Hibiscus extract mitigates salt induced carotid adventitial changes in rats

Abstract

The tunica adventitia is an active vascular compartment that actively participates in modulation of vascular structure, function and pathophysiology. Adventitial thickness has recently been accepted as a surrogate marker of atherosclerosis. The effects of salt and chemicals that ameliorate those effects are important in understanding vascular structure, function and pathology. There are few studies on hibiscus and high salt induced vascular pathology. This study, therefore, investigated the effects of hibiscus on salt induced vascular changes on rat carotid artery. The experimental animals were divided into 3 groups of 8 animals each – (i) controls; (ii) high salt diet alone and (iii) high salt + hibiscus extract for a period of eight weeks. At ages 2, 5 and 8weeks 2 – 3 animals were sacrificed for study. They were anaesthetized with ether and perfused with formal saline. Specimens were then obtained from the middle of common carotid artery, fixed in 5% formaldehyde solution, processed routinely for paraffin embedding and 5-micron thick sections stained with Hematoxylin / Eosin and also with Mason’s Trichome/ Aniline blue. Adventitial thickness and volumetric densities of collagen were measured using morphometric techniques. High salt consumption induced statistically significant increase in adventitial thickness from 297.45μm at week 2 to 659.4μm in week 8. In hibiscus fed rats, this increase progressively reduced to 482.55μm in week 8. Volumetric density of collagen was 57% in high salt fed rats but reduced to 45.66% in hibiscus fed rats (p<0.001). The increase in tunica adventitial thickness and collagen density which is induced by high salt can be mitigated by hibiscus extract. This implies that hibiscus has potential to restore salt induced vascular injury. Further studies are recommended to refine the extract.

Keywords: adventitial thickness, high salt, hibiscus, collagen, density