Thus, this provided an elegant way of quantifying receptor numbers and was used to demonstrate that the density of metabotropic γ-aminobutyric acid type-B receptors (GABABR) are reduced in the dentate gyrus of an AD model mouse expressing mutated human amyloid precursor protein and presenilin1 (APP/PS1) [73,74,75]. The gene discussed is APP; the disease is Alzheimer disease.