RESUMEN
Objective To investigate the effects of metformin on insulin sensitivity and secretion in patients with obesity and insulin resistance. Methods This study enrolled 42 obesity patients with insulin resistance who were regularly followed-up in Peking Union Medical College Hospital from September 2012 to May 2016. They were divided into two groups according to their different status of glucose metabolism: normal glucose tolerance( NGT) and impaired glucose regulation( IGR) . Life style intervention and metformin were given to all these patients. The antropometric and metabolic data were collected before treatment, 3 and 6 months after treatment respectively. Results 42 patients, aged (23.6±6.5) years, including 11 males and 31 females were enrolled. 19 of them were NGT and 23 were IGR (8 of IGT and 15 of IFG) . Among all these patients, fasting insulin was significantly higher at 3 months after treatment(P＜0.05).The same results were shown in group-NGT(P＜0.05). Fasting insulin was significantly lower at 6 months after treatment than at baseline among all patients( P＜0.05) . HOMA-IR showed no significant difference between the baseline and 3 months after treatment, but significantly higher at baseline and 3 months after treatment than 6 months after therapy( P＜0.001) . HOMA-beta was significantly( P＜0.001) lower be-fore treatment and 6 months treatment the effect was more significant than 3 months after treatment among all pa-tients. HOMA-beta was significantly lower at baseline in group-IGR than at baseline in group-NGT ( P＜0.05) . Conclusions The effect of metformin on insulin secretion is earlier than that of improving the insulin sensitivity in patients with obesity and insulin resistance. Metformin is more likely to promote insulin secretion in patients with normal glucose tolerance than those with IGR within 3 months of intervention.
RESUMEN
<p><b>OBJECTIVE</b>To explore the effects of ghrelin on learning and memory abilities and expressions of DKK-1 and β-catenin in the hippocampus of diabetic rats.</p><p><b>METHODS</b>Sixty male SD rats were randomly assigned into 4 groups, namely the control group, diabetic group, ghrelin-treated diabetic group (DM1 group), and ghrelin- and D-lys3-GHRP-6 (a GHSR-1a receptor antagonist)-treated diabetic group (DM2 group). Diabetic rat models were established by a single intraperitoneal injection of streptozotocin (65 mg/kg). The learning and memory abilities of the rats were assessed with Morris water maze (MWM) test. The ultrastructure of the hippocampal CA1 area of the rats were observed with electron microscopy. Serum levels of DKK-1 were examined by ELISA, and the expressions of DKK-1 and β-catenin in the hippocampus were examined by quantitative real-time PCR and Western blotting.</p><p><b>RESULTS</b>Compared with the control group, the diabetic rats exhibited significantly impaired learning and memory abilities (P<0.05), increased expression of DKK-1 and lowered β-catenin expression in the hippocampus (P<0.05), significant ultrastructural injuries and disordered arrangement of neurons with the nuclear pycnosis in the hippocampal CA1 area. Ghrelin treatment of the diabetic rats obviously improved their learning and memory abilities (P<0.05), reduced DKK-1 and increased β-catenin expressions (P<0.05), ameliorated ultrastructural damages in the hippocampal CA1 area and restored normal neuronal alignment with clear cell layers. Such effects of ghrelin were antagonized by treatment with D-lys3-GHRP-6 in the diabetic rats.</p><p><b>CONCLUSION</b>Ghrelin can alleviate learning and memory dysfunction in diabetic rats possibly by down-regulating the expressions of DKK-1 and activating the WNT signaling pathways.</p>