Noopept Normalizes Parameters of the Incretin System in Rats with Experimental Diabetes

Experiments on adult Wistar rats with streptozotocin-induced diabetes showed that antihyperglycemic activity of an original nootropic and neuroprotective drug Noopept (N-phenylacetyl-L-prolylglycine ethyl ester) is more pronounced under conditions of oral application than after intraperitoneal injection. These data provided a basis for studying the effect of Noopept on major indexes of the incretin system. Streptozotocin was shown to decrease the concentrations of incretin GLP-1 and insulin in the blood. Noopept had a normalizing effect on these parameters. This influence of Noopept was not related to the inhibition of a major enzyme metabolizing incretins (dipeptidyl peptidase IV). A reference drug sitagliptin also increased the contents of incretins and insulin, which was associated with the inhibition of dipeptidyl peptidase IV. It is known that GLP-1 increases NGF expression in the insular system. Our results suggest that the increase in incretin activity contributes to the antiapoptotic effect of Noopept on pancreatic β cells. The mechanism for an increase in blood GLP-1 level after oral application of Noopept requires further investigations.