Chronic stress augments esophageal inflammation, and alters the expression of transient receptor potential vanilloid�1 and protease‑activated receptor 2 in a murine model

Abstract

Stress is a pivotal factor for inflammation, reactive oxygen species (ROS) production and formation of visceral hypersensitivity (VH) in the process of gastroesophageal reflux disease (GERD). In the present study, the effects of stress on esophageal inflammation, oxidative stress and VH were investigated in a chronic restraint stress mouse model. c57Bl/6J male mice were subjected to 2 weeks of intermittent restraint stress, and histopathological analysis revealed that stress induced esophageal inflammation and fibrosis, while no distinct changes were detected in non-stressed control mice. In addition, increased NADPH oxidase 4 expression was observed in the plasma and esophagus of stressed mice, indicating accumulation of ROS. The expression levels of antioxidants, including Mn-superoxide dismutase (MnSOD), cu/Zn-Sod, catalase and glutathione peroxidase, were also analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, transient receptor potential vanilloid 1 (TrPV-1) and protease-activated receptor 2 (Par-2), which are crucial receptors for VH, were measured by immunohistochemistry and RT-qPCR. The results demonstrated that stress markedly reduced antioxidant expression, while it significantly upregulated TRPV-1 and PAR-2 expression levels in the mouse esophagus. Finally, 2 weeks of restraint stress significantly increased the esophageal and plasma levels of inflammatory cytokines, including interleukin (IL)-6, IL-8, interferon-γ and tumor necrosis factor-α. Taken together, the present study results indicated that stress-induced esophageal inflammation and ROS generation involves VH.

OEsophageal Ion Transport Mechanisms and Significance Under Pathological Conditions

“…TRPV1 is overexpressed in the oesophageal mucosa of patients with non-erosive reflux disease (NERD) and erosive esophagitis and also in animal models of NERD (Guarino et al, 2010;Silva et al, 2018). Increased levels of TRPV1 was also observed in stress-induced oesophageal inflammation (Wulamu et al, 2019). The role of TRPV1 in inflammation can be explained by the fact that activation of the channel promotes the secretion of inflammatory mediators (platelet-activating factor (PAF), Il-1 β, Il-6) that initiates the inflammatory cascade in the mucosa of the oesophagus.…”

<p>Chronic Restraint Stress Induces Gastric Mucosal Inflammation with Enhanced Oxidative Stress in a Murine Model</p>

“…The mice in the stress group underwent immobilization stress for 2 h (between 10:00 a.m. and 12:00 p.m.) each day for 14 consecutive days. [10][11][12][13][14] During the stress period (immobilizing for 2 h) the mice were not supplied with water and food, after which they were placed back to their individual cages and supplied with food and water freely. Body weight and food intake were monitored every 2 days during the stress period.…”

“…The streptavidin-biotinylated peroxidase complex methods described in our previous studies were employed in immunohistochemistry. [10][11][12][13][14][15] All sections of the extracted stomach tissue from each mouse were deparaffinized with xylene prior to dehydration with a series of ethanol treatments. These tissues were then incubated overnight at 4°C with primary antibodies, including anti-CD11b Sangyo Co., Saitama, Japan).…”

“…Plasma samples were obtained from all mice and processed as previously described. [10][11][12][13][14] The plasma levels of Nox4 (cat no; SEB924Mu, Cloud-Clone Corp.), a competitive ELISA kit, was used to determine the Nox-4 levels following the manufacturer's instructions. Plasma 8-OHdG levels were determined using a competitive ELISA kit (8-OHdG Check, cat no; KOG-200SE, highly sensitive kit, Japan Institute for the Control of Aging).…”

“…8,9 Chronic stress modifies the expression of a generegulating antioxidant system and NADPH oxidase (Nox), which is a major driver of ROS production in many types of cells. [10][11][12][13][14][15] Nox-induced ROS is the main source of oxidative stress that accelerates the progression of various inflammatory diseases, including adipose, 11 intestinal, 12 and esophageal inflammation. 13 Considering the limited research on gastric inflammation, this study investigates how chronic stress triggers gastric inflammation by observing rodents placed under chronic restraint stress.…”