Effects Of Periplaneta Americana Extract On Experimental Ulcerative Colitis And Related Mechanisms

Ulcerative colitis(UC) is a chronic non-specific inflammatory bowel disease with unknown etiology and recurrent episodes, which is a kind of digestive system common refractory diseases. In recent years, UC incidence with a fast-growing trend in China has attracted more and more attention. Currently, medical therapy of ulcerative colitis often combined oral or retention enema treatment with Chinese herbs, which not only can improve the efficacy and reduce the relapse rate, and can reduce medicine dosage and side effects of long-term use of western medicine.Periplaneta americana L., as a traditional Chinese medicine, have the effect of make free the passage of blood in the vessels. In recent years, preparations made from P.americana used in digestive system diseases, such as radioactive esophagitis, acute erosive gastritis, peptic ulcer, ulcerative colitis. However, few studies have provided its specific mechanism of action. Thus, this study through animal experiments designed to clarify therapeutic effects of of P.americana ethanol extraction against UC. Furthermore, from the perspective of bacterial translocation, to explore the therapeutic benefit of P.americana. At last, taking each pole moiety of P.americana extract as research object to investigate the benefit to fibroblasts function and immune activity, which to clarify the possible mechanism against UC. The main contents and results of this study are as follows:(1) The chemical compositions of P. americana extract were analyzed. The results showed that the main compositions of P. americana extract were polypeptides(17.56 mg/g), amino acids(5.75 mg/g), polyols(11.60 mg/g), glycosaminoglycan(4.65 mg/g) and uracil(0.189 mg/g)(2) Dinitrochlorobenzene and acetic acid-induced colitis rat model was applied to assess the effect of PAE on colitis. The 42 colitis rats were randomly divided into 6 groups(n=7): model group, PAE three groups(20, 40, 80 mg/kg), the SASP group, normal control group. The next day after modeling treated with drugs for 10 days and estimated disease activity index daily. Rats rectums about 3 cm above the anus were collected after the trial end. Rectal inflammation was assessed by myeloperoxidase activity and histological changes. The results showed that PAE can reduce the rats disease activity index(DAI), alleviate intestinal inflammation indicators and the pathological changes as destruction of the gland, goblet cells disappeared, epithelial defects, inflammatory cell infiltration et al.(3) This trial selected Escherichia coli labeled with green fluorescent protein as tracer bacteria, combineing with UC animal model to study the effect of P.americana extract on bacterial translocation of UC rats. The 24 colitis rats were treated with PAE for 4 days, meanwhile gavaged with tracer bacteria. Mesenteric lymph nodes, colon, liver, spleen and kidney were harvested for bacteria culture.Results showed that: compared with those in the model group, PAE high-dose group(80 mg/kg) significantly reduced the bacterial translocation of UC rats(p <0.05).(4) To investigate the effect of Periplaneta americana extract and its polar parts on NIH3T3 fibroblast cell function. MTT method was used to detect the effects of the extract on the proliferation of NIH3T3 cells, and the effect of promoting proliferation reached a peak at PAE concentration of 250 μg/mL. The hydroxyproline kit for determination the effects of extract on collagen accumulation which showed that PAE had a positive role on collagen accumulation. Total cellular protein synthesis was measured using Kaumas blue which show that PAE can promote the synthesis of total cellular protein. The wounding healing assay showed that PAE can make more cells into the wound model and accelerate cell healing and promote cell migration.(5) Cyclophosphamide-induced hypoimmunity mice model was applied to assess the effect of P.americana extract and its polar extract on immunomodulatory activity. The results showed that Bu OH fraction can improve thymus index and spleen index, and enhance cell immunity and humoral immunity of mice.Thus, P.americana extract have immunomodulatory effects. Among polar fractions of P.americana extract, BuOH fraction possessed the best immunomodulatory activity.