An inhibitory role for morphine on the release of dopamine into hypophysial portal blood and on the synthesis of dopamine in tuberoinfundibular neurons

Details

Serval ID
serval:BIB_69FF0330E987
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
An inhibitory role for morphine on the release of dopamine into hypophysial portal blood and on the synthesis of dopamine in tuberoinfundibular neurons
Journal
Brain Research
Author(s)
Reymond  M. J., Kaur  C., Porter  J. C.
ISSN
0006-8993
Publication state
Published
Issued date
03/1983
Peer-reviewed
Oui
Volume
262
Number
2
Pages
253-8
Notes
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S. --- Old month value: Mar 7
Abstract
The intracerebroventricular administration of morphine to ovariectomized rats resulted in a marked decrease in the concentration of dopamine in plasma of hypophysial portal blood. A 90% reduction in the rate of release of hypothalamic dopamine into hypophysial portal blood occurred during the 60 min following the intraventricular administration of 60 ng of morphine sulfate. A dose-related decrease in the rate of release of dopamine into the portal vasculature was observed between 7.5 ng and 60 ng of morphine sulfate. Regardless of the quantity of morphine sulfate (1-500 ng) given to the animals, the concentrations of norepinephrine and epinephrine in hypophysial portal plasma and femoral arterial plasma remained unchanged. The efficacy of morphine on the release of dopamine into hypophysial portal blood was not associated with an equal efficacy of the drug on the synthesis of dopamine in tuberoinfundibular neurons, as evaluated by the accumulation of dihydroxyphenylalanine (DOPA) in the median eminence of rats given 3-hydroxybenzylhydrazine (NSD 1015). No effect of morphine was observed on DOPA accumulation in the median eminence of NSD-treated rats that had received 50 ng of morphine sulfate intracerebroventricularly, and only a 50% reduction was observed in the accumulation of DOPA in the median eminence of rats given 500 ng of morphine sulfate. These findings are supportive of the view that morphine inhibits both the release and synthesis of dopamine but is more effective in inhibiting the release than synthesis of dopamine.
Keywords
Animals Dihydroxyphenylalanine/blood Dopamine/*blood Epinephrine/blood Female Hypothalamus/*drug effects Injections, Intraventricular Median Eminence/*drug effects Morphine/*pharmacology Muridae Neural Inhibition/drug effects Neurons/drug effects Norepinephrine/blood Pituitary Gland, Anterior/*drug effects Prolactin/blood Receptors, Dopamine/drug effects
Pubmed
Web of science
Create date
11/02/2008 14:11
Last modification date
20/08/2019 14:24
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