PT320, a GLP-1 receptor agonist, mitigates nucleus accumbens–associated depression- and anxiety-like behaviors in MitoPark mice of Parkinson's disease

Abstract

Background Neuropsychiatric symptoms such as anxiety and depression substantially impair quality of life in Parkinson's disease (PD), yet the underlying neural circuits remain poorly defined. The MitoPark (MP) mouse, a dopaminergic mitochondrial dysfunction model, recapitulates both motor and non-motor features of PD. Objective To determine whether the sustained-release GLP-1 receptor agonist PT320 (exenatide) alleviates anxiety- and depression-like behaviors in MP mice and to identify the involved neural substrates. Methods The temporal progression of anxiety- and depression-like behaviors was characterized in MP mice. PT320 was administered biweekly starting at either 5 weeks (early treatment) or 15 weeks (late treatment), with longitudinal evaluation until 20 weeks. Behavioral outcomes were correlated with molecular, transcriptomic, and neurochemical analyses in the nucleus accumbens (NAc), including Western blotting, bulk RNA sequencing, fast-scan cyclic voltammetry, and tyrosine hydroxylase immunostaining. Results Early PT320 treatment effectively prevented the emergence of anxiety- and depression-like phenotypes in MP mice. Behavioral improvement was associated with restoration of BDNF signaling and activation of the Akt–CREB pathway in the NAc. Transcriptomic analysis revealed increased expression of Akt3, CREB, BDNF, and TrkB, along with modulation of genes related to mitochondrial homeostasis. Late PT320 treatment partially ameliorated neuropsychiatric deficits, coinciding with enhanced phasic dopamine release and recovery of tyrosine hydroxylase expression in the NAc. Conclusions These findings identify the NAc as a critical regulator of affective disturbances in this PD model. By restoring neurotrophic signaling and dopaminergic function, PT320 represents a promising therapeutic strategy for PD-related anxiety and depression.