Recent evidence supports two clinical subtypes of Parkinson’s disease (PD): a body first subtype and a brain first subtype, distinguished by the apparent site of disease onset and subsequent progression. Animal models that specifically reproduce the features of each subtype are needed to investigate underlying mechanisms and to evaluate novel therapeutics. The work summarized here reports an experimental rat model intended to recapitulate the body first PD subtype by initiating pathology via peripheral exposure to environmental agents.
The model uses combined oral administration of Paraquat (P) and Lectin (L). Rats received daily P+L (p.o.) for a 90-day exposure period. Behavioral testing was carried out at multiple intervals during and after exposure, and animals underwent post-mortem histopathological evaluation at 21 weeks. The abstract reports the exposure schedule and assessment timeline but does not specify exact dose amounts, numbers of animals per group, or full methodological details in the summary.
Motor symptoms emerged in a progressive pattern consistent with a peripheral onset that later involves the central nervous system. According to the report, motor deficits appeared unilaterally beginning at week 4 following initiation of P+L treatment and later progressed to bilateral motor impairment. Importantly, the motor phenotype was responsive to levodopa, indicating dopaminergic-system–related motor dysfunction in this model.
The model therefore reproduces a temporal pattern of asymmetric onset and gradual bilateral involvement, which mirrors clinical descriptions of progressive motor decline in PD and supports its relevance to the body first subtype.
Beyond motor deficits, the P+L–treated rats displayed non-motor PD–related phenotypes. The animals showed cognitive impairment in the Novel Object Recognition Test and the Y maze, indicating deficits in recognition memory and working spatial memory, respectively. The model also manifested sleep abnormalities, although the specific nature of the sleep changes (for example, sleep fragmentation, alterations in sleep architecture, or circadian shifts) is not detailed in the abstract.
These non-motor features strengthen the translational relevance of the model because non-motor symptoms are central to PD morbidity and are particularly prominent in body-first presentations.
Post-mortem histological analyses identified neurodegenerative and proteinopathy features consistent with PD. The authors report nigrostriatal dopaminergic degeneration, which aligns with the observed levodopa-responsive motor deficits. Additionally, they detected proteinase K–resistant phosphorylated S129 alpha-synucleinopathy in both the gut and the brain. The presence of proteinase K–resistant S129 alpha-synuclein in peripheral (gut) tissue and central nervous system tissue supports a peripheral-to-central propagation hypothesis consistent with a body first disease process.
The abstract does not provide quantified pathology measures, cell counts, regional specificity beyond the nigrostriatal axis, or images; these details presumably appear in the full preprint.
Taken together, the reported behavioral and pathological findings indicate that chronic oral P+L exposure in rats produces a progressive phenotype with motor asymmetry, levodopa responsiveness, cognitive deficits, sleep disturbances, and synucleinopathy in both gut and brain—features that collectively mirror the body first PD subtype. The authors propose that this model could be used to explore disease mechanisms and to screen neuroprotective or disease-modifying experimental therapies targeted to peripheral triggers and propagation pathways.
Limitations noted in the abstract summary include the preprint status of the report (not peer reviewed) and absence of key methodological details in the summary. Specifics such as exact dosing regimens, sample sizes, quantitative behavioral and histological outcomes, controls used, and statistical analyses were not reported in the abstract and should be consulted in the full manuscript for rigorous evaluation.
The study lists several funders in the source metadata, including awards from the National Institutes of Health (NIDDK and NINDS) and Department of Defense grants. The article is a preprint posted on bioRxiv on July 19, 2026, and has not been certified by peer review. Competing interests were declared as none by the authors.