Expression Of SSTR4 And SSTR5 In Jejunum Of Rat With Post-infection Irritable Bowel Syndrome After Cryptosporidium Parvum

Objective:To study the changes of the expression of somatostatin receptor(SSTR)4 and SSTR5 in Cryptosporidium infected neonatal rats and the effect of octreotide on the expression of SSTR4 and SSTR5 in jejunum of rats with irritable bowel syndrome after infection.Methods:Identification and counting of the oocysts obtained from the gifted Cryptosporidium,After immunosuppression of SD rats,106 Cryptosporidium oocysts were given orally.The feces were collected on the 3rd to 15th days after infection and the oocysts of Cryptosporidium were purified.After counting,the concentration was diluted to 109/L.128,5-day-old SD rats were divided into control group,drug control group,infection group and drug group,and the other 10 were confirmed infection group(5 infected with Cryptosporidium and 5 as normal control group).A total of 64 SD rats were injected intragastrically with Cryptosporidium oocysts(109/L,0.1 mL/each)in the infection group and drug group.The control group and the drug control group were given 64 Day-old SD rats were injected intragastrically with PBS(0.1ml).On the 7th day after infection,the suckling mice of the infected group were sacrificed,and each segment of the intestine was taken and fixed.HE staining was performed to observe whether the jejunum was infected by Cryptosporidium and the infection was confirmed.The drug control group and the drug group were intraperitoneally injected with octreotide(50 μg kg-1·d-1)on day 11-17 after infection,and the control group and infection group were given the same dose of normal saline.The jejunal tissue of the rats was collected at the 14th,17th,37th and 50th day after infection respectively.The expression of SSTR4 and SSTR5 in jejunum of rats was determined by immunohistochemistry,Real time-PCR and Western blot.Results:The results of immunohistochemistry showed that SSTR4 mainly expressed in the jejunum crypt of rats,but little expressed in the submucosa and the absorptive cells.Compared with the blank control group,the expression of SSTR4 in the jejunum of the infected group increased on the 14th,17th,and 37th day after infection(P<0.05).Compared with the infected group,the expression of SSTR4 in the jejunum of the treated group was decreased(P<0.05).However,SSTR5 mainly expressed in the submucosa,but only in small amount.Compared with the blank control group,the expression level of SSTR5 in the jejunum of the infected group was increased on the 14th,17th and 50th days after infection(P<0.05).Compared with the infected group,the expression of SSTR5 in the jejunum was decreased in the treated group(P<0.05).Real time-PCR results showed that compared with the blank control group,the expression levels of SSTR4 and SSTR5 mRNA in the jejunum of infected group were increased on the 14th,17th.37th and 50th days after infection(P<0.05),Compared with the infected group,on the 17th,37th and 50th days after infection.The expression of SSTR4 and SSTR5 mRNA in the jejunum was significantly decreased(P<0.01).Compared with the blank control group,SSTR4 and SSTR5 mRNA expression levels in the jejunum of the control group were increased on the 14th and 17th day after intragastric administration(P<0.05).On the 50th day after intragastric administration,jejunum SSTR4 and SSTR5 mRNA were administered to the control group.The expression level was significantly reduced(P<0.01).Western blot results showed that compared with the blank control group,the expression levels of SSTR4 and SSTR5 in the model group were increased,while the expression levels of SSTR4 and SSTR5 in the jejunum of the octreotide treatment group were decreased,the difference was statistically Significance(P<0.05).Conclusions:The increased expression of SSTR4 and SSTR5 indicates that they are involved in the development of irritable bowel syndrome after Cryptosporidium infection.The decreased expression of SSTR4 and SSTR5 after octreotide treatment.