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Dynamic Observation of Dopamine Autoreceptor Effects in Rat Striatal Slices
Author(s) -
Kennedy Robert T.,
Jones Sara R.,
Wightman R. Mark
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb09391.x
Subject(s) - autoreceptor , sulpiride , chemistry , pulse (music) , dopamine , stimulation , quinpirole , neurotransmitter , perfusion , biophysics , agonist , glutamate receptor , medicine , endocrinology , dopaminergic , biology , receptor , biochemistry , engineering , detector , electrical engineering
Abstract: Fast‐scan cyclic voltammetry has been used to measure dopamine (DA) synaptic overflow in slices of rat caudate nucleus induced by electrical stimulation with one‐, two‐, and 50‐pulse, 10‐Hz trains. Synaptic overflow in this preparation is shown to be the result of the competing effects of release and cellular uptake. Release caused by all pulses was attenuated by the D 2 agonist quinpirole (1 μ M ). The rapid time response of the measurements (100 ms) allows the autoinhibition induced by endogenous, released DA to be resolved in real time. The concentration of DA released during the second pulse of a train was 58% of that released by the first pulse, an effect that is partially blocked by the addition of 2 μ M sulpiride, a D 2 antagonist, to the perfusion buffer. DA release during the first stimulus pulse is unaffected by 2 μM sulpiride, suggesting that autoreceptors are not normally occupied in this preparation. Release caused by the third pulse was 14% of the first pulse and also could be partially enhanced by 2 μ M sulpiride. The duration of the inhibition of release induced by endogenous DA was estimated by varying the interval between one‐pulse stimulations until the overflow of DA induced by the second pulse was equal to that on the first; a half‐time of ∼ 17 s was found. The addition of picrotoxin (100 μ M ) and glutamate (10 μ M ) to the perfusion buffer did not affect stimulated release of DA, although the addition of atropine (100 μ M ) attenuated overflow for all the trains tested.