Therapeutic effect of protease-activated receptor 2 agonist SLIGRL-[NH.sub.2] on loperamide-induced Sprague-Dawley rat constipation model and the related mechanism

• Published in: Drug design, development and therapy development and therapy, 2018-01, Vol.10, p.2403
• Main Authors: Zhang, Yonggang, Ge, Tingrui, Xiang, Ping, Mao, Haibing, Tang, Shumin, Li, Aimin, Lin, Lin, Wei, Yinting
• Format: Article
• Language: English
• Subjects: Constipation; Enzyme-linked immunosorbent assay; Enzymes; Health aspects; Loperamide; Peptides; Polymerase chain reaction; Proteases; Vasoactive intestinal peptides
• ISSN: 1177-8881; 1177-8881
• DOI: 10.2147/DDDT.S160628

Purpose: To investigate the therapeutic effects of protease-activated receptor 2 (PAR-2) agonist SLIGRL-[NH.sub.2] on loperamide-induced Sprague-Dawley (SD) rat constipation animal models. Materials and methods: Loperamide was injected subcutaneously to induce constipation twice a day for 3 days. SD rats (n= 30) were randomly divided into five groups: non-constipation group (control, n = 6), constipation group (constipation, n = 6), constipation + SLIGRL-[NH.sub.2] low-dosage group (SLIGRL-[NH.sub.2] low, n=6), constipation + SLIGRL-[NH.sub.2] high-dosage group (SLIGRL-[NH.sub.2] high, n = 6), and constipation + prucalopride (positive control, n = 6). The SLIGRL-[NH.sub.2] low group and SLIGRL-[NH.sub.2] high group were administered with 2.5 [micro]mol/kg and 5 [micro]mol/kg SLIGRL-[NH.sub.2], respectively, and the prucalopride group received 2 mg/kg prucalopride. The control and constipation group received 1x PBS under the same pattern. SLIGRL-[NH.sub.2] and prucalopride were orally administrated once daily for 7 days. On the final day of oral administration, food intake, water intake, the number of stool pellets, weight, and fecal water content was calculated; moreover, the colons of rats in different groups were collected and histological features were examined by hematoxylin and eosin staining; furthermore, the expression of anoctamin-1 was determined by Immunohistochemical methods, and the expressions of c-kit and PAR-2 were examined using real-time quantitative polymerase chain reaction and Western blot methods; finally, the expressions of neurotransmitter vasoactive intestinal peptide (VIP) and substance P (SP) were examined using enzyme-linked immunosorbent assay methods. Results: The feeding and excretion behaviors, intestinal transit ratio, and the histological feature of the colon in the constipated rats were all improved by SLIGRL-[NH.sub.2] treatment; moreover, SLIGRL-[NH.sub.2] treatment induced significant increase in the expression of PAR-2 and also increased number of interstitial Cajal cells. Furthermore, SLIGRL-[NH.sub.2] also decreased the contents of the inhibitory neurotransmitter VIP and increased the expression of the excitatory neurotransmitter SP. High dose of SLIGRL-[NH.sub.2] has shown similar anti-constipation effects as prucalopride. Conclusion: These results suggested that SLIGRL-[NH.sub.2] can enhance gastrointestinal transit and alleviate in rats with loperamide-induced constipation. Keywords: constipation, PAR-2, SLIGRL-[N