Portal hypertension produces an evolutive hepato-intestinal pro- and anti-inflammatory response in the rat

Mast cell-mediated splanchnic cholestatic inflammation

INTRODUCTION

Splanchnic mast cells increase in chronic liver and in acute-on-chronic liver diseases. We administered Ketotifen, a mast cell stabilizer, and measured the mast cells in the splanchnic organs of cholestatic rats.

MATERIAL AND METHODS

These groups were studied: sham-operated rats (S; n = 15), untreated microsurgical cholestasic rats (C; n = 20) and rats treated with Ketotifen: early (SK-e; n = 20 and CKe; n = 18), and late (SK-l; n = 15 and CK-l; n = 14).

RESULTS

The cholestatic rats showed systemic and splanchnic impairments, such as ascites, portal hypertension, and biliary proliferation and fibrosis. The rats also showed a splanchnic increase of TNF-α, IL-1β and MCP-1, and a reduction of IL-4, IL-10 and antioxidants. An increase of VEGF in the ileum and mesenteric lymphatic complex was associated with a liver reduction of TGF-β1. Ketotifen reduces the degree of hepatic insufficiency and the splanchnic inflammatory mediators, as well as VEGF and TGF-ß1 levels. Ketotifen also reduces the connective tissue mast cells in the mesenteric lymphatic complex of cholestatic rats, while increases the hepatic mucosal mast cells.

CONCLUSIONS

In cholestatic rats, Ketotifen improves liver function and ascites, and also reduces pro-inflammatory mediators in the splanchnic area. The decrease in connective tissue mast cells in the mesenteric lymphatic complex due to the administration of Ketotifen would lead to the improvement of the inflammatory splanchnic response, and consequently the abovementioned complications.

Disease dependent qualitative and quantitative differences in the inflammatory response to ascites occurring in cirrhotics

AIM: To assess differing patterns and levels of ascitic fluid cyctokine and growth factors exist between those with a high risk and low risk of spontaneous bacterial peritonitis (SBP).

METHODS: A total of 57 consecutive patients with ascites requiring a large volume paracentesis were studied. Their age, gender, specific underlying disease conditions were recorded after a review of their clinical records. Each underwent a routine assessment prior to their paracentesis consisting of a complete blood count, complete metabolic profile and prothrombin time/international normalized ratio (INR) determination. The ascitic fluid was cultured and a complete cell count and albumin determination was obtained on the fluid. In addition, blood and ascitic fluid was assessed for the levels of interleukin interleukin (IL)-1A, IL-1B, IL-2, IL-4, IL-8, IL-10, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) utilizing the Randox Biochip platforms (Boston, MA). A serum-ascites gradient, for each cytokine and growth factor was calculated. The results are reported as mean ± SEM between disease groups with statistical analysis consisting of the student t-test (two tailed) with a P value of 0.05 defining significance.

RESULTS: No clinically important demographic or biochemical differences between the 4 groups studied were evident. In contrast, marked difference in the cytokine and growth factors levels and pattern were evident between the 4 disease groups. Individuals with alcoholic cirrhosis had the highest levels of IL-1A, IL-1B, IL-4, IFNγ. Those with malignant disease had the highest levels of IL-2. Those with hepatitis C virus (HCV) associated cirrhosis had the highest value for IL-6, IL-8, IL-10, MCP-1 and VEGF. Those with cardiac disease had the highest level of TNF-α and EGF. The calculated serum- ascites gradients for the cardiac and malignant disease groups had a greater frequency of negative values signifying greater levels of IL-8, IL-10 and MCP-1 in ascites than did those with alcohol or HCV disease.

CONCLUSION: These data document important differences in the cytokine and growth factor levels in plasma, ascitic fluid and the calculated plasma - ascites fluid gradients in cirrhotics requiring a large volume paracentesis. These differences may be important in determining the risk for bacterial peritonitis.

