Striatal molecular signature of subchronic subthalamic nucleus high frequency stimulation in parkinsonian rat

This study addresses the molecular mechanisms underlying the action of subthalamic nucleus high frequency stimulation (STN-HFS) in the treatment of Parkinson’s disease and its interaction with levoDOPA (L-DOPA), focusing on the striatum. The objectives were 1) to identify the molecular signature of STN-HFS action at striatal level, associated with its efficient antiparkinsonian action, and 2) to investigate the molecular substrates of the interaction between the two treatments in order to evidence possible genes involved in dyskinesia. Striatal gene expression profile was assessed in rats with nigral DOPAmine neuron lesion, either treated or not, using agilent microarrays and qPCR verification. The treatments consisted in anti-akinetic STN-HFS (5 days), chronic L-DOPA treatment inducing dyskinesia (LIDs) or the combination of the two treatments that exacerbated LIDs. STN-HFS modulated 71 genes with functional or biochemical annotation, including genes sharing the GO terms regulation of growth, regulation of apoptosis, extracellular region. Ttr, Igf2, Sostdc1 and Nr4A3 (Nor-1), are among the 5 genes showing the highest specific upregulation. Down-regulated genes include Prkcd, Sirt5 and Bbc3. These results show that genes involved in neuroprotection and/or neurogenesis are key components of STN-HFS action in the striatum. STN-HFS and LDOPA treatment share very few common gene regulation features suggesting that the molecular substrates underlying their striatal action are mostly different. In addition to genes already reported to be associated with LIDs (Pdyn, Trh, Grm4/mGlu4, Cnr1/CB1), the comparison between DOPA and DOPA/STN-HFS identifies immunity-related genes: C1s, Rt1-Da and Irf7a, as potential players in L-DOPA side effects. Total RNA was extracted from striatal tissue from four groups of 3 animals bearing 6-hydroxyDOPAmine (6-OHDA)-induced lesion of the nigrostriatal DA pathway: lesion alone without any subsequent treatment (L), L-DOPA treatment for 19 days (D), STN-HFS for 5 days (S) and combination of L-DOPA and STN-HFS (DS).