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Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats
BACKGROUND: An endogenous dopaminergic (DA) tone acting on D(3) receptors has been shown to inhibit tuberoinfundibular (TI) DA neuron activity and stimulate prolactin (PRL) surge in the afternoon of estrogen-primed ovariectomized (OVX+E(2)) rats. Whether D(2) receptor (D(2)R) is also involved in the...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4019350/ https://www.ncbi.nlm.nih.gov/pubmed/24884386 http://dx.doi.org/10.1186/1423-0127-21-37 |
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author | Liang, Shu-Ling Hsu, Sheng-Chieh Pan, Jenn-Tser |
author_facet | Liang, Shu-Ling Hsu, Sheng-Chieh Pan, Jenn-Tser |
author_sort | Liang, Shu-Ling |
collection | PubMed |
description | BACKGROUND: An endogenous dopaminergic (DA) tone acting on D(3) receptors has been shown to inhibit tuberoinfundibular (TI) DA neuron activity and stimulate prolactin (PRL) surge in the afternoon of estrogen-primed ovariectomized (OVX+E(2)) rats. Whether D(2) receptor (D(2)R) is also involved in the regulation of TIDA and PRL rhythms was determined in this study. RESULTS: Intracerebroventricular (icv) injection of PHNO, a D(2)R agonist, in the morning inhibited TIDA and midbrain DA neurons’ activities, and stimulated PRL secretion. The effects of PHNO were significantly reversed by co-administration of raclopride, a D(2)R antagonist. A single injection of raclopride at 1200 h significantly reversed the lowered TIDA neuron activity and the increased serum PRL level at 1500 h. Dopamine D(2)R mRNA expression in medial basal hypothalamus (MBH) exhibited a diurnal rhythm, i.e., low in the morning and high in the afternoon, which was opposite to that of TIDA neuron activity. The D(2)R rhythm was abolished in OVX+E(2) rats kept under constant lighting but not in OVX rats with regular lighting exposures. Pretreatment with an antisense oligodeoxynucleotides (AODN, 10 μg/3 μl/day, icv) against D(2)R mRNA for 2 days significantly reduced D(2)R mRNAs in central DA neurons, and reversed both lowered TIDA neuron activity and increased serum PRL level in the afternoon on day 3. A diurnal rhythm of D(2)R mRNA expression was also observed in midbrain DA neurons and the rhythm was significantly knocked down by the AODN pretreatment. CONCLUSIONS: We conclude that a diurnal change of D(2)R mRNA expression in MBH may underlie the diurnal rhythms of TIDA neuron activity and PRL secretion in OVX+E(2) rats. |
format | Online Article Text |
id | pubmed-4019350 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-40193502014-05-14 Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats Liang, Shu-Ling Hsu, Sheng-Chieh Pan, Jenn-Tser J Biomed Sci Research BACKGROUND: An endogenous dopaminergic (DA) tone acting on D(3) receptors has been shown to inhibit tuberoinfundibular (TI) DA neuron activity and stimulate prolactin (PRL) surge in the afternoon of estrogen-primed ovariectomized (OVX+E(2)) rats. Whether D(2) receptor (D(2)R) is also involved in the regulation of TIDA and PRL rhythms was determined in this study. RESULTS: Intracerebroventricular (icv) injection of PHNO, a D(2)R agonist, in the morning inhibited TIDA and midbrain DA neurons’ activities, and stimulated PRL secretion. The effects of PHNO were significantly reversed by co-administration of raclopride, a D(2)R antagonist. A single injection of raclopride at 1200 h significantly reversed the lowered TIDA neuron activity and the increased serum PRL level at 1500 h. Dopamine D(2)R mRNA expression in medial basal hypothalamus (MBH) exhibited a diurnal rhythm, i.e., low in the morning and high in the afternoon, which was opposite to that of TIDA neuron activity. The D(2)R rhythm was abolished in OVX+E(2) rats kept under constant lighting but not in OVX rats with regular lighting exposures. Pretreatment with an antisense oligodeoxynucleotides (AODN, 10 μg/3 μl/day, icv) against D(2)R mRNA for 2 days significantly reduced D(2)R mRNAs in central DA neurons, and reversed both lowered TIDA neuron activity and increased serum PRL level in the afternoon on day 3. A diurnal rhythm of D(2)R mRNA expression was also observed in midbrain DA neurons and the rhythm was significantly knocked down by the AODN pretreatment. CONCLUSIONS: We conclude that a diurnal change of D(2)R mRNA expression in MBH may underlie the diurnal rhythms of TIDA neuron activity and PRL secretion in OVX+E(2) rats. BioMed Central 2014-05-03 /pmc/articles/PMC4019350/ /pubmed/24884386 http://dx.doi.org/10.1186/1423-0127-21-37 Text en Copyright © 2014 Liang et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/4.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Liang, Shu-Ling Hsu, Sheng-Chieh Pan, Jenn-Tser Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title | Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title_full | Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title_fullStr | Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title_full_unstemmed | Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title_short | Involvement of dopamine D(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
title_sort | involvement of dopamine d(2) receptor in the diurnal changes of tuberoinfundibular dopaminergic neuron activity and prolactin secretion in female rats |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4019350/ https://www.ncbi.nlm.nih.gov/pubmed/24884386 http://dx.doi.org/10.1186/1423-0127-21-37 |
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