on time of alcohol exposure. In contrast to AMY and NAC, the number of DE microRNAs at 120h continued to decline in the PFC, perhaps indicating that microRNA regulation in the PFC is under greater homeostatic regulatory control given the complexity of the transcriptome networks responding to alcohol challenge [7, 44]. In PFC, several DE microRNAs are members of the same family, especially at the 0h time point. (S2 Table). The greater redundancy of DE microRNA family members in PFC compared with AMY and NAC could suggest a higher degree of transcriptional fine tuning or regulatory prioritization in this brain region. In addition, temporal patterns of DE microRNA gene targets also varied significantly among brain regions. AMY and PFC microRNAs were most responsive to the direct effects of ethanol (0h), whereas NAC displayed a greater response to ethanol withdrawal (8h). This is supported by the finding that the greatest number of DE gene targets in AMY and PFC were associated with microRNAs DE at 0h while the greatest number of DE gene targets in NAC were associated with microRNAs DE at 8h (Fig 4).
