Assessing Dopaminergic Activity in Mice

For assessment of baseline activity (ref. ^{16 (link)}), animals were placed in a square apparatus (27.31 cm Length × 27.31 cm width × 20.32 cm height) consisting of 48 infrared beams (Med Associates) for 30 min. For behavioral assessment with stimulation of DA release, mice were injected intraperitoneally (IP) with 5 mg/kg of d-amphetamine and allowed to freely explore the open field box for a total of 60 min. This approach was used to reveal subtle differences in DAergic neurons, as used previously in PINK1 and Parkin knockout models^{53 (link)–55 (link)}. Data were collected with Open Field Activity Software (Med Associates) in 1 min intervals over the test period. For experiments to rescue baseline hypoactivity in the 14 month post-AAV:ThCre;Esrrg^flfl-injected mice, l-3,4-dihydroxyphenylalanine (L-DOPA; Millipore Sigma D1507) was injected IP at a 6 mg/kg concentration with Benserazide (12 mg/kg; Millipore Sigma B7283), and mice were allowed to explore the open field box for 60 min.