1, showing

an abolishment of the AEA-induced inhibition of FA oxidation by SR141716 in a concentration-dependent selleck kinase inhibitor manner. Furthermore, the stimulatory effect of SR141716 on FA oxidation rates was maintained when measured in disrupted cells, suggesting that it was not exclusively the result of an increase in FA uptake by hepatocytes (Fig. 5B). In addition, the lower malonyl-CoA content (Fig. 5C) and the higher carnitine palmitoyltransferase I (CPT-I) mRNA levels (Fig. 5D) measured in slices treated with SR141716 are also consistent with an improvement of FA catabolism. To examine whether the beneficial effects of CB1R blockade on FA oxidation could also be applicable to the steatotic liver, we measured palmitic acid oxidation in liver slices from ob/ob mice. Interestingly, treating liver slices with SR141716 at 10 μM significantly increased ß-oxidation activity, both in the absence and in the presence of AEA (Fig. 5E), whereas a treatment with SR141716 at 100 nM was ineffective (data

not shown). In this experiment, AEA did not reduce ß-oxidation activity, likely because the latter was already very low in livers of ob/ob mice. In 21-hour treatment experiments, the activation of ß-oxidation induced by CB1R antagonism could result from long-term Temozolomide cell line metabolic adaptation involving the alteration of gene-expression levels. To further investigate this notion, the short-term effect of SR141716 on this parameter PTK6 was also tested. For this, ß-oxidation rates were measured

in liver slices from ob/ob mice, in which CB1R expression was high, in the presence or not of SR141716 and AEA for only 2 hours. AEA inhibited FA oxidation, and this effect was completely abolished by SR141716 for concentration values from 0.1 to 100 μM (Fig. 5F). Interestingly, SR141716 alone did not induced ß-oxidation activity in these short-term conditions. Given the central role of AMPK in regulating carbohydrate and lipid metabolism, we investigated whether blocking CB1R could affect the activation of AMPK. The kinetic data presented in Fig. 6 indicate that SR141716 was able to markedly induce the phosphorylation of AMPK during the first 15 minutes of exposition, compared to control. It has been proposed that overactivation of liver ECS promotes lipogenesis and induced steatosis,16, 27 which could contribute to the pathogenesis of nonalcoholic steatohepatitis, a common characteristic of overweight or obese patients with type 2 diabetes. Despite several studies showing that administration of CB1R antagonist is associated with a reduction of fatty liver,6, 13 only a few studies investigated the specific role of hepatic CB1R.16, 17, 27 This study provides evidence that hepatic CB1R have a major role in the molecular and enzymatic regulation of liver-energy metabolism.