Chronic administration of octreotide ameliorates portal hypertension and portal hypertensive gastropathy in rats with cirrhosis

A 3-month course of long-acting repeatable octreotide (sandostatin LAR) improves portal hypertension in patients with cirrhosis: a randomized controlled study

OBJECTIVE

In patients with cirrhosis, acute octreotide administration may transiently decrease the hepatic venous pressure gradient (HVPG). Information on long-term effects of octreotide is limited and controversial. We evaluated portal and systemic hemodynamics following a prolonged administration of long-acting octreotide in patients with cirrhosis.

METHODS

Eighteen cirrhotic patients (alcoholic 12; age 55 yr [44-69]; Pugh's score 7.8; HVPG 17.3 mmHg [12-22]), no steatohepatitis on histology, were randomized to intramuscular octreotide 20 mg (group A) q 4 wk for 3 months or placebo (group B) in a double-blind fashion. At baseline and 3 months, we measured the HVPG, systemic hemodynamics, endothelin-1 (ET-1), and vascular endothelial growth factor (VEGF) in hepatic venous blood.

RESULTS

Patients remained compensated except for one episode of infection in each group. At 3 months, the HVPG decreased in group A but not in group B (16.5 +/- 1.3 to 11.8 +/- 1.5 mmHg, P < 0.01; 18.2 +/- 1 to 17 +/- 1.1 mmHg, P= 0.4). Systemic hemodynamics and liver function remained unchanged. In group A, but not in group B, VEGF decreased (21.2 +/- 4.7 to 13.7 +/- 3.5 pg/mL, P < 0.01; 22.5 +/- 7.8 to 19.2 +/- 5.4 pg/mL, P= 0.4). ET-1 remained stable. Changes in HVPG and VEGF were correlated (r = 0.49, P < 0.05).

CONCLUSIONS

Three months of long-acting octreotide in selected cirrhotic patients with portal hypertension decreases the HVPG independent of systemic hemodynamics and liver function. The decrease in VEGF blood levels suggests an improvement in splanchnic hyperemia.

Lanreotide on collateral response to endothelin-1 and vasopressin in cirrhotic rats

BACKGROUND

Portosystemic collaterals in cirrhosis are often complicated with hemorrhage. Endothelin-1 (ET-1) and arginine vasopressin (AVP) have been shown to directly constrict collaterals of portal hypertensive rats. Furthermore, octreotide, a long-acting somatostatin analog, enhances ET-1-related collateral vasoconstriction if administered in the perfusate before ET-1 incubation. However, long-term effects of somatostatin analogs on collateral response to ET-1 and AVP remain unclarified. This study investigated the effects of lanreotide (a longer-acting somatostatin analog when compared with octreotide) on the portosystemic collateral vascular reactiveness to ET-1 and AVP in cirrhotic rats.

METHODS

Liver cirrhosis was induced in Sprague-Dawley rats by common bile duct ligation (BDL). On the 33rd day after BDL, rats received 1 intramuscular injection with lanreotide (10 mg/kg) or distilled water. On the 43rd day after BDL, systemic, and portal hemodynamics were evaluated. By an in situ perfusion model, ET-1 (10(-10) - 10(-7) mol/L) and AVP (10(-10) - 3 x 10(-7) mol/L) were applied to assess the collateral responses.

RESULTS

Heart rate, mean arterial pressure, and portal pressure were not modified by lanreotide. Lanreotide pretreatment enhanced collateral vascular response to ET-1 and reached statistical significance at 10(-7) mol/L without inducing changes to AVP.

CONCLUSION

Lanreotide augmented the collateral vascular responsiveness to ET-1 but not to AVP in cirrhotic rats.

