Riluzole Attenuates L-DOPA-Induced Abnormal Involuntary Movements Through Decreasing CREB1 Activity: Insights from a Rat Model

Abstract

Chronic administration of L-DOPA, the first-line treatment of dystonic symptoms in childhood or in Parkinson's disease, often leads to the development of abnormal involuntary movements (AIMs), which represent an important clinical problem. Although it is known that Riluzole attenuates L-DOPA-induced AIMs, the molecular mechanisms underlying this effect are not understood. Therefore, we studied the behavior and performed RNA sequencing of the striatum in three groups of rats that all received a unilateral lesion with 6-hydroxydopamine in their medial forebrain bundle, followed by the administration of saline, L-DOPA, or L-DOPA combined with Riluzole. First, we provide evidence that Riluzole attenuates AIMs in this rat model. Subsequently, analysis of the transcriptomics data revealed that Riluzole is predicted to reduce the activity of CREB1, a transcription factor that regulates the expression of multiple proteins that interact in a molecular landscape involved in apoptosis. Although this mechanism underlying the beneficial effect of Riluzole on AIMs needs to be confirmed, it provides clues towards novel or existing compounds for the treatment of AIMs that modulate the activity of CREB1 and, hence, its downstream targets.

Keywords: 6-OHDA-lesioned rats; AIMs; CREB1; Dyskinesia; Riluzole.

Fig. 1

Schematic diagram of the protocol employed including the time course of the experiment and the different assays that were used

Fig. 2

Induction of AIMs by L-DOPA in 6-OHDA-lesioned rats and their mitigation by Riluzole. Data shown as mean ± S.E.M. AIMs scores. Significant differences between the saline and L-DOPA-treated groups are indicated as **p < 0.01 and ****p < 0.001 and between the L-DOPA and L-DOPA + Riluzole-treated groups as ^####p < 0.001

Fig. 3

The molecular landscape is located in a neuron and shows the functional interactions between proteins encoded by 43 of the 58 CREB1 target genes regulated in the opposite direction by L-DOPA and after Riluzole co-administration in our AIMs model

Fig. 4

Putative mechanisms of how Riluzole could counteract CREB1-mediated gene expression by decreasing the activity of CREB1. Firstly, through a number of mechanisms, Riluzole reduces glutamatergic neurotransmission, which includes less glutamate binding to post-synaptic NMDA glutamate receptors. As a result, NMDA-mediated ERK1/2 signaling and the subsequent activation of CREB1 are also reduced. Secondly, Riluzole could inhibit PKC, a kinase that positively regulates NMDA receptors and activates CREB1 (directly or through activating ERK1/2), leading to a reduced CREB1 activity. The key players in this mechanism—L-DOPA, NMDA glutamate receptors, the kinases ERK1/2 and PKC, and CREB1 itself—are shown