Adaptive vasodilatory response after octreotide treatment

Electroacupuncture attenuates vascular hyporeactivity in a rat model of portal hypertension induced by bile duct ligation

BACKGROUND

A hyperdynamic circulation and impaired vascular responsiveness to vasoconstrictors are observed in portal hypertension (PHT) rats. Inflammation is a major contributor to the hyperdynamic circulation state in murine models of PHT. Electroacupuncture (EA) may ameliorate the inflammatory response and limit arterial vasodilatation and portal pressure. This study investigated the possible mechanisms underlying putative hemodynamics effects of EA in normal and PHT rats.

METHODS

PHT was induced by bile duct ligation (BDL) surgery over 4 weeks in rats. Sham-operated and BDL rats were treated with low-frequency EA (2 Hz) at ST36 10 min three times weekly for one or two consecutive weeks (for a total of 3 or 7 treatments, respectively). Serum tumor necrosis factor-α (TNF-α), nitrite/nitrate (NOx) and 6-keto-prostaglandin F1α (6-keto-PGF1α) were analyzed, and hemodynamic variation and contractile responses to phorbol-12,13-dibutyrate and phenylephrine in aortic and superior mesenteric arterial rings were recorded. Inducible (i) and endothelial (3) nitric oxide synthase (NOS), cyclooxygenase-1 (COX-1), and protein kinase C-α (PKC-α) levels were determined by Western blotting.

RESULTS

EA significantly reduced portal pressure and serum TNF-α, NOx and 6-keto-PGF1α levels compared to the untreated BDL group, enhanced maximum contractile responses in the aorta, up-regulated PKC-α, and down-regulated iNOS and COX-1 levels. In addition, EA decreased the aortic angiogenesis signaling cascade, reflected by down-regulation of vascular endothelial growth factor (VEGF) abundance and transforming growth factor β receptor (TGFβR)I/II expression, as assessed by immunostaining.

CONCLUSION

EA attenuates TNF-α, NO and 6-keto-PGF1α overproduction, modulates the vascular levels of constitutive NOS and PKC-α, blunts the development of the angiogenesis cascade, and enhances vascular contractile force in PHT rats.

Effect of Oral Administration of Weissella confusa on Fecal and Plasma Ethanol Concentrations, Lipids and Glucose Metabolism in Wistar Rats Fed High Fructose and Fat Diet

Background and Purpose

In previous investigations, Weissella confusa was shown to lack the metabolic pathway from fructose to mannitol and to produce ethanol when cultivated in the presence of fructose. Hence, we assessed the effect of oral administration of W. confusa (strain NRRL-B-14171) on blood and fecal ethanol concentrations, glucose and lipid metabolism and traits of the metabolic syndrome in Wistar rats (n=27) fed diets with two different fat and fructose levels and with or without the addition of W. confusa during a total intervention time of 15 weeks (105 days).

Materials and Methods

From week 1 to 6, rats were given a medium fructose and fat (MFru-MF) diet containing 28% fructose and 10% fat without the addition of W. confusa (control group, n=13) or mixed with 30 g per kg diet of lyophilized W. confusa (10.56 ± 0.20 log CFU/g; W. confusa group, n=14). From week 7 to 15, the percentage of dietary fructose and fat in the control and W. confusa group was increased to 56% and 16%, respectively (high fructose-high fat (HFru-HF) diet).

Results

In HFru-HF-fed rats, W. confusa was detected in feces, regardless of whether W. confusa was added to the diet or not, but not in rats receiving the MFru-MF diet without added W. confusa or in an additional control group (n=10) fed standard rat food without fructose, increased fat content and W. confusa. This indicates that fecal W. confusa may be derived from orally administered W. confusa as well as - in the case of high fructose and fat intake and obesity of rats - from the intestinal microbiota. As shown by multifactorial ANOVA, blood ethanol, the relative liver weight, serum triglycerides, and serum cholesterol as well as fecal ethanol, ADH, acetate, propionate and butyrate, but not lactate, were significantly higher in the W. confusa - compared to the control group.

