COA-Cl induces dopamine release and tyrosine hydroxylase phosphorylation: In vivo reverse microdialysis and in vitro analysis.

We found that local perfusion of COA-Cl (0.1, 0.4, or 1.0 mM) into the dorsal striatum of living mice produced a significant and dose-dependent increase in extracellular DA levels, with the highest dose of 1.0 mM COA-Cl producing an approximately 5-fold increase in DA. Consistent with in vivo findings, 0.1 and 0.2 mM COA-Cl significantly and dose-dependently enhanced DA release 3.0 to 5.0-fold in PC12 cells, an in vitro model of DA-responsive neurons. Interestingly, the increase in striatal DA levels by COA-Cl in vivo was similar in magnitude to that observed in PC12 cells. Treatment with 0.1 mM COA-Cl significantly increased both Ser31 and Ser40 phosphorylation of tyrosine hydroxylase (TH) in PC12 cells, and Ser40 phosphorylation in iCell neurons, without altering total TH protein levels. Further, we examined whether COA-Cl could stimulate neurite outgrowth in PC12 cells and iCell neurons and found that COA-Cl significantly induced neurite outgrowth in both cell lines. Our results provide the first evidence that COA-Cl can stimulate dose-dependent DA release and activation of TH phosphorylation, suggesting that COA-Cl may be a promising therapeutic candidate for the treatment of neurological dysfunction associated with low DA.