| Endocrinological responses during suckling in Hatano high- and low-avoidance rats. | |
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MedLine Citation:
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PMID: 15283687 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Hatano high-avoidance (HAA) and low-avoidance (LAA) animals were originally selected from Sprague-Dawley rats for good and poor active avoidance learning in a shuttle box. We studied the endocrinological profile in lactating rats to determine the effect of suckling during mid-lactation in HAA and LAA rats. The pups were separated from their mother rats 6 h before the onset of suckling and blood samples were drawn from unanaesthetized mother rats via a jugular cannula at 0, 5 and 15 min after the suckling stimulus and then 15, 45 and 105 min after pups were removed. Plasma concentrations of oxytocin in HAA rats were significantly higher than in LAA rats during the suckling period. Plasma concentrations of prolactin and ACTH in HAA rats were significantly higher than in LAA rats during the suckling period, and at 15 min and 45 min after the pups were removed. However, there were no strain differences in circulating corticosterone between the two lines, indicating that the response of the hypothalamo-pituitary axis to the suckling stimulus was greater in HAA rats than in LAA rats, whereas the ACTH-induced adrenal response of corticosterone release was higher in LAA rats than in HAA rats. Since dopamine from the median eminence inhibits prolactin secretion from the lactotrophs of the anterior pituitary, and tuberoinfundibular dopaminergic neurones are partially regulated by the level of circulating prolactin, we evaluated the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine biosynthesis. TH, measured by the accumulation of 3,4-dihydroxyphenylalanine, was significantly higher in HAA rats than in LAA rats before the suckling stimulus. After the suckling stimulus, TH activity in HAA rats was significantly lower than before suckling, whereas TH activity in LAA rats was not changed. These findings clearly demonstrated that apparent differences between the two Hatano lines exist in endocrinological profiles during suckling. These strain differences probably originate from neurotransmitter changes, such as dopamine. |
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Authors:
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S Asai; R Ohta; M Shirota; A Tohei; G Watanabe; K Taya |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of endocrinology Volume: 182 ISSN: 0022-0795 ISO Abbreviation: J. Endocrinol. Publication Date: 2004 Aug |
Date Detail:
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Created Date: 2004-07-30 Completed Date: 2004-09-20 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0375363 Medline TA: J Endocrinol Country: England |
Other Details:
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Languages: eng Pagination: 267-72 Citation Subset: IM |
Affiliation:
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Department of Basic Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Gifu 501-1193, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenocorticotropic Hormone
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blood* Animals Animals, Suckling Avoidance Learning* Dopamine / biosynthesis Female Lactation / metabolism* Oxytocin / blood* Prolactin / blood* Rats Rats, Inbred Strains Rats, Sprague-Dawley Tyrosine 3-Monooxygenase / analysis, metabolism Weight Gain |
| Chemical | |
Reg. No./Substance:
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50-56-6/Oxytocin; 9002-60-2/Adrenocorticotropic Hormone; 9002-62-4/Prolactin; EC 1.14.16.2/Tyrosine 3-Monooxygenase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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