IL-6 microinjected in the nucleus tractus solitarii attenuates cardiac baroreceptor reflex function in rats.
Recent gene array and molecular studies have suggested that an abnormal gene expression profile of interleukin-6 (IL-6) in the nucleus tractus solitarii (NTS), a pivotal region for regulating arterial pressure, may be related to the development of neurogenic hypertension. However, the precise functional role of IL-6 in the NTS remains unknown. In the present study, we have tested whether IL-6 affects cardiovascular control at the level of the NTS. IL-6 (1, 10, and 100 fmol) was microinjected in the NTS of Wistar rats (280-350 g) under urethane anesthesia. Although the baseline levels of arterial pressure and heart rate did not change following IL-6 injections, the cardiac baroreflex in response to increased arterial pressure was dose-dependently attenuated. In addition, IL-6 (100 fmol) microinjections also attenuated l-glutamate-induced bradycardia at the level of the NTS. Immunohistochemical detection of IL-6 in naïve rats demonstrated that it was predominantly observed in neurons within the brain stem, including the NTS. These findings suggest that IL-6 within the NTS may play an important role for regulating cardiovascular control via modulation of input signals from baroreceptor afferents. Whether the abnormal gene expression of IL-6 in the NTS is associated in a causal way with hypertension remains to be resolved.
Takagishi
Miwa
M
Department of Physiology, Wakayama Medical University School of Medicine, Wakayama, Japan.
Waki
Hidefumi
H
Bhuiyan
Mohammad E R
ME
Gouraud
Sabine S
SS
Kohsaka
Akira
A
Cui
He
H
Yamazaki
Toshiya
T
Paton
Julian F R
JF
Maeda
Masanobu
M
D000818:Animals; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D015850:Interleukin-6 / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D023421:Models, Animal; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects* / Q000378:metabolism
D015850:Interleukin-6