Cocaine addiction is characterized by a gradual loss of control over drug use, but molecular mechanisms regulating vulnerability to this process remain unclear. Here we report that microRNA-212 (miR-212) is upregulated in the dorsal striatum of rats with a history of extended access to cocaine. Striatal miR-212 decreases responsiveness to the motivational properties of cocaine by dramatically amplifying the stimulatory effects of the drug on CREB signaling. This action occurs through miR-212-enhanced Raf-1 activity, resulting in adenylyl cyclase sensitization and increased expression of the essential CREB co-activator TORC (Transducer of Regulated CREB; also known as CRTC). Our findings suggest that striatal miR-212 signaling plays a key role in determining vulnerability to cocaine addiction, reveal novel molecular regulators that control the complex actions of cocaine in brain reward circuitries, and provide an entirely new direction for the development of anti-addiction therapeutics based on modulation of noncoding RNAs.

The presence of workers that forgo reproduction and care for their siblings is a defining feature of eusociality and a major challenge for evolutionary theory. It has been proposed that worker behavior evolved from maternal care behavior. We explored this idea by studying gene expression in the primitively eusocial wasp Polistes metricus. Because little genomic information existed for this species, we used 454 sequencing to generate 391,157 brain complementary DNA reads, resulting in robust hits to 3017 genes from the honey bee genome, from which we identified and assayed orthologs of 32 honey bee behaviorally related genes. Wasp brain gene expression in workers was more similar to that in foundresses, which show maternal care, than to that in queens and gynes, which do not. Insulin-related genes were among the differentially regulated genes, suggesting that the evolution of eusociality involved major nutritional and reproductive pathways.

cerebral cortex ͉ glutamatergic signaling ͉ regulatory RNA N MDA receptors (NMDA-R) control many executive brain functions, such as working memory, and their dysfunction is implicated in a host of brain disorders (1-4). Notably, hypofunctional NMDA-R signaling, particularly in the prefrontal cortex (PFC), has been implicated in the cognitive and behavioral disturbances characteristic of schizophrenia (5), autism (6, 7), attention deficit hyperactivity disorder (ADHD) (8, 9), mood disorders (10), and other psychiatric illnesses. The cellular mechanisms by which disrupted NMDA-R transmission drives behavioral pathology are still unclear, although several of the major proteins involved in this pathway, such as calcium/calmodulin-dependent protein kinase II (CaMKII) (11), have been identified. In this study, we examine whether neurobehavioral abnormalities associated with NMDA-R hypofunction can be attributed to a novel class of regulatory RNA molecules, microRNAs (miRNAs).miRNAs have attracted much attention as regulators of neuronal development and synaptic plasticity (12-15). Furthermore, psychiatric disorders such as schizophrenia, autism, and Tourette's syndrome are associated with dysregulated levels of miRNAs (16)(17)(18)(19)(20). miRNAs are small (Ϸ22 nt) noncoding transcripts that can control expression of protein-coding mRNAs at the posttranscriptional level (21). Pleiotropic miRNAs can control gene expression by binding to complementary sequences in the 3Ј untranslated region (3Ј UTR) of target mRNA transcripts to facilitate their degradation and/or inhibit their translation (15,22,23). Understanding this layer of gene regulation therefore promises to enrich our knowledge of brain function and pathology. Dizocilpine is a highly selective phencyclidine-like NMDA-R antagonist that can rapidly produce schizophrenia-like behavioral deficits in humans and rodents (24). We examined whether a psychotomimetic dose of dizocilpine (0.5 mg/kg, i.p.) altered miRNA expression in brain regions of C57BL/6 mice, by using miRNA microarray profiling as an initial screening approach. Our analysis was focused on the PFC because of the considerable evidence linking this brain region with behavioral pathology in psychiatric illnesses (19). We extracted the small RNAs from the PFC of the mice 15 min after administration of a single dose of dizocilpine, i.e., a time-point at which dizocilpine-induced behavioral disturbances such as hyperlocomotion and stereotypy are readily observed (25). Of note, there was a robust reduction of miR-219 out of 182 miRNAs detectable by microarray in PFC tissues (Table S1). miR-219 is a conserved miRNA expressed in both rodent and human brains, but not in other tissues (26,27). These data demonstrate that concentrations of a brain-specific miRNA, which may play a role in regulating NMDA-R function, are altered during states of NMDA-R hypofunction.In support of the microarray data, RT-PCR analyses demonstrated that miR-219 levels were significantly reduced by Ϸ50% (a change from an average cycle th...