Ventromedial hypothalamic nucleus in regulation of stress-induced gastric mucosal injury in rats

The insular cortex-nucleus tractus solitarius glutamatergic pathway involved in acute stress-induced gastric mucosal damage in rats

Previous studies have shown that acute stress-induced gastric mucosal damage is linked to excessive activation of parasympathetic nervous system. The Insular Cortex (IC), the higher centers of the parasympathetic nervous system, serves as both the integration site of gastric sensory information and play a crucial role in the regulation of gastric function. However, whether the IC is involved in Restraint water-immersion stress (RWIS)-induced gastric mucosal damage has not been reported. In this study, we examined the expression of neuronal c-Fos, PSD95 and SYN-1 protein expression in IC during RWIS by immunofluorescence and western blot techniques, as well as assessed IC blood oxygenation level dependant (BOLD) through functional MRI. Chemical genetics techniques specifically modulate the activity of IC glutamatergic neurons and IC-nucleus tractus solitary (NTS) glutamatergic pathway to elucidate their contributions to RWIS-induced gastric mucosal damage. The results showed that the expression of c-Fos, PSD95, and SYN-1 protein in IC increased significantly after RWIS, along with a noticeable enhancement in fMRI signal intensity. Furthermore, inhibiting IC glutamatergic neurons and the IC-NTS glutamatergic neural pathway resulted in a significant reduction in gastric mucosal damage, an increase in the expression of Occludin, Claudin-1, and PCNA in the gastric wall, while the expression of nNOS decreased and CHAT increased. These findings suggest that during RWIS, IC glutaminergic neurons are activated, promoting stress-induced gastric mucosal damage through the IC-NTS-vagal nerve pathway.

Oxytocin-Mediate Modulation of Splenic Immunosuppression in Chronic Social Stress Through Neuroendocrine Pathways

Chronic social stress (CSS) is a significant public health challenge that negatively impacts behavior and immune function through brain-spleen interactions. Oxytocin (OT), a neuropeptide critical for social behavior and immune regulation, is upregulated during CSS, though its underlying mechanisms remain unclear. This study investigates the role of OT in splenic immune modulation using a murine model of CSS. Behavioral evaluations, serum oxytocin quantification, and splenic immunophenotypic analysis were performed. Splenic denervation confirmed OT's neuromodulatory role, whereas OTR antagonism revealed its endocrine function. CSS-induced OT elevation was associated with immunosuppression, characterized by increased Foxp3⁺ regulatory T cells and reduced CD4⁺ T and CD19⁺ B cells. OT also modulated macrophage polarization, inhibiting M1-like (pro-inflammatory) and enhancing M2-like (anti-inflammatory) phenotypes. Denervation or pharmacological blockade of OT signaling partly reversed CSS-induced splenic immunosuppression but adversely affected survival in CSS-exposed mice. Additionally, denervation or OTR antagonism reduced the mice's response to social defeat, as shown by decreased social avoidance behavior. These findings suggest that OT-mediated immunosuppression likely represents a compensatory mechanism in response to chronic social stress. Targeting the OT-immune axis could offer innovative therapeutic approaches for stress-associated disorders by restoring immune homeostasis while maintaining behavioral integrity.

Astrocytes in the spinal cord contributed to acute stress-induced gastric damage via the gap junction protein CX43

Rat restraint water-immersion stress (RWIS) is a compound stress of high intensity and is widely used to study the pathological mechanisms of stress gastric ulcers. The spinal cord, as a part of the central nervous system, plays a dominant role in the gastrointestinal tract, but whether the spinal cord is involved in rat restraint water-immersion stress (RWIS)-induced gastric mucosal damage has not been reported. In this study, we examined the expression of spinal astrocytic glial fibrillary acidic protein (GFAP), neuronal c-Fos, connexin 43 (Cx43), and p-ERK1/2 during RWIS by immunohistochemistry and Western blotting. In addition, we intrathecally injected the astrocytic toxin L-a-aminoadipate (L-AA), gap junction blocker carbenoxolone (CBX), and ERK1/2 signaling pathway inhibitor PD98059 to explore the role of astrocytes in the spinal cord in RWIS-induced gastric mucosal damage and its possible mechanism in rats. The results showed that the expression of GFAP, c-Fos, Cx43, and p-ERK1/2 was significantly elevated in the spinal cord after RWIS. Intrathecal injection of both the astrocyte toxin L-AA and the gap junction blocker CBX significantly attenuated RWIS-induced gastric mucosal damage and decreased the activation of astrocytes and neurons induced in the spinal cord. Meanwhile, the ERK1/2 signaling pathway inhibitor PD98059 significantly inhibited gastric mucosal damage, gastric motility and RWIS-induced activation of spinal cord neurons and astrocytes. These results suggest that spinal astrocytes may regulate the RWIS-induced activation of neurons via CX43 gap junctions and play a critical role in RWIS-induced gastric mucosa damage through the ERK1/2 signaling pathway.

