Effects of anxiolytics or cannabinoid receptor ligands (cannabinoids: CBs) on nicotine (NC)-induced depression-related behavioral alterations. The parameter values at 30 min time point are shown for the single (a) and repeated (b) NC treatment groups. Data represent means ± SD (n = 7 for each group). The symbols for differences are the same as the other figures. The abbreviations of the co-administered anxiolytics or CBs as demonstrated below the X-axis are noted in the text.