Gastroprotective Effects of Astragaloside IV against Acute Gastric Lesion in Rats

Abstract

Background: Protection of the gastric mucosa from acute lesions induced by various irritants is a pertinent issue in the field of critical care medicine. In this study, we investigated the gastroprotective effects of astragaloside IV on acute gastric lesions in rats under stressful conditions.

Methods: Rats were randomized into six groups. Group 1 and 2 received 10% Tween 80 (vehicle). Group 3 received 20 mg/kg of omeprazole, a proton pump inhibitor. Groups 4, 5 and 6 received astragaloside IV at concentration of 1, 10, and 50 mg/kg, respectively. As a means to induce gastric lesions, Groups 2-6 were subjected to water immersion and restraint stress for 12 hours after treatment.

Results: Our present studies show that compared to rats in group 2, treatment with 1 to 50 mg/kg astragaloside IV significantly decreased the size of gastric lesions, MDA, TNFα and MCP1 levels, in addition to normalizing gastric pH, gastric mucus and SOD levels (P<0.05). Histomorphological examination confirmed that treatment with astragaloside IV elicited a dosage-dependent protective effect on the gastric mucosa. Furthermore, pretreatment with astragaloside IV resulted in significant elevations in HSP70 and reduction in Bax, along with over-expression of PLCγ response level, which was further confirmed via immunohistochemical analysis.

Conclusions: The acute gastric lesions induced are attenuated by pretreatment with astragaloside IV which is possibly due to the enhancing of the expression of HSP70 with concomitant antioxidant, anti-inflammatory and anti-apoptotic capacity.

Fig 1. The effects of astragaloside IV treatment on the gastric lesions area, pH value and mucus production.

Astragaloside IV or omeprazole were administered 1 h prior to WRS-induced gastric lesion to assess the protective effect. Lesion control group rats received Tween 80. After 12h, rats were sacrificed and lesion area, pH value and mucus production were measured. NC, negative control; Lesion, Lesion control; Ome: omeprazole. Data expressed as mean ± standard error of mean. *Significant difference (P< 0.05) when compared with the lesion control (group 2), ^#Significant difference (P< 0.05) when compared with the omeprazole (group 3) using one-way ANOVA followed by Tukey-Kramer Multiple Comparisons Test.

Fig 2. Representative photomicrographs of gastric mucosa in rats (H&E staining, ×100).

In rats from negative control group, normal gastric tissue has intact gastric pits and glands. Rats exposed to WRS (lesion control) have severe mucosal erosion and submucosal edema with macrophage and eosinophil infiltrates. In rats pretreated with Omeprazole (20 mg/kg), inflammatory exudates and edema can be detected in submucosal. Rats pre-treated with astragaloside IV have a reduction in submucosal edema and leukocyte infiltration in a dose- dependent manner (1–50 mg/kg).

Fig 3. The effects of astragaloside IV on the SOD, MDA, TNFα and MCP1 response level in gastric homogenate.

The SOD, MDA, TNFα and MCP1 response level were quantified using ELISA. All results expressed as mean ± standard error of mean. *Significant difference (P< 0.05) when compared with the lesion control (group 2). ^#Significant difference (P< 0.05) when compared with the omeprazole (group 3).

Fig 4. The effects of astragaloside IV treatment on the HSP70 gene expression and HSP70, BAX and PLCγ response levels.

HSP70 gene expression levels were quantified using qRT-PCR. HSP70, BAX, and PLCγ response level were quantified using ELISA. Immunohistochemical analysis demonstrated the expression of HSP70 proteins (Magnification 20x). All results are presented as mean ± standard error of mean.*P< 0.05vs.the lesion control,^#P< 0.05vs. the omeprazole group using one-way ANOVA followed by Tukey-Kramer Multiple Comparisons Test.