Cardioprotective Effects of Solidago microglossa DC. in Nicotine-Treated Hypertensive Rats

Abstract

Solidago microglossa DC. (Asteraceae), "arnica brasileira," is a Brazilian species popularly used to treat hypertension or renal ailments. This study investigated the cardioprotective effects of standardized S. microglossa extract (EESM) in nicotine-treated spontaneously hypertensive rats (SHRs). Moreover, the molecular mechanisms involved in the cardiovascular effects were also investigated. The acute toxicity was evaluated in female Wistar rats. Afterwards, six-month-old male spontaneously hypertensive rats received the EESM (14, 28, and 56 mg/kg), hydrochlorothiazide (25 mg/kg), and vehicle (filtered water; 0.1 mL/100 g) once daily for 28 days. All treatments were associated with 1.8 mg/kg of nicotine. At the end of the experimental period, the renal function, electrocardiographic profile, blood pressure, ventricular function, biochemical parameter, and mesenteric vascular bed reactivity were evaluated. Relative organ weights and cardiac morphometry were also investigated. Nicotine treatment in 6-month-old SHRs induced a significant reduction in renal function, with reduced urinary volume and lower renal elimination of sodium and creatinine. In addition, serum markers of the redox state and blood pressure levels remained significantly elevated, contributing to changes in vascular reactivity and left ventricular hypertrophy associated with reduced ventricular function. After 28 days of treatment, we found that the highest dose of EESM could mitigate all renal and cardiovascular changes developed by the nicotine-treated hypertensive rats. This study presented EESM as a possible cardioprotective drug that prevents cardiovascular dysfunctions in nicotine-treated hypertensive rats. Our data suggest EESM as a potential adjuvant therapy when cardioprotective effects are required.

Figure 1

Representative images of the left ventricle of nicotine-treated hypertensive rats that received the EESM for 28 days. The black arrow represents an area of fibrous connective tissue deposition (scar). The black circle delimits an extensive area of fibrous tissue deposition associated with necrosis of cardiac fibers. EESM: hypertensive rats that received three different doses of the Solidago microglossa extract; HCTZ: hypertensive animals that received daily doses of hydrochlorothiazide (25 mg/kg); HE: hematoxylin and eosin stain; NC: hypertensive animals that received daily doses of the vehicle; Naïve: normotensive animals that received only the vehicle.