Discussion

This is the first in vivo trial demonstrating that heterofermentative lactic acid bacteria lacking the mannitol pathway (like W. confusa) can increase fecal and blood ethanol concentrations in mammals on a high fructose-high fat diet. This may explain why W. confusa resulted in hyperlipidemia and may promote development of NAFLD in the host.

Effects of terlipressin and somatostatin on liver and thorax blood volumes in patients with cirrhosis

BACKGROUND

Variceal bleeding in cirrhosis can cause liver ischaemia and deteriorate the hyperdynamic state; thus, the effects of vasoconstrictor therapy on liver blood volume (LBV) and thorax blood volume (ThBV) are important.

AIM

To evaluate and compare the effects of terlipressin and somatostatin on LBV and ThBV in stable patients with cirrhosis and portal hypertension.

METHODS

Twenty patients were studied (Child-Pugh class A/B/C: 5/8/7). The radioactivities in the liver region (LRR) and the thorax region (ThRR) by single-head gamma camera technique, as indicators of LBV and ThBV, respectively, and systemic haemodynamics were measured at baseline and after intravenous infusion of 2 mg of terlipressin (n=10) or somatostatin 250 mg/h after an initial bolus of 250 mg (n=10).

RESULTS

LRR and ThRR decreased significantly with increasing severity of cirrhosis. Thirty minutes after terlipressin infusion, LRR and ThRR increased by 7.8 ± 4.4% (NS) and 14 ± 5.3% (P=0.01) compared with baseline values; the increase in ThRR was significantly related to the increase in LRR (r=0.682, P=0.03). In contrast, somatostatin reduced LRR and ThRR by 13.3 ± 6.5% (P=0.07) and 1 ± 4% (NS) respectively. LRR and ThRR increased significantly in the terlipressin group compared with the somatostatin group (P=0.01 and P=0.02 respectively). Terlipressin reduced cardiac output and heart rate (both P=0.01) and increased the mean arterial pressure (MAP) and systemic vascular resistance (P=0.009 and P=0.002 respectively); MAP decreased after somatostatin infusion (P=0.03).

CONCLUSIONS

Terlipressin, but not somatostatin, maintains LBV, increases ThBV and improves the hyperdynamic state in cirrhosis. These effects can be beneficial in variceal bleeding, particularly in patients with advanced liver disease.

Effects of N-acetylcysteine administration in hepatic microcirculation of rats with biliary cirrhosis

BACKGROUND/AIMS

Increased intrahepatic resistance (IHR) in cirrhosis is due to fibrosis and hepatic endothelial dysfunction (HED). Besides producing fibrosis, increased reactive oxygen species (ROS) promotes ROS-related nitration of anti-oxidative enzymes in cirrhotic livers. Tyrosine nitration (nitrotyrosilation)-related inactivation of anti-oxidative enzymes is increased in cirrhotic livers. This study investigates effects of N-acetylcysteine (NAC) administrations in bile-duct-ligation (BDL) rats.

METHODS

This study measured portal venous pressure (PVP), IHR, hepatic endothelial function, hepatic levels of anti-oxidants and oxidants, type III procollagen (PIIIP), proteins expression of thromboxane synthase (TXS), nitrotyrosine, manganese superoxide dismutase (MnSOD), and hepatic NOx and thromboxane A(2) (TXA(2)) production in perfusates.

RESULTS

The improvement of HED was associated with decreased PVP and IHR, hepatic protein and mRNA levels of PIIIP, protein expression of TXS and nitrotyrosine, oxidants and production of TXA(2) in NAC-treated BDL rat livers. Conversely, hepatic NOx production, anti-oxidants, and protein expression of MnSOD were increased in NAC-treated BDL rat livers.

CONCLUSIONS

In NAC-treated cirrhotic rats, the decrease in IHR was mainly caused by its anti-oxidative effect-related prevention of hepatic fibrogenesis associated with the decrease of oxidants-related nitrotyrosilation and improvement of HED.

