[Protective effects and mechanisms of berberine hydrochloride on intestinal mucosal barrier injury in rats with sepsis].

Objective: To investigate the protective effect of berberine hydrochloride on intestinal mucosal barrier damage in sepsis rats and its mechanism.

Methods: Forty-eight male SD rats were divided into a control group (Sham group, 6 cases), a sepsis model group (LPS group, 14 cases), a berberine hydrochloride intervention group (Ber group, 14 cases), and a Notch signaling pathway inhibition group (DAPT group, 14 cases) according to random number table method. The DAPT group was intraperitoneally injected with 5 mg/kg Notch signaling pathway inhibition DAPT 2 hours before modeling. The sepsis model was established by intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS); Sham group was injected with an equal amount of saline (2 mL). The Ber group and DAPT group were treated with gavage of 50 mg/kg berberine hydrochloride 2 hours after modeling; Sham group and LPS group were treated with gavage of an equal amount of saline (2 mL). The temperature, weight, behavior and survival rate of rats were observed at 0, 6, 12 and 24 hours of modeling. After 24 hours of modeling, abdominal aortic blood was collected under anesthesia, and intestinal tissues were obtained after euthanasia. The pathological changes of ileum were observed under light microscope. The ultrastructure of ileum was observed under transmission electron microscope. Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of serum diamine oxidase (DAO), intestinal fatty acid binding protein (iFABP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). Real time-polymerase chain reaction (RT-PCR) and Western blotting were used to detect the mRNA and protein expressions of tight junction proteins (Occludin and Claudin1), Notch1 and their downstream target signals in the ileum tissue.

Results: After 24 hours of modeling, compared with the Sham group, the LPS group, Ber group, and DAPT group showed a decrease in weight and an increase in temperature. Among them, the LPS group showed the most significant changes, followed by the DAPT group, and the Ber group showed the least significant changes. The survival rates of the LPS group, Ber group, and DAPT group were all lower than those of the Sham group [42.9% (6/14), 57.1% (8/14), 57.1% (8/14) vs. 100% (6/6)], and six rats were taken from each group for subsequent testing. Macroscopic observation of the intestine showed that the LPS group had the most severe edema in the ileum tissue and abdominal bleeding, with significant improvement in the Ber group and followed by the DAPT group. Under the light microscope, the LPS group showed disordered arrangement of glandular tissue in the ileum mucosa, significantly reduced goblet cells, and extensive infiltration of inflammatory cells, which were significantly improved in the Ber group but less improved in the DAPT group. Under electron microscopy, the LPS group showed extensive shedding of ileal microvilli and severe damage to the tight junction complex structure of intestinal epithelial cells, which was significantly improved in the Ber group but less improved in the DAPT group. The levels of serum DAO, iFABP, TNF-α, IL-6 in the LPS group were significantly higher than those in the Sham group, while the above indicators in the Ber group were significantly lower than those in the LPS group [DAO (μg/L): 4.94±0.44 vs. 6.53±0.49, iFABP (ng/L): 709.67±176.97 vs. 1 417.71±431.44, TNF-α (ng/L): 74.70±8.15 vs. 110.36±3.51, IL-6 (ng/L): 77.34±9.80 vs. 101.65±6.92, all P < 0.01], while the above indicators in the DAPT group were significantly higher than those in the Ber group. The results of RT-PCR and Western blotting showed that the mRNA and protein expressions of Occludin, Claudin1, Notch1, and Hes1 in the ileum tissue of LPS group rats were decreased compared to the Sham group, which were significantly increased in the Ber group compared with the LPS group [mRNA expression: Occludin mRNA (2^-ΔΔCt): 1.61±0.74 vs. 0.30±0.12, Claudin1 mRNA (2^-ΔΔCt): 1.97±0.37 vs. 0.58±0.14, Notch1 mRNA (2^-ΔΔCt): 1.29±0.29 vs. 0.36±0.10, Hes1 mRNA (2^-ΔΔCt): 1.22±0.39 vs. 0.27±0.04; protein expression: Occludin/GAPDH: 1.17±0.14 vs. 0.74±0.04, Claudin1/GAPDH: 1.14±0.06 vs. 0.58±0.10, Notch1/GAPDH: 0.87±0.11 vs. 0.56±0.09, Hes1/GAPDH: 1.02±0.13 vs. 0.62±0.01; all P < 0.05], while those in the DAPT group were significantly lower than those in the Ber group.

Conclusions: Early use of berberine hydrochloride can significantly improve intestinal mucosal barrier damage in sepsis rats, and its mechanism may be related to inhibiting inflammatory response and regulating the expression of intestinal mechanical barrier tight junction protein through Notch1 signal.