this intermediate pathway. One study has shown that nicotine treatment up- and down-regulates a number of miRNAs, in particular miR-140*, which regulates the expression of a number of genes including dynamin 1 (Dmn1) that may be involved in endocytosis and be important in drug-induced neural plasticity (15) and nicotine dependence (16). Similarly, miR-504* has been implicated in the regulation of allele-specific differential expression of a functional SNP in the 3′ UTR of DRD1 that has been associated with nicotine addiction (17).
