Sıçan Striatal Dilimlerinden Bazal ve Uyarılma Koşullarında Asetilkolin ve Kolin Salıverilmesine Dopamin Reseptör Antagonistlerinin Etkisi

Authors : Ismail H. Ulus

Pages : 17-25

View : 28 | Download : 9

Publication Date : 2011-03-01

Article Type : Research

Abstract :Objective: The aim of the study was to determine the effects of dopamine receptor antagonists on acetylcholine and choline metabolism in rat brain striatal slices. Methods: Striatal slices from rat brain were perfused with physiological medium under basal and stimulated conditions in the presence of various concentrations of dopamine receptor antagonists. Acetylcholine and choline contents of the perfusate and tissue were assayed radioenzymatically. Results: Under resting conditions the rate of acetylcholine and choline release into the pefusate were 49±5 pmol/mg protein/10 min and 321±14 pmol/mg protein/10 min, respectively. Presence of dopamine receptor antagonists [Flufenazin 0,1-100 μM , haloperidol 1-10 μM , thioridazine 1-10 μM , sulpride 1-100 μM and eticlopride 1-10 μM ] in the perfusion medium failed to alter the basal rate of acetylcholine and choline release. When the slices were stimulated by high K+ 50 μM or electrically 15 Hz, 1 ms ve 80 mA , the release of acetylcholine increased to 938±108 pmol/ mg protein/10 min or 398±22 pmol/mg protein/10 min, respectively. Sulpride 100 μM and eticlopride 10 μM , but not flufenazin 0,1-100 μM , haloperidol 1-10 μM or thioridazine 1-10 μM , decreased acetylcholine release by about 50%, during electrical or high K+ stimulation. Flufenazine 10 μM attenuated the decrease in acetylcholine release induced by piripedil 100 μM , an agonist of dopamine receptors, during K+ depolarization. Sulpride 100 μM or eticlopride 10 μM failed to block the effect of piripedil on acetylcholine release during electrical or high K+ stimulation, contrarily they showed tendency to enhance it. Chemical destruction of dopamine neurons by 6-hydroxydopamine decreased dopamine release but failed to alter acetylcholine and choline release from the striatal slices either at rest or during stimulation. Conclusion: These data show that some dopamine receptor antagonists e.g., sulpride and eticloprid , but not others e.g., flufenazine, haloperidol and thioridazine , decrease acetylcholine release from stimulated striatal slices without altering choline release, and tissue contents of acetylcholine and choline
Keywords : Acetylcholine, choline, striatum, dopamine receptor antagonist, rat