Uloga kanabinoidnih CB1 receptora u patogenezi nealkoholne masne bolesti jetre izazvane dijetom bogatom mastima kod miševa

Abstract

Nealkoholna masna bolest jetre (NAFLD) obuhvata širok spektar bolesti jetre, od inicijalne steatoze do steatohepatitisa, koji može dalje da progredira do fibroze i ciroze jetre, uz mogućnost razvoja hepatocelularnog karcinoma. Ključnu ulogu u patogenezi NAFLD, na samom početku, ima insulinska rezistencija (IR) u masnom tkivu, koja povećava lipolizu i dopremanje masnih kiselina (MK) u jetru, a takođe utiče i na posrast de novo sinteze MK u heptocitima. Tako, najpre dolazi do razvoja steatoze, koja povećava osetljivost hepatocita na oštećenje dejstvom faktora aktivacije inflamatorne kaskade i fibrogeneze, dovodeći do dalje progresije bolesti u steatohepatitis i fibrozu jetre. Među ovim faktorima najznačajniji su oksidativni/nitrozativni stres, mitohondrijalna disfunkcija, lipotoksičnost, proinflamatorni citokini, kao i disbalans produkcije adipokina. Dosadašnja eksperimentalna i klinička istraživanja ukazala su na značajnu ulogu endokanabinoidnog sistema (ES) u razvoju NAFLD. U našoj studiji korišćena je dijeta bogata mastima (HFD, engl. high fat diet), koja izaziva strukturne, funkcionalne i metaboličke promene u jetri miševa slične ispoljavanjima NAFLD i metaboličkog sindroma u ljudi (porast nivoa oksidativnog i nitrozativnog stresa u hepatocitima, razvoj dislipidemije, IR, hepatičke steatoze, inflamacije i fibroze). Ciljevi ove disertacije su bili: da se ispita uloga kanabinoidnih CB1 receptora u patogenezi NAFLD sa posebnim osvrtom na ulogu u razvoju oksidativnog/nitrozativnog stresa, uticaj na kapacitet antioksidativne zaštite, kao i koncentraciju Zn, Cu, Mn i Fe u tkivu jetre; da se ispita uticaj CB1 receptora na lipidni status, profil MK u jetri (palmitinska, stearinska, oleinska, linoleinska i arahidonska kiselina), kao i adipokine (leptin, apelin, rezistin i visfatin) i proinflamatorne citokine (IL-6 i IFN-γ) u masnom tkivu i jetri; da se ispita uticaj blokade CB1 receptora na glikemiju, koncentraciju insulina i HOMA indeks. NAFLD je izazvana mužjacima miševa C57BL/6 soja, uzrasta 8 nedelja, primenom HFD. Pre samog eksperimenta sve životinje (n=40) bile su hranjene kontrolnom dijetom...

Non alcoholic fatty liver disease (NAFLD) encompasses a wide range of liver diseases from initial steatosis to steatohepatitis, which may further progress to liver fibrosis or cirrhosis and potentially develop hepatocellular carcinoma. At the very beginning, insulin resistance (IR) in adipose tissue has the key role in the NAFLD pathogenesis, increasing lipolysis and supply of fatty acids (FA) to liver and also affecting the increase of de novo synthesis of FA in hepatocytes. In this manner steatosis occurs first, increasing the sensitivity to the damage occurred due to the factors which activate inflammatory cascade and fibrogenesis and lead to further progression of the disease towards steatohepatitis and liver fibrosis. The most significant among these factors are oxidative/nitrosative stress, mitochondrial dysfunction, lipotoxicity, proinflammatory cytokines, as well as the adipokine production imbalance. Previous experimental and clinical research has emphasized the considerable role of the endocannabinoid system (ECS) in the development of NAFLD. In our study we used high fat diet (HFD) which causes structural, functional and metabolic changes in mouse liver similar to the manifestations of NAFLD and metabolic syndrome in humans (increased level of oxidative and nitrosative stress in hepatocytes, development of dyslipidemia, IR, hepatic steatosis, inflammation and fibrosis). The goals of this thesis were: to test the role of cannabinoid CB1 receptors in the pathogenesis of NAFLD with particular overview of their role in the development of oxidative/nitrosative stress, impact on the capacity of antioxidative protection, as well as Zn, Cu, Mn and Fe concentrations in liver tissue; to test the impact of CB1 receptors on the lipid profile, FA profile in liver (palmitic, stearic, oleic, linoleic and arachidonic), as well as adipokines (leptin, apelin, resistin and visfatin) and proinflammatory cytokines (IL-6 and IFN- γ) in adipose tissue and liver; to test the impact of blocking CB1 receptors on glycemia, insulin concentration and HOMA-IR index. HFD was applied on 8 weeks old male mice of C57BL/6 strain, which caused NAFLD to occur. Before the very experiment all the animals (n=40) were fed a control diet...