Spatial multi-omics reveals OAT-associated arginine-proline metabolic remodeling in Paraquat-induced Parkinsonian and depression-like phenotypes.

Paraquat (PQ) is a highly toxic bipyridyl herbicide that remains in agricultural use in some regions despite bans or severe restrictions elsewhere and is also widely used as a model toxicant for investigating environmentally induced neurodegeneration. However, the spatial metabolic alterations associated with PQ-induced neurobehavioral impairment remain incompletely understood. In this study, we performed AFADESI-MSI-based spatial metabolomic profiling and Visium spatial transcriptomic profiling on PQ-exposed mouse brains, and integrated these analyses with targeted metabolite assays, molecular validation and pharmacological intervention. PQ exposure induced motor coordination deficits, anhedonia-like behavior, increased behavioral despair and systemic metabolic disruption, including altered glucose, lipid and lactate metabolism. Spatial metabolomics showed that PQ did not cause a uniform whole-brain metabolic shift, but instead induced redistribution of multiple metabolic components across anatomically distinct brain regions. Region-resolved metabolomic analysis of the amygdala, cortex, hippocampus, thalamus and hypothalamus identified recurrent differential metabolites and PQ-associated co-abundance modules prominently enriched in arginine and proline metabolism. Within this pathway, L-arginine, citrulline, L-proline and glutamate were increased across multiple regions, whereas L-ornithine remained largely unchanged. ST profiling suggested increased Oat expression signals, while immunofluorescence and enzyme activity assays further confirmed increased ornithine aminotransferase (OAT) protein expression and activity. Virtual Oat perturbation implicated neurotransmission, synaptic plasticity and neurodegeneration-related pathways, while pharmacological OAT inhibition with 5-fluoromethylornithine reduced PQ-enhanced OAT activity and partially improved behavioral abnormalities. These findings support OAT-associated arginine and proline metabolic remodeling as a spatially distributed metabolic feature of PQ-induced Parkinsonian motor deficits and depression-like phenotypes, providing a brain-region-resolved metabolic perspective on environmental neurotoxicity.