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Toll-like receptor 9 plays a key role in the autonomic cardiac and baroreflex control of arterial pressure.

Authors :
Rodrigues, Fernanda Luciano
Silva, Luiz Eduardo V.
Hott, Sara Cristina
Bomfim, Gisele F.
da Silva, Carlos Alberto Aguiar
Fazan Jr., Rubens
Resstel, Leonardo B. M.
Tostes, Rita C.
Carneiro, Fernando S.
Source :
American Journal of Physiology: Regulatory, Integrative & Comparative Physiology; 4/15/2015, Vol. 308 Issue 8, pR714-R723, 10p
Publication Year :
2015

Abstract

The crosstalk between the immune and the autonomic nervous system may impact the cardiovascular function. Toll-like receptors are components of the innate immune system and play developmental and physiological roles. Toll-like receptor 9 (TLR9) is involved in the pathogenesis of cardiovascular diseases, such as hypertension and heart failure. Since such diseases are commonly accompanied by autonomic imbalance and lower baroreflex sensitivity, we hypothesized that TLR9 modulates cardiac autonomic and baroreflex control of arterial pressure (AP). Toll-like receptor 9 knockout (TLR9 KO) and wild-type (WT) mice were implanted with catheters into carotid artery and jugular vein and allowed to recover for 3 days. After basal recording of AP, mice received methyl-atropine or propranolol. AP and pulse interval (PI) variability were evaluated in the time and frequency domain (spectral analysis), as well as by multiscale entropy. Spontaneous baroreflex was studied by sequence technique. Behavioral and cardiovascular responses to fear-conditioning stress were also evaluated. AP was similar between groups, but TLR9 KO mice exhibited lower basal heart rate (HR). AP variability was not different, but PI variability was increased in TLR9 KO mice. The total entropy was higher in TLR9 KO mice. Moreover, baroreflex function was found higher in TLR9 KO mice. Atropine-induced tachycardia was increased in TLR9 KO mice, whereas the propranolol-induced bradycardia was similar to WT mice. TLR9 KO mice exhibit increased behavioral and decreased tachycardia responses to fear-conditioning stress. In conclusion, our findings suggest that TLR9 may negatively modulate cardiac vagal tone and baroreflex in mice. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03636119
Volume :
308
Issue :
8
Database :
Complementary Index
Journal :
American Journal of Physiology: Regulatory, Integrative & Comparative Physiology
Publication Type :
Academic Journal
Accession number :
102234474
Full Text :
https://doi.org/10.1152/ajpregu.00150.2014