%0 Generic
%9 Doctoral Dissertation
%A WANG, YUEXIANG
%D 2012
%F pittir:10955
%K dopamine, voltammetry, microdialysis, autoinhibition, medial forebrain bundle, kynurenate, heterogeneity
%T EXPLORING EXTRACELLULAR DOPAMINE CONCENTRATION AND ITS  REGULATION ON DOPAMINE RELEASE BY VOLTAMMETRY
%U http://d-scholarship-dev.library.pitt.edu/10955/
%X Extracellular dopamine (DA) is critical in regulating DA release as well as interacting with other  neurotransmission systems. Microdialysis and voltammetry are the major techniques for extracellular DA  measurement in vivo. These two techniques provide distinct results due to their different detection  volumes. Carbon fiber microelectrode is 10,000 times smaller than that of a microdialysis probe. With  such a small size, carbon fiber microelectrode provides a high spatial resolution and causes unobservable  damage to the brain which paints a completely different picture of DA release in the brain as compared to  the knowledge obtained by microdialysis.  In Chapter I, with the high temporal and spatial resolution provided by carbon fiber  microelectrode in conjunction with fast scan cyclic voltammetry (FSCV), we are able to detect DA  terminal populations with different autoinhibition levels in rat striatum. We revealed a coupling between  resting DA and local autoinhibition level. The recording sites with high resting DA concentration (micromolar)  exhibit a high autoinhibition on evoked DA release induced by medial forebrain bundle (MFB)  stimulation, and vice versa. These different types of DA release will never be observed by microdialysis  due to its large dimension. On the contrary, microdialysis result is an average of all the DA release sites  (high and low) that the microdialysis probe goes through. This averaging method could contribute to the  low measurement of the DA concentration by microdialysis.  In Chapter II, we examined the resting DA by a carbon fiber microelectrode at ~200 micron away  from a microdialysis probe. We found TTX-insensitive DA was decreased by microdialysis probe  implantation. This reduction contributes to the low DA measurement by microdialysis.  In Chapter III, we monitored evoked DA induced by MFB stimulation in the tissue near  microdialysis probe. We found DA terminals near a microdialysis probe are hyper-sensitive to D2  receptor antagonist and DA transporter inhibitor. This suggests that the DA terminals in the tissue near  microdialysis probe are under an altered neurochemical state with a loss of DA homeostasis.