Fig. 3.

Rapamycin reduced glucose-stimulated insulin secretion in vivo and ex vivo. a Plasma insulin level was assessed before (0 min) and 30 min (30 min) after intraperitoneal glucose injection (1.5 g glucose/kg). Rapamycin blunted glucose-induced insulin secretion (30 min) in vivo (p < 0.05, paired t test). Each group had six to ten animals. b Analyses of the same plasma samples revealed that rapamycin also blunted glucose-induced C-peptide secretion (30 min) in vivo (p < 0.05, paired t test). c Rapamycin treatment did not alter the plasma insulin/C-peptide ratio with or without glucose stimulation. d Rapamycin treatment increased HOMA-IR index (p < 0.05, Mann–Whitney U test). e Pancreatic islets isolated from rapamycin-treated mice showed a decreased insulin secretion upon glucose stimulation. Insulin level was normalized to total protein extract from the isolated islets (p < 0.05, paired t test). f Three weeks of rapamycin treatment reduced total insulin content in islets (p < 0.05, unpaired t test). For experiments using isolated islets (d–f), each data point was for five to seven sets of ten islets pooled from five mice