NSF Award
0642188
This project examines a novel concept in neurotransmitter release. Specifically, dopamione (DA) can be released by two mechanisms: 1) release from pre-existing vesicles at nerve terminals, the classic mechanism for neurotransmitter release, and 2) transporter-mediated DA efflux, i.e. reverse-mode operation of DAT using approaches that are ongoing in only a few labs in this country. Understanding how reverse transport of DAT is modulated, and its significance in normal physiology, is essential for detailed understanding of DAT function in the brain. We anticipate that the fundamental insights from our research will serve to elucidate mechanisms underling the function of all biogenic amines in the brain. Once released, neurotransmitters such as DA must be cleared to control the magnitude and duration of synaptic signaling. Neurotransmitter transporters are the primary molecules responsible for this clearing. Surprisingly, our recent findings indicate that the transporter for DA (DAT) mediates the release of DA into the synapse via reverse transport mechanisms. In preliminary studies, we have found that DAT-dependent DA efflux requires an increase in intracellular Na+ and Ca++, and that covalent modification of DAT by phosphorylation is critical for DAT-induced DA efflux. Quantitative and real-time assessment of DAT function using simultaneous whole-cell patch clamp electrophysiology of single cells and amperometry recordings of oxidative currents produced by released DA will be used in these studies, as well as confocal microscopy and biochemical approaches. We propose to characterize DAT-dependent DA efflux from cells stably expressing either wildtype DAT or structures intentionally,employing the drugs methamphetamine and amphetamine as tools to study DAT functions in differing efflux-promoting conformations. <br/><br/>At Meharry Medical College, more than 98% of graduate students more than 70% of medical students engaging in research are African American ( 56% are female). Therefore, a direct consequence of the PI's research program is that it will foster the participation of females and minorities in the quantitative sciences in general, and in neuroscience in particular. The PI will continue her current involvement in sharing research with the lay community and with young people interested in science (including hands-on workshops for elementary students and K- 12 presentations to science and math magnet schools ( 38% minorities) in the Nashville Public School System). The PI will continue to participate in the Nashville Brain Awareness Week events and in demonstrations at the Adventure Science Center. At Meharry, The PI mentors graduate students who participate in the NSF Teaching Fellowship Vanderbilt-Meharry program. The PI mentors students in summer enrichment programs as part of collaboration with FISK University for undergraduate and graduate recruitment. Consequently, The PI plans to continuing recruiting and training interested college students, sharing her expertise and enthusiasm for quantitative biology and electrophysiology with a range of interested youth, many of whom come from under-represented minority populations.