A wound-like inflammatory aortic response in chronic portal hypertensive rats

Long-term prehepatic portal hypertension in the rat produces a low-grade splanchnic inflammation with liver steatosis and dyslipidemia. It has been suggested that in this experimental model these inflammatory alterations could represent a risk factor of vascular disease. Therefore, our aim was to investigate whether long-term prehepatic portal hypertension (PH) induces vascular pathology, fundamentally inflammatory aortopathy. Male Wistar sham-operated (SO) rats and rats with triple partial portal vein ligation in the very long-term (22 months) of postoperative evolution were used. Serum lipid profile, pro- and anti- inflammatory cytokines and ACTH and corticosterone were assayed by spectrophotometric and ELISA techniques. Aorta mRNA expression of oxidative and nitrosative stress enzymes, NFκB e IκB, immune-related cytokine production and vascular fibrosis parameters, were evaluated by real time RT-PCR. In addition, aortic p22phox subunit immunostaining, morphometry and vascular fibrosis in aorta were analyzed. PH rats have increased serum cholesterol, triglyceride, low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), while high-density lipoproteins (HDL) were lower than in SO rats. Serum ACTH and corticosterone decreased in PH rats. Also, serum TNF-α, IL-1β and IL-6 were significantly higher in PH-rats. Portal hypertensive-rats showed aortic oxidative stress with increased mRNA expressions of NAD(P)H oxidase p22phox, XDh, SOD and eNOS; higher aortic levels of pro-inflammatory cytokines, including TNF-α, IL-1β and IL-6; remodeling markers, like collagen I, CTGF and MMP-9; and finally, higher protein production of p22phox and collagen and extracellular matrix density were significantly higher in rats with PH. The results from the current study suggest that very long-term prehepatic portal hypertension in rats induces an abdominal aortic inflammatory and fibrotic response. Therefore, it could be considered that portal hypertension aggravates aortic inflammaging and one of its more severe complications, which is remodeling by a wound healing reaction.

Gut-brain chemokine changes in portal hypertensive rats

BACKGROUND

Hepatic encephalopathy is a syndrome whose physiopathology is poorly understood; therefore, current diagnostic tests are imperfect and modern therapy is nonspecific. Particularly, it has been suggested that inflammation plays an important role in the pathogenesis of portal hypertensive encephalopathy in the rat.

AIM

We have studied an experimental model of portal hypertension based on a triple partial portal vein ligation in the rat to verify this hypothesis.

METHODS

One month after portal hypertension we assayed in the splanchnic area (liver, small bowel and mesenteric lymph nodes) and in the central nervous system (hippocampus and cerebellum) fractalkine (CX3CL1) and stromal cell-derived factor alpha (SDF1-α) as well as their respective receptors (CX3CR1 and CXCR4) because of their key role in inflammatory processes.

RESULTS

The significant increase of fractalkine in mesenteric lymph nodes (P<0.05) and its receptor (CX3CR1) in the small bowel (P<0.05) and hippocampus (P<0.01), associated with the increased expression of SDF1-α in the hippocampus (P<0.01) and the cerebellum (P<0.01) suggest that prehepatic portal hypertension in the rat induces important alterations in the expression of chemokines in the gut-brain axis.

CONCLUSION

The present study revealed that portal hypertension is associated with splanchnic-brain inflammatory alterations mediated by chemokines.

Bacterial translocation to mesenteric lymph nodes increases in chronic portal hypertensive rats

PURPOSE

Bacterial translocation is a frequent complication in portal hypertension related to cirrhosis in the human clinical area. The aim of this study was to verify the existence of intestinal bacterial translocation to mesenteric lymph nodes in male Wistar rats with triple partial portal vein ligation during short- (48 h) and long-term (1 month) postoperative evolution.

RESULTS

At 48 h, ileal total aerobes bacteria (p < 0.001) and Lactobacillus decrease in sham-operated (SO) and portal hypertensive (PH) rats. At 1 month, ileal Enterococci and Streptococcus sp. show a statistically significant decrease in SO- and PH-rats. Lactobacillus decreases in the colon in SO- (p < 0.01) and in PH-rats (p < 0.001). At 1 month, colonic Enterococci decreases compared to control (p < 0.001) and SO-rats (p < 0.01). These intestinal microfloral changes are associated with bacterial translocation to mesenteric lymph nodes at 48 h (50%; p = 0.004) and 1 month (100%; p < 0.001) of postoperative evolution in PH-rats.

