title: IL-6 microinjected in the nucleus tractus solitarii attenuates cardiac baroreceptor reflex function in rats.
abstract: 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.
authors.affiliation: Department of Physiology, Wakayama Medical University School of Medicine, Wakayama, Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Takagishi
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Waki
authors.forename: Mohammad E R
authors.initials: ME
authors.lastname: Bhuiyan
authors.forename: Sabine S
authors.initials: SS
authors.lastname: Gouraud
authors.forename: Akira
authors.initials: A
authors.lastname: Kohsaka
authors.forename: He
authors.initials: H
authors.lastname: Cui
authors.forename: Toshiya
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Julian F R
authors.initials: JF
authors.lastname: Paton
authors.forename: Masanobu
authors.initials: M
authors.lastname: Maeda
mesh_terms: 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
chemical_list: D015850:Interleukin-6