Document Detail

Reproductive experience and expression of dopamine D(2) receptor mRNA: a possible mechanism for reduced prolactin secretion in primiparous rats.
MedLine Citation:
PMID:  17850459     Owner:  NLM     Status:  MEDLINE    
Reproductive experience (i.e. pregnancy and lactation) leads to reduced levels of circulating prolactin in both women and rats. Stimulation of prolactin secretion by dopamine antagonists is also blunted following reproductive experience in both species. Whereas a parity-induced reduction in haloperidol-stimulated prolactin secretion is evident in ovariectomised rats, it is unknown whether a similar attenuation of prolactin secretion is present in reproductively experienced, cycling pro-oestrous rats. The present study examined this possibility. Moreover, to determine possible mechanisms involved in parity-mediated changes in prolactin secretion, both dopamine utilisation within the arcuate nucleus/median eminence and expression of dopamine D(2) receptor mRNA (short and long forms) in the anterior pituitary were measured across the afternoon of pro-oestrous in reproductively experience and inexperienced females. Prolactin secretion was lower on the afternoon of pro-oestrous in primiparous females compared to age-matched, nulliparous controls. In addition, haloperidol-stimulated prolactin secretion was reduced in ovariectomised, reproductively experienced females. Although no differences in dopamine utilisation were observed as a function of reproductive experience, parity did affect the expression of both forms of D(2) receptor mRNA in the anterior pituitary. Compared with nulliparous controls, primiparous females had increased D(2 long) mRNA expression at 12.00 h on pro-oestrous as well as increased D(2 short) mRNA expression at 14.00 h. Because the ratio of D(2 long)/D(2 short) can significantly effect lactotroph proliferation and prolactin secretion, a shift in relative expression of the two D(2) receptor isoforms within the anterior pituitary of parous females may help account for the reduction in prolactin secretion that occurs following reproductive experience.
E M Byrnes; R S Bridges
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neuroendocrinology     Volume:  19     ISSN:  0953-8194     ISO Abbreviation:  J. Neuroendocrinol.     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-09-13     Completed Date:  2007-11-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8913461     Medline TA:  J Neuroendocrinol     Country:  England    
Other Details:
Languages:  eng     Pagination:  773-8     Citation Subset:  IM    
Department of Biomedical Sciences, Tufts University, Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA.
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MeSH Terms
Lactation / physiology*
Parity / physiology*
Pituitary Gland, Anterior / metabolism*,  secretion
Proestrus / physiology
Prolactin / secretion*
Protein Isoforms
RNA, Messenger / metabolism*
Rats, Sprague-Dawley
Receptors, Dopamine D2 / genetics,  metabolism*
Reg. No./Substance:
0/Protein Isoforms; 0/RNA, Messenger; 0/Receptors, Dopamine D2; 9002-62-4/Prolactin

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