Fig. 2.

a Withdrawal from a single boul of acute ethanol intoxication (week 1) resulted in a significant but transient increase in brain reward threshold only with the highest dose of ethanol tested (2.0 g/kg: ^aP < 0.05, compared with vehicle controls at given time-point post-injection). The effect was significant at 6 hours, a time when blood alcohol levels had declined to virtually undetectable levels following this dose of ethanol. Repeated treatment with this dose for two additional weeks resulted in a progressive broadening of the duration of significant threshold elevations. By comparison, treatment with 1.5 g/kg ethanol resulted in significant but transient elevations only after three repeated bouts of intoxication/withdrawal, and no statistically reliable changes were seen after one or two treatments (data not shown). Treatment with 1.0 g/kg did not produce any statistically reliable threshold changes regardless of treatment week (data not shown). Data are expressed as mean ± SEM percentage of baseline threshold, n = 8–10 per dose group. [Taken with permission from Schulteis and Liu 2006.] b Time-dependent elevation of intracranial self-stimulation thresholds during ethanol withdrawal. Mean blood alcohol levels were 197.29 mg%, Data are expressed as mean ± SEM percentage of baseline threshold, ^ap < 0.05, thresholds that were significantly elevated above control levels at 2–48 hours post-ethanol. Open circles indicate the control condition. Closed circles indicate the ethanol withdrawal condition. [Taken with permission from Schulteis et al. 1995.]