CONCLUSIONS

The enlargement of the stenosed portal tract related to triple partial portal vein ligation in the rat, since it increases the resistance to the portal blood flow, may be a key factor involved in one of the pathological consequences of portal hypertension, as is bacterial translocation to mesenteric lymph nodes.

Expression of NALP3 in the spleen of mice with portal hypertension

This study examined the mRNA expression of NALP3 in the spleen of the mice with hypersplenism due to portal hypertension (PH). The mouse hypersplenism models were established by oral administration of tetrachloromethane (2 mL/kg/week for 12 weeks by oral gavage). All the mice were randomly divided into a control group and an experimental group. The blood routine test was conducted, spleen index was calculated and spleen was histologically examined. Portal vein sera were taken for detection of the level of uric acid. The mRNA expressions of NALP3 and IL-1beta in the spleen were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that the platelet count was significantly lower in the experimental group [(674 + or - 102) x 10(9)/L] than in the control group [(1307 + or - 181) x 10(9)/L] (P<0.05), while the spleen index was significantly higher [(9.83 + or - 1.36) microg/g] in the experimental group than in the control group [(4.11 + or - 0.47) microg/g] (P<0.05). The histopathological changes of spleen followed the pattern of congestive splenomegaly. No significant difference was found in the uric acid level in the portal vein between the control group and the experiment group. The mRNA expressions of NALP3 and IL-1beta were up-regulated significantly in the spleen in the experimental group as compared with those in the control group (P<0.05). It was concluded that NALP3 and IL-1beta may play important roles in the pathogenesis of hypersplenism.

Splanchnic Th(2) and Th(1) cytokine redistribution in microsurgical cholestatic rats

BACKGROUND

Long-term extrahepatic cholestasis in the rat induces ductular proliferation and fibrosis in the liver, portal hypertension, splenomegaly, portosystemic collateral circulation, and ascites. These splanchnic alterations could have an inflammatory pathophysiology.

MATERIAL AND METHODS

We measured serum levels of hepatobiliary injury markers and the acute phase proteins, alpha-1-major acid protein (alpha(1)-MAP) and alpha-1-acid glycoprotein (alpha(1)-GPA) in rats 6 wk after microsurgical extrahepatic cholestasis. We also assayed Th(1) (TNF-alpha and IL-1beta) and Th(2) (IL-4 and IL-10) cytokine levels in the liver, ileum, spleen, and mesenteric lymph complex by enzyme-linked immunosorbent assay (ELISA) techniques. Liver fibrosis was measured by Sirius red stain and by using an image system computer-assisted method and mast cell liver infiltration by Giemsa stain.

RESULTS

The cholestatic rats showed an increase (P<0.001) in serum levels of bile acids, total and direct bilirubin, AST, ALT, AST/ALT index, gamma-GT, alkaline phosphatase, alpha(1)- MAP, alpha(1)-GPA, and LDH (P<0.05) in relation to sham-operated rats. TNF-alpha, IL-1beta, IL-4, and IL-10 increased in the ileum (P<0.01) and mesenteric lymph complex (P<0.001), and decreased in the liver (P<0.001). A marked bile proliferation associated with fibrosis (P<0.001) and mast cell infiltration was also shown in the liver of cholestatic rats.

CONCLUSION

The splanchnic redistribution of cytokines, with an increase of Th(1) and Th(2) production in the small bowel and in the mesenteric lymph complex, supports the key role of inflammatory mechanisms in rats with secondary biliary fibrosis.

Advances in research on portal hypertensive enteropathy

Portal hypertensive enteropathy, whose fundamental pathologic change is a vasculopathy characterized histopathologically by mucosal and submucosal vessel dilatation, oedema and congestion, mainly results from a combination of increased intrahepatic vascular resistance and increased blood flow through the portal venous system. Though portal hypertensive enteropathy usually has non-specific clinical manifestations, it is a major cause of lower gastrointestinal bleeding. Up to now, there has been no standard for the diagnosis and grading of portal hypertensive enteropathy. Unfortunately, the experience of treatment for portal hypertensive enteropathy only comes from some small-sample trials. For these reasons, an in-depth study of portal hypertensive enteropathy is still necessary. In this article, we will review the advances in research on portal hypertensive enteropathy.

