Document Detail

Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate.
MedLine Citation:
PMID:  16269575     Owner:  NLM     Status:  MEDLINE    
Systemic corticosterone (Cort) modulates arterial baroreflex control of both heart rate and renal sympathetic nerve activity. Because baroreceptor afferents terminate in the dorsal hindbrain (DHB), an area with dense corticosteroid receptor expression, we tested the hypothesis that prolonged activation of DHB Cort receptors increases the midpoint and reduces the gain of arterial baroreflex control of heart rate in conscious rats. Small (3-4 mg) pellets of Cort (DHB Cort) or Silastic (DHB Sham) were placed on the surface of the DHB, or Cort was administered systemically by placing a Cort pellet on the surface of the dura (Dura Cort). Baroreflex control of heart rate was determined in conscious male Sprague Dawley rats on each of 4 days after initiation of treatment. Plots of arterial pressure vs. heart rate were analyzed using a four-parameter logistic function. After 3 days of treatment, the arterial pressure midpoint for baroreflex control of heart rate was increased in DHB Cort rats (123 +/- 2 mmHg) relative to both DHB Sham (108 +/- 3 mmHg) and Dura Cort rats (109 +/- 2 mmHg, P < 0.05). On day 4, baseline arterial pressure was greater in DHB Cort (112 +/- 2 mmHg) compared with DHB Sham (105 +/- 2 mmHg) and Dura Cort animals (106 +/- 2 mmHg, P < 0.05), and the arterial pressure midpoint was significantly greater than mean arterial pressure in the DHB Cort group only. Also on day 4, maximum baroreflex gain was reduced in DHB Cort (2.72 +/- 0.12 beats x min(-1) x mmHg(-1)) relative to DHB Sham and Dura Cort rats (3.51 +/- 0.28 and 3.37 +/- 0.27 beats x min(-1) x mmHg(-1), P < 0.05). We conclude that Cort acts in the DHB to increase the midpoint and reduce the gain of the heart rate baroreflex function.
Andrea G Bechtold; Deborah A Scheuer
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2005-11-03
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  290     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-15     Completed Date:  2006-06-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R1003-11     Citation Subset:  IM    
Division of Pharmacology, University of Missouri-Kansas City, Kansas City, Missouri 64108, USA.
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MeSH Terms
Arteries / physiology*
Baroreflex / drug effects*,  physiology
Carrier Proteins / pharmacology*
Catheters, Indwelling
Dimethylpolysiloxanes / pharmacology*
Glucocorticoids / pharmacology*
Heart Rate / drug effects*
Neuropeptides / pharmacology*
Pressoreceptors / metabolism
Rats, Sprague-Dawley
Rhombencephalon / physiology*
Silicones / pharmacology*
Grant Support
Reg. No./Substance:
0/CORT protein, human; 0/Carrier Proteins; 0/Dimethylpolysiloxanes; 0/Glucocorticoids; 0/Neuropeptides; 0/Silicones; 63148-62-9/baysilon

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