Eltoprazine modulated gamma oscillations on ameliorating L‐dopa‐induced dyskinesia in rats

AIM: Parkinson's disease (PD) is a pervasive neurodegenerative disease, and levodopa (L‐dopa) is its preferred treatment. The pathophysiological mechanism of levodopa‐induced dyskinesia (LID), the most common complication of long‐term L‐dopa administration, remains obscure. Accumulated evidence suggests that the dopaminergic as well as non‐dopaminergic systems contribute to LID development. As a 5‐hydroxytryptamine 1A/1B receptor agonist, eltoprazine ameliorates dyskinesia, although little is known about its electrophysiological mechanism. The aim of this study was to investigate the cumulative effects of chronic L‐dopa administration and the potential mechanism of eltoprazine's amelioration of dyskinesia at the electrophysiological level in rats. METHODS: Neural electrophysiological analysis techniques were conducted on the acquired local field potential (LFP) data from primary motor cortex (M1) and dorsolateral striatum (DLS) during different pathological states to obtain the information of power spectrum density, theta‐gamma phase–amplitude coupling (PAC), and functional connectivity. Behavior tests and AIMs scoring were performed to verify PD model establishment and evaluate LID severity. RESULTS: We detected exaggerated gamma activities in the dyskinetic state, with different features and impacts in distinct regions. Gamma oscillations in M1 were narrowband manner, whereas that in DLS had a broadband appearance. Striatal exaggerated theta‐gamma PAC in the LID state contributed to broadband gamma oscillation, and aperiodic‐corrected cortical beta power correlated robustly with aperiodic‐corrected gamma power in M1. M1–DLS coherence and phase‐locking values (PLVs) in the gamma band were enhanced following L‐dopa administration. Eltoprazine intervention reduced gamma oscillations, theta–gamma PAC in the DLS, and coherence and PLVs in the gamma band to alleviate dyskinesia. CONCLUSION: Excessive cortical gamma oscillation is a compelling clinical indicator of dyskinesia. The detection of enhanced PAC and functional connectivity of gamma‐band oscillation can be used to guide and optimize deep brain stimulation parameters. Eltoprazine has potential clinical application for dyskinesia.