Protective effect of chelerythrine against ethanol-induced gastric ulcer in mice

Highlights

• CHE significantly reduced the gastric mucosal lesion in a dose-dependent manner.

• CHE also inhibited NO, MPO, IL-6 and TNF-α level in the gastric ulcer mice.

• CHE also markedly attenuated the overexpression of NF-κB in gastric mucosa of mice.

Abstract

The quaternary benzo[c]phenanthridine alkaloid, chelerythrine (CHE), is of great practical and research interest because of its pronounced, widespread physiological effects, primarily antimicrobial and anti-inflammatory, arising from its ability to interact with proteins and DNA. Although CHE was originally shown to possess anti-inflammatory properties, its effects on acute gastric ulcer have not been previously explored. The aim of the present study is to evaluate the protective effect of CHE on ethanol induced gastric ulcer in mice. Administration of CHE at doses of 1, 5 and 10 mg/kg bodyweight prior to ethanol ingestion dose-dependently inhibited gastric ulcer. The gastric mucosal lesion was assessed by ulcer area, gastric juice acidity, myeloperoxidase (MPO) activities, macroscopic and histopathological examinations. CHE significantly reduced the gastric ulcer index, myeloperoxidase activities, macroscopic and histological score in a dose-dependent manner. In addition, CHE also significantly inhibited nitric oxide (NO) concentration, pro-inflammatory interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) level in serum and gastric mucosal in the mice exposed to ethanol induced ulceration in a dose-dependent manner. In addition, immunohistochemical analysis revealed that CHE markedly attenuated the overexpression of nuclear factor-κB in gastric mucosa of mice. It was concluded that CHE represents a potential therapeutic option to reduce the risk of gastric ulceration. In addition, acute toxicity study revealed no abnormal sign to the mice treated with CHE (15 mg/kg). These findings suggest that the gastroprotective activity of CHE might contribute in adjusting the inflammatory cytokine by regulating the NF-κB signalling pathway.

Introduction

Gastric ulcer is a common disease with multiple etiologies, defined as a discontinuity in the gastric mucosa penetration through the muscularis mucosa [1]. It was reported to be associated with the imbalance between the aggressive factors (physical, chemical or psychological) in the lumen and protective mechanisms in the duodenal mucosa represented by mucus and bicarbonate secretions, as well as by prostaglandins, sulphydryl compounds, polyamines, nitric oxide (NO) and dopamine [2], causing chronic inflammation that leads to a defect in the regulation of gastrin production [3]. Gastrointestinal problems have now become a global problem, and many studies were conducted towards fixing it. The ability of some ulcer models to suppress secretion of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), and protect ethanol ulcer by scavenging of ROS and preventing apoptosis has provided a means for intense investigations [4], [5]. It was suggested that, cytokines such as TNF-α, IL-6 and IL-10 play important roles in the acute phase inflammation as well as in maintenance and regulation of the severity of gastric ulcers [6]. Over expression and translocation of the NF-κB subunits (p65 and p50) to the nucleus promote the over expression of proinflammatory mediators such as TNF-α and IL-6 [7]. Increasing evidence reveals that the inhibition of NF-κB activity may lead to alleviating the severity of inflammatory diseases [8]. Therefore, understanding the molecular mechanisms involved in this pathway is an essential step towards countering the damaging effects of pro-inflammatory mediators in gastric ulcer. On the other hand, neutrophil infiltration into the gastric mucosa is also a critical process in the pathogenesis of a variety of gastric ulcers [9], [10]. It has been shown that ethanol-induced neutrophil infiltration in the gastric mucosa is closely related to the genesis of lesions [11]. The neutrophil infiltration into the gastricmucosal tissues can be reflected by the determination of the activities of myeloperoxidase (MPO) and NO, both of which serve as key indicators of neutrophil infiltration in various experimental gastric injuries [12], [13].

Chelerythrine (CHE) (Fig. 1), a quaternary benzo[c]phenanthridine alkaloid, is common in the Papaveraceae and Rutaceae families of plants. This alkaloid shows a broad range of biological activities, primarily antimicrobial and anti-inflammatory, arising from its ability to interact with proteins and DNA [14]. Mechanisms of the anti-inflammatory effect of CHE may include inhibition of 5-lipoxygenase [15], attenuation of the oxidative burst [16], and blocking the P2X7 receptor activity [17]. Besides, CHE affects various signaling pathways via the inhibition of protein kinase C and mitogen-activated protein kinase phosphatase-1 [18]. Our previous studies clearly suggested that CHE is a potent inhibitor of cyclooxygenase-2, which may be relevant to the inhibition of the release/production of exudates and prostaglandin E2 [19], and can inhibit the expression of pro-inflammatory cytokines in cultured cells and experimental models [20], implying that CHE may be developed to a potential strategy in treatment for gastric ulcers. Besides, our previous studies have also demonstrated that CHE exerted its anti-inflammatory effects by inhibiting proinflammatory cytokines (such as TNF-α) production and interfered with mitogen-activated protein kinase (MAPK) signaling pathways [20]. Since gastric ulcer is the inflammatory disease, we supposed that CHE can be used to treat gastric ulcers. Unfortunately, to date, there has been no information on whether CHE is therapeutic for gastric ulcers. Therefore, we hypothesized that CHE could exert its gastroprotective and ulcer healing actions effect on gastric ulcers by inhibiting proinflammatory cytokines production and the activation of NF-κB signaling pathway. Here, we investigated the effect of CHE on a murine model of ethanol-induced gastric ulcer in order to provide experimental evidence that CHE serves as a possible treatment for patients with gastric ulcers.