The somatostatin analogue octreotide inhibits angiogenesis in the earliest, but not in advanced, stages of portal hypertension in rats

Background: Angiogenesis is an important determinant of the pathophysiology of portal hypertension contributing to the formation of portosystemic collateral vessels and the hyperdynamic splanchnic circulation associated to this syndrome. Somatostatin and its analogues, like octreotide, have been shown to be powerful inhibitors of experimental angiogenesis. Aim: To determine whether octreotide has angioinhibitory effects in portal hypertensive rats. Methods: Partial portal vein-ligated (PPVL) rats were treated with octreotide or vehicle during 4 or 7 days. Splanchnic neovascularization and VEGF expression were determined by histological analysis and western blotting. Expression of the somatostatin receptor subtype 2 (SSTR2), which mediates the anti-angiogenic effects of octreotide, was also analyzed. Formation of portosystemic collaterals (radioactive microspheres) and hemodynamic parameters were also measured. Results: Octreotide treatment during 4 days markedly and significantly decreased splanchnic neovascularization, VEGF expression by 63% and portal pressure by 15%, whereas portosystemic collateralization and splanchnic blood flow were not modified. After 1 week of octreotide injection, portal pressure was reduced by 20%, but inhibition of angiogenesis escaped from octreotide therapy, a phenomenon that could be related to the finding that expression of SSTR2 receptor decreased progressively (up to 78% reduction) during the evolution of portal hypertension. Conclusion: This study provides the first experimental evidence showing that octreotide may be an effective anti-angiogenic therapy early after induction of portal hypertension, but not in advanced stages most likely due to SSTR2 down-regulation during the progression of portal hypertension in rats. These findings shed light on new mechanisms of action of octreotide in portal hypertension.

An update on somatostatin receptor signaling in native systems and new insights on their pathophysiology

The peptide somatostatin (SRIF) has important physiological effects, mostly inhibitory, which have formed the basis for the clinical use of SRIF compounds. SRIF binding to its 5 guanine nucleotide-binding proteins-coupled receptors leads to the modulation of multiple transduction pathways. However, our current understanding of signaling exerted by receptors endogenously expressed in different cells/tissues reflects a rather complicated picture. On the other hand, the complexity of SRIF receptor signaling in pathologies, including pituitary and nervous system diseases, may be studied not only as alternative intervention points for the modulation of SRIF function but also to exploit new chemical space for drug-like molecules.

The effects of treatment with octreotide, diuretics, or both on portal hemodynamics in nonazotemic cirrhotic patients with ascites

GOALS

To evaluate the effects of diuretic treatment, octreotide, or both on portal hemodynamics in nonazotemic cirrhotic patients with ascites.

BACKGROUND

Diuretics and octreotide have been associated with a decrease in portal pressure in cirrhotic patients, suggested to be mediated by plasma volume depletion and splanchnic vasoconstriction, respectively. However, liver cirrhosis is characterized by activation of the renin-angiotensin-aldosterone axis, which increases hepatic vascular resistance and is augmented or suppressed by diuretics or octreotide, respectively.

STUDY

Twenty nonazotemic cirrhotic patients with ascites were treated with furosemide and spironolactone. Of them, 10 (group 1) discontinued diuretic treatment for 7 days. Thereafter for 5 days, each patient received subcutaneous octreotide, 300 microg twice per day; ten of them (group 2) received the octreotide in addition to their usual diuretic treatment. Portal and systemic hemodynamics with Doppler ultrasound and endogenous vasoactive systems were evaluated while the patients received diuretics (both groups), after discontinuation of diuretics (group 1), and after octreotide administration (both groups).

RESULTS

The withdrawal of diuretics did not alter portal hemodynamics, but it impaired systemic hemodynamics and suppressed the renin-aldosterone axis. The addition of octreotide to diuretic treatment but not octreotide alone improved portal and systemic hemodynamics. In both groups the initiation of octreotide administration suppressed the renin-aldosterone axis and plasma glucagon levels.

CONCLUSIONS

In nonazotemic cirrhotic patients with ascites, the combination of diuretics and octreotide improves systemic hemodynamics and inhibits the diuretic-related component of the activated renin-aldosterone axis, which in turn augments the portal hypotensive effect of diuretic-induced plasma volume depletion.

Effects of somatostatin, terlipressin and somatostatin plus terlipressin on portal and systemic hemodynamics and renal sodium excretion in patients with cirrhosis

BACKGROUND AND AIM

Terlipressin and somatostatin are the most preferable agents for the control of variceal bleeding in cirrhotic patients. The present study evaluated the hemodynamic effects of somatostatin, terlipressin and somatostatin plus terlipressin in cirrhotic patients with portal hypertension, as well as the effect of each regimen on renal sodium excretion.

