Both 3,4-dihydroxyphenylalanine and dopamine releases are regulated by Ca2+-induced Ca2+ releasing system in rat striatum.
To clarify the striatal Ca2+-dependent monoaminergic exocytosis mechanisms, this study determined the effects of the Ca2+-induced Ca2+ releasing system (CICR), containing inositol-trisphosphate-receptor (IP3R) and ryanodine-receptor (RyR), on striatal releases of dopamine and its precursor, 3,4-dihydroxyphenylalanine (DOPA), using microdialysis. The basal dopamine release is regulated by IP3R but not by RyR, whereas basal DOPA release does not require CICR. The K+-evoked releases of DOPA and dopamine were enhanced by IP3R agonist, whereas RyR agonist reduced it. Additionally, inhibition of dopamine release induced by RyR hyperactivation was prevented by inhibition of L-type voltage-sensitive Ca2+-channel activity. These present results suggest that CICR-associated regulation of striatal releases of DOPA and dopamine is restrictive during the resting stage, whereas CICRs play an important role as a reserve mechanism of exocytosis of striatal DOPA and dopamine during the hyperexcitable stage.
Zhu
Gang
G
Department of Neuropsychiatry, Hirosaki University, Hirosaki 036-8562, Japan.
Okada
Motohiro
M
Yoshida
Shukuko
S
Hirose
Shinichi
S
Kaneko
Sunao
S
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry / Q000379:methods; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007980:Levodopa / Q000494:pharmacology; D047028:Macrocyclic Compounds; D008297:Male; D017551:Microdialysis / Q000379:methods; D010080:Oxazoles / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000502:physiology; D012430:Ruthenium Red / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D047028:Macrocyclic Compounds; D010080:Oxazoles; D018160:Receptors, Cytoplasmic and Nuclear; D019837:Ryanodine Receptor Calcium Release Channel; C108644:xestospongin A; D012430:Ruthenium Red; C085029:adenophostin A; D012433:Ryanodine; D007980:Levodopa; D015544:Inositol 1,4,5-Trisphosphate; D014700:Verapamil; D000241:Adenosine; D011188:Potassium; D002118:Calcium; D004298:Dopamine