Ketotifen-loaded microspheres prepared by spray-drying poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) polymers: characterization and in vivo evaluation

Ketotifen (KT) was encapsulated into poly(D,L-lactide) (PLA) and poly(D,L-lactide-co-glycolide) (PLGA 50/50) by spray-drying to investigate the use of biodegradable drug-loaded microspheres as delivery systems in the intraperitoneal cavity. Ketotifen stability was evaluated by HPLC, and degradation was not observed. Drug entrapment efficiency was 74 +/- 7% (82 +/- 8 microg KT/mg for PLA) and 81 +/- 6% (90 +/- 7 microg KT/mg for PLGA 50/50). PLA microspheres released ketotifen (57% of encapsulated KT) in 350 h at two release rates (221 microg/h, 15 min to 2 h; 1.13 microg/h, 5-350 h). A quicker release of ketotifen took place from PLGA 50/50 microspheres (67.4% of encapsulated KT) in 50 h (322 microg/h, 15 min to 2 h; 16.18 microg/h, 5-50 h). After intraperitoneal administration (10 mg KT/kg b.w.), microsphere aggregations were detected in adipose tissue. Ketotifen concentration was determined in plasma by HPLC. The drug released from PLA and PLGA 50/50 microspheres was detected at 384 and 336 h, respectively. Noncompartmental analysis was performed to determine pharmacokinetic parameters. The inclusion of ketotifen in PLGA and PLA microspheres resulted in significant changes in the plasma disposition of the drug. Overall, these ketotifen-loaded microspheres yielded an intraperitoneal drug release that may be suitable for use as delivery systems in the treatment of inflammatory response in portal hypertension.

Chronic prehepatic portal hypertension in the rat: is it a type of metabolic inflammatory syndrome?

BACKGROUND

A progressive development of hepatic steatosis with an increase in the lipid hepatocyte content and the formation of megamitochondria have been demonstrated in rats with prehepatic portal hypertension. The aim of this study is to verify the existence of liver and serum lipid metabolism impairments in rats with long-term (2 years) portal hypertension.

METHODS

Male Wistar rats: Control (n = 10) and with prehepatic portal hypertension by triple partial portal vein ligation (n = 9) were used. Liver content of Triglycerides (TG), phospholipids (PL) and cholesterol and serum cholesterol, lipoproteins (HDL and LDL), TG, glucose and Lipid Binding Protein (LBP) were assayed with specific colorimetric commercial kits. Serum levels of insulin and somatostatin were assayed by RIA.

RESULTS

The liver content of TG (6.30 +/- 1.95 vs. 4.17 +/- 0.59 microg/ml; p < 0.01) and cholesterol (1.48 +/- 0.15 vs. 1.10 +/- 0.13 microg/ml; p < 0.001) increased in rats with portal hypertension. The serum levels of cholesterol (97.00+26.02 vs. 114.78 +/- 37.72 mg/dl), TG (153.41 +/- 80.39 vs. 324.39 +/- 134.9 mg/dl; p < 0.01), HDL (20.45 +/- 5.14 vs. 55.15 +/- 17.47 mg/dl; p < 0.001) and somatostatin (1.32 +/- 0.31 vs. 1.59 +0.37 mg/dl) decreased, whereas LDL (37.83 +/- 15.39 vs. 16.77 +/- 6.81 mg/dl; p < 0.001) and LBP (308.47 +/- 194.53 vs. 60.27 +/- 42.96 ng/ml; p < 0.001) increased.

CONCLUSION

Portal hypertension in the rat presents changes in the lipid and carbohydrate metabolisms similar to those produced in chronic inflammatory conditions and sepsis in humans. These underlying alterations could be involved in the development of hepatic steatosis and, therefore, in those described in the metabolic syndrome in humans.

