MPTP-Treated Zebrafish Recapitulate 'Late-Stage' Parkinson's-like Cognitive Decline

Abstract

The zebrafish is a promising model species in biomedical research, including neurotoxicology and neuroactive drug screening. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) evokes degeneration of dopaminergic neurons and is commonly used to model Parkinson's disease (PD) in laboratory animals, including zebrafish. However, cognitive phenotypes in MPTP-evoked experimental PD models remain poorly understood. Here, we established an LD₅₀ (292 mg/kg) for intraperitoneal MPTP administration in adult zebrafish, and report impaired spatial working memory (poorer spontaneous alternation in the Y-maze) in a PD model utilizing fish treated with 200 µg of this agent. In addition to conventional behavioral analyses, we also employed artificial intelligence (AI)-based approaches to independently and without bias characterize MPTP effects on zebrafish behavior during the Y-maze test. These analyses yielded a distinct cluster for 200-μg MPTP (vs. other) groups, suggesting that high-dose MPTP produced distinct, computationally detectable patterns of zebrafish swimming. Collectively, these findings support MPTP treatment in adult zebrafish as a late-stage experimental PD model with overt cognitive phenotypes.

Keywords: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP); Parkinson’s disease; artificial intelligence; inhibitory avoidance task; spontaneous alternation; zebrafish.

Figure 1

Schematic representation of Y maze apparatus, as in [30], with minor modifications. Removable arms were constantly swapped around.

Figure 2

LD₅₀ values calculated using the linear regression of the constructed curves, based on the graphical method of Miller and Tainter in the Excel software.

Figure 3

Analysis of cognitive functions in adult zebrafish in the aquatic Y-maze test (panel (A), assessed as % of spontaneous alternation behavior, SAB, n = 9–19 per group, analyzed using the unpaired two-sample t-test and Pearson correlation (Panel (B)) and the inhibitory avoidance test (IAT, n = 9–19 per group, panel (C), analyzed using paired sample t-test). Data are presented as the violin and dot plots. Red dots with lines represent mean ± SD; * p < 0.05 vs. control fish, unpaired two-sample t-test, # p < 0.05 vs. control day 1, paired t-test.

Figure 4

Artificial intelligence (AI)-based convolution neural network (CNN) used for analyses in two computational experiments involving a combined dataset (Panel (A)) and cross-day comparison (Panel (B)). Each node represents class (drug-trial) used for the AI training and testing procedure. Embedded line values represent AI prediction accuracy obtained from experimental testing runs following CNN training.