The Effect of Berberine on the PI3K/Akt/NF-kB Signaling Pathway in Colonic Tissues of Morphine-Induced Acute Constipation Mice

Abstract

Background: Opioid-induced constipation not only directly affects the quality of life of patients, but also causes complications that seriously affect their health. This study aimed to observe the effect of berberine (BBR) on morphine (MP)-induced acute constipation in mice. Methods: The acute constipation model was tested by subcutaneous injection of MP at doses of 2, 5, or 10 mg/kg. According to the degree of constipation, MP (10 mg/kg) was selected as the MP dose for the MP-mediated model in the following experiment that included eight groups: Vehicle, MP, BBR (2 mg/kg), BBR (5 mg/kg), BBR (10 mg/kg), MP+BBR (2 mg/kg), MP+BBR (5 mg/kg), and MP+BBR (10 mg/kg). BBR was injected once intraperitoneally 30 minutes before a single injection of MP in each mouse. Defecation function, as reflected by accumulated fecal weight, fecal pellet number, and fecal water content, was measured over a 6-hour period. At the end of the experiment, colonic tissues of mice were extracted under general anesthesia. The expression of mRNA level of phosphatidylinositol 3-protein kinase (PI3K) and protein kinase B (Akt) was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR). The expression levels of phosphorylated PI3K, Akt and nuclear factor kappa-B (NF-kB) and the total protein expression levels of PI3K, Akt, NF-kB, interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α) were detected by western blot assays. The ratio of phosphorylation levels of PI3K, Akt and NF-kB to total protein levels was calculated. The distribution of phosphorylated Akt (p-Akt) and p-NF-kB in colonic tissue was stained by immunohistochemistry and the mean intensity value was calculated. Results: Single administration of MP caused acute constipation in mice. BBR did not change defecation function compared with the blank group (p > 0.05). When BBR was used in combination with MP at doses 2, 5, and 10 mg/kg, no statistically significant differences from MP alone were observed (p > 0.05). Compared with the blank group, BBR caused no significant difference in the expression of PI3K and Akt at the mRNA level (p > 0.05). However, at the protein level, MP increased the relative expressions of p-PI3K, p-Akt, and p-NF-kB compared with the blank group (p < 0.05), and BBR completely reversed the activation (p < 0.05). Similar changes were observed in the expression of TNF-α and IL-6 that is downstream of NF-kB (p < 0.05). Conclusions: Though BBR did not affect MP-mediated constipation in mice, it ameliorated colonic inflammation by completely reversing MP-mediated activation of the PI3K/Akt/NF-kB signaling pathway.