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

The mast cell integrates the splanchnic and systemic inflammatory response in portal hypertension

Portal hypertension is a clinical syndrome that is difficult to study in an isolated manner since it is always associated with a greater or lesser degree of liver functional impairment. The aim of this review is to integrate the complications related to chronic liver disease by using both, the array of mast cell functions and mediators, since they possibly are involved in the pathophysiological mechanisms of these complications. The portal vein ligated rat is the experimental model most widely used to study this syndrome and it has been considered that a systemic inflammatory response is produced. This response is mediated among other inflammatory cells by mast cells and it evolves in three linked pathological functional systems. The nervous functional system presents ischemia-reperfusion and edema (oxidative stress) and would be responsible for hyperdynamic circulation; the immune functional system causes tissue infiltration by inflammatory cells, particularly mast cells and bacteria (enzymatic stress) and the endocrine functional system presents endothelial proliferation (antioxidative and antienzymatic stress) and angiogenesis. Mast cells could develop a key role in the expression of these three phenotypes because their mediators have the ability to produce all the aforementioned alterations, both at the splanchnic level (portal hypertensive enteropathy, mesenteric adenitis, liver steatosis) and the systemic level (portal hypertensive encephalopathy). This hypothetical splanchnic and systemic inflammatory response would be aggravated during the progression of the chronic liver disease, since the antioxidant ability of the body decreases. Thus, a critical state is produced, in which the appearance of noxious factors would favor the development of a dedifferentiation process protagonized by the nervous functional system. This system rapidly induces an ischemia-reperfusion phenotype with hydration and salinization of the body (hepatorenal syndrome, ascites) which, in turn would reduce the metabolic needs of the body and facilitate its temporary survival.

Evolutive phases of experimental prehepatic portal hypertension

Partial portal vein ligation is the experimental model most frequently used to study prehepatic portal hypertension. Different systemic and splanchnic biochemical and histological alterations in short-term (28-45 days) and long-term (12-14 months) evolutive phases which has been described in this experimental model suggest the existence of different pathophysiological mechanisms involved in their production. The enteropathy produced could develop in three phases: an early or acute phase with vasomotor hemodynamic alterations (ischemia-reperfusion associated with intestinal hyperemia, edema and oxidative stress); an intermediate phase with immunological alterations (mesenteric lymphadenopathy, increased mucosal infiltration by mast cells and the hepato-intestinal release of pro- and anti-inflammatory mediators); and a late or chronic phase with intestinal remodeling (vascular and epithelial). The alterations which are produced in these three evolutive phases make it possible to propose an inflammatory etiopathogeny for hypertensive portal enteropathy.

Partial portal vein ligation plus thioacetamide: a method to obtain a new model of cirrhosis and chronic portal hypertension in the rat

To obtain a new model of chronic portal hypertension in the rat, two classical methods to produce portal hypertension, partial portal vein ligation and the oral administration of thioacetamide (TAA), have been combined. Male Wistar rats were divided into four groups: 1 (control; n = 10), 2 [triple partial portal vein ligation (TPVL); n = 9], 3 (TAA; n = 11), and 4 (TPVL plus TAA; n = 9). After 3 months, portal pressure, types of portosystemic collateral circulation, laboratory hepatic function tests (aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase) and liver histology were studied. The animals belonging to group 2 (TPVL) developed extrahepatic portosystemic collateral circulation, associated with mesenteric venous vasculopathy without hepatic destructurization or portal hypertension. Animals from group 3 (TAA) developed cirrhosis and portal hypertension but not extrahepatic portosystemic collateral circulation, or mesenteric venous vasculopathy. Finally, the animals from group 4 (TPVL + TAA) developed cirrhosis, portal hypertension, portosystemic collateral circulation, and mesenteric venous vasculopathy. The association of TPVL and TAA can be used to obtain a model of chronic portal hypertension in the rat that includes all the alterations that patients with hepatic cirrhosis usually have. This could, therefore, prove to be a useful tool to study the pathophysiological mechanisms involved in these alterations.

