Comparison of dopamine uptake and release in vitro in sheep and rat striatum.
Cocaine inhibits tritium-labeled dopamine ([3H]DA) uptake in rat (IC50 approximately 400 nM) and sheep (IC50 approximately 1 microM) striatum. GBR 12909, a selective DA uptake inhibitor, potently inhibits [3H]DA uptake in rat (IC50 less than 10 nM), but is less effective (only 60% of the uptake is inhibited at a concentration of 10 microM) and less potent (IC50 approximately 300 nM) in sheep. [3H]DA release from slices of rat or sheep striatum is stimulated by potassium (15-50 mM). In the presence of nomifensine (10 microM), cocaine (10 microM) had no effect on potassium-stimulated [3H]DA release in either species. [3H]DA release is increased by N-methyl-D-aspartate (NMDA) (10-1000 microM) in rat striatum but NMDA did not stimulate [3H]DA release in sheep striatum. These findings suggest that NMDA receptors either are absent from or do not regulate release of preloaded [3H]DA in sheep striatum.
Jacocks
H M
HM
Department of Pharmacology, Uniformed Services University, Bethesda, MD 20814-4799.
Izenwasser
S
S
Werling
L L
LL
Cox
B M
BM
D000818:Animals; D003042:Cocaine / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000493:pharmacokinetics*; D018492:Dopamine Antagonists; D005260:Female; D005473:Fluoxetine / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012756:Sheep
D018492:Dopamine Antagonists; D014179:Neurotransmitter Uptake Inhibitors; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; D005473:Fluoxetine; C011386:nisoxetine; C043425:vanoxerine; D003042:Cocaine; D004298:Dopamine; D009638:Norepinephrine