Pharmacological and functional evidence for extracellular 3,4-dihydroxyphenylacetic acid as an index of metabolic activity of the adrenergic neurons: an in vivo voltammetry study in the rat rostral ventrolateral medulla.
Catecholamine metabolism was studied in vivo in the C1 adrenergic area of the rostral ventrolateral medulla oblongata in rats, using differential normal pulse voltammetry coupled with an activated carbon fiber microelectrode. Pharmacological evidence indicates that 3,4-dihydroxyphenylacetic acid, the major dopamine metabolite, is responsible for the electrochemical signal appearance in the C1 group, and that it reflects the catecholamine synthesis rate, as previously reported in the locus coeruleus. Indeed, 3,4-dihydroxyphenylacetic acid was estimated to be formed from 77% of the intracellular dopamine, since its synthesis was increased by only 23%, after blockade of the dopamine-beta-hydroxylase activity. Neuronal activation by retrograde electrical stimulation increased the electrochemical signal, as well as hemorrhage and hypotension, suggesting that the level of extracellular 3,4-dihydroxyphenylacetic acid is a good biochemical index of the C1 adrenergic cellular activity in baseline conditions and during cellular activation.
Gillon
J Y
JY
Laboratoire de Neuropharmacologie, Faculté de Pharmacie, UMR 105, CNRS, Lyon, France.
Richard
F
F
Quintin
L
L
Pujol
J F
JF
Renaud
B
B
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002395:Catecholamines / Q000378:metabolism / Q000502:physiology; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors; D004558:Electric Stimulation; D004563:Electrochemistry; D004594:Electrophysiology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006470:Hemorrhage / Q000503:physiopathology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism*; D008781:Methyltyrosines / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019805:alpha-Methyltyrosine
D015415:Biomarkers; D002395:Catecholamines; D008781:Methyltyrosines; D015102:3,4-Dihydroxyphenylacetic Acid; D019805:alpha-Methyltyrosine; D010293:Pargyline; D004299:Dopamine beta-Hydroxylase