Figure 5.

Influence of chronic caffeine administration upon the Δ⁹-tetrahydrocannabinol (THC)-induced short-term spatial memory deficits in mice. Caffeine was given daily (3 mg/kg, >12 h before trials), for 15 days before testing the effect of THC (see Methods). (a–d) Mice familiarized with the escape strategies during the first 5 tasks (training) and all groups showed improved performance in (a) the number of trials to reach criterion, (b) the escape latency, (c) swim pathlength, whereas (d) average swim speed remained constant. THC (5 mg/kg), or vehicle, was then tested in the absence (task 6) and in the presence (task 7) of AM251 (3 mg/kg). Subjects rested for 1 day off drug after task 6, to allow full metabolization of THC. For clarity of comparison between groups, symbols were nudged at tasks 6 and 7. Note that chronic caffeine exacerbated the spatial memory deficits induced by acute THC, and this effect of THC was fully prevented by previous administration of AM251. All data represent mean±standard error of mean (SEM) of n=7–8. ^*p<0.05, two-way analysis of variance, followed by Tukey's post hoc test (see text for more details).