Effects of Psidium guajava L. leaves extract on blood pressure control and IL-10 production in salt-dependent hypertensive rats.

Abstract

Psidium guajava (guava) leaves extract displays anti-hypertensive properties by mechanisms not yet fully un- derstood. Here, we investigated whether sympathetic drive and immune signaling mechanisms are involved with the antihypertensive effect of the guava extract in a model of salt-dependent hypertension. Raw guava extract (rPsE) was characterized by colorimetric and UPLC-MS techniques. Two doses of rPsE (100 and 200 mg/kg) were evaluated for anti-hypertensive effect using a suspension system (PsE). Weaned male Wistar rats were put on a high-salt diet (HSD, 0.90 % Na+) for 16 weeks and received gavages of PsE for the last 4 weeks. Blood pressure (BP) was measured at the end of treatment in conscious rats. The neurogenic pressor effect was assessed by ganglionic blockade with hexamethonium. Autonomic modulation of heart rate was evaluated by spectral analysis. The effects of orally administered PsE on lumbar sympathetic nerve activity (LSNA) were assessed in anesthetized rats. Blood IL-10, IL-17A, and TNF were measured. The increased neurogenic pressor effect of HSD rats was reduced by PsE 100 mg/kg, but not by 200 mg/kg. PsE (200 mg/kg) administration in anesthetized rats produced a greater fall in BP of HSD rats compared to standard salt diet (SSD) rats. PsE hypotensive response elicited an unproportionable increase in LSNA of HSD rats compared to SSD rats. PsE (200 mg/kg) increased plasma concentrations of IL-10 but had no effect on TNF or IL-17A. Our data indicate that the antihypertensive effects of PsE may involve autonomic mechanisms and immunomodulation by overexpression of IL-10 in salt- dependent hypertensive rats.