*4.3. Animals*

Female transgenic mice, which express mutated human amyloid precursor protein (APP) and presenilin 1 (PS1) under control of the Thy1-promoter (APPKM670/671NL, PSL166P) (referred to as APP/PS1-21 mice) [32,33] and age-matched wild-type littermates in a C57BL/6J genetic background were maintained at the University of Oslo and transferred to the imaging site at least three weeks prior to the PET examinations. In total, 50 mice were used in the experiments. All animals were housed in groups of 3–5 animals in individually ventilated (IVC) type III cages under controlled environmental conditions (22 ± 3 ◦C, 40% to 70% humidity, 12-h light/dark cycle) and had free access to standard laboratory animal diet (ssniff R/M-H, ssniff Spezialdiäten GmbH, Soest, Germany) and water ad libitum. The study was reviewed by the responsible national authorities (Amt der Niederösterreichischen Landesregierung) and approved under study numbers LF1-TVG-48/003-2014 approval date: 08 January 2015 and LF1-TVG-48/044-2019 approval date: 07 May 2019. All study procedures were in accordance with the European Community's Council Directive of September 22, 2010 (2010/63/EU). The animal experimental data reported in this study are in compliance with the ARRIVE (Animal Research: Reporting In Vivo Experiments) guidelines.
