10, 11 An elevation of serum endothelin-1 has been noted in NASH, and has been positively related to the severity of liver fibrosis.12 An enhanced peripheral vasoconstrictive response to endothelin-1

has been widely reported in NASH patients and rats.12, 13 However, studies investigating Nutlin-3 research buy an enhanced intrahepatic vasoconstrictive response to endothelin-1 in NASH cirrhotic livers are still limited. Endocannabinoids are lipid mediators that increase in liver of diet-induced obesity models. Besides hyperleptinemia, an activated hepatic endocannabinoid system is significantly involved in the pathogenesis of NASH and cirrhosis.14, 15 Nonetheless, the relationship between hyperleptinemia, activated endocannabinoids system, aggravated hepatic steatosis, and fibrogenesis and increased IHR in NASH cirrhotic rats remains unclear. Collectively, our study aims to explore the possible contribution of hyperleptinemia to the pathogenesis of the endothelin-1 and endocannabinoids-mediated mechanisms that cause increased IHR and portal hypertension in NASH cirrhotic rats. HF/MCD, high fat/methionine-choline-deficient; PCI-32765 nmr HSC, hepatic stellate cells; IHR, intrahepatic resistance; NASH, nonalcoholic steatohepatitis; OBRb: leptin receptor. Detailed Materials

and Methods are provided in the Supporting Information. The Zucker rats, which bear a mutation (fa) in the leptin receptor (OBRb) gene, fed HF/MCD diets were used.4-6, 13 The HF/MCD diet used consisted of 37% calories

(Cal) from fat (corn oil), 24.5% Cal from protein (lactalbumin hydrolysate), and 38.5% Cal from carbohydrate (dextrose) together with vitamins and minerals (Dyets, Bethlehem, PA) deficient in methionine and choline as recommended. The normal diet was a paired feeding protocol that controlled calorie intake using a methionine choline-sufficient diet. Alanine-glyoxylate transaminase In the first series of studies (n = 8 in each group), two groups of 3-week-old Zucker rats and two groups of age-matched lean rats were fed either the HF/MCD or normal diet for 16 weeks. This resulted in four groups: HF/MCD-Zucker rats, normal-Zucker rats, HF/MCD-lean rats, and normal-lean rats. Among the above four groups, NASH cirrhotic livers and hyperleptinemia were only observed in the HF/MCD-Zucker rats. Thus, normal-Zucker rats, HF/MCD-lean rats, and normal-lean rats that were without NASH cirrhotic livers and hyperleptinemia served as the controls for this study. In a second series of studies, the exogenous administration of mouse endotoxin free recombinant leptin (100 μg/kg/day, intraperitoneal) was given to HF/MCD+leptin-lean and normal+leptin-lean rats (n = 6) in order to directly explore the leptin-related hepatic effects in rats that have intact OBRb. In our preliminary experiments, different durations (5, 7, 10, and 13 weeks) of leptin were administrated.