Volume 138, Issue 2, April 2014

Editor's Highlight: Polychlorinated biphenyls (PCBs) have been banned since 1977 in the U.S. With over 200 different congeners based on the multiple positions for chlorination, PCBs exhibit a wide range of health effects. Some of the congeners that appear to be more persistent in human tissues are chiral. As if having over 200 different combinations of chlorination wasn't sufficiently complex, these chiral congeners, termed atropisomers, display unique neuronal effects. As shown by Yang and coworkers, one such atropisomer, (-)PCB 136 (2,2′, 3,3′, 6,6′, hexachlorobiphenyl), promotes dendritic arborization in hippocampal neurons, while its (+) atropisomer does not. These actions appear to be mediated by the ryanodine receptor. The atropisomer-selective effects add a new layer of complexity to our understanding of PCB congeners and their effects on the brain. Given the past widespread use of these compounds, their ability to persist in human tissue, and the demonstrable effects on neuronal function, it would be wise to further examine the effects of PCBs in neurodevelopmental and neurodegenerative diseases. —Gary W. Miller