Macrophage inflammatory protein-2 induced by TNF-alpha plays a pivotal role in concanavalin A-induced liver injury in mice.

BACKGROUND/AIMS: Macrophage inflammatory protein-2 (MIP-2), one of the CXC chemokines, is involved in the recruitment of neutrophils in several tissue injuries. In this study, we investigated the role of MIP-2 in concanavalin A (Con A)-induced liver injury in mice. METHODS: Liver injury was induced by intravenous injection of Con A (15 mg/kg) and plasma alanine aminotransferase (ALT), MIP-2 levels were determined and histological assessment of the liver was performed. Anti-mouse MIP-2 antibody was intravenously administered 30 min before Con A injection. RESULTS: The plasma ALT level significantly elevated and reached a maximum at 8 h after Con A injection. The plasma MIP-2 level was also elevated and reached a peak value at 2 h after Con A injection. The elevated ALT level by Con A injection was significantly inhibited by the MIP-2 antibody. The elevated plasma MIP-2 level after Con A injection was significantly reduced by the tumor necrosis factor alpha (TNF-alpha) antibody, and MIP-2 was induced in plasma after recombinant TNF-alpha injection. Hepatic necrosis and infiltration of neutrophils were observed after Con A injection, and these histological changes were attenuated by the MIP-2 antibody. CONCLUSIONS: These findings suggest that Con A induces TNF-alpha release, and this TNF-alpha stimulates MIP-2 induction, at least partially contributing to the liver injury mediated through the recruitment of neutrophils.

Role of calcitonin gene-related peptide and capsaicin-sensitive afferents in central thyrotropin-releasing hormone-induced hepatic hyperemia.

The involvement of capsaicin-sensitive afferent neurons and calcitonin gene-related peptide (CGRP) in the central thyrotropin-releasing hormone (TRH)-induced hepatic hyperemia was investigated in urethane anesthetized rats. Both systemic capsaicin pretreatment and intravenous administration of CGRP receptor antagonist, human CGRP-(8-37), completely abolished the stimulatory effect of hepatic blood flow induced by intracisternal injection of TRH analog (RX-77368; p-Glu-His-(3,3'-dimethyl)-Pro-NH2, 100 ng), assessed by the hydrogen gas clearance method. These data demonstrate the involvement of capsaicin-sensitive afferent neurons and CGRP in the central TRH-induced stimulation of hepatic blood flow.

Effect of ursodeoxycholic acid on autoimmune-associated chronic hepatitis C.

BACKGROUND: Hypergammaglobulinaemia and various auto-antibodies which are commonly seen in autoimmune hepatitis are also found in patients with chronic hepatitis C. We recently reported that ursodeoxycholic acid (UDCA) improved liver function tests and immunoserological markers in patients with type I autoimmune hepatitis. The aim of this study was to prospectively evaluate the efficacy of UDCA on autoimmune-associated chronic hepatitis C. METHODS: Immunoglobulin G (IgG), anti-nuclear antibodies (ANA) and anti-smooth muscle antibodies (ASMA) were determined in 95 patients with chronic hepatitis C. All patients were positive for hepatitis C virus RNA. Autoimmune-associated chronic hepatitis C (C-AIH) was defined by elevated serum IgG level (> or = 2.0 g/dL) and high titres of ANA and/or ASMA (> or = 1 : 160). Nine (9%) of 95 patients were diagnosed as C-AIH. All the C-AIH patients and 30 of the remaining 86 chronic hepatitis C patients without autoimmune features (CHC) were treated with UDCA (600 mg/day) for 1 year. RESULTS: Autoimmune-associated chronic hepatitis C patients included one man and eight women and their AIH scores, as defined by the International Autoimmune Hepatitis Group, were significantly higher than the CHC patients. Before UDCA therapy, there were no significant differences in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and y-glutamyl transpeptidase (gamma-GTP) levels between C-AIH and CHC patients. However, after 1 year UDCA therapy, AST, ALT and gamma-GTP were significantly lower in C-AIH patients (P< 0.05) than in CHC patients. In C-AIH, ANA titres in seven of nine patients and ASMA titres in five of seven patients were reduced after 1 year UDCA treatment. CONCLUSIONS: These results suggest that UDCA is a useful therapeutic agent for autoimmune-associated chronic hepatitis C.

Neuropeptide Y stimulates bile secretion via Y1 receptor in the left dorsal vagal complex in rats.

Neuropeptide Y (NPY) injected into the cerebrospinal fluid and the left dorsal vagal complex enhances bile acid-independent and bicarbonate-dependent bile secretion through vagal muscarinic pathways in animal models. NPY binds to and activates six different receptor subtypes, and NPY Y1 and Y2 receptors are distributed in the dorsal vagal complex. We sought to determine which NPY receptor subtypes are involved in central stimulation of bile secretion by examining the effect of microinjection of specific NPY receptor agonists into the dorsal vagal complex. The bile duct was cannulated in urethane-anesthetized and bile acid-compensated rats. After measuring basal secretion, NPY, peptide YY (PYY), [Leu31, Pro34]NPY, NPY(13-36), or NPY(3-36) was microinjected into the either right or left dorsal vagal complex and bile secretion was observed for 100 minutes. Hepatic branch vagotomy was performed 2 hours before the peptide injection. Microinjection of NPY and PYY (8 pmol) into the left dorsal vagal complex increased bile secretion. [Leu31, Pro34]NPY microinjected into the left dorsal vagal complex also dose-dependently (1-8 pmol) stimulated bile acid-independent and bicarbonate-dependent bile secretion. Microinjection of NPY(13-36) into the left dorsal vagal complex did not stimulate and NPY(3-36) dose-dependently inhibited bile secretion. Stimulation of bile secretion by [Leu31, Pro34]NPY was abolished by hepatic branch vagotomy. NPY acts in the left dorsal vagal complex to stimulate bile acid-independent and bicarbonate-dependent bile secretion via Y1 receptor subtype.

