Effects of U‐50,488H withdrawal on catecholaminergic neurones of the rat ventricle

1 In the present study the changes in noradrenaline (NA) and dopamine (DA) content and turnover during naloxone‐induced withdrawal were analysed in the right ventricle of rats chronically treated with the κ‐agonist U‐50,488H. 2 Rats were rendered tolerant by administration of U‐50,488H twice a day f...

Full description

Saved in:
Bibliographic Details
Published in:British journal of pharmacology 1998-07, Vol.124 (6), p.1060-1064
Main Authors: Milanés, M. V., Laorden, M. L.
Format: Article
Language:English
Subjects:
3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer - pharmacology
3,4-Dihydroxyphenylacetic Acid - metabolism
Animals
Biological and medical sciences
Dopamine - metabolism
Heart Ventricles - cytology
Heart Ventricles - drug effects
Heart Ventricles - metabolism
Male
Medical sciences
Naloxone - pharmacology
Neurons - metabolism
Neuropharmacology
Neurotransmitters. Neurotransmission. Receptors
Norepinephrine - metabolism
Normetanephrine - metabolism
Peptidergic system (neuropeptide, opioid peptide, opiates...). Adenosinergic and purinergic systems
Pharmacology. Drug treatments
Rats
Rats, Sprague-Dawley
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:1 In the present study the changes in noradrenaline (NA) and dopamine (DA) content and turnover during naloxone‐induced withdrawal were analysed in the right ventricle of rats chronically treated with the κ‐agonist U‐50,488H. 2 Rats were rendered tolerant by administration of U‐50,488H twice a day for 4 days. On the day of death the animals were injected with saline or naloxone (3 mg kg−1, s.c.) to precipitate a withdrawal syndrome. 3 After naloxone administration to U‐50,488H‐ treated rats we found neither behaviour signs of physical dependence nor changes in the tissue content of noradrenaline (NA). However, naloxone induced a decrease in both cardiac normetanephrine (NM) levels and NA turnover. 4 Similarly, naloxone enhanced the dopamine content and decreased the 3,4‐dihydroxyphenylacetic acid (DOPAC) concentration and dopamine turnover. 5 Importantly and in contrast to μ‐agonists, the present results demonstrate that U‐50,488H withdrawal produced a decrease in the NA and dopamine turnover, without behavioural signs of physical dependence. British Journal of Pharmacology (1998) 124, 1060–1064; doi:10.1038/sj.bjp.0701939
ISSN:0007-1188
1476-5381
DOI:10.1038/sj.bjp.0701939