Regulation Of Estrogen For Duodenal Glucose Absorption And Its Mechanism

Objective:The glucose absorption in small intestine is the condition for maintaining the energy balance of the body.And estrogen plays a role in regulating the body in many aspects.Some studies have found that estrogen is involved in regulating the glucose absorption in the small intestine.However,the mechanism for the glucose absorption in the small intestine is neglected for a long time.Therefore,in this study,we explore the effect and the mechanism of the influence of estrogen on the glucose absorption in duodenum,aiming toprovide theoretical basis for the clinical treatment of obesity.Methods: 1.Choose 12 healthy female volunteers who is 20-30 years old and has a regular menstrual cycle.Take orally 50% of glucose respectively in the menstrual period(the period of lowest estrogen level in vivo)and ovulation period(the period of highest estrogen level in vivo)and measure the changes of glucose levels in blood.2.The establishment of animal model Choose 80 female mice in its ripening period(6 weeks old)C57 and treat them with sham surgery and ovarian resection under the general anesthesia.Take 40 female C57 mice as the group of ovarian resection,and 40 female C57 mice as the group of sham operation.(1)Weight the mice regularly at 10 o ' clock every morning from the second day of surgery.(2)Two weeks after surgery:(1)Kill the mice,draw blood through the vena cava,and measure the level of estradiol throughusing Radioimmunoassay(RIA).(2)Observe the change of short-circuit current(?Isc)difference caused by glucose absorption in duodenal mucosa of the 5 mice in group ofovarian resection and 5 mice ingroup of sham operation by Ussing Chamber experiment.(3)Immunofluorescence was used to locate the expression sites of calcium-sensing receptor.Detect the Protein Quantification and its expression of CaSR on small intestinal epithelial tissue of two groups by using Reverse transcription-polymerase chain reaction(RT-PCR)and western-blot experiment.3.Detect the influence of the ?Isc difference caused by glucose absorption after the addition of EGTA(Calcium chela tor),NPS(Receptor blocker of CaSR),inositol-1,4,5-triphosphate(IP3),2-Aminoethoxydiphenylborane(2-APB),Phosphoin ositide-specific phospholipase C(PI-PLC),and receptor blocker U73122 through Ussing chamber experiment.Results:(1)Oral glucose tolerance test(OGTT)shows that the OGTT glucose levels in blood of healthy women in menstrual periodis significantly higher than in ovulation period(P<0.05);(2)The body weight of ovarian group is significantly higher than that of sham operation Group(P<0.05);OGTT shows that the OGTT glucose levels in blood of C57 mice in ovarian groupis significantly higher than that of sham operation Group(P<0.05);(3)The changes of the ?Isc difference caused by glucose absorption in the ovarian group is significantly higher than that of the sham operation Group(P<0.05);(4)The results of immunofluorescence,RT-PCR and Western-blot show that the receptor CASR was expressed in the duodenal of Mice,it is mainly expressed in the serosal side.The expression of CaSR protein in small intestine epithelial tissue of mice in the ovarian group is significantly lower than that of sham operation Group(P<0.05);(5)By Ussing Chamber test found that the changes of the ?Isc difference caused by glucose absorption is significantly inhibited after the addition of EGTA,NPS,2-APBand U73122(P<0.05).Conclusion:Estrogen inhibits the glucose absorption in small intestine.When the secretion of estrogen decreases,it can promote the absorption of glucose by duodenum.And the mechanism may be achieved by affecting the expression of CASR on small intestinal epithelial cells and the mediated intracellular calcium signal.