Fig. 8.
Effects of morphine with or without concomitant administration of YNT-185 on the latency of acoustic startle response (A) and respiratory rate (B). Rats were administered morphine (5 mg/kg, subcutaneous) and vehicle (acidic saline, intraperitoneal; n = 6), morphine (5 mg/kg, subcutaneous) and YNT-185 (40 mg/kg, intraperitoneal; n = 5), or saline (subcutaenous) and vehicle (acidic saline, intraperitoneal; control group, n = 6). Thirty min after administration, acoustic startle test was performed with a 102-dB stimulus. The latency of startle response was measured as the time between the startle stimulus and the first movement detected. Latency of startle response was longer in rats given morphine and vehicle control compared with control rats and rats given morphine with concomitant YNT-185 administration (*P < 0.05, **P < 0.01, Kruskal-Wallis test with Bonferroni adjusted Mann–Whitney U test). The box plots show median with 25th and 75th percentile, and whiskers represent the 5% and 95% range. Respiratory rates were counted immediately before the acoustic startle test. Respiratory rate did not differ among the three groups (P = 0.110, one-way ANOVA). Data are presented as mean and SD (error bars).