ABSTRACT
Aim To study the anti-diabetic effects of natural product gastrodin ( GSTD ) in KK-Ay mice. Methods C57BL/6J mice were used as normal con-trol, while KK-Ay diabetic mice were divided into five groups, namely the untreated group, GSTD 10 mg· kg-1, 20 mg·kg-1, 50 mg·kg-1 groups, and the metformin ( Met) 200 mg·kg-1 group, respectively, with 10 mice in each group. GSTD and Met were ad-ministered intragastrically for eight weeks. Before ex-periment and once a week during the experiment, the fasting blood glucose ( FBG) levels were determined. During the 7th week of drug treatment, oral glucose tolerance test ( OGTT ) and insulin tolerance test ( ITT) were conducted. Before the end of experiment, 24 h urine samples were collected for the assay of rela-tive parameters. At the end of experiment, blood sam-ples were collected for the assay of glycosylated hemo-globin ( GHb) ; serums were isolated for the determina-tion of insulin concentration and other biochemical in-dexes. After sacrifice, the livers, kidneys, and pan-creases of the mice were harvested for pathological ex-amination; the contents of advanced glycation end product ( AGE) and triglyceride ( TG) in renal tissues were assayed by kits. Results GSTD at all doses sig-nificantly reduced FBG, urine glucose, GHb, serum insulin level, and the insulin resistance index in KK-Ay diabetic mice. In addition, GSTD greatly inhibited body weight gain and improved glucose tolerance and insulin tolerance ( P <0.05 or P <0.01 vs untreated group ) . The pathological examination showed that GSTD significantly increased the glycogen content of liver tissues, reduced islet volume and improved its pathological changes. In addition, the glomerulosclero-sis induced by diabetes was greatly ameliorated by GSTD. Meanwhile, GSTD greatly reduced serum crea-tine ( Scr) , 24 h urine amount, 24 h urine total pro-tein and microalbumin ( mAlb) , as well as renal AGE and TG contents in KK-Ay mice ( P <0.05 or P <0.01 vs untreated group) . The anti-diabetic effect of GSTD at 50 mg·kg-1 was comparable to that of 200 mg·kg-1 of Met. Conclusions When used to treat KK-Ay diabetic mice, GSTD has potent activities in lowering blood glucose, improving insulin resistance and ameliorating diabetic nephropathy. However, the detailed mechanisms of GSTD in modulating glucose metabolism and increasing insulin sensitivity still need further investigation.
ABSTRACT
Aim To explore the protective effect of lo-ganin ( an active component in Cornus officinalis ) on podocyte injury induced by advanced glycation end products ( AGEs) and its possible mechanism. Meth-ods Mouse podocytes were cultured in vitro and di-vided into Normal group, model group ( AGEs group) , loganin group and aminoguanidine group ( set as posi-tive control) . After being incubated with loganin( final concentrations are 0. 1, 1, 10 μmol · L-1 ) for 1 h, podocytes were stimulated by AGEs of 100 mg · L-1 for 24 h. Then, the cell viability was measured by u-sing MTT method. Podocytes apoptosis was evaluated by Hoechst33342/PI staining and flow cytometry. Re-ceptors of advanced glycation end products ( RAGE ) ,desmin and apoptosis-related protein like Bax, Bcl-2, cleaved caspase-3 in podocytes were detected by Western blot. Results Loganin ameliorated podocyte injury induced by AGEs, down-regulated the expression of desmin and RAGE. Loganin also reduced the apoptotic rate of podocytes and decreased the ratio of Bax/ Bcl-2 and the expression of pro-apoptotic protein cleaved caspase-3 in podocytes. Conclusion Loganin could ameliorate podocyte injury, and its mechanism may be related to the decrease of the expression of RAGE and inhibition of the apoptotic pathway.