| This experiment studied the pharmacokinetics of porcine Glucagon-like peptide-2(pGLP-2),PEGylated porcine glucagon-like peptide-2(PEG-pGLP-2)and pGLP-2 micro-spheres in rat,and then the intestinal therapeutic effects of different doses and frequency of administration of PEG-pGLP-2 in dextran sulfate sodium(DSS)induced colitis in rats was conducted..Pharmacokinetics of long-acting pGLP-2 in rat:Eighteen Sprague-Dawley(SD)male rats with 280g body weight were randomly divided into three groups:pGLP-2 group(subcutaneously(s.c.)administration with 5.64 nmol/kg pGLP-2),PEG-pGLP-2 group(s.c.administration with 5.64 nmol/kg PEG-pGLP-2)and pGLP-2 microspheres group(s.c.administration with 15 mg microspheres).Results showed that PEG-pGLP-2 increased half-life(t1/2)by 4-fold,increased the mean residence time(MRT)and the area under the curve(AUC0-t)by 3-fold,reduced clearance(CL)to a half as compared to pGLP-2 group.Peak concentration(Cmax)was similar between two drugs,and peak time(Tmax)of PEG-pGLP-2 was later than pGLP-2.The ti/2 of pGLP-2 microspheres was 72.2±6.02 h and MRT was 90.66±7.41 h.The intestinal therapeutic effects of different doses of PEG-pGLP-2 in rat:Thirty-five health SD rats were randomly allocated to control group,DSS group,low dose group,middle dose group and high dose group,seven rats in each group.Rats in control group received water and were subcutaneously injected with 300 μL saline every day;other rats received 5%DSS for successive 7 days and were subcutaneously injected with 300 μL saline everyday(DSS group),22 μg PEG-pGLP-2(low dose group),44 μg PEG-pGLP-2(middle dose group),176 μg PEG-pGLP-2(high dose group)everyday.At day 8,all rats were sacrificed after weighting.The length and weight of small intestinal and colon were measured immediately.The blood,duodenum and colon were collected to be tested.Results showed:Rats treated with DSS significantly decreased body weight,colonic length and the height of villus compared to rats in control group(P<0.05).Compared to DSS group,body weight,colonic length,colonic weight and the height of villus of rats in low dose group significantly(P<0.05)increased,body weight,colonic weight,the height of villus,and the ratio between villus and crypt of rats in middle dose group significantly(P<0.05)increased,body weight and the height of villus of rats in high dose group significantly(P<0.05)increased.Treatment of DSS significantly(P<0.05)increased the colonic damage score and the expression of IL-1,IL-1,IL-7,IL-10,IFN-y and TNF-a in colon as compared to control group.Compared to DSS group,colonic damage score and the expression of IL-1,IL-7 and TNF-a of rats in low dose group,middle dose group and high dose group all significantly(P<0.05)decreased;the expression of IL-10 significantly(P<0.05)decreased in low dose group,the expression of IL-10 and IFN-y(P<0.05)significantly decreased in middle dose group.Treatment of DSS significantly increased the expression of Claudin-1 in colon and decreased the expression of ZO-1(P<0.05),when compared to control group.Compared to DSS group,the expression of ZO-1 in high dose group significantly(P<0.05)increased,the expression of Occludin significantly(P<0.05)increased and the expression of Claudin-1 significantly(P<0.05)decreased in middle dose group and high dose group..The intestinal therapeutic effects of different frequency of administration in rat:Health SD rats were randomly allocated to control group,DSS group,one day group,two day group and three day group,seven rats in each group.Rats in control group received water and were subcutaneously injected with 300μL saline every day;other rats received 5%DSS for successive 7 days and were subcutaneously injected with 300 μL saline everyday(DSS group),44 μg/d PEG-pGLP-2(one day group),88 μg/2d PEG-pGLP-2(two day group),132 μg/3d PEG-pGLP-2(three day group)once everyday.At day 8,all rats were sacrificed after weighting.The length and weight of small intestinal and colon were measured immediately.The blood,duodenum and colon were collected to be tested.Results showed:Rats treated with DSS significantly(P<0.05)decreased body weight,colonic length,colonic weight,and the height of villus when compared to control group.Compared to DSS group,body weight,colonic weight,the height of villus and the ratio between villus and crypt of rats in one day group significantly(P<0.05)increased,body weight,colonic length and the height of villus of rats in two day group significantly(P<0.05)increased,body weight and the ratio between villus and crypt of rats in three day group significantly(P<0.05)increased.Treatment of DSS significantly(P<0.05)increased the colonic damage score and the expression of IL-1,IL-1,IL-10 and IFN-γ in colon as compared to control group.Compared to DSS group,the colonic damage score in one day group,two day group and three day group all significantly(P<0.05)decreased,the expression of IL-1,IL-1,IL-7,IL-10 and IFN-γ in one day group significantly(P<0.05)decreased,the expression of IL-1,IL-6,IL-7,IL-10 and IFN-y in two day group significantly(P<0.05)decreased,the expression of IL-1,IL-6,IL-7 and IFN-y in three day group significantly(P<0.05)decreased.Treatment of DSS significantly(P<0.05)increased the expression of Claudin-1 in colon and decreased the expression of ZO-1,when compared to control group.Compared to DSS group,the expression of ZO-1 and Occlduin significantly(P<0.05)increased and the expression of Claudin-1 significantly(P<0.05)decreased in one day group,the expression of Claudin-1 significantly(P<0.05)decreased and the expression of Occlduin significantly(P<0.05)increased in two day group and three day group.Overall,PEGylated pGLP-2 greatly improved the pharmacological profiles,increased t1/2,Tmax and MRT,decreased CL.pGLP-2 microspheres also showed the longer half time and more stable release.PEG-pGLP-2 could effectively repair colitis,reversed body weight loss,improve the integrity of the intestinal epithelium and reduce the expression of inflammatory factors in rats,and the effect of middle dose(44 μg)was best.All frequency of administration in this study took effect,considering the effect and convenience,the treatment of 88 μg PEG-pGLP-2 every two days was best. |
