FIGURE 2.

Variation in Initial Response to THC Among BXDs. A significant effect of THC treatment relative to baseline (p < 0.001) was observed for all traits. Initial response to THC is shown as the difference between baseline and initial THC treatment. Strains are shown on the x-axis and initial response (difference between baseline response on day 0 and response to THC on day 1) is shown on the y-axis. Negative values indicate a decrease in response on day 1 compared to day 0 and positive values indicate an increase in response. Parental strains are indicated in blue (B6) and red (D2) and BXD strains are shown in black. (A) There is a significant effect of strain (p < 0.001) on initial response to THC for time spent mobile in the open field 30 min post-injection. Male and female responses were combined as there were no significant interaction effects involving sex. Responses to THC varied ∼90-fold among strains for the mobility trait. (B) The antinociceptive effects of THC were quantified using tail withdrawal latency in response to a thermal stimulus at 60 min post-injection. Male and female responses were combined as there were no significant interaction effects involving sex. Response to THC varied nearly 8-fold across strains, however, no significant effects of strain were observed for the antinociception trait. (C,D) There is a significant main effect of strain (p < 0.05) on initial hypothermic response 60 min post-injection of THC for both females (C) and males (D). Hypothermic response to THC in females varies 13-fold across strains compared to 24-fold variation in response in males. Summarized B6 and D2 responses shown for comparison (Parks et al., 2020).