Combined Intervention Of Swimming And Metformin Ameliorates The Insulin Resistance And Abnormal Glucose And Lipid Metabolism In Murine Gestational Diabetes Mellitus

Objective: Swimming,a type of aerobic exercise,can effectively prevent and manage hyperglycemia,but the effect of mild swimming alone on reducing blood glucose level is not obvious.Metformin,an oral antidiabetic drug,has obvious hypoglycemic effect,is also inexpensive,but the long-term beneficial effect of its high dose on pregnant women and fetus has not been confirmed.We propose that combined intervention of mild swimming and low dose of metformin,may effectively reduce the blood glucose level in GDM,but avoid the adverse effects of excessive use of metformin,thus improving the pregnancy outcomes.Methods: All mice were maintained under specific-pathogen-free(SPF)conditions and housed with 12 h light/dark cycle in controlled environment with temperature of(23±2)°C and relative humidity of(50±5)%.Food and water were available ad libitum before starting experiments.After a week of adaptation,female mice were placed together with males at a ratio of 2:1.Mating was confirmed by the presence of a vaginal mucous plug in next morning,defined as gestational day(GD)0.Specifically,the GDM mouse model was established by a single injection of streptozocin as 40mg/kg/per mouse on GD6,GD7,and GD8,respectively.The diabetic state was confirmed when the fasting blood glucose concentration exceeded 11.1 mmol/l(200 mg/dl)and the normal control mice received 0.9% saline.The successful models were randomly distributed into 4 groups(10 animals/group): GDM control(DC),GDM treated with swimming(DS),GDM treated with metformin(DM)and GDM treated with swimming plus metformin(DSM).At the same time,10 normal mice were randomly selected for Normal Control(NC)group.During the experiment,the animals were allowed free access to food and water at all times and without use of insulin and other hypoglycemic drugs.The mice in DS and DSM groups swum 20 min per day from GD11 to GD18 in a plastic tank.The mice in DM and DSM groups were intervened by oral gavage of enteric metformin-hydrochloride tablets as 200mg/kg per mouse from GD11 to GD18.Dams were euthanized on GD18 by intraperitoneal injection of sodium pentobarbital,from which liver tissues,skeletal muscle were immediately collected and other metabolic characteristics were recorded.In addition,biochemical methods were used to detect the blood lipid,liver lipid levels,ELISA was used to determine insulin level,RT-PCR was used to detect PEPCK and G6 Pase m RNA gene expression,Western blot was used to determine related protein expression in insulin signaling pathway.Results: Compared with those in NC group,fetuses in DC group obtained significant decreases in the body weight,crown-rump length,placental weight and placental diameter.The intervention of swimming or/and metformin can improve the growth restriction in varying degrees,these characteristic differences were mostly corrected by combined action of swimming plus metformin,in which there was no significant difference between the NC group and the DSM group after swimming combined with metformin.Serum glucose,TC,TG,LDL-C levels were increased significantly,while HDL-C,insulin levels were decreased significantly in the DC group compared with the NC group.Compared with the DC group,swimming or metformin intervention slightly or moderately improves hyperglycemia,insulin sensitivity and lipid metabolism,while combined therapy of swimming plus metformin markedly ameliorated hyperglycemia,and may reduce serum TG,TC,LDL-C and liver TC levels,decrease the level of insulin in serum.The detection of related proteins in the insulin signaling pathway showed that single metformin intervention and swimming plus metformin intervention may activate the activity of AKT to promote the insulin signal pathway,the superposition effect of combined intervention is significant.In addition,swimming or/and metformin may reduce the expression of PEPCK and G6 Pase protein,thereby inhibiting the synthesis of gluconeogenesis to decrease the glucose levels,the combined intervention by metformin plus swimming was more effective than any single action.The intervention of swimming or/and metformin may also regulate the expression of ACC and other proteins,inhibiting the synthesis of fat and improving the disturbed lipid metabolism caused by GDM,the superposition effect of swimming combined with metformin was the most obvious.Conclusion: Insulin resistance exerts a strong effect on the disorder of glucose and lipid metabolism related to the GDM.Exercise,drugs and exercise combined with drug interventions may improve the disorder of glucose and lipid metabolism in GDM mice to different degrees.The combined intervention by metformin plus swimming may be more effective than any single action to ameliorate glucose and lipid metabolism via improving insulin sensitivity in GDM mice.