Three days into abstinence following prolonged dependence, we observed a rebound burst of proliferation in the dentate gyrus. This was accompanied by a trend for increased neurogenesis. These findings are consistent with and expand on results from previous studies. In the 4-d binge intoxication model, initial depression of dentate gyrus neurogenesis was also followed by a rebound burst of proliferation some days into abstinence (Nixon et al. 2008; Nixon & Crews, 2004). This resulted in increased neurogenesis, as well as an increase in microglia that persisted in the brain for long periods, mimicking the increase in microglia found in brains of human alcoholics (He et al. 2007). Following the prolonged brain alcohol dependence in the present study, a similar burst in hippocampal proliferation was observed, although we did not detect a subsequent significant increase in newly differentiated neurons. It is possible that a burst in neurogenesis was missed by the time-points chosen (Brown et al. 2003). Alternatively, following prolonged rather than acute brain alcohol exposure, increased proliferation may to a lesser extent result in formation of new neurons that differentiate
