Noradrenaline inhibits central serotonin release through alpha 2-adrenoceptors located on serotonergic nerve terminals.
The effect of noradrenaline on the depolarization-evoked release of 3H-5-hydroxytryptamine was investigated in superfused synaptosomes prepared from rat cortex and hippocampus and prelabelled with the radioactive indoleamine. Noradrenaline reduced in a concentration-dependent way the release of 3H-5-hydroxytryptamine elicited by 15 mM KCl. The inhibition was counteracted by the alpha-adrenoceptor antagonists phentolamine or yohimbine, but not by prazosin. The results indicate that, in rat brain, the inhibition of 5-hydroxytryptamine release by noradrenaline is mediated by adrenoceptors of the alpha 2-type localized on the terminal serotonergic fibres.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009411:Nerve Endings / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D012701:Serotonin; D009638:Norepinephrine