If you are a fellow child of the 80s, you probably visualize a fried egg when you think of drug addiction. Fried eggs are delicious, but the reality about drug use is much more devastating and sobering…all the way to the level of the dendrites on our neurons. A recent paper describes the use of psychoactive drugs to help identify regulators of dendrite morphology. MicroRNAs (miRs) are RNA structures that regulate gene expression by preventing the translation of specific mRNA sequences into proteins. miRs function throughout development, notably in the morphology and function of dendritic spines, which are small neuronal processes important in the transmission of a neuron’s signals. Psychoactive drugs such as nicotine, cocaine, and amphetamines can trigger changes in neuronal structure and function, and a recent paper identifies miRs as regulators of these changes. Lippi and colleagues found altered levels of miR-29a/b after exposing mice to psychostimulants. Altered levels of these miRs affect synaptic transmission and dendritic spine morphology, as seen in the images above. Healthy dendrites (top, left) have a mix of spine morphologies (top, right). After transfection with miR-29a (bottom, left) or miR-29b (bottom, right), the proportion of mushroom-shaped dendrites dropped significantly. miR-29a/b increases the number of filopodial protrusions through its targeting of the Arp2/3 actin nucleation complex.
Lippi, G., Steinert, J., Marczylo, E., D'Oro, S., Fiore, R., Forsythe, I., Schratt, G., Zoli, M., Nicotera, P., & Young, K. (2011). Targeting of the Arpc3 actin nucleation factor by miR-29a/b regulates dendritic spine morphology originally published in The Journal of Cell Biology, 194 (6), 889-904 DOI: 10.1083/jcb.201103006
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