Influences of neuronal uptake and D2 autoreceptors on regulation of extracellular dopamine in the core, shell and rostral pole of the rat nucleus accumbens.
Fast cyclic voltammetry in rat brain slices containing the nucleus accumbens, was used to examine the regulation of the extracellular concentration of electrically stimulated dopamine overflow in the core, shell and rostral pole. One microM (-)-sulpiride, significantly increased dopamine overflow in all 3 regions but only when the duration of stimulation was greater than 500 ms. One microM cocaine, significantly potentiated dopamine overflow in all 3 regions following all patterns of stimulation. In the presence of 1 microM cocaine, superfusion with 1 microM (-)-sulpiride did not result in a further increase in dopamine overflow at any frequency of stimulation in the rostral pole, but significant increases in dopamine overflow were observed after stimulation with 20 pulses at 10 or 20 Hz in the core or shell; the degree of potentiation was greater in the shell than core. Quinpirole inhibited single pulse stimulated dopamine overflow in a concentration dependent manner (maximum inhibition (100%) in all regions) but was significantly less potent in the rostral pole than in the core or shell. Increasing the number of pulses to 2 or 4 pulses at 50 Hz resulted in a shift of the quinpirole dose-response curve to the right in all regions and in the rostral pole, a significant reduction in the maximum inhibition of dopamine overflow to both stimulation parameters. In the shell a significant reduction in maximum inhibition was only seen with 4 pulses at 50 Hz stimulation, whereas in the core there was no change in the maximum inhibitory effect of quinpirole. Neuronal uptake and D2 autoreceptor activity contribute to regulation of the extracellular concentration of dopamine in core, shell and rostral pole. The relative importance of either uptake or autoreceptor control is region and stimulus dependent.
Wieczorek
W
W
Department of Pharmacology, Queen Mary and Westfield College, University of London, UK.
Kruk
Z L
ZL
D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004873:Ergolines / Q000494:pharmacology; D008297:Male; D009714:Nucleus Accumbens / Q000378:metabolism*; D019257:Quinpirole; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism*
D018491:Dopamine Agonists; D004873:Ergolines; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D004298:Dopamine