Nicotine-Induced Morphological Changes in Rat Aorta: The Protective Role of Melatonin

Abstract

We analyzed the morphological changes in rat aortas during nicotine administration in order to investigate the involvement of vascular smooth muscle cells (VSMCs) in the regulation of vascular wall homeostasis. We also considered the possibility of restoring VSMC changes using melatonin as an antioxidant. We studied 4 groups of animals over 56 days. Three groups of rats were used as controls (the first without treatment, the second with melatonin alone and the third with nicotine alone). The last group of rats was orally treated with nicotine for the first 28 days and with melatonin for the last 28 days. Morphological changes in vessels were evaluated by histological procedures and immunohistochemical analysis using thrombospondin-1 (TSP-1), transforming growth factor-β1 (TGF-β1), plasminogen activator inhibitor-1 (PAI-1) and CD31 antibodies. We demonstrated that TSP-1, TGF-β1 and PAI-1 increased after nicotine administration. We believe that TSP-1 is responsible for neointima formation and that it is able to influence TGF-β1 and PAI-1 expression. Histological and immunohistochemical analysis by CD31 antibody showed that only a few endothelial cells were present in the aorta after nicotine administration compared to controls and rats treated with melatonin after nicotine administration. Moreover, histological analysis showed that neointima formation was present after nicotine treatment. Furthermore, melatonin inhibited neointima formation increasing TSP-1 expression. The ability of melatonin to inhibit neointima formation suggests that it could be a useful treatment for homeostasis of vascular walls.

RETRACTED: Sirtuin1 Role in the Melatonin Protective Effects Against Obesity-Related Heart Injury

“…Alternate heart paraffin sections were deparaffinized, rehydrated, and then incubated with the following primary antibodies: polyclonal anti-rabbit PGC-1α (diluted 1:400; Abcam, Cambridge, United Kingdom), monoclonal anti-mouse heme oxygenase-1 (HO-1) (diluted 1:400; Abcam, Cambridge, United Kingdom), polyclonal anti-rabbit Nrf2 (diluted 1:150; Abcam, Cambridge, United Kingdom), polyclonal anti-rabbit nucleotide oligomerization domain like receptor 3 (NLRP3) inflammasome (diluted 1: 600; Novus Biologicals, Abingdon, United Kingdom), polyclonal anti-goat TNF-α (diluted 1:300; Santa Cruz Biotechnology, Santa Cruz, CA, United States), and polyclonal anti-goat IL-6 (diluted 1:200; Santa Cruz Biotechnology, Santa Cruz, CA, United States). After washing, the sections were labeled with specific Alexa Fluor conjugated secondary antibodies (diluted 1:200; Invitrogen-Thermo Fisher Scientific, IL, United States) (Rodella et al, 2010(Rodella et al, , 2012. Finally, the sections were counterstained with 4 -6-diamidino-2phenylindole (DAPI), mounted and observed with fluorescent microscopy (i50 Eclipse, Nikon, Hamburg, Germany) at a final magnification of 400× .…”

Endothelium and Its Alterations in Cardiovascular Diseases: Life Style Intervention

“…Moreover, melatonin was demonstrated to prevent tissue injury and structural and functional alterations in the vasculature induced by cigarette smoking. Our research group observed and confirmed that melatonin minimized the damage induced by nicotine, reestablished the physiological balance between vasodilatation (increasing eNOS) and vasoconstriction (decreasing ET-1), induced antioxidant enzymes, and downregulated adhesive molecules on ECs [46, 220, 221]. …”

“…Our research group demonstrated that the administration of nicotine in rats depleted the bioavailability of NO, increased ROS, and damaged the structural integrity of aortic endothelium inducing cardiovascular disorders. The possible mechanism proposed to explain the damage of nicotine was the disruption of the physiological balance of vascular tone, the increased expression of ET-1, inducible NOS, and the reduced expression of eNOS and so NO and SOD [220, 221]. Furthermore, we observed both an increase in ICAM-1 and VCAM-1 expression that induced, in turn, the adhesion of monocytes and lymphocytes at EC level promoting the formation of the atherosclerotic lesion [46].…”

Thrombospondin-1 mediates oncogenic Ras–induced senescence in premalignant lung tumors

“…Interestingly, chronic cigarette smoke exposure increases TSP-1 expression, apoptotic cell numbers, and parenchymal cell loss, which are characteristics of emphysema development (62). In addition, Rezzani and colleagues have shown that nicotine upregulates TSP-1 expression in rat aortas, which suggests that TSP-1 can be a biomarker for smoking cessation (63). Our present findings revealed a novel role of TSP-1 as a tumor suppressor mediating oncogenic Ras-induced senescence with potentially significant clinical implications.…”