The inflammatory bases of hepatic encephalopathy

A hypothesis about the inflammatory etiopathogeny mediated by astroglia of hepatic encephalopathy is being proposed. Three evolutive phases are considered in chronic hepatic encephalopathy: an immediate or nervous phase with ischemia-reperfusion, which is associated with reperfusion injury, edema and oxidative stress; an intermediate or immune phase with microglia hyperactivity, which produces cytotoxic cytokines and chemokines and is involved in enzyme hyperproduction and phagocytosis; and a late or endocrine phase, in which neuroglial remodeling, with an alteration of angiogenesis and neurogenesis, stands out. The increasingly complex trophic meaning that the metabolic alterations have in the successive phases making up this chronic inflammation could explain the metabolic regression produced in acute and acute-on-chronic hepatic encephalopathy. In these two types of hepatic encephalopathy, characterized by edema, neuronal nutrition by diffusion would guarantee an appropriate support of substrates, in accordance with the reduced metabolic needs of the cerebral tissue.

[Chronic inflammatory portal hypertensive enteropathy in the rat]

INTRODUCTION

Experimental portal hypertensive enteropathy could have an inflammatory etiopathogenesis and, if so, it would produce intestinal remodeling. The aim of this study was to test this hypothesis.

MATERIAL AND METHOD

Male Wistar rats with portal hypertension (PHT) produced by partial portal vein ligation were divided into four groups: group I (control; n = 9), group II (PHT; n = 8) at 3 months after surgery, group III (control; n = 8), and group IV (PHT; n = 10) at 1 year after surgery. The density of duodenal goblet cells and ileal levels of tumor necrosis factor (TNF)alpha, interleukin (IL)-1beta, and IL-10 were studied using an ELISA method.

RESULTS

At 3 months after surgery, rats with PHT showed an increase in the number of goblet cells in the small bowel (103.63 +/- 14.37 vs 99.42 +/- 19.19/1,000 microm2). This change was associated with an increase (p < 0.05) in ileal levels of TNFalpha (0.20 +/- 0.09 vs 0.08 +/- 0.02 pmol/mg protein), and IL-1beta (0.40 +/- 0.21 vs 0.19 +/- 0.09 pmol/mg protein), as well as with a decrease (p < 0.05) in ileal IL-10 levels (0.06 +/- 0.02 vs 0.12 +/- 0.03 pmol/mg protein). At 1 year after surgery, rats with PHT showed hyperplasia of goblet cells in the small bowel (172.79 +/- 40.46 vs 121.76 +/- 20.74 /1,000 microm2) (p < 0.01), associated with an increase in ileal levels of TNFalpha (0.37 +/- 0.18 vs 0.17 +/- 0.08 pmol/mg protein) (p < 0.05), IL-1beta (0.28 +/- 0.14 vs 0.205 +/- 0.05 pmol/mg protein), and IL-10 (0.25 +/- 0.14 vs 0.20 +/- 0.11 pmol/mg protein).

CONCLUSIONS

The increase in TNFalpha and IL-1beta levels and the decrease in IL-10 level in the small bowel in rats with chronic prehepatic PHT suggest the existence of an inflammatory process related to goblet cell hyperplasia. This inflammation could be responsible for the intestinal epithelial remodeling that occurs in the long term in this experimental model.

Hepatic lipid metabolism changes in short- and long-term prehepatic portal hypertensive rats

AIM: To verify the impairment of the hepatic lipid metabolism in prehepatic portal hypertension.

METHODS: The concentrations of free fatty acids, diacylglycerol, triglycerides, and phospholipids were assayed by using D-[U-¹⁴C] glucose incorporation in the different lipid fractions and thin-layer chromatography and cholesterol was measured by spectrophotometry, in liver samples of Wistar rats with partial portal vein ligation at short- (1 mo) and long-term (1 year) (i.e. portal hypertensive rats) and the control rats.

RESULTS: In the portal hypertensive rats, liver phospholipid synthesis significantly decreased (7.42 ± 0.50 vs 4.70 ± 0.44 nCi/g protein; P < 0.01) and was associated with an increased synthesis of free fatty acids (2.08 ± 0.14 vs 3.36 ± 0.33 nCi/g protein; P < 0.05), diacylglycerol (1.93 ± 0.2 vs 2.26 ± 0.28 nCi/g protein), triglycerides (2.40 ± 0.30 vs 4.49 ± 0.15 nCi/g protein) and cholesterol (24.28 ± 2.12 vs 57.66 ± 3.26 mg/g protein; P < 0.01).

