Objective To determine if glucocerebrosidase 1 deficiency is a susceptibility factor to 1-methyl-4-phenylpyridinium (MPP+) toxicity using a zebrafish model.
Background and hypothesis Heterozygous mutations in the glucocerebrosidase gene (GBA1) are a strong genetic risk factor for Parkinson's disease (PD). Genetic risk factors may increase susceptibility to exogenous neurotoxins. We hypothesized GBA1 haploinsufficiency may increase susceptibility to the classical PD neurotoxin MPTP.
Methods A stable gba1+/− zebrafish line was in-crossed to generate embryos of all genotypes. At 2 days post fertilization (dpf), 100 dechorionated embryos (and 100 controls) were separated into 6 well plates, and exposed to 3 mM MPP+. At 3dpf embryos were fixed in 4% paraformaldehyde. Whole mount in-situ hybridisation was performed using a tyrosine hydroxylase (TH) probe. Embryos were genotyped for gba1 by PCR. TH positive neurons were counted in 10 embryos of each genotype under 20x microscopy.
Results MPP+ embryos exhibited approximately 25% reduction in TH neurons compared to controls with no differences between genotypes.
Conclusion MPP+ exposure results in a loss of TH positive neurons. GBA1 deficiency does not potentiate this. We provide “proof of principle” data for the usefulness of PD mutant zebrafish strains to test possible interactions between PD genetic risk factors and relevant toxins.