zuojin pill on depressive behavior and gastrointestinal function in rats with chronic unpredictable mild stress: Role of the brain-gut axis

ETHNOPHARMACOLOGICAL RELEVANCE

Zoujin pill (ZJP), a medication used to treat gastrointestinal disorders since the 15th Century in China, have been reported to exert anti-depressant effects in various models.

STUDY AIM

To assess the effects of ZJP on gastrointestinal function and depressive behavior in rats under chronic unpredictable mild stress (CUMS), and to examine the underlying mechanisms related to brain-gut axis.

METHODS

The rats suffered the stressor once daily for 5 weeks. ZJP (0.6 and 1.2 g/kg) and fluoxetine (15 mg/kg) as positive control were administered to the rats through gastric intubation once daily for 5 consecutive weeks. The anti-depression effects were compared by performing sucrose preference tests and open field tests. Gastrointestinal motility was investigated by determining the gastrointestinal transit rate and by electrogastrogram. The serum levels of the gastrointestinal hormone (GAS, MOT, VIP, SP), inflammatory cytokine (IL-1β, IL-6; , TNFα) and glucagon-like peptide-1 (GLP-1) were assayed by enzyme-linked immunosorbent assay. For monoamine neurotransmitters (NE, 5-HT, DA), the levels were determined by high-performance liquid chromatography and electrochemical detection in conjunction, which was applied on the samples taken from the hypothalamus, hippocampus, and striatum.

RESULTS

The depression-like symptoms among rats under CUMS were significantly relieved by ZJP administration (0.6 and 1.2 g/kg). Gastrointestinal motility was also improved by restoring gastric electrical rhythm and promoting gastrointestinal propulsion. The ZJP at 0.6 g/kg dosage obviously up-regulated 5-HT and DA levels in hippocampus. The ZJP at 1.2 g/kg dosage could increase 5-HT and DA levels in hypothalamus, striatum, and hippocampus, while down-regulated the NE level in hypothalamus and hippocampus. ZJP also reversed the alterations in serum gastrointestinal hormones. Furthermore, treatment with ZJP significantly reduced levels of IL-1β, IL-6 and TNF-α and increased serum GLP-1 compared with the CUMS group. Fluoxetine also exerted similar anti-depressant effects in the absence of effects on gastrointestinal motility and the levels of serum hormone, inflammatory cytokine and GLP-1.

CONCLUSION

ZJP imposed anti-depressant and gastrointestinal regulating functions in rats under CUMS, suggesting potential clinical application. .

Metoprolol prevents neuronal dendrite remodeling in a canine model of chronic obstructive sleep apnea

Obstructive sleep apnea (OSA) is closely associated with central nervous system diseases and could lead to autonomic nerve dysfunction, which is often seen in neurodegenerative diseases. Previous studies have shown that metoprolol prevents several chronic OSA-induced cardiovascular diseases through inhibiting autonomic nerve hyperactivity. It remains unclear whether chronic OSA can lead to dendritic remodeling in the brain, and whether metoprolol affects the dendritic remodeling. In this study we investigated the effect of metoprolol on dendrite morphology in a canine model of chronic OSA, which was established in beagles through clamping and reopening the endotracheal tube for 4 h every other day for 12 weeks. OSA beagles were administered metoprolol (5 mg· kg⁻¹· d⁻¹). The dendritic number, length, crossings and spine density of neurons in hippocampi and prefrontal cortices were assessed by Golgi staining. And the protein levels of hypoxia-inducible factor-1α (HIF-1α) and brain-derived neurotrophic factor (BDNF) were measured by Western blotting. We showed that chronic OSA successfully induced significant brain hypoxia evidenced by increased HIF-1α levels in CA1 region and dentate gyrus of hippocampi, as well as in prefrontal cortex. Furthermore, OSA led to markedly decreased dendrite number, length and intersections, spine loss as well as reduced BDNF levels. Administration of metoprolol effectively prevented the dendritic remodeling and spine loss induced by chronic OSA. In addition, administration of metoprolol reversed the decreased BDNF, which might be associated with the metoprolol-induced neuronal protection. In conclusion, metoprolol protects against neuronal dendritic remodeling in hippocampi and prefrontal cortices induced by chronic OSA in canine.

Chronic Diarrhea and Constipation Are More Common in Depressed Individuals

BACKGROUND AND AIMS

Depression is a major health issue in the United States and is highly comorbid with gastrointestinal conditions. We collected data from the National Health and Nutrition Examination Survey (NHANES), a representative sample of the US population, to study the relationship between depression and bowel habits.

METHODS

Using data from the NHANES (2009-2010), we identified 495 depressed and 4709 non-depressed adults who filled out the Bowel Health Questionnaire. Depression was defined according to a validated questionnaire. We used multivariable analysis, controlling for clinical and demographic variables, to evaluate the relationship between mood and bowel habits.

