Figure 4.

Blockade of R7BP actions prevents the development of morphine tolerance. Mice received 20 mg/kg morphine once a day for 5 consecutive days and 52 °C hot plate responses were monitored before and 30 min after morphine administration. R7BPKO mice show the same analgesic response throughout the study, whereas wild-type animals develop tolerance by the third day of morphine administration. Data are expressed as mean±SEM, ^*p<0.001, two-way ANOVA, followed by the Bonferroni post hoc test (n=8–11 per group).