Xpression PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/20978850 of the dopamine transporter, so their mechanisms of action are probably to be complex114. Lastly, arginine exporter protein ARGO2 — which can be vital in microRNA-mediated gene silencing — together with a number of particular microRNAs have recently been implicated in cocaine regulation of gene expression selectively within the D2 subclass of striatal MSNs115. Other drugs of abuse have already been linked to microRNAs at the same time. Opioid receptor activation downregulates miR-190 in cultured rat hippocampal neurons inside a beta-arrestin2-dependent manner116, and the let-7 family of microRNA precursors is upregulated by chronic morphine exposure in mice117. Interestingly, the opioid receptor is itself a direct target for let-7, as well as the resulting repression of the receptor has been suggested as a novel mechanism for opiate tolerance117. In zebrafish and in cultured immature rat neurons, morphine decreases miR-133b expression, and this may well influence dopamine neuron differentiation114. Also, both acute and chronic alcohol exposure upregulates miR-9 in cultured striatal neurons, and this could contribute to alcohol tolerance through regulation of large-conductance Ca2+ activated K+ (BK) channels118. miR-9 appears to preferentially downregulate BK channel isoforms which are sensitive to alcohol potentiation, probably shifting BK channel expression toward additional tolerant subytpes119. miR-9 also targets the D2 dopamine receptor119, and so most likely influences alcohol reward. Inside the future, next-generation sequencing of microRNAs in a number of brain regions after exposure to drugs of abuse will be vital to uncover regulation of specific microRNAs and ultimately the genes they regulate. Indeed, this method has currently begun, as such screens are revealing various mcicroRNAs regulated within the NAc immediately after chronic cocaine115,120. By way of example, cocaine regulation on the miR-8 household suggests novel mechanisms for drug-induced alterations in the neuronal cytoskeletal and synaptic structure120. Exploring this mechanism in drug-induced regulation of NAc dendritic morphology is an vital line of future investigation.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptFuture DirectionsThis Overview has summarized the rising array of findings that support a role for regulation with the transcriptional prospective of myriad genes within the brain’s maladaptations to drugs of abuse. The mechanisms of transcriptional and epigenetic regulation are themselves varied and hugely complicated, and future studies are necessary to catalogue the vast quantity of regulatory events that happen too as to know the precise underlying mechanismsNat Rev Neurosci. Author manuscript; readily available in PMC 2012 May 1.Robison and NestlerPageinvolved. Important concerns involve: What controls the recruitment or expulsion of individual transcriptional regulatory proteins to a particular target gene? Our hypothesis is the fact that the underlying epigenetic state of that gene can be a critical determining issue, but then what controls the formation and maintenance of distinct epigenetic states at particular genes? Also, what will be the intracellular signaling cascades that transduce the initial drug action at the neurotransmitter-receptor level towards the neuronal nucleus to regulate the epigenetic state of precise IQ-1 site subsets of genes? The existing literature on transcriptional and epigenetic mechanisms of addiction is restricted in various crucial techniques. Most research to date have employed conditioned place preference an.
