Figure 4.

Impaired spatial and fear memories by repeated Δ⁹-THC exposure are occluded by COX-2 inhibition. A. Impaired fear memory is attenuated by COX-2 inhibition. 24 hrs after a footshock coniditioning, animals were administered with Δ⁹-THC (10 mg/kg) or NS398 (10 mg/kg) once a day for 7 days. Freezing behavior was recorded 24 hrs after the cessation of the last injections. B. COX-2 KO and WT mice received training in the Morris water maze for 5 days without any treatments (naïve). Starting at day 6, WT animals received vehicle, Δ⁹-THC (10 mg/kg), NS398 (10 mg/kg), Δ⁹-THC+NS398, once a day for 7 days. COX-2 KO mice received vehicle or Δ⁹-THC (10 mg/kg) for 7 days. Tests were performed 30 min following the injections. C1-3, Probe trial test was conducted 24 hrs after the cessation of the last Δ⁹-THC injection. The number of times crossed the target zone, the amount of time stayed in the target quadrant, and swim speed in different treatments in probe trial tests were detected. Error bars represent ±SEM, **P<0.01 compared with the vehicle control (n=9~12 animals/group, two-way ANOVA, Bonferronni post-hoc test). (See also Figures S5, S7.)