Table 1.

List of miRNAs regulated by opioids.

miRNA	Mechanisms affected	Factors (or genes) involved	References
miR-190	Down-regulated by fentanyl, resulting in induction of NeuroD Dendritic spine stability	pERK, β-arrestin2, pYY1, and Talin2	(Zheng et al. 2010c; Zheng et al. 2010a; Zheng et al. 2010b)
miR-133b	Down-regulated by morphine, resulting in induction of Pitx3 Differentiation of dopaminergic neurons	ERK 1/2, TH, and DAT	(Sanchez-Simon et al. 2010)
miR-15b and -181b	Induced (miR-15b) or decreased (miR-181b) by morphine Inflammation and HIV-1 infection	FGF-2, MCP-2, and IL-6	(Dave and Khalili 2010)
miR-28, 125b, 150, and 382	Down-regulated by morphine Opioid-mediated immunosuppression in HIV-1 infection	IFN-α/β	(Wang et al. 2011b)
miR-23b	Induced by morphine	MOR	(Wu et al. 2008; Wu et al. 2009)
let-7	Induced by morphine Opioid tolerance	MOR	(He et al. 2010)
miR-339	Induced by morphine and fentanyl	MOR	Unpublished

CYP2D6, cytochrome P450 2D6; DAT, dopamine transporter; Drd3, dopamine D3R; FosB, FBJ murine osteosarcoma viral oncogene homolog B; IFN, interferon; IL-6, Interleukin-6; MCP-2, monocyte chemoattractant protein-2; MOR, mu opioid receptor; pERK, phosphorylated ERK; pYY1, phosphorylated YY1; TH, tyrosine hydroxylase.