Effects of isoproterenol treatment for 7 days on inflammatory mediators in the rat aorta

Abstract

The aim of the present study was to evaluate the effect of overstimulation of β-adrenoceptors on vascular inflammatory mediators. Wistar rats were treated with the β-adrenoceptor agonist isoproterenol (0.3 mg·kg⁻¹·day⁻¹ sc) or vehicle (control) for 7 days. At the end of treatment, the right carotid artery was catheterized for arterial and left ventricular (LV) hemodynamic evaluation. Isoproterenol treatment increased LV weight but did not change hemodynamic parameters. Aortic mRNA and protein expression were quantified by real-time RT-PCR and Western blot analysis, respectively. Isoproterenol enhanced aortic mRNA and protein expression of IL-1β (124% and 125%) and IL-6 (231% and 40%) compared with controls but did not change TNF-α expression. The nuclear-to-cytoplasmatic protein expression ration of the NF-κB p65 subunit was increased by isoproterenol treatment (51%); in addition, it reduced the cytoplasmatic expression of IκB-α (52%) in aortas. An electrophoretic mobility shift assay was performed using the aorta, and increased NF-κB DNA binding (31%) was observed in isoproterenol-treated rats compared with controls ( P < 0.05). Isoproterenol treatment increased phenylephrine-induced contraction in aortic rigs ( P < 0.05), which was significantly reduced by superoxide dismutase (150 U/ml) and sodium salicylate (5 mM). Cotreatment with thalidomide (150 mg·kg⁻¹·day⁻¹ for 7 days) also reduced hyperreactivity to phenylephrine induced by isoproterenol. In conclusion, overstimulation of β-adrenoceptors increased proinflammatory cytokines and upregulated NF-κB in the rat aorta. Moreover, local oxidative stress and the proinflammatory state seem to play key roles in the altered vascular reactivity of the rat aorta induced by chronic β-adrenergic stimulation.