C. Ortemann et al., IN-VIVO MICRODIALYSIS STUDY OF THE EXTRACELLULAR 3,4-DIHYDROXYPHENYLACETIC ACID IN THE RAT LOCUS-CERULEUS - TOPOGRAPHICAL AND PHARMACOLOGICAL ASPECTS, Journal of neurochemistry, 61(2), 1993, pp. 594-601
In vivo microdialysis coupled with HPLC and electrochemical detection
was used to monitor extracellular levels of 3,4-dihydroxyphenylacetic
acid (DOPAC) of the locus ceruleus (LC) in halothane-anesthetized rats
. The identity of DOPAC was confirmed by experiments showing that the
chromatographic peak was totally suppressed after inhibition of monoam
ine oxidase by pargyline. Histological examinations allowed to relate
the quantity of DOPAC measured in the dialysates with the localization
of the probe implantation site. We found that the DOPAC concentration
was inversely proportional to the distance between the probe and the
lateral border of the LC. Regardless of the caudorostral level of the
nucleus, concentrations were maximal when the axis of the probe was 10
0 mum from the lateral border of the LC and decreased by 53% when this
distance reached 300 mum. Activation of LC noradrenergic neurons by s
ystemic administration of the alpha2-antagonist piperoxane increased b
y 100% DOPAC concentrations in LC dialysates. These results suggest th
at the DOPAC measured by microdialysis could be considered an indicato
r of the functional state of LC noradrenergic neurons.