Effects of Melatonin Supplementation on the Aortic Wall in a Diet-Induced Obesity Rat Model

Background Cardiovascular disease (CVD) is still the leading cause of death globally. Alterations in the arterial wall architecture predict CVD morbidity and mortality and are associated with other CVD risk factors. Aortic wall thickness is closely linked to short-and long-term CVD morbidity and mortality, even without pronounced atherosclerotic changes. Obesity increases the risk of a broad spectrum of pathologies with vascular manifestation, which are often pathogenically associated with chronic oxidative stress and inflammatory response. Hence, as an antioxidant and anti-inflammatory agent, the pineal gland hormone melatonin is expected to have vasoprotective effects. This study evaluated the effects of melatonin supplementation on aortic wall thickness by assessing the cross-sectional associations of abdominal obesity with aortic intima-media thickness in a diet-induced obesity rat model. Methodology The model comprised of male Wistar rats that were on a high-fructose diet (HFD) (20% glucose-fructose corn syrup) for 12 weeks; the rats were divided into four groups (n = 8): control, HFD, HFD and melatonin supplementation (per os -4 mg/kg/24h), and control and melatonin supplementation. All rats received a standard rodent diet and tap water. Zoometric measurements and the Lee index were calculated. Morphometric analysis of the abdominal aorta was performed by staining with hematoxylin-eosin and measuring the thickness of the abdominal aortic wall. For this, we used the Aperio Image Scope software. To evaluate the functional properties of the abdominal aorta, the modified Kernogan's index (KI) was employed. Results The results showed significantly elevated body weight (Lee index), KI, and wall thickness of the aorta abdominalis with morphometric changes in the vessel wall in HFD rats compared to the control group. Melatonin supplementation prevented these changes. Conclusions The administration of HFD to Wistar rats led to pathomorphological and morphometric changes in their abdominal aorta, which constitute the main diagnostic criteria of endothelial dysfunction. Melatonin supplementation regressed vascular wall remodeling and restored its functional capacity.