A Steroidal Glycoside from Polygonatum odoratum (Mill.) Druce. Improves Insulin Resistance but does not Alter Insulin Secretion in 90% Pancreatectomized Rats

Abstract

The aim of this study was to investigate the effects of three steroidal glycosides (SG-100, SG-280, and SG-460) obtained from Polygonatum odoratum (Mill.) Druce. on insulin secretion, insulin action, and relative glucose uptake in various tissues of 90% pancreatectomized male Sprague-Dawley rats. One of the compounds (30 mg/kg body weight daily) with a 40%-fat diet was orally administered to a group of such rats for 13 weeks. On the day after a hyperglycemic clamp, euglycemic hyperinsulinemic clamp with 1 μCi of [1-¹⁴C]2-deoxyglucose per 100 g body weight was used. Serum glucose levels were lowest in the rats receiving SG-100. Insulin secretion from pancreatic β-cells did not change with SG administration. Whole-body glucose disposal rates increased with SG-100 administration by 39%. SG-100 increased the glycogen contents and glycogen synthase activity in the soleus muscle of pancreatectomized rats. Uptake of [1-¹⁴C]2-deoxyglucose into the soleus muscle was higher in such rats receiving SG-100 than in rats receiving other compounds. In conclusion, SG-100 has an antihyperglycemic effect by promoting peripheral insulin sensitivity without changing insulin secretion.

Polygonatum odoratum (Mill.) Druce., hyperglycemic clamp, euglycemic hyperinsulinemic clamp, glucose uptake, glycogen synthase