SILIBININ, A PLANT-EXTRACT WITH ANTIOXIDANT AND MEMBRANE STABILIZING PROPERTIES, PROTECTS EXOCRINE PANCREAS FROM CYCLOSPORINE-A TOXICITY

Silymarin can be extracted from the milk thistle, and silibinin is the main component of the plant extract. Possibly due to their antioxidan t and membrane-stabilizing properties, the compounds have been shown t o protect different organs and cells against a number of insults. Thus liver, kidney, erythrocytes and platelets have been protected from th e toxic effects of ethanol, carbon tetrachloride, cold ischemia and dr ugs, respectively. The effect of silibinin on endocrine and exocrine p ancreas, however, has not been studied. We therefore investigated whet her silibinin treatment attenuates cyclosporin A (CiA) toxicity on rat endocrine and exocrine pancreas. Groups of 15 male Wistar rats were t reated for 8 days with CiA and/or silibinin. On day 9, endocrine and e xocrine pancreatic functions were tested in vitro. At the end of the t reatment period, blood glucose levels in vivo were significantly highe r in rats treated with CiA, while silibinin did not affect glucose lev els. In vitro, insulin secretion was inhibited after treatment with si libinin, but amylase secretion was not affected. After treatment with CiA both insulin and amylase secretion were reduced. Silibinin and CIA had an additive inhibitory effect on insulin secretion, but silibinin attenuated CiA-induced inhibition of amylase secretion. Despite CiA t reatment, amylase secretion was in fact restored to normal with the hi ghest dose of silibinin. Thus silibinin inhibits glucose-stimulated in sulin release in vitro, while not affecting blood glucose concentratio n in vivo. This combination of effects could be useful in the treatmen t of non-insulin-dependent diabetes mellitus. Furthermore, silibinin p rotects the exocrine pancreas from CiA toxicity. As this inhibitory ef fect is probably unspecific, silibinin may also protect the exocrine p ancreas against other insult principles, such as alcohol.