Zinc controls cell pores to regulate storage and release of catecholamine

Neuroscientists think zinc is involved in learning and memory, but they don’t fully understand what it’s doing at the single-cell level. Using two electrochemical methods, Andrew G. Ewing and coworkers at Chalmers University of Technology and the University of Gothenburg have now shown that zinc regulates the storage of the messenger molecule catecholamine and the dynamics of its release from cells (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201700095). To measure the amount of catecholamine in cellular vesicles, the researchers insert nano-tip carbon-fiber electrodes directly into cells. The vesicles rupture on the electrodes and release all of their contents. The researchers also use single-cell amperometry to measure catecholamine as it is released from the cells. They found that cultured adrenal cells treated with zinc store less catecholamine than untreated cells. Even though the treated cells store less, they actually release the same amount of catecholamine as the untreated cells because they’re releasing nearly all of what they have taken in. That release also occurs much more slowly than the release from untreated cells. The electrochemical measurements suggest that zinc helps stabilize the opening between the vesicle and the cell membrane, thereby controlling the opening and closing process and the flow of catecholamine. “Our results provide the missing link between zinc and the regulation of neurotransmitter release processes, which might be important in memory formation and storage,” the researchers write.