Prolactin stimulates the release of oxytocin in lactating rats

Evidence for a physiological role via an action at the neural lobe

Steven L. Parker, William Armstrong, Celia D. Sladek, Clark E. Grosvenor, William R. Crowley

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

The present studies were designed to investigate whether prolactin (PRL) influences the secretion of oxytocin (OT) in lactating rats, and to test whether the previously reported inhibitory and stimulatory effects of dopamine-2 (D-2) agonists and antagonists, respectively, on OT release might be secondary to their respective inhibitory and stimulatory effects on the release of PRL. Intravenous administration of either rat (r) or ovine (o) PRL to lactating, nonsuckled rats increased basal plasma concentrations of OT. rGH was ineffective, but administration of oGH did produce some stimulation of OT release. Both oPRL and rPRL significantly enhanced the electrical stimulation-induced release of OT from isolated stalk-neurointermediate lobes, in vitro, without affecting the basal release of the peptide. oGH was ineffective on basal or stimulated in vitro OT release, and neither hormone altered basal or stimulation-induced release of vasopressin from these tissues. Both rPRL and oPRL reversed the inhibitory effect of the D-2 dopamine agonist bromocriptine. Immunoneutralization of circulating PRL with a highly specific antiserum abolished the increases in OT in response to either suckling or to administration of the D-2 dopamine antagonist domperidone. These findings suggest that (1) an action of PRL released by suckling may be of physiological importance in promoting the release of OT in lactating rats: (2) that PRL may increase OT release, at least in part, through a stimulatory action on the neural lobe, and perhaps directly on OT-containing neurosecretory nerve endings, and (3) that the previously reported inhibitory effect of D-2 dopamine receptor stimulation, and the stimulatory effect of a D-2 dopamine antagonist on OT release may be secondary to their analogous actions on the release of PRL.

Original languageEnglish (US)
Pages (from-to)503-510
Number of pages8
JournalNeuroendocrinology
Volume53
Issue number5
DOIs
StatePublished - Jan 1 1991

Fingerprint

Posterior Pituitary Gland
Oxytocin
Prolactin
Dopamine Antagonists
Domperidone
Nerve Endings
Bromocriptine
Dopamine Agonists
Dopamine Receptors
Vasopressins
Intravenous Administration
Electric Stimulation
Immune Sera
Dopamine
Sheep

All Science Journal Classification (ASJC) codes

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism
  • Cellular and Molecular Neuroscience
  • Endocrine and Autonomic Systems
  • Neuroscience(all)

Cite this

Prolactin stimulates the release of oxytocin in lactating rats : Evidence for a physiological role via an action at the neural lobe. / Parker, Steven L.; Armstrong, William; Sladek, Celia D.; Grosvenor, Clark E.; Crowley, William R.

In: Neuroendocrinology, Vol. 53, No. 5, 01.01.1991, p. 503-510.

Research output: Contribution to journalArticle

Parker, Steven L. ; Armstrong, William ; Sladek, Celia D. ; Grosvenor, Clark E. ; Crowley, William R. / Prolactin stimulates the release of oxytocin in lactating rats : Evidence for a physiological role via an action at the neural lobe. In: Neuroendocrinology. 1991 ; Vol. 53, No. 5. pp. 503-510.
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