Fig 1. DHA supplementation attenuates the anxiety induced by morphine without altering analgesia or locomotion, established effects of this opiate.
A. Wheel running activity was measured over 16h; 3h of light, 12h of dark, 1h of light. The distance run (cm) every hour is shown in the 3 left panels and the total distance run in the column graphs on the right. DHA supplementation did not alter wheel running in male mice receiving saline (Ai) which by day 8 had increased their activity compared with day 1. *, # p<0.05 vs pre-saline injection activity, shown in the solid (control diet) or dashed (DHA group) lines, of the same treatment. B. Total distance run, depicted in the column graphs, shows that morphine reduced wheel running in both DHA and control groups when compared with pre-treatment levels; **, *** p<0.05 and 0.005 respectively vs basal activity in the control group. ##, ### p<0.05 and 0.005 respectively vs basal activity in the DHA group. However, the hourly time bin data show that DHA attenuated this reduction at specific time-points, 5 and 15 h post-morphine injection on day 1, and 5 hours on day 8, *p<0.05, ***p<0.001 vs control morphine at the same timepoint. B. Elevated Plus Maze (EPM). The time spent and frequency of entry into the second, outer half of the EPM was assessed 5h following the last injection of the 8th day of the morphine or saline injection protocol. Mice on the control diet receiving morphine spent less time and entered less into this region than control mice receiving saline. Supplemental DHA partially reversed this profile. *, ***p<0.05 and 0.001 respectively vs the control saline group, #p<0.05 vs control saline and control morphine. C. Morphine-induced analgesia. The effect of DHA on morphine-induced thermal analgesia was assessed by the tail immersion test at 49.5°C. There was no effect of diet on basal tail-flick latency. Morphine (10mg/kg s.c.) delayed this response in both control and DHA groups (*** p<0.001 vs baseline measures). D. Morphine induced locomotion. i. This effect if morphine was assessed immediately following the first of the daily morphine injections on days 1, 4 and 8 of the TDA morphine injection protocol. The total distance traveled showed no effect of DHA on either the initial locomotor response, or subsequent, sensitized responses, which increased above saline-treated mice on the matching diet, *p<0.05, ***p<0.001 vs saline of the matching control or DHA diet.