Endorphins and morphine modulate dopamine turnover in rat brain

S. N. Deyo, R. M. Swift, R. J. Miller

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

There is evidence that some of the actions of both endogenous and exogenous opioids (e.g. stimulation of prolactin release) are mediated via interaction with catecholaminergic systems. Morphine (1.67, 5 and 15 mg/kg i.p.) altered dopamine turnover as measured by the α-methylparatyrosine method (αMPT) in the median eminence, neostriatum and frontal cortex of male Sprague-Dawley rats. The turnover rate of dopamine was reduced in the median eminence and frontal cortex but accellerated in the striatum. In the frontal cortex all doses were effective in reducing turnover rate but only the two higher doses were effective in the median eminence. All three doses accelerated turnover in the striatum. In the nucleus accumbens, morphine (5 mg/kg i.p.) accelerated dopamine turnover. Naloxone effectively reversed the effects of morphine at all doses in all brain areas while having no effect on turnover given alone. In median eminence, neostriatum and frontal cortex, intraventricular injection of [D-Ala2,D-Leu5] enkephalin (25μg) and β-endorphin (15μg) produced the same effects on dopamine turnover as morphine. The actions of these peptides were also blocked by naloxone. It is hypothesized that opiates and opioid peptides increase prolactin release by reducing the activity of hypothalamic dopaminergic systems.

Original languageEnglish (US)
JournalFederation Proceedings
Volume38
Issue number3 I
StatePublished - Jan 1 1979

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Endorphins
Median Eminence
Frontal Lobe
Morphine
Dopamine
Neostriatum
Opioid Peptides
Brain
Naloxone
Prolactin
Intraventricular Injections
Nucleus Accumbens
Opioid Analgesics
Sprague Dawley Rats
Peptides

ASJC Scopus subject areas

  • Medicine(all)

Cite this

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Endorphins and morphine modulate dopamine turnover in rat brain. / Deyo, S. N.; Swift, R. M.; Miller, R. J.

In: Federation Proceedings, Vol. 38, No. 3 I, 01.01.1979.

Research output: Contribution to journalArticle

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