Effects of GLP-1 and GIP in Animal and In Vitro Studies

Animal and in vitro studies have suggested additional physiologic effects of GLP-1 and GIP.

*Systemic infusion of GIP (10 pmol/kg, administered for 14 days via an Alzet®
micro-osmotic pump) decreased expression of a proapoptotic protein (Bax) and
increased expression of an antiapoptotic protein (Bcl-2) in pancreatic beta cells
of lean and diabetic obese rats. GIP infusion also decreased levels of islet-cell
apoptosis (measured by a DNA fragmentation assay).²¹

Alzet micro-osmotic pump is a registered trademark of DURECT Corporation.

The results from animal models and in vitro experiments suggest a possible role of GLP-1 and GIP in enhancing beta-cell replication and survival.^16,18,19 These incretin effects have not been investigated in humans.