EFFECT OF ISOSORBIDE DINITRATE ON GASTRIC BLOOD FLOW IN RATS WITH LIVER CIRRHOSIS DETERMINED BY ANALYZING GASTRIC BLOOD FLOW, PORTAL VEIN PRESSURE AND BLOOD GAS

We investigated the effects of isosorbide dinitrate (IDN) on gastric blood flow (GBF), portal venous pressure (PVP) and blood gas of rats with liver cirrhosis (LC) accompanied by portal hypertension. Thirty male Wistar rats (LC in 17 and normal in 13) were used. Before and after IDN administration, GBF, PVP and blood gas in the femoral artery and portal vein were measured. Portal blood oxygen concentration was estimated by calculating the ratio of PO2 in portal blood and that in arterial blood (PpvO2/PaO2) of each rat. The GBF in the LC rats was significantly lower than that in the normal rats. In the LC group, IDN administration significantly increased the GBF. The PpvO2/PaO2 value in the group with LC was significantly lower after IDN administration than that before IDN administration. In the investigation whether changes in PVP or Ppv/PaO2 contributed more to the change in GBF after IDN administration, a significant correlation was found between rates of change in GBF and PpvO2/PaO2 were significantly correlated (r= -0.733, p <0.05). The effect of IDN on changes in the stomach accompanying portal hypertension is mainly attributable to a decrease in preload, which suppresses inflow to the stomach, as reflected by a decrease in PpvO2/ PaO2, rather than to a decrease in afterload on GBF, as reflected by a decrease in PVP.

Role of acute elevation of portal venous pressure by exogenous glucagon on gastric mucosal injury in rats with portal hypertension

Time-course studies revealed the increased susceptibility of the gastric mucosa to noxious injury in portal hypertension correlates with the level of elevated portal venous pressure and hyperglucagonemia. Whether acute elevation of portal venous pressure by exogenous glucagon aggravates such injury is not known. We tested the hypothesis that glucagon in a dose sufficient to acutely elevate portal venous pressure aggravates noxious injury of the gastric mucosa in rats with portal hypertension. Infusion of a portal hypotensive dose of somatostatin should reverse these changes. In anesthetized rats with portal vein ligation, glucagon, somatostatin or the combination was administered intravenously in a randomized, coded fashion. Acidified ethanol-induced gastric mucosal injury was determined. Portal venous pressure and gastric mucosal perfusion and oxygenation (reflectance spectrophotometry) were monitored to confirm the effects of the respective intravenous treatments. Exogenous glucagon exacerbated acidified ethanol-induced gastric mucosal injury. The exacerbation was attenuated by somatostatin. These changes paralleled the portal hypertensive and hypotensive effects of glucagon and somatostatin, respectively. Our data suggest that a unique mechanism is triggered with the onset of portal hypertension. In an antagonistic manner, glucagon and somatostatin modulate this novel mechanism that controls portal venous pressure and susceptibility of the gastric mucosa to noxious injury.

Adaptive vasodilatory response after octreotide treatment

Despite the suppression of glucagon release, an adaptive response aimed at maintaining vasodilatation after octreotide treatment may exist in portal hypertension. The present study was undertaken to evaluate the possible interaction between endothelium and non-endothelium-derived vasodilators after 1-wk octreotide administration in cirrhotic rats. Rats were allocated to receive either vehicle or octreotide (30 or 100 microg/kg every 12 h subcutaneously). Hemodynamic values, plasma glucagon levels, endothelium-related vasodilatory activities, and aortic endothelial nitric oxide synthase (eNOS) expression were determined after treatment. Octreotide administration decreased plasma glucagon and increased serum 6-keto-PGF(1 alpha) and NOx levels without affecting the hemodynamic values. In cirrhotic rats receiving octreotide, there was a blunt response to either L-NAME or indomethacin administration alone, but this blunt pressor response disappeared after simultaneous administration of the two drugs. Additionally, an increased aortic eNOS expression was observed in cirrhotic rats receiving 1-wk octreotide. It is concluded that 1-wk octreotide treatment did not correct the hemodynamic derangement in cirrhotic rats. The enhanced endothelium-related vasodilatory activity was noted after octreotide treatment that overcame the octreotide-induced hemodynamic effects in portal hypertension.