A nod to gut-brain signalling: Nod-like receptors are critical for gut-brain axis signalling in mice

Perinatal serotonergic manipulation shapes anhedonic and cognitive behaviors in a sex- and age-dependent manner: Identification of related biological functions at central and peripheral level

Poor knowledge about psychiatric disorders often results in similar diagnoses for patients with different symptoms, thus limiting the effectiveness of the available medications. As suggested by several lines of evidence, to improve these shortcomings, it is essential to identify biomarkers associated with specific symptoms and to stratify patients into more homogeneous populations taking a further step toward personalized medicine. Here, we aimed to associate specific behavioral phenotypes with specific molecular alterations by employing an animal model based on the pharmacological manipulation of the serotonergic system, which mimics a condition of vulnerability to develop psychiatric disorders. In particular, we treated female and male rats with fluoxetine (FLX 15 mg/kg dissolved in drinking water) during prenatal or early postnatal life, and we evaluated different pathological-like phenotypes (cognitive deficit, anhedonia, and anxiety) by exposing the rats to a battery of behavioral tests during adolescence and adulthood. In addition, we carried out molecular analyses on specific brain areas and in the blood. Our results showed that perinatal FLX administration determined age- and sex-dependent effects, with males being more sensitive to prenatal manipulation and manifesting anhedonic-like behavior and females to early postnatal exposure, exhibiting cognitive deficits and a less anxious phenotype. Furthermore, we identified, peripherally and centrally, biological functions altered by perinatal serotonin modulation regardless of the timing of exposure and sex, and other pathways specific for the pathological-like phenotypes. The results presented here provide new insights into potential biomarkers associated with specific behavioral phenotypes that may be useful for broadening knowledge about psychiatric conditions.

Study on the toxic-mechanism of triclosan chronic exposure to zebrafish (Danio rerio) based on gut-brain axis

Triclosan (TCS), as a broad-spectrum bactericide, is extensively used in the fine chemical and textile industries. It is recognized as a new type of environmental endocrine disruptor with frequent detection and environmental pollution. However, the toxicity mechanism regarding neurodevelopment and neurobehavior remains unclear. This study is intended to explore the underlying toxic mechanism of TCS based on gut-brain axis. TCS-chronic exposure affected the development of zebrafish, induced feminization, obesity physical signs and abnormal organ index and caused neurobehavioral abnormalities by inhibiting both neurotransmitter acetylcholinesterase and dopamine activity, promoting brain neuron apoptosis and accelerating diencephalic lesions. Meanwhile, TCS-chronic exposure led to gut microbiota dysbiosis and decreased diversity, such as increased pathogenic bacteria and decreased probiotics in adult zebrafish gut, which caused many pathological damages, including partial shedding and ablation of intestinal villi, inflammatory infiltration, thinning of intestinal wall, and increased goblet cell in villus. Based on the communication between intestinal peripheral nerves and CNS, the above histopathological injuries and disorders were well underpinned and illustrated by the changes of biomarkers and the expression of related marker genes in the gut-brain axis. Additionally, short-chain fatty acids (SCFA), as the regulators of intestinal sympathetic nerve activation, are also secreting products of intestinal microflora and play a crucial role in regulating the balance of intestinal flora and protecting intestinal homeostasis. SCFA in low doses can effectively alleviate and rescue the toxic effects under TCS exposure, which evidenced that TCS exerted systemic toxic effects on the gut-brain axis by influencing the composition and diversity of gut flora in zebrafish, and fully demonstrated the interaction effect between intestine and brain. Hence, these findings contribute to the understanding, prevention, and diagnosis of endocrine disrupting diseases caused by environmental pollutants from the perspective of the gut-brain axis, and strengthening the early warning, management and control of TCS pollution.