Inhibitory effects of L-threo-DOPS, an L-noradrenaline precursor, on locus coeruleus-originating neurons in the caudate nucleus.
Electrophysiological studies using reserpine-treated cats were carried out to elucidate the effects of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) on the noradrenergic pathway from the locus coeruleus (LC) to the caudate nucleus (CN) neurons, which were activated by iontophoretically applied bromocriptine, a dopamine D-2 receptor agonist. In the CN neurons, glutamate-induced firing was inhibited by iontophoretic application of noradrenaline, but not by repetitive stimulation of the LC or iontophoretically applied L-threo-DOPS. After intraventricular administration of L-threo-DOPS, however, LC stimulation inhibited the glutamate-induced firing. These results suggest that L-noradrenaline that was produced from the conversion of L-threo-DOPS inhibited the CN neurons which possess dopamine D-2 receptors.
Hirose
A
A
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Sasa
M
M
Ohno
Y
Y
Takaori
S
S
D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects*; D015259:Dopamine Agents / Q000494:pharmacology; D015103:Droxidopa / Q000494:pharmacology*; D007478:Iontophoresis; D008125:Locus Coeruleus / Q000187:drug effects* / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology; D012694:Serine / Q000031:analogs & derivatives*
D015259:Dopamine Agents; D001971:Bromocriptine; D012694:Serine; D012110:Reserpine; D015103:Droxidopa; D009638:Norepinephrine