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.

The neurotherapeutic role of a selenium-functionalized quinoline in hypothalamic obese rats

RATIONALE

Obesity is considered one of the major global health problems and increases the risk of several medical complications, such as diabetes and mental illnesses.

OBJECTIVE

The present study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) on obesity parameters, behavioral and neurochemical alterations in hypothalamic obese rats.

METHODS

Male Wistar rats received subcutaneous neonatal injections of monosodium glutamate (MSG, 4g/kg) or saline. After the Lee Index evaluation, rats were divided into groups and treated with 4-PSQ (5 mg/kg, intragastric route) or canola oil once a day (post-natal days (PND) 60→76). Open-field, elevated plus-maze, forced swim task, object recognition/location memory, and stepdown inhibitory avoidance tasks were conducted from PND 66 to 74. On PND 76, rats were euthanized and epididymal fat, blood, cerebral cortex, andhippocampus were removed. Blood biochemical parameters and cortical/hippocampal acetylcholinesterase (AChE) and Na /K -ATPase activities were assessed.

RESULTS

MSG increased the Lee Index characterizing the chemically induced hypothalamic obesity model. 4-PSQ reversed the increases of epididymal fat, blood glucose, and triglyceride levels caused by MSG exposure. 4-PSQ attenuated anxiety-like and depression-like behaviors induced by neonatal administrations of MSG. Memory deficits found in MSG-obese rats were reversed by treatment with 4-PSQ. Neurochemical alterations produced by MSG evidenced by stimulation ofNa⁺/K⁺-ATPase and AChE activities in the cerebral cortex and hippocampus of rats were normalized by 4-PSQ treatment.

CONCLUSIONS

In brief, 4-PSQ therapy improved hypothalamic obesity-related parameters, as well as psychiatric symptoms, cognitive impairment, and neurochemical alterations found in obese rats.

Neurons and Astrocytes in Ventrolateral Periaqueductal Gray Contribute to Restraint Water Immersion Stress-Induced Gastric Mucosal Damage via the ERK1/2 Signaling Pathway

BACKGROUND

The restraint water immersion stress (RWIS) model includes both psychological and physical stimulation, which may lead to gastrointestinal disorders and cause gastric mucosal damage. The ventrolateral periaqueductal gray (VLPAG) contributes to gastrointestinal function, but whether it is involved in RWIS-induced gastric mucosal damage has not yet been reported.

METHODS

The expression of glial fibrillary acidic protein, neuronal c-Fos, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG after RWIS was assessed using western blotting and immunocytochemical staining methods. Lateral ventricle injection of astrocytic toxin L-a-aminoadipate and treatment with extracellular signal-regulated kinase (ERK)1/2 signaling pathway inhibitor PD98059 were further used to study protein expression and distribution in the VLPAG after RWIS.

RESULTS

The expression of c-Fos, glial fibrillary acidic protein, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG significantly increased following RWIS and peaked at 1 hour after RWIS. Lateral ventricle injection of the astrocytic toxin L-a-aminoadipate significantly alleviated gastric mucosal injury and decreased the activation of neurons and astrocytes. Treatment with the ERK1/2 signaling pathway inhibitor PD98059 obviously suppressed gastric mucosal damage as well as the RWIS-induced activation of neurons and astrocytes in the VLPAG.

CONCLUSIONS

These results suggested that activation of VLPAG neurons and astrocytes induced by RWIS through the ERK1/2 signaling pathway may play a critical role in RWIS-induced gastric mucosa damage.

