Novel, non-peptidic somatostatin receptor subtype 5 antagonists improve glucose tolerance in rodents

Abstract Background Somatostatin regulates numerous endocrine processes, including glucose homeostasis. The contribution and effects of the 5 somatostatin receptors are still unclear, in part due to the lack of suitable subtype specific receptor antagonists. We explored the effects of two novel, non-peptidic, orally bioavailable somatostatin receptor subtype 5 antagonists named Compound A and Compound B on glycemia in animal models of type 2 diabetes after an initial in vitro characterization. Methods and results Compound A led to a dose-dependent decrease in glucose and insulin excursions during an OGTT in Zucker (fa/fa) rats after single treatment by up to 17% and 49%, respectively. Diet-induced obese mice showed after three weeks treatment with compounds A and B a dose-dependent decrease of the glucose excursion of up to 45% and 37%, respectively. In contrast to the acute effect observed in Zucker rats, Compound A showed a dose-dependent insulin increase by up to 72%, whereas body weight, liver triglycerides, ALT and AST were dose-dependently decreased. Conclusions SSTR5 antagonists have the potential for short- and long-term improvements of the glucose homeostasis in rodent models of type 2 diabetes. Further work on the mechanism and the relevance for human disease is warranted.