title: In vivo voltammetry and microdialysis monitoring of monoamine metabolism in the rat brainstem neurons.
abstract: Two "in vivo" techniques allow the monitoring of extracellular levels of monoamines and related compounds in selected rat brainstem regions: voltammetry and microdialysis. "In vivo" voltammetry has a high regional selectivity: for example, we have been able to perform a subregional study and to show that the increase in extracellular DOPAC induced by 30 min-hypotension was twice as larg in the rostral as in the caudal rat locus coeruleus. The spatial resolution, as expressed by x 1/2 (see text), is 4 times better for voltammetry (50 microns) than for microdialysis (190 microns). Another advantage of voltammetry is its excellent time resolution. However, microdialysis has a much better biochemical specificity than voltammetry. Furthermore it allows some enzymatic activities, such as tyrosine hydroxylase, to be measured almost continuously in catecholaminergic brain nuclei. From a functional point of view, the results of our experiments (alpha 2 ligand administration, arterial hypotension or stress) illustrate the respective interest and complementarity of these two "in vivo" techniques. Their current developments will lead to a better temporal and biochemical resolution combined with an increase in the number of substances analyzed "in vivo", including peptides and nitric oxide.
authors.affiliation: Laboratoire de Neuropharmacologie, Faculté de Pharmacie Université Claude Bernard, Lyon, France.
authors.forename: L
authors.initials: L
authors.lastname: Lambás-Señas
authors.forename: C
authors.initials: C
authors.lastname: Vachette
authors.forename: F
authors.initials: F
authors.lastname: Robert
authors.forename: C
authors.initials: C
authors.lastname: Ortemann
authors.forename: B
authors.initials: B
authors.lastname: Renaud
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D001933:Brain Stem / Q000378:metabolism*; D004563:Electrochemistry / Q000379:methods; D008125:Locus Coeruleus / Q000378:metabolism; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism; D017551:Microdialysis / Q000379:methods; D009474:Neurons / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015306:Biogenic Monoamines; D015102:3,4-Dihydroxyphenylacetic Acid