Iontophoresis of morphine into the arcuate nucleus: Effects on dopamine concentrations in hypophysial portal plasma and serum prolactin concentrations

J. T. Haskins, G. A. Gudelsky, R. L. Moss, J. C. Porter

Research output: Contribution to journalArticle

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Abstract

The effects of morphine on the release of dopamine from tuberoinfundibular neurons and the release of PRL from the anterior pituitary gland were studied in diestrous female rats. Morphine ions ejected iontophoretically in minute quantities into the arcuate nuclei (using one electrode per nucleus) were found to reduce markedly the concentration of dopamine in hypophysial portal plasma. Thirty minutes after the iontophoretic ejection of morphine using charges of 3.6 and 6.6 millicoulombs/electrode, the concentrations of dopamine in hypophysial portal plasma were reduced 70% and 83%, respectively, relative to the preiontophoretic values. When morphine was iontophoresed into each arcuate nucleus using a charge of 1.5 millicoulombs/electrode, there was no change in the concentration of dopamine in hypophysial portal plasma. The suppressive effect of morphine on dopamine release was prevented by pretreatment of the animals with naloxone (5 mg/kg, ip). In addition to the reduction of the concentration of dopamine in hypophysial portal plasma, the iontophoresis of morphine into the arcuate nuclei enhanced the serum concentration of PRL. On the basis of the present observations, it is suggested that morphine acts on an opiate receptor within the arcuate nucleus to suppress the secretion of dopamine from tuberoinfundibular neurons into hypophysial portal blood, thereby enhancing pituitary gland secretion of PRL.

Original languageEnglish (US)
Pages (from-to)767-771
Number of pages5
JournalEndocrinology
Volume108
Issue number3
StatePublished - 1981

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Iontophoresis
Arcuate Nucleus of Hypothalamus
Prolactin
Morphine
Dopamine
Serum
Electrodes
Dopaminergic Neurons
Anterior Pituitary Gland
Opioid Receptors
Pituitary Gland
Naloxone
Ions

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Iontophoresis of morphine into the arcuate nucleus : Effects on dopamine concentrations in hypophysial portal plasma and serum prolactin concentrations. / Haskins, J. T.; Gudelsky, G. A.; Moss, R. L.; Porter, J. C.

In: Endocrinology, Vol. 108, No. 3, 1981, p. 767-771.

Research output: Contribution to journalArticle

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