CONCLUSION: Prehepatic portal hypertension in rats impairs the liver lipid metabolism. This impairment consists in an increase in lipid deposits (triglycerides, diacylglycerol and cholesterol) in the liver, accompanied by a decrease in phospholipid synthesis.

Prehepatic portal hypertension induces alterations in cytochrome oxidase activity in the rat adrenal gland

One approach to assess neuroendocrine response to portal hypertension in short-term portal vein-stenosed rats consists in studying metabolic and functional activity patterns in adrenal glands using mitochondrial enzyme cytochrome c oxidase (COX) as a histochemical marker. Male Wistar rats were divided into two groups: a control group (Group I; n = 8), in which the animals did not undergo any operative intervention, and a triple calibrated portal vein stenosis group (TPVS) (Group II; n = 7). The sections of suprarenal glands were histochemically stained for COX and the optical densitometry was measured by a computer image analyzer attached to a microscope. In TPVS rats, COX activity in the adrenal gland cortex is lower than in control rats and affects the fascicular (52.30, 47.16-60.98, vs. 67.12, 60.31-73.89, p = .002), glomerular (49.68, 46.19-53.56 vs. 70.47, 64.64-73.51, p < .001), and reticular (47.35, 35.63-54.39, vs. 55.37, 49.76-58.97; p < .05) layers. In contrast, COX activity in the adrenal gland medulla is similar in TPVS rats and in control rats (29.91, 29.54-31.18, vs. 29.67, 28.95-30.23). The changes in adrenocortical COX activity in short-term-TPVS rats could constitute a pathogenic factor for both splanchnic and systemic hyperdynamic circulations, described in this experimental model of prehepatic portal hypertension.

Role of ammonia and nitric oxide in the decrease in plasma prolactin levels in prehepatic portal hypertensive male rats

OBJECTIVES

Since very little is known about neuroendocrine changes that occur in portal-systemic hepatic encephalopathy, we studied plasma prolactin (PRL) levels and the involvement of hyperammonemia, nitric oxide (NO) and dopaminergic and adrenergic systems in the control of this hormone secretion in a male rat model of prehepatic portal hypertension (PH).

METHODS

We conducted in vivo studies to determine plasma ammonia and PRL levels. Dopamine (DA), dihydroxyphenylacetic acid (DOPAC), epinephrine and norepinephrine content in medial basal hypothalamus (MBH) and anterior pituitary (AP) were measured. In addition, NO synthase (NOS) activity and protein expression were evaluated in APs. In in vitro studies, the APs from intact rats were incubated with different doses of ammonia and PRL secretion was determined. In ex vivo studies, the APs from normal and PH rats were incubated in the presence of ammonia and/or a NOS inhibitor, NG-nitro-L-arginine-methyl ester (L-NAME) and PRL secretion was determined.

RESULTS

PH rats had a significant increase in plasma ammonia levels (p < 0.001) and a decrease in plasma PRL levels (p < 0.05). Neither DA nor DOPAC content or DOPAC/DA ratios were modified in both MBH and APs; however, we observed a significant increase in norepinephrine content in both MBH and AP (p < 0.001 and p < 0.05, respectively) and a significant increase in epinephrine in APs (p < 0.001). Moreover, PH produced an increase in NOS activity (p < 0.01) and NOS protein expression (p < 0.0001) in APs. The ammonia (100 microM) significantly reduced PRL secretion from APs in vitro (p < 0.05). The presence of L-NAME, an inhibitor of NOS, abrogated the inhibitory effect of ammonia on PRL secretion from APs from control and PH rats.

CONCLUSIONS

We found that plasma PRL levels were decreased in PH rats probably due to the high ammonia levels. The central noradrenergic system could also mediate this decrease. Also, the increase in NOS activity and/or content in AP induced NO production that directly inhibited PRL secretion from the AP, without the participation of the dopaminergic system.