Facilitation of Ca2+ store-dependent noradrenaline release after an N-methyl-D-aspartate receptor antagonist in the rat supraoptic nucleus.
We examined the role of N-methyl-d-aspartate (NMDA) receptors in the control of noradrenaline release in the supraoptic nucleus (SON) using a microdialysis method in urethane-anaesthetized rats. Local application of 0.5 mm NMDA into the SON by retrodialysis decreased noradrenaline content in the dialysate from the SON. On the other hand, MK-801, a channel blocker of NMDA receptors, or D(-)2-amino-5-phosphonopentanoic acid (AP-5), a competitive NMDA receptor antagonist, increased the basal noradrenaline content. Tetrodotoxin did not completely block the noradrenaline increase after NMDA antagonists. Infusion of Ca2+-free solution containing Ni2+ and Cd2+, or a mixture of omega-agatoxin IVA and omega-conotoxin GVIA, voltage-sensitive Ca2+ channels blockers, did not block noradrenaline increase after AP-5, but blocked noradrenaline increase after high K+. Infusion of intracellular Ca2+ blockers, thapsigargin or TMB-8, impaired noradrenaline increase after AP-5 but not that after high K+. These data are consistent with the hypothesis that activation of an NMDA receptor inhibits an intracellular Ca2+ store-dependent noradrenaline release from nerve terminals in the SON.
Liu
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Department of Physiology, Jichi Medical School, Minamikawachi-machi, Tochigi-ken, Japan.
Onaka
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Yagi
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D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000502:physiology*; D003891:Desipramine / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D016202:N-Methylaspartate / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D018759:Adrenergic Uptake Inhibitors; D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D018691:Excitatory Amino Acid Antagonists; D010880:Piperidines; D016194:Receptors, N-Methyl-D-Aspartate; D013779:Tetrodotoxin; D016202:N-Methylaspartate; C010739:ifenprodil; D002118:Calcium; D003891:Desipramine; D009638:Norepinephrine