METHODS

Twenty-four patients with esophageal varices were randomly assigned to receive either an intravenous infusion of a placebo (n = 12) or somatostatin 250 microg/h after an initial bolus of 250 microg (n = 12) for 60 min. Thereafter, each patient received an intravenous injection of terlipressin 2 mg while the intravenous infusion of either somatostatin or placebo was maintained. Portal and systemic hemodynamic parameters, assessed by Doppler sonography, and urinary sodium excretion were evaluated at baseline, 60 min after placebo or somatostatin, and 30 min after terlipressin.

RESULTS

Placebo had no effect on the patients studied. After terlipressin, portal vein velocity, portal flow volume and cardiac output (CO) significantly decreased (0.09 vs 0.15 m/s, 0.56 vs 1 L/min and 6.4 vs 7.6 L/min, respectively [values are medians]), while mean arterial pressure (MAP) and systemic vascular resistance significantly increased (103.3 vs 89.9 mmHg and 1541 vs 1108dyn.s/cm(5), respectively). Fractional sodium excretion significantly increased in patients without ascites (0.43 vs 0.16%) while it did not change in patients with ascites. Somatostatin did not alter portal hemodynamics whereas it significantly reduced MAP, heart rate (HR) and CO (86.9 vs 98.6 mmHg, 65 vs 73 bpm and 8.4 vs 9.1 L/min, respectively) and, in patients with ascites, sodium excretion (0.13 vs 0.23%). The addition of terlipressin to somatostatin induced similar changes to those observed after terlipressin alone. The magnitude of increase in MAP was significantly higher in patients receiving terlipressin alone than in those receiving somatostatin plus terlipressin (15 vs 5.3%), while CO was conversely affected (-28.5 vs-20.9%).

CONCLUSIONS

Combined treatment with somatostatin and terlipressin does not exert an additive portal hypotensive effect in cirrhotic patients as compared to terlipressin alone, whereas somatostatin alone may impair systemic hemodynamics. Compared with somatostatin, terlipressin exerts a more beneficial effect on renal sodium excretion in patients with or without ascites.

The effects of chronic treatment with octreotide versus octreotide plus midodrine on systemic hemodynamics and renal hemodynamics and function in nonazotemic cirrhotic patients with ascites

OBJECTIVES

The adrenergic agonist midodrine improved circulatory and renal dysfunction when acutely administered in nonazotemic cirrhotic patients with ascites while its combination with octreotide has recently been proposed as an effective treatment of type 1 hepatorenal syndrome (HRS). However, the effects of octreotide on systemic hemodynamics and renal function in cirrhotic patients are controversial. This study evaluated the effects of chronic treatment with octreotide versus octreotide plus midodrine on systemic hemodynamics and renal hemodynamics, and function in nonazotemic cirrhotic patients with ascites.

METHODS

Twenty-five patients were studied at baseline and 11 days after administration of subcutaneous octreotide 300 mug, b.i.d. alone (n = 12) or together with oral midodrine 7.5 mg, t.i.d. (n = 13).

RESULTS

Octreotide did not improve systemic hemodynamics whereas the addition of midodrine significantly decreased cardiac index (CI) and heart rate (HR), and increased mean arterial pressure (MAP) and systemic vascular resistance (SVR). Octreotide caused a decrease in renal vascular resistance (RVR) and increased renal blood flow (RBF) but significantly reduced glomerular filtration rate. The association of midodrine to octreotide did not modify renal hemodynamics and function as compared to baseline while it caused an almost significant minor increase in RVR and a significant minor decrease in RBF as compared to octreotide alone. Consequently, a significant minor increase in glomerular filtration rate was demonstrated. The plasma values of active renin, aldosterone, and glucagon were significantly reduced in either group.

CONCLUSIONS

Octreotide does not improve systemic hemodynamics in nonazotemic cirrhotic patients with ascites while it impairs renal function. On the other hand, the addition of midodrine can ameliorate the hyperdynamic circulation without inducing renal dysfunction in these patients.