Unilateral 6-OHDA lesion
The unilaterally 6-OHDA lesioned rat, the most popular and best validated rodent model of Parkinson’s disease and LID (Cenci et al. , 2018; Duty et al. , 2011; Schwarting et al. , 1996) was used. One-hundred three (103) naïve rats (150 g) were unilaterally injected under isoflurane anesthesia in the (right) medial forebrain bundle with 12 µg of 6-OHDA hydrobromide (dissolved in 0.02% ascorbate-saline), according to the following stereotaxic coordinates from bregma and the dural surface (in mm): antero-posterior (AP) -4.4, medio-lateral (ML) 1.2, dorso-ventral (DV) -7.8, tooth bar at -2.4 mm (Paxinos et al. , 1986), as previously described (Arcuri et al. , 2018; Marti et al. , 2012; Pisanò et al. , 2020). Animals were pretreated with antibiotics (SynuloxTM, 50 µl/Kg, i.p.), and the wound was sutured and infiltrated with 2% lidocaine solution (EsteveTM). Two weeks later, rats were screened by assessing the motor asymmetry score in two different ethological tests (the bar and drag tests) (Marti et al. , 2005). Rats showing immobility time >20 sec at the contralateral paw in the bar test, and <3 steps at the contralateral paw (or alternatively a contralateral/ipsilateral paw ratio <50%) were used in the study (Brugnoli et al. , 2020; Pisanò et al. , 2020).