| Objective: Estrogen and progesterone are closely related to the occurrence of diabetes.Their role in the development of diabetes is related to the physical state of the body and the levels of estrogen and progesterone in the blood.It is not entirely clear how the estrogenic and progestogenic effects are combined.Therefore,the present study was to establish a model of type 1 diabetes mellitus in mice by intraperitoneal injection of streptozotocin(STZ)to investigate the interaction and relationship between estrogen and progesterone in the development of diabetes mellitus,and to provide a theoretical basis for the diagnosis and treatment of diabetes and the role of sex hormones in glucose and lipid metabolism.Methods: Female Kunming mice were purchased and their ovaries were removed and recovered for one week.They were randomly divided into 11 groups:(1)ovariectomy group(OVX),(2)ovariectomy + intraperitoneal injection of STZ(OVX+STZ),(3)ovariectomy + intraperitoneal injection of STZ + subcutaneous injection of 17-? estradiol at the dose of 0.01 mg/kg body weight(E0.01),(4)ovariectomy + intraperitoneal injection of STZ + subcutaneous injection of 17-?estradiol at the dose of 0.1 mg/kg body weight(E0.1),(5)variectomy + intraperitoneal injection of STZ plus subcutaneous injection of 17-? estradiol at the dose of 1 mg/kg body weight(E1),(6)ovariectomy + intraperitoneal injection of STZ + subcutaneous injection of progesterone at the dose of 0.1 mg/kg body weight(P0.1),(7)ovariectomy+ intraperitoneal injection of STZ + subcutaneous injection of progesterone at the dose of 2 mg/kg body weight(P2),(8)Ovariectomy + intraperitoneal injection of STZ+ subcutaneous injection of progesterone at the dose of 8 mg/kg body weight(P8),(9)ovariectomy + intraperitoneal injection of STZ + subcutaneous injection of 17-?estradiol at the dose of 0.1 mg/kg body weight and progesterone at the dose of 0.1mg/kg body weight(EP0.1),(10)Ovariectomy + intraperitoneal injection of STZ +subcutaneous injection of 17-? estradiol at the dose of 0.1 mg/kg body weight andprogesterone at the dose of 2 mg/kg body weight(EP2),(11)Ovariectomy +intraperitoneal injection of STZ + subcutaneous injection of 17-? estradiol at the dose of 0.1 mg/kg body weight and progesterone at the dose of 8 mg/kg body weight(EP8).STZ was continuously administered intraperitoneally at the dose of 50 mg/kg body weight per day for 5 days,while progesterone,17-? estradiol,or a combination of17-? estradiol and progesterone was injected subcutaneously on alternate days.Blood glucose and body weight were measured once a week.Five weeks after administration of sex hormone,glucose tolerance and insulin resistance tests were performed.At the same time,the blood was taken from the eyeball of some mice and then the other mice were dissociated and killed,and their tissues were frozen and fixed respectively.HE staining was used to observe the islet cells;Chemiluminescence and Elisa techonology were used to detect the serum levels of 17?-estradiol,progesterone,C peptide and insulin;RT-PCR and immunofluorescence techniques were used to detect the expression levels of skeletal muscle glucose transporter 4(GLUT4),liver glucose transporter 2(GLUT2),glucokinase(Gck),Glucose-6-phosphatase(G-6-P),phosphoenolpyruvate carboxylase(PCK)and insulin receptor(IR).Results: The blood glucose was significantly increased,the body weight increased slowly and there appeared obvious glucosuria in STZ-induced type 1diabetic mice;Glucose tolerance was significantly impaired,the number of islet cells was decreased,the blood concentrations of C-peptide and insulin were also significantly reduced;skeletal muscle GLUT4 and liver Gck expressions were decreased and the expressions of GLUT2,G-6-P and PCK in liver were significantly up-regulated,but there were no obvious change in insulin resistance and insulin receptor expression between the groups of OVX+STZ and OVX.Medium-dose(0.1mg/kg body weight)and high-dose(1mg/kg body weight)17?-estradiol could significantly delay the development of type 1 diabetes mellitus in mice caused by STZ.Meanwhile,the value of blood glucose was markedly declined;low dose(0.01mg/kg body weight)17?-estradiol showed no significant effect on blood glucose.Medium-dose(0.1mg/kg body weight)17?-estradiol also improved glucose tolerance,protected islet cells,promoted C-peptide and insulin secretion,increased skeletal muscle GLUT4 and liver Gck expressions,significantly down-regulated the liver GLUT2,PCK,and G-6-P mRNA expressions.Administration of moderate dose(2mg/kg body weight)of progesterone alone could effectively decrease the glucose level in STZ-induced diabetes mice,protectedislet cells,increased the level of C-Peptide and insulin;progesterone could also up-regulate the mRNA expressions of GLUT4 in skeletal muscle and Gck in liver,down-regulate the expressions of GLUT2,PCK,and G-6-P mRNA in the liver.The different administration doses showed the different effects on STZ-induced diabetes mice.There was no dose dependent effect and also had no apparent improvement in glucose tolerance.The combination of low dose(0.1mg/kg body weight)or moderate dose(2mg/kg body weight)of progesterone with 0.1 mg/kg 17?-estradiol delayed the development of type 1 diabetes in mice induced by STZ,protected islet cells,promoted C-peptide and insulin secretion,decreased the level of blood glucose,and showed a certain synnergistic effects;but for the expressions of skeletal muscle GLUT4 as well as the liver GLUT2,Gck,PCK and G-6-P mRNA,when the low dose(0.1mg/kg body weight)or high dose(8mg/kg body weight)progesterone respectively combined with0.1 mg/kg body weight 17?-estradiol there were apparent the antagonistic effects.However,the combination of medium dose(2 mg/kg body weight)progesterone and0.1 mg/kg body weight17?-estradiol showed a synergistic effect.Conclusion:1.Estradiol and progesterone alone can delay the occurrence of type 1 diabetes in mice caused by STZ,but there is no the dose-response relationship;the middle dose of estradiol(0.1mg/kg body weight)and progesterone(2mg/kg body weight)injected subcutaneously can make the plasma concentration of estradiol and progesterone reach the physiological dose range,which shows significant inhibitory effect in the increase of mice blood glucose induced by STZ.2.The mechanisms of estradiol and progesterone in delaying diabetes mellitus are various,which probably relate to the protection of islet cells,the promotion of insulin release and the changes of skeletal muscle glucose transport and liver glucose metabolism.3.The physiological dose of progesterone combined with estradiol has a certain synergistic effect on the delaying effect of diabetes and the changes of glucose transport and glucose metabolism caused by estradiol in STZ-induced diabetes,and can enhance the preventive effect of estradiol on diabetes. |
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