Effect Of Swine Ghrelin Gene Delivered By Chitosan Nanoparticles On The Growth Of Mice

Ghrelin(GHRL),a 28-amino acid peptide with an n-octanoylation modification indispensable for its activity,was originally discovered in human and rat stomach as an endogenous ligand of growth hormone secretagogue receptor(GHSR).Research finds that Ghrelin not only stimulates the release of GH,but also regulates gastrointestinal motility,energy metabolism balance,and play an improtant role in many kinds of diseases or pathologic state of human and growth promotion of animal after it bind with receptor.In this research,Ghrelin gene we cloned from fundus glands of swine through RT-PCR technique and pcDNA3.1(+)-Ghrelin eukaryotic expression vector was constructed through lead NheⅠand XhoⅠenzyme cutting site into both ends of it.With chitosan as carrier,prepared CS-pcDNA3.1(+)-Ghrelin nanoparticle(mean diameter, 180.4±13.5) by using amb-coacervation.The detection of CS-pcDNA3.1(+)-Ghrenlin nanoparticle:the nanoparticle envelop rate is 95±1.27%and DNA content is 37±2.0%. Intramuscular administration of CS-pcDNA3.1(+)-Ghrelin nanoparticle to weaning Mice (dose of 1mg/kg.BW) for finding the influence of Mice's growth.As the result,the cumulate weight gain of injesting naked plasmid group was the most obviously in the frist five days(containing plasmid nanoparticles group:4.41±0.23g,naked plasmid group: 5.42±0.61g,physiological saline group:3.39±0.96g).But from day 0 to 25,the cumulate weight gain of containing plasmid nanoparticles group was separately 12.0%and 25.4% higher than naked plasmid group and physiological saline group(P＜0.05).At the 30th day, the GH level which in mice's blood was detected.The GH level of containing plasmid nanoparticles group(2.36±0.32ng/mL) is markedly higher than physiological saline group (1.75±0.23ng/mL) and naked plasmid group(1.78±0.26ng/mL),but the GH level of naked plasmid group is slightly higher than physiological saline group.Conclusion:Ghrelin gene has growth promotion function in Mice,but theCS-pcDNA3.1(+)-Ghrelin nanoparticle which has been covered by chitosan is more effective and permanent,this function is came true by increasing the density of GH in blood.This research has settled rationale and experiment for clinical application of Ghrelin nanometer delayed release plasmid.