RESULTS

In our weighed sample, 24.6% of depressed individuals and 12.6% of non-depressed individuals reported disordered bowel habits. Chronic diarrhea was significantly more prevalent in depressed individuals (15.53%; 95% CI, 11.34%-20.90%) than non-depressed individuals (6.05%; 95% CI, 5.24%-6.98%; P = .0001). Chronic constipation was also more common in depressed individuals (9.10%; 95% CI, 7.02%-11.69%) than non-depressed individuals (6.55%; 95% CI, 5.55%-7.70% CI; P = .003). Mean depression scores in patients with chronic diarrhea (4.9 ± 5.8) and with chronic constipation (4.4 ± 4.93) were significantly higher than mean depression scores for individuals with normal bowel habits (3.2 ± 4.6) (P < .001). Moderate and severe depression were significantly associated with chronic diarrhea but not chronic constipation. Only mild depression was significantly associated with chronic constipation.

CONCLUSIONS

In an analysis of the NHANES database, we found a higher proportion of depressed individuals to have chronic diarrhea and constipation than non-depressed individuals; chronic diarrhea was more strongly associated with depression. Our findings provide support for the relationship between mood and specific bowel habits, accounting for multiple co-variables in a large sample of the general US population.

Gut permeability and depressive symptom severity in unmedicated adolescents

OBJECTIVE

This study examined gut permeability in unmedicated adolescents with and without major depressive disorder.

METHOD

Medically healthy, non-medicated, 12-17 year-old females in a major depressive episode (MDE) or healthy controls, without any psychiatric condition, were enrolled. They completed the Children's Depression Rating Scale-Revised (CDRS-R) and underwent a clinical interview. Preejection period (PEP) and respiratory sinus arrhythmia (RSA) data were collected to measure autonomic nervous system activity. Following an overnight fast, participants ingested lactulose and mannitol and collected urine for 4 hours while still fasting, to examine gut permeability. Plasma cytokines (interleukin 1β, interleukin 6, and tumor necrosis factor α) were measured. Correlational analyses were used to examine the associations between relevant variables.

RESULTS

41 female participants (age: 14.8 ± 1.6 years, n = 25 with MDE) were enrolled. PEP, but not RSA, was inversely associated with neurovegetative symptom severity on the CDRS-R (r = -0.31, p < 0.06). In the 30 participants with gut permeability data, the lactulose to mannitol ratio (LMR) was significantly positively associated with depression severity, particularly neurovegetative symptom severity (r = 0.37, p < 0.05). Notably, the association between neurovegetative symptom severity and PEP was substantially reduced after adjusting for LMR. Additionally, depression severity was significantly associated with circulating cytokines.

CONCLUSIONS

This is the first study to examine gut permeability in unmedicated adolescents, offering preliminary support for a mechanistic pathway linking sympathetic nervous system activation to increased gut permeability and activation of the innate immune system, likely contributing to the emergence of neurovegetative symptoms of depression.

Exercise influence on the microbiome-gut-brain axis

The microbiome in the gut is a diverse environment, housing the majority of our bacterial microbes. This microecosystem has a symbiotic relationship with the surrounding multicellular organism, and a balance and diversity of specific phyla of bacteria support general health. When gut bacteria diversity diminishes, there are systemic consequences, such as gastrointestinal and psychological distress. This pathway of communication is known as the microbiome-gut-brain axis. Interventions such as probiotic supplementation that influence microbiome also improve both gut and brain disorders. Recent evidence suggests that aerobic exercise improves the diversity and abundance of genera from the Firmcutes phylum, which may be the link between the positive effects of exercise on the gut and brain. The purpose of this review is to explain the complex communication pathway of the microbiome-gut-brain axis and further examine the role of exercise on influencing this communication highway.

The prognosis and changes of regional brain gray matter volume in MDD with gastrointestinal symptoms

Objective: It is common that major depressive disorder (MDD) is accompanied by gastrointestinal (GI) symptoms. However, few studies have focused on the clinical characteristics and its possible mechanism, while brain gray matter (GM) structure is important in the pathogenesis of GI symptoms. In this study, we aimed to investigate the basic clinical characteristics and regional GM volume changes in MDD accompanied by GI symptoms. Method: Patients with MDD (n=49) and age, gender, and educational level-matched healthy controls (n=30) were recruited. Patients with MDD were divided into two groups based on the GI status: MDD with (n=27) and without (n=22) GI symptoms. The 24-item Hamilton Depression Rating Scale (HAMD) was administered. T1-weighted anatomical images were obtained and analyzed. Correlation analysis was used to identify the possible associations between changed regional GM volume and GI symptoms and depressive symptoms. Results: The HAMD reductive ratio for 2 weeks of treatment in the GI symptoms group was significantly higher than the non-GI symptoms group (P<0.05). The regional GM volume showed significant differences among the three groups (Gaussian Random Field [GRF] correction, voxel-P<0.01, cluster-P <0.05). Compared with non-GI symptoms group, GI symptoms group exhibited significantly increased GM volume in the left hippocampus, left parahippocampal gyrus, right parahippocampal gyrus; and decreased GM volume in the right middle frontal gyrus, right precentral gyrus, right cuneus, right precuneus, right superior occipital gyrus (GRF correction, voxel-P <0.01, cluster-P <0.05). These altered brain areas were correlated with the GI symptoms, not depressive symptoms. Conclusion: The changed regional brain GM volume in GI-MDD group may be the pathogenesis for the GI symptoms. In addition, the GI symptoms may predict the prognosis of MDD.