This study establishes a refined chronic low-dose MPTP/probenecid regimen in mature adult mice that yields progressive motor and cognitive impairments, sustained loss of tyrosine hydroxylase-positive neurons, and phosphorylated α-synuclein aggregation while preserving high survival for longitudinal…

Delivers a survivable, progressive PD model that better mirrors chronic neurodegeneration and α-synuclein pathology, making it a useful platform for longitudinal therapeutic testing and mechanistic studies (e.g., mitochondrial and synuclein-targeted interventions).

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive degeneration of dopaminergic neurons, leading to decreased dopamine levels and motor deficits. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is frequently used to induce dopaminergic neuron death in mouse models to mimic PD pathology. However, many acute/subacute protocols cause relatively rapid, sometimes partially reversible nigrostriatal injury, rather than slow, progressive neurodegeneration observed in idiopathic PD. While chronic MPTP regimens can better mimic disease progression, the high systemic toxicity of MPTP raises concerns about survival, particularly in mature or aged mice. In this study, we developed a refined chronic low-dose MPTP/probenecid regimen in mature adult C57BL/6 J mice comprising ten injections over five weeks. An initial challenge dose (25 mg/kg) excluded hypersensitive animals (four mice), allowing a subsequent reduced-dose maintenance regimen (20 mg/kg) to achieve 100% survival. Longitudinal assessment revealed a gradual phenotypic decline in treated animals. At two months post-treatment, MPTP/p mice exhibited fragmented locomotor activity, increased grooming, and impaired short-term spatial memory, which progressed to reduced motor endurance and postural instability by four months. Neuropathological evaluation confirmed significant loss of tyrosine hydroxylase-positive neurons and phosphorylated α-synuclein aggregation in the substantia nigra. Collectively, this optimized chronic MPTP/p protocol recapitulates the gradual emergence of motor, cognitive, and neuropathological hallmarks of PD, while maintaining animal survival rate necessary for longitudinal investigation. This model therefore offers a robust platform for therapeutic testing and is particularly well-suited for integration with gene knockout models to elucidate molecular mechanisms underlying PD.