Efficacy of ursodeoxycholic acid in Japanese patients with type 1 autoimmune hepatitis.

Ursodeoxycholic acid (UDCA) has been shown to have beneficial effects on patients with primary biliary cirrhosis, suggesting that UDCA has immunomodulating effects. We investigated the effect of UDCA in patients with autoimmune hepatitis (AIH) which is characterized by immunological abnormalities. Eight patients with type 1 AIH were treated with 600 mg of UDCA per day for 2 years. Based on the criteria of the International Autoimmune Hepatitis Group, five patients were diagnosed as definite and three as probable type 1 AIH. Liver function tests were performed every 4 weeks, before and during UDCA therapy and the serum levels of anti-nuclear antibodies (ANA), smooth muscle antibodies (SMA), immunoglobulin G and gamma globulin were determined every 3 months. The levels of serum aspartate aminotransferase and alanine aminotransferase significantly decreased from 154 +/- 24 IU/L and 170 +/- 17 IU/L before UDCA therapy to 31 +/- 3 IU/L and 25 +/- 5 IU/L (P < 0.001) after 1 year of treatment and 28 +/- 2 IU/L and 23 +/- 4 IU/L (P < 0.001) after 2 years of treatment. After 2 years of treatment, the levels of serum immunoglobulin G and gamma globulin significantly decreased (P < 0.05) and ANA titres (5/8 patients) were reduced and SMA (3/5 patients) became negative. Furthermore, hepatic histopathological changes of four patients were assessed after 1 year of treatment, and an improvement of intrahepatic inflammation, but not fibrosis, was observed. In conclusion, these results suggest that UDCA has a beneficial therapeutic effect in patients with type 1 autoimmune hepatitis.

Effect of intracisternal thyrotropin-releasing hormone on hepatic blood flow in rats.

Central neuropeptides play a role in many physiological regulatory processes through the autonomic nervous system. Thyrotropin-releasing hormone (TRH) is distributed in the central nervous system and acts as a neurotransmitter to regulate gastric functions through vagal-muscarinic pathways. The central effect of the TRH analog on hepatic blood flow was investigated in urethan-anesthetized rats. Hepatic blood flow was determined by the hydrogen gas clearance technique. Intracisternal injection of the stable TRH analog RX-77368 (5-100 ng) dose dependently increased hepatic blood flow with peak response at 15 min after the peptide was administered (net change from basal for vehicle and 5, 10, 100, and 500 ng RX-77368 was 2.0 +/- 0.2, 8.9 +/- 0.8, 19.4 +/- 2.6, 32.6 +/- 3.3, and 28.5 +/- 6.8 ml.min-1.100 g-1, respectively), and this stimulatory effect returned to baseline at 90 min. The stimulation of hepatic blood flow by the intracisternally administered TRH analog was abolished by atropine methyl nitrate (0.15 mg/kg ip), indomethacin (5 mg/kg ip), NG-nitro-L-arginine methyl ester (10 mg/kg iv), and hepatic branch vagotomy but not by cervical spinal cord transection (C6 level). Intravenous injection of RX-77368 did not have any effect on hepatic blood flow. These results indicate that TRH acts in the central nervous system to stimulate hepatic blood flow through vagal-muscarinic and indomethacin- and nitric oxide-dependent pathways.

Central thyrotropin-releasing hormone stimulates hepatic DNA synthesis in rats.

Central neuropeptides play a role as physiological regulators in the autonomic nervous system. One of these neuropeptides, thyrotropin-releasing hormone (TRH), is distributed throughout the central nervous system (CNS) and acts as a neurotransmitter to regulate gastric functions through the vagus nerve. However, the autonomic nervous system is also involved in hepatic regeneration, but the effect of TRH is unknown. Therefore, the CNS's effect of TRH on hepatic DNA synthesis was studied in rats. Hepatic DNA synthesis was assessed by [Methyl-3H]thymidine incorporation 6, 12, 24, 48, and 72 hours after intracisternal injection of the TRH analog, RX 77368 (1, 5, 10, and 100 ng), and by 5-bromo-2'-deoxyuridine (BrdU) labeling of the liver section. Hepatic DNA synthesis was stimulated by intracisternal TRH analog (10 ng), with a peak response at 24 hours after peptide injection, and returned to baseline by 72 hours. This stimulatory effect by central TRH analog on hepatic DNA synthesis was dose-related, ranging from 1 ng to 10 ng (dpm/microg DNA at 24 hours [mean +/- SE]: saline, 95 +/- 6; 1 ng, 114 +/- 14; 5 ng, 318 +/- 57; 10 ng, 693 +/- 78; 100 ng, 710 +/- 135). Hepatocytes were randomly labeled by BrdU 24 hours after intracisternal TRH analog (10 ng). Intravenous TRH analog (10 ng) did not influence hepatic DNA synthesis. The stimulatory effect of TRH analog was blocked by hepatic branch vagotomy and atropine, but not by hepatic sympathectomy, 6-hydroxydopamine, insulin antibody, or hypophysectomy. These results indicate that TRH acts in the CNS to stimulate hepatic DNA synthesis through vagal and cholinergic mechanisms, and that TRH may be the chemical messenger involved in brain regulation of hepatic proliferation.

Neuropeptide Y in the dorsal vagal complex stimulates bicarbonate-dependent bile secretion in rats.

BACKGROUND & AIMS: Central administration of neuropeptide Y (