ABSTRACT
Objective Based on the observation of the changes of symptoms, histopathology, visceral sensitivity, mast cell activation, autophagy, and Beclin-1 and Claudin-2 expression in rats, we established and evaluated a new rat model of diarrhea-predominant irritable bowel syndrome (D-IBS) induced by restraint-stress combined with capsaicin (CAP) administration.Methods Forty healthy 5-week old male Sprague Dawley (SD) rats were randomly divided into normal group, model group I, model group II and model group III, with 10 rats in each group.The D-IBS model was established by restraint-stress combined with intragastric administration of CAP (2 mL/100 g body weight, 0.125% in group I, 0.250% in group II, 0.500% in group III), tail clipping and forelimb restriction for 30 minutes every day for 2 weeks.The rats in the control group were treated with saline for 2 weeks.The number of contraction of abdominal wall and arched back were measured by Power Lab instrument.The mast cell activation was detected using aldehyde-magenta-orange G staining.Light and electron microscopic examinations were performed to detect the morphology and autophagy of colonic tissues.The expressions of Beclin-1 and Claudin-2 in the colonic mucosa were detected by streptavidin-biotin complex (SABC) immunohistochemical staining.Results All rats in the model group III died during the experiment.Compared with the control group and model group I, the stool frequency was increased and the visceral sensitivity threshold decreased in the model group II, and there were statistically significant differences between the model group II and the control and model groups I (P < 0.05).The colonic mucosa, mucosal epithelium and glands in each group showed normal morphology and there was no submucosal vasodilatation and diffuse inflammatory cell infiltration.Except for the control group, round purple-reddish staining spots were observed in the rat mucosal stroma or submucosa in the model groups I and II, indicating an increased expression of mast cells.The autophagy, expressions of Beclin-1 and Claudin-2 in the colonic epithelium were significantly increased in the model group II compared with control group and model group I (P< 0.05).Conclusions The model of D-IBS induced by restraint-stress combined with capsaicin is characterized by increased diarrhea, visceral hypersensitivity, increased mast cell expression and autophagy of intestinal epithelial cells, and disruption of the intestinal mucosal barrier.This model is simple to set up and shows similar symptoms of human irritable bowel syndrome.Therefore, it is worthy of popularization and application.
ABSTRACT
In order to improve the efficiency of drug screening on serotonin transporter (SERT) inhibitors, a high-throughput screening (HTS) model is established in RBL-2H3 cells. The RBL-2H3 cells are very similar to the serotonin genetic neuro, in modulation of post-receptor mechanisms and transduction pathway of SERT reactivated. Depending on a fluorescence substrate ASP+ used in detection method of inhibitor rates, it's convenient, quick, accurate and effective, not making the environmental biohazard compared with radioactive experiments. Furthermore, biological screening model combined with computer aided virtual screening technique describing high-throughput virtual screening (HTVS). Bayesian classification method and molecular fingerprint similarity were applied to virtual screening technique, for screening compounds in compound library. Some compounds have been found, and then validated further by biological screening model. Combination of HTS and HTVS improves the efficiency of screening SERT inhibitors.
ABSTRACT
In this study two genistein derivatives (G1 and G2) are reported as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and differences in the inhibition of AChE are described. Although they differ in structure by a single methyl group, the inhibitory effect of G1 (IC50=264 nmol/L) on AChE was 80 times stronger than that of G2 (IC50=21,210 nmol/L). Enzyme-kinetic analysis, molecular docking and molecular dynamics (MD) simulations were conducted to better understand the molecular basis for this difference. The results obtained by kinetic analysis demonstrated that G1 can interact with both the catalytic active site and peripheral anionic site of AChE. The predicted binding free energies of two complexes calculated by the molecular mechanics/generalized born surface area (MM/GBSA) method were consistent with the experimental data. The analysis of the individual energy terms suggested that a difference between the net electrostatic contributions (ΔE ele+ΔG GB) was responsible for the binding affinities of these two inhibitors. Additionally, analysis of the molecular mechanics and MM/GBSA free energy decomposition revealed that the difference between G1 and G2 originated from interactions with Tyr124, Glu292, Val294 and Phe338 of AChE. In conclusion, the results reveal significant differences at the molecular level in the mechanism of inhibition of AChE by these structurally related compounds.
ABSTRACT
The emerging of network pharmacology and polypharmacology forces the scientists to recognize and explore new mechanisms of existing drugs. The drug target prediction can play a key significance on the elucidation of the molecular mechanism of drugs and drug reposition. In this paper, we systematically review the existing approaches to the prediction of biological targets of small molecule based on chemoinformatics, including ligand-based prediction, receptor-based prediction and data mining-based prediction. We also depict the strength of these methods as well as their applications, and put forward their developing direction.