Depressor action of L-threo-dihydroxyphenylserine in the rat nucleus tractus solitarii.
Microinjections of L-threo-dihydroxyphenylserine (L-threo-DOPS, 0.1-3 ng), a synthetic precursor amino acid of noradrenaline, into the medial area of the nucleus tractus solitarii produced dose-dependent depressor and bradycardic responses in anesthetized rats treated with or without i.p. 3-hydroxybenzylhydrazine, a central inhibitor of L-aromatic amino acid decarboxylase. D-threo-DOPS (3 ng) produced no effect. L-Dihydroxyphenylalanine (L-DOPA) methyl ester (1 microgram), a competitive antagonist of L-DOPA, microinjected into the nucleus tractus solitarii, blocked the depressor and bradycardic responses to L-threo-DOPS itself produces vasodepressor actions without its conversion to noradrenaline, probably via a recognition site for L-DOPA in the rat nucleus tractus solitarii.
Miyamae
T
T
Department of Pharmacology, Yokohama City University School of Medicine, Japan.
Yue
J L
JL
Goshima
Y
Y
Misu
Y
Y
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D015103:Droxidopa / Q000494:pharmacology*; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced; D007980:Levodopa / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects*; D013237:Stereoisomerism
D007980:Levodopa; D015103:Droxidopa; C035420:levodopa methyl ester