Fig. 3

Coefficient of 30 breath durations (%) quantified prior (pre) to and after (post) 5-HT infusion before (baseline) and after ICV injections of various concentrations of dronabinol (100, 10, 1 or 0.1 μg; N = 6 for each dose) or vehicle (DMSO; N = 6). There were no significant differences in ICV treatment (P = 0.45) or interaction between time and ICV treatment (p = 0.46). However, there was a main effect of time (p < 0.01), with post hoc analysis showing a significant increase in respiratory instability after 5-HT infusion (p < 0.01). Data (mean ± SEM) were analyzed using mixed model analysis with a two-way repeated/fixed measure (time × ICV treatment)