Brain tumour necrosis factor-alpha modulates neurotransmitters in hypothalamic paraventricular nucleus in heart failure.
OBJECTIVE
Increased proinflammatory cytokines after myocardial infarction augment the progression of heart failure (HF) and are of prognostic significance. Recently, we demonstrated that increased proinflammatory cytokines in the brains of HF rats increased paraventricular nucleus (PVN) superoxide and down-regulated neuronal nitric oxide synthase (nNOS), contributing to sympathoexcitation. In this study, we explored the possible roles of brain proinflammatory cytokines and their effects on modulating PVN neurotransmitters in the exaggerated sympathetic activity in HF.


RESULTS
Sprague-Dawley rats with HF or sham-operated control (SHAM) rats were treated for 4 weeks with a continuous intracerebroventricular (ICV) infusion of the cytokine blockers-pentoxifylline (PTX, 10 microg/h and 40 microg/h), etanercept (ETN, 5 microg/h and 10 microg/h), or vehicle. Another set of HF and SHAM rats were treated with intraperitoneal (ip) infusion of a similar dose of PTX or ETN. HF rats had increased neuronal excitation accompanied by higher levels of glutamate, norepinephrine (NE), and tyrosine hydroxylase (TH), and lower levels of gamma-aminobutyric acid (GABA), nNOS, and 67-kDa isoform of glutamate decarboxylase (GAD67) in the PVN when compared with SHAM rats. Plasma cytokines, NE, epinephrine, angiotensin II, and renal sympathetic nerve activity (RSNA) were also increased in HF rats. ICV treatment with low doses of PTX or ETN attenuated, and high doses prevented, increases in levels of glutamate, NE, and TH, and decreases in levels of GABA, nNOS, and GAD67 in the PVN in HF rats. The same ICV treatments also attenuated the increased RSNA seen in HF rats. IP treatment with similar doses of PTX or ETN did not affect glutamate, NE, TH, GABA, nNOS, and GAD67 in the PVN and had no effect on RSNA of HF rats.


CONCLUSIONS
This study, for the first time, demonstrates that proinflammatory cytokines modulate neurotransmitters in the PVN and contribute to sympathoexcitation in HF.
Kang
Yu-Ming
YM
Department of Physiology, Shantou University Medical College, Shantou 515041, China. ymkang@lsu.edu
He
Rong-Li
RL
Yang
Li-Min
LM
Qin
Da-Nian
DN
Guggilam
Anuradha
A
Elks
Carrie
C
Yan
Ning
N
Guo
Zheng
Z
Francis
Joseph
J
D000818:Animals; D001921:Brain / Q000503:physiopathology*; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000502:physiology; D000068800:Etanercept; D006333:Heart Failure / Q000503:physiopathology*; D007074:Immunoglobulin G / Q000008:administration & dosage; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors / Q000502:physiology; D007668:Kidney / Q000294:innervation; D008297:Male; D018377:Neurotransmitter Agents / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D010286:Paraventricular Hypothalamic Nucleus / Q000503:physiopathology*; D010431:Pentoxifylline / Q000008:administration & dosage; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018124:Receptors, Tumor Necrosis Factor / Q000008:administration & dosage; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000502:physiology*
D016207:Cytokines; D007074:Immunoglobulin G; D018836:Inflammation Mediators; D018377:Neurotransmitter Agents; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D000068800:Etanercept; D010431:Pentoxifylline