(neuropeptide Y) expression was found to be upregulated and its gene promoter hyperacetylated, while egr-1 (early growth response 1) was found to be downregulated and hypoacetylated after cocaine withdrawal [52]. Together, these findings tightly correlate gene activity in the brain in vivo to levels of histone acetylation, a finding which is consistent with the role of histone acetylation in cell culture and yeast.
