British Journal of Nutrition

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British Journal of Nutrition (2010), 104:291-297 Cambridge University Press
Copyright © The Authors 2010
doi:10.1017/S0007114510000450

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Behaviour, Appetite and Obesity

Mechanism of impaired baroreflex sensitivity in Wistar rats fed a high-fat and -carbohydrate diet


Jing Aia1, Feng Lianga1, Hongyu Zhoua1, Jing Zhaoa1, Ning Wanga1, Songling Zhua1 and Baofeng Yanga1 c1

a1 Department of Pharmacology, and the State-Province Key Laboratory of Biomedicine and Pharmaceutics, Harbin Medical University, Harbin 150081, China
Article author query
ai j [PubMed]  [Google Scholar]
liang f [PubMed]  [Google Scholar]
zhou h [PubMed]  [Google Scholar]
zhao j [PubMed]  [Google Scholar]
wang n [PubMed]  [Google Scholar]
zhu s [PubMed]  [Google Scholar]
yang b [PubMed]  [Google Scholar]

Abstract

Both high-fat and high-carbohydrate diets have been considered in association with the impairment of baroreflex sensitivity. However, the mechanisms are unclear. In the present study, the effects of a complex high-fat and high-carbohydrate diet (HFCD) on baroreflex circuitry were investigated. A HFCD emulsion was formulated and orally administered to rats for 30 d. Rats were then anaesthetised and baroreflex sensitivity was measured following intravenous injection of phenylephrine (PE) and sodium nitroprusside (SNP) at various doses. Morphological changes of the brainstem were detected by transmission electron microscopy. Baroreflex sensitivity-associated gene and protein expression was determined by quantitative RT-PCR and Western blot analysis. We found that: (1) the HFCD significantly attenuated heart rate responses to arterial blood pressure (ABP) increases induced by PE, but had no effect on heart rate responses to ABP decreases induced by SNP; (2) the HFCD induced medullary sheath thickening, myelinated nerve atrophy and hyaloplasm dissolving; (3) protein levels of substance P, calcitonin gene-related peptide, GlutR2 and γ-aminobutyric acid A receptors were all markedly decreased in the brainstems of rats administered with the HFCD. These findings conclude that a HFCD could impair the baroreflex sensitivity of rats. Remodelled morphology and decreased neurotransmitters and receptors in the domains of the nucleus tractus solitarii and nucleus ambiguus are participating in this process.

(Received June 19 2009)

(Revised January 14 2010)

(Accepted January 18 2010)

(Online publication March 01 2010)

Key Words:Diet; Vagal neurons; Nucleus tractus solitarii; Nucleus ambiguus; Rats

Correspondence:

c1 Corresponding author: Dr Baofeng Yang, fax +86 451 86667511, email a.z.hrbmu@gmail.com

Footnotes

Abbreviations: ABP, arterial blood pressure; BRS, baroreflex sensitivity; CGRP, calcitonin gene-related peptide; GABAA, γ-aminobutyric acid A; HFCD, high-fat and high-carbohydrate diet; HR, heart rate; MABP, mean arterial blood pressure; NA, nucleus ambiguus; NTS, nucleus tractus solitarii; PE, phenylephrine; SNP, sodium nitroprusside; SP, substance P


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