Subcutaneous RFID Microchip Implantation in Mice

Radio frequency identification microchips were injected subcutaneously into the lower left or right quadrant of the abdomen of each mouse at 12 weeks of age for the C57BL/6J study and 7 weeks of age for the B6-TgN(HD82Gln)81Dbo/H study. These microchips were contained in standard ISO-biocompatible glass capsules (11.5 × 2 mm; PeddyMark Ltd., UK). The procedure was performed on sedated mice (Isoflo; Abbott, UK) after topical application of local anesthetic cream on the injection site prior to the procedure (EMLA Cream 5%; AstraZeneca, UK) as described in Hobson et al. (2020 (link)). The animals were allowed to recover from the microchip procedure for at least 1 week before being placed in the HCA rigs for data collection. The procedure for data collection has been described previously in Bains et al. (2016 (link)) and Hobson et al. (2020 (link)), briefly, microchipped animals were placed in the HCA rigs for 72 h of continuous recording for every age group. At the end of the 72-h recording period for that age, the animals in their IVCs were returned to the standard IVC rack, until the animals reached the next age group to be recorded, where the procedure was repeated for another 72 h.