Cocaine abuse results in increased craving for the drug. But in the long run, cocaine intake induces the expression of a microRNA in the brain, and this seems to limit further drug intake.

Extended cocaine taking triggers several structural and functional changes in the brain that may lead to compulsive drug seeking, but the mechanisms that regulate the process are unclear. Here, a microRNA — miR-212 — is identified that is upregulated in the striatum of rats with a history of extended access to cocaine. The authors suggest that miR-212 protects against the development of compulsive drug taking, and that it may act through the CREB protein, a known regulator of the rewarding effects of cocaine.

Ultraluminous X-ray sources are the most luminous class of black hole located outside the nuclei of active galaxies. They are often associated with shock-ionized nebulae, though with no evidence of collimated jets. Now, however, it is reported that the large nebula S26 in the nearby galaxy NGC 7793 is powered by a black hole with a pair of collimated jets. The jets seem to be 104 times more energetic than the X-ray emission from the core.