Testing Schedule

Treatment and trait measurements are described in Figures 1B,C and in Parks et al. (2020). BXD mice of each sex and strain were included (see Supplementary Table 1 for exact numbers). On the first day (Day −1), no injections were given. On the second day (Day 0, baseline), all mice received an injection of VEH (100 μl per 30 g). On Day 1, mice received an injection of 10 mg/kg THC. On each day, body temperature, tail withdrawal latency in response to a thermal stimulus, and activity (time mobile) in the open field (OF) were measured at multiple time points in the same animal. Rectal body temperature was measured using a ThermoWorks digital thermometer with a mouse rectal probe adaptor at time 0 and 60 min post-injection. Tail withdrawal latency was measured 60 min post-injection by gently restraining each mouse in a 50 mL conical tube. The tail was then submerged ∼2 cm into a 52°C water bath. The latency to remove the tail was recorded to the nearest second. In most cases, tail flick latency was measured by two independent experimenters, and the resulting scores were averaged. Time spent mobile or immobile (periods of no movement lasting for 3 or more seconds) was measured 30 min post-injection in a 40 cm × 40 cm × 40 cm OF over a 10 min interval using video recording and ANY-maze (Stoelting) tracking software.