Monoamine metabolism in the locus coeruleus measured concurrently with behavior during opiate withdrawal: an in vivo microdialysis study in freely moving rats.
Using microdialysis, changes in monoamine metabolism were monitored in the locus coeruleus of freely moving rats during opiate withdrawal concomitantly with behavioral symptoms. Rats were infused with morphine (2 mg/kg/h, s.c.) or saline for 5 days and challenged with naltrexone (100 mg/kg, s.c.) on day 6. Following naltrexone challenge, the classic behavioral symptoms of morphine withdrawal were observed in rats treated with morphine but not in saline-infused rats. In morphine-dependent rats, naltrexone induced a marked increase (280%) in dialysate concentrations of 3,4-dihydroxyphenylacetic acid, an index of the functional activity of the noradrenergic neurons in the locus coeruleus. The local concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid were also increased (70%) during morphine withdrawal. Taken together, these results (a) confirm in unanesthetized rats the hypothesis of an activation by opiate withdrawal of noradrenergic neurons in the locus coeruleus and (b) suggest an increase in serotonergic transmission in the same nucleus during morphine withdrawal.
Javelle
N
N
Laboratoire de Neuropharmacologie et Neurochimie, INSERM CJF 95-06, Faculté de Pharmacie, Université Claude Bernard, Lyon, France.
Renaud
B
B
Lambás-Señas
L
L
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000701:Analgesics, Opioid / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D015306:Biogenic Monoamines / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008125:Locus Coeruleus / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome
D000701:Analgesics, Opioid; D015306:Biogenic Monoamines; D008996:Monoamine Oxidase Inhibitors; D009292:Narcotic Antagonists; D015102:3,4-Dihydroxyphenylacetic Acid; D006897:Hydroxyindoleacetic Acid; D009271:Naltrexone; D009020:Morphine; D010293:Pargyline