This technology includes transgenic mice in which designer rat M3 muscarinic receptor mutants were expressed only in islet 13-cells (directed by rat insulin promoter II), were unable to bind acetylcholine (the endogenous ligand) but could be selectively activated by an otherwise pharmacologically inert compound (clozapine-N-oxide (CNO)). The R-q receptor contained a Y148C point mutation, which enabled CNO to selectively activate G proteins of the Gq/11 family. The R-5 receptor contained an A238G mutation, which enabled CNO to selectively activate G proteins of the G5 family.
CNO-treatment that selectively activated 13-cell Gq111 increased first and second phase insulin release, greatly improved glucose tolerance in high-fat diet obese insulin-resistant mice, and increased 13-cell mass.
Novel mouse model.