Spermidine treatment alleviates motor dysfunction in transgenic MJD zebrafish together with signs of autophagy induction. (A) Mutant ataxin-3 zebrafish (84Q) were treated with spermidine (60–250 µM) for 5 days and motor behaviour was measured at 6 dpf. Vehicle treated mutant ataxin-3 larvae swam shorter distances compared to the non-transgenic control and spermidine treatment rescued this phenotype (***p < 0.001 and *p < 0.05, n = 96–140). (B) Spermidine treated mutant ataxin-3 larvae were subjected to immunoblotting (B). Densitometric analysis of (C) full-length and (D) cleaved- human ataxin-3 revealed a significant decrease in ataxin-3 expression in spermidine treated EGFP-ATXN3 84Q fish compared to the vehicle treated mutants (** p = 0.002 and p = 0.020 respectively, n = 8–10). Various substrates of the autophagy pathway showed indications of positive autophagic flux. (E) No difference was found in levels of beclin-1, (F) p62 was found to be significantly decreased (*p = 0.0432) and (G) LC3II was found to be increased. (p = 0.0426, all n = 8–10). A one-way ANOVA followed by Tukey post hoc analysis and a paired student t-test was utilised for statistical analysis. Data represents mean ± SEM. Data points reflected in C-G are experimental treatments of approximately 20–25 larvae
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