Fig. 5

The opioid receptor antagonist naloxone does not replicate or reverse AS1-mediated attraction to noxious stimuli. A AITC aversion assay. Naloxone alone does not affect AITC avoidance, and when co-applied with AS1 this drug does not reverse AS1-induced attraction towards AITC. N = 80 fish for the DMSO condition, 71 for 5 μM AS1, 80 for 1 μM Naloxone, and 70 for 1 μM Naloxone + 5 μM AS1. * indicate significant difference from the DMSO control at each time point. B Phototaxis assay. All non-AS1-treated fish significantly chose the light side of the arena, whereas all AS1-treated fish significantly preferred the dark, regardless of whether 1 μM naloxone was applied. N = 39 fish for the DMSO condition, 41 fish for the 2.5 μM AS1 condition, 41 fish for 1 μM naloxone, and 39 fish for 1 μM naloxone + 2.5 μM AS1. C The percentage of fish in the light at 30-s intervals in the 4-min trials of the phototaxis assay shown in B, averaged across the five trials. * indicate significant difference from the DMSO (0 μM Naloxone) control at each time point. As shown, AS1-treated fish quickly migrate to the dark half of the arena at the onset of each trial, whereas fish that did not receive AS1 migrate to the light half of the arena, regardless of whether naloxone has been applied. * p < 0.05, ** p < 0.01, *** p < 0.001. Two-way ANOVA with Tukey’s multiple comparisons test used in A–C. To determine if fish were significantly choosing one side of the arena over the other a one-sample t test was performed with a hypothetical mean of 50%