Frouni I, Kwan C, Bédard D, Kang W, Hamadjida A, Nuara SG, Gourdon JC, Huot P. Effect of the mGlu
4 positive allosteric modulator ADX-88178 on parkinsonism, psychosis-like behaviours and dyskinesia in the MPTP-lesioned marmoset.
Psychopharmacology (Berl) 2023;
240:2093-2099. [PMID:
37516708 DOI:
10.1007/s00213-023-06428-1]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/17/2023] [Indexed: 07/31/2023]
Abstract
RATIONALE
Positive allosteric modulation of metabotropic glutamate type 4 (mGlu4) receptors is a promising strategy to alleviate parkinsonian disability and L-3,4-dihydroxyphenylalanine (L-DOPA) induced dyskinesia. ADX-88178 is a highly selective mGlu4 positive allosteric modulator (PAM) that previously enhanced the anti-parkinsonian action of L-DOPA in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease (PD).
OBJECTIVES
We sought to explore the effects of ADX-88178 on psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. We also aimed to determine the effect of ADX-88178 on parkinsonism and dyskinesia.
METHODS
Six MPTP-lesioned marmosets were administered L-DOPA chronically to induce stable PLBs and dyskinesias. They were then administered ADX-88178 (0.01, 0.1 and 1 mg/kg) or vehicle, in combination with L-DOPA/benserazide (15/3.75 mg/kg), both sub-cutaneously, in a randomised fashion. PLBs, parkinsonism and dyskinesia were then measured.
RESULTS
ADX-88178 mildly worsened global PLBs at the dose of 1 mg/kg (by 13%, P = 0.020). L-DOPA alone conferred 158 min of on-time, while the duration of on-time was 212 min (34% increase, P = 0.011), after adding ADX-88178 1 mg/kg to L-DOPA. Accordingly, ADX-88178 1 mg/kg reduced global parkinsonian disability, by 38% (P = 0.0096). ADX-88178 1 mg/kg diminished peak dose dyskinesia by 34% (P = 0.015). Minimal effects were provided by lower doses.
CONCLUSIONS
Whereas these results provide additional evidence of the anti-parkinsonian and anti-dyskinetic effects of mGlu4 positive allosteric modulation as an adjunct to L-DOPA, they also suggest that ADX-88178 may exacerbate dopaminergic psychosis. Further studies are needed to evaluate this possible adverse effect of mGlu4 PAMs on PD psychosis.
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