Presynaptic modulation of K+-evoked [3H]dopamine release in striatal and frontal cortical synaptosomes of normotensive and spontaneous-hypertensive rats.
Regional differences in presynaptic [3H]dopamine ([3H]DA) release and its modulation by D2 DA-receptors between the frontal cortex and striatum obtained from Wystar-Kyoto (WKY) and spontaneous-hypertensive rats (SHR) have been evaluated using superfused synaptosomes. Synaptosomal tritium content was significantly lower in the frontal cortex than in the striatum in both SHR and WKY (approximately 45% and 48%, respectively), but no differences in tritium content were obtained between strains. However, the 15 mM K+-evoked [3H]DA overflow was lower in the SHR as compared to WKY rats in both brain regions (striatum approximately 23%, frontal cortex approximately 21). Concentration-response curves for quinpirole (1nM-10 microM)-mediated inhibition of 15mM K+-evoked [3H]DA release showed no differences between SHR and WKY. These results suggest that SHR has less ability to release [3H]DA as compared to WKY rats, but SHR did not show differences in the autoregulation of such release in both the frontal cortex and striatum.
Yousfi-Alaoui
M A
MA
Departament de Farmacologia i Terapèutica, Facultat de Medicina, Univeristat Autònoma de Barcelona, Bellaterra, Spain.
Hospital
S
S
Garcia-Sanz
A
A
Badia
A
A
Clos
M V
MV
D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D017729:Presynaptic Terminals / Q000502:physiology*; D019257:Quinpirole / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR / Q000378:metabolism; D011921:Rats, Inbred WKY; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000502:physiology; D012016:Reference Values; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D014316:Tritium; D019257:Quinpirole; D011188:Potassium; D004298:Dopamine