A versatile ultrafine and super-absorptive H+-modified montmorillonite: application for metabolic syndrome intervention and gastric mucosal protection

Metabolic syndrome (MetS) includes central obesity, hypertension, insulin resistance, and dyslipidemia and is closely related to nonalcoholic fatty liver disease, atherosclerotic cardiovascular disease (CVD) and type 2 diabetes mellitus, involving multiple causative factors. Current drug therapies for intervention and amelioration of MetS are essential in clinical treatment of metabolic disease. In this report, we proposed an H⁺-modified montmorillonite (H-MMT) using an acid modification method with ultrafine structure and super absorption ability as a potential drug for MetS. Hamsters fed a high-fat diet were orally treated with H-MMT and simvastatin was applied as a control. H-MMT lowered lipids by decreasing intestinal absorption and promoting lipid excretion, subsequently preventing obesity, fatty liver, and hyperlipidemia. Moreover, H-MMT was significantly safer and better tolerated by the liver compared to simvastatin, which was hepatotoxic. In addition, we found that H-MMT had protective effects on gastric mucosal damage. Therefore, this versatile H-MMT provides a potential strategy to effectively improve MetS and provide gastric mucosal protection in clinical applications.

Monosynaptic Input Mapping of Diencephalic Projections to the Cerebrospinal Fluid-Contacting Nucleus in the Rat

Objective: To investigate the projections the cerebrospinal fluid-contacting (CSF-contacting) nucleus receives from the diencephalon and to speculate on the functional significance of these connections.

Methods: The retrograde tracer cholera toxin B subunit (CB) was injected into the CSF-contacting nucleus in SD rats according to the experimental formula of the stereotaxic coordinates. Animals were perfused 7–10 days after the injection, and the diencephalon was sliced at 40 μm with a freezing microtome. CB-immunofluorescence was performed on all diencephalic sections. The features of CB-positive neuron distribution in the diencephalon were observed with a fluorescence microscope.

Results: The retrograde labeled CB-positive neurons were found in the epithalamus, subthalamus, and hypothalamus. Three functional diencephalic areas including 43 sub-regions revealed projections to the CSF-contacting nucleus. The CB-positive neurons were distributed in different density ranges: sparse, moderate, and dense.

Conclusion: Based on the connectivity patterns of the CSF-contacting nucleus that receives anatomical inputs from the diencephalon, we preliminarily assume that the CSF-contacting nucleus participates in homeostasis regulation, visceral activity, stress, emotion, pain and addiction, and sleeping and arousal. The present study firstly illustrates the broad projections of the CSF-contacting nucleus from the diencephalon, which implies the complicated functions of the nucleus especially for the unique roles of coordination in neural and body fluids regulations.

Medial prefrontal cortex exacerbates gastric dysfunction of rats upon restraint water‑immersion stress

Restraint water-immersion stress (RWIS) can induce a gastric mucosal lesions within a few hours. The medial prefrontal cortex (mPFC) is involved in the RWIS process. The present study investigated the modulatory effects and molecular mechanisms of the mPFC on gastric function under an RWIS state. Male Wistar rats were divided into four groups; namely, the control, RWIS 4 h (RWIS for 4 h only), sham-operated and bilateral-lesioned (bilateral-lesioned mPFC) groups. The gastric erosion index (EI) and gastric motility (GM) were determined, and the proteomic profiles of the mPFC were assessed by isobaric tags for relative and absolute quantitation (iTRAQ) coupled with two-dimensional liquid chromatography and tandem mass spectrometry. Additionally, iTRAQ results were verified by western blot analysis. Compared with the RWIS 4 h group and the sham-control group, the bilateral-lesioned group exhibited a significantly lower EI (P<0.01). In the bilateral-lesioned group, RWIS led to a significant decrease in EI and GM. When comparing the control and RWIS 4 h groups, 129 dysregulated proteins were identified, of which 88 were upregulated and 41 were downregulated. Gene Ontology functional analysis demonstrated that 29 dysregulated proteins, including postsynaptic density protein 95, were directly associated with axon morphology, axon growth and synaptic plasticity. Ingenuity pathway analysis revealed that the dysregulated proteins were mainly involved in neurological disease signaling pathways, including the NF-κB and ERK signaling pathways. These data indicated that the presence of the mPFC exacerbates gastric mucosal injury in awake rats during RWIS. Although the quantitative proteomic analysis elucidated the nervous system molecular targets associated with the production of gastric mucosal lesions, such as the role of PSD95. The underlying molecular mechanisms of synaptic plasticity need to be further elucidated.