2.1. Abnormal Involuntary Movements (AIMs) Rat Model

In this study, we used samples from an Abnormal Involuntary Movements (AIMs) animal model described in our previous paper [16]. As shown in Figure 1, juvenile male Wistar rats underwent a unilateral stereotaxic surgery with the injection of 6-Hydroxydopamin (6-OHDA) into the left medial forebrain bundle at post-natal day (PND) 21. Two weeks after surgery (PND 35), the animals were randomly divided into 3 groups and received a chronic treatment (6 times in 2 weeks, intra-peritoneally (i.p.)). The first group was administered with saline (UNT); the second group (L-DOPA) was chronically administered with a solution of L-DOPA methyl ester hydrochloride and benserazide (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) in saline (6/15 mg/kg, i.p.), while the third group (L-DOPA + R) was administered L-DOPA/benserazide (6/15 mg/kg, i.p.) and Riluzole (Sigma-Aldrich Chemie GmbH, Germany) dissolved in 1% Tween (6 mg/kg, i.p.). At the end of the chronic treatment at PND 53, the animals were sacrificed two hours after the administration of a final pharmacological treatment. The brain was removed and contralateral (control) and ipsilateral (lesioned) striata were extracted, snapped frozen in liquid nitrogen, and stored at −80 °C.

Schematic representation of the experimental workflow. Rats received a unilateral injection of 6-OHDA at PND 21 followed by a 2-weeks sub-chronic treatment (from PND 35 to PND 49) according to their respective group (L-DOPA, UNT, L-DOPA + Riluzole). The rats received one final treatment at PND 53; striata were collected and analyzed for changes in methylation levels.