Fig. 1

Time course effect of glucosamine on the development of tolerance to morphine (20 mg/kg, s.c., twice daily), during 9 days in mice. a: maximum possible effect (%), b: Paw withdrawal latency. Glucosamine was administered via gavage (500, 1000 and 2000 mg/kg, twice daily, for 9 days). Analgesia was measured 30 min after the treatment, on the hot plate apparatus. Values are expressed as mean ± SEM (n = 6). Statistical analyses was performed by mixed model ANOVA with repeated measure and post hoc bonferroni for evaluating antinociceptive activity. *p < 0.05, **p < 0.01 comparison between morphine and control (normal saline) groups. #p < 0.05, ##p < 0.01, ###p < 0.001 treated glucosamine+morphine as compared to morphine treated group. +p < 0.05, ++p < 0.01, treated glucosamine+morphine as compared to control (normal saline) group