Effect of Captopril and Melatonin on Fibrotic Rebuilding of the Aorta in 24 Hour Light-Induced Hypertension

Abstract

Chronic continuous light exposure leads to melatonin deficiency along with complex neurohumoral activation resulting in hypertension development in rats. The aim of this study was to show, whether continuous light induces fibrotic rebuilding of the aorta and whether the treatment with melatonin or angiotensin converting enzyme inhibitor captopril can prevent these potential alterations. In a six-week experiment, 3-month-old Wistar rats were divided into 4 groups (ten per group): controls, rats exposed to continuous light, exposed to continuous light plus treated with captopril (100 mg/kg/24 h) and exposed to continuous light plus treated with melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP) and collagen type I and III in the media of thoracic aorta were measured. Continuous light induced hypertension and fibrotic rebuilding of the aorta in terms of enhancement of collagen I and III concentration in the aortic media. Both captopril and melatonin prevented SBP rise and reduced collagen III concentration in the aorta. However, only melatonin reduced collagen I and the sum of collagen I and III in the aortic tissue. We conclude that in continuous light-induced hypertension, administration of melatonin, along with SBP reduction, decreases collagen I and III concentration in the aorta. It is suggested that antifibrotic effect of melatonin may reduce the stiffness of the aorta and small arteries and beneficially influence the nature of the pulse wave and peripheral vascular resistance.

Melatonin and the cardiovascular system in animals: systematic review and meta-analysis

“…In addition, we selected three articles from BIREME and 0 articles from the Cochrane database. The inclusion and exclusion criteria are described in Figure 1 (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38). Articles were primarily excluded when assessments were performed in human subjects, apart from being unrelated to components of PICO; we mainly focused on experimental animal studies.…”

“…In Table 4, we employed the criteria of Henderson et al (18). We found that 61.11% (21,22,(25)(26)(27)30,31,33,35,36,38) of selected studies had an appropriate sample size and 61.11% (21,23,25,26,27,30,31,(33)(34)(35)(36) had randomized animals, according to their materials and methods. All articles were blinded to the outcome assessment (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38).…”

“…We found that 61.11% (21,22,(25)(26)(27)30,31,33,35,36,38) of selected studies had an appropriate sample size and 61.11% (21,23,25,26,27,30,31,(33)(34)(35)(36) had randomized animals, according to their materials and methods. All articles were blinded to the outcome assessment (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38). We could not determine the criterion underlying the flow of animals through experiments, as no explicit statement regarding the same was available in the materials and methods.…”

“…We observed that Table 1 -Study characteristics of selected control experimental studies assessing melatonin and the cardiovascular system. For studies where the objective was inter-study standardization of an experimental design, 39% (25)(26)(27)(28)32,35,37) reached this standard (Table 4).…”

Role of Melatonin in Angiotensin and Aging

“…RAAS inhibition has been shown to be crucial in preventing cardiac remodeling and heart failure. Inhibition of AT1 receptors and RAAS reverses age-related fibrosis, severe myocardial hypertrophy, and cerebrovascular damage caused by the buildup of oxidative substances in the blood vessels of animals [ 75 , 76 , 77 , 78 ]. The serum antibodies that target the AT1 receptor have been shown to contribute to vascular allograft rejection in kidney transplant patients; however, treatment with losartan, an AT1 receptor antagonist, blocked the agonistic AT1 receptor response to the antibodies [ 79 ].…”