Cannabinoid type 1 receptor antagonism delays ascites formation in rats with cirrhosis.

OBJECTIVE

Endocannabinoids contribute to hemodynamic abnormalities of cirrhosis. Whether this favors renal sodium retention and ascites formation is unknown. We determined whether cannabinoid type 1 receptor antagonism prevents sodium retention and ascites formation in preascitic cirrhotic rats.

METHODS

Once renal sodium handling was impaired, rats with carbon tetrachloride-induced cirrhosis were randomized to receive either vehicle or rimonabant (3 [group 1] or 10 [group 2] mg x kg(-1) x day(-1)) for 2 weeks. Natriuresis, sodium intake, and sodium balance were measured daily. At the end of the protocol, systemic hemodynamics, renal blood flow, ascites volume, and liver fibrosis were assessed.

RESULTS

A significant reduction in ascites formation (group 1: 54%; group 2: 10%; vehicle: 90%) and volume (group 1: 1.6 +/- 0.3 mL; group 2: 0.5 mL; vehicle: 5.5 +/- 0.8 mL) occurred in treated rats. Rimonabant significantly improved sodium balance during week 2 (group 1: 0.98 +/- 0.08 mmol; group 2: 0.7 +/- 0.08 mmol; vehicle: 3.05 +/- 0.11 mmol). Both treated groups showed lower cardiac output and higher mean arterial pressure, peripheral vascular resistance, and renal blood flow (P < .05). Liver fibrosis was reduced in group 2 by 30% (P < .05 vs vehicle). Mean arterial pressure inversely correlated with sodium balance (R = -0.61; P = .003), but not with fibrosis score.

CONCLUSIONS

Rimonabant improves sodium balance and delays decompensation in preascitic cirrhosis. This is achieved though an improvement in systemic and renal hemodynamics, although it cannot be excluded that the antifibrotic effect of the drug may play a role.