Levels of five miRNAs in rat hippocampus by qRT-PCR. Values are mean ± SD. Repeated cocaine-exposed rats that acquired cocaine CPP serves as “CCA” group, and repeated saline-exposed rats serves as SCA control. The cocaine CPP-extinguished rats serves as CCE group, and rats with saline CPP and subsequent extinction trainings serves as SCE control. n = 3 samples/12 rats per group. **p < 0.01, *p < 0.05 vs. controls (SCA or SCE rats). ##p < 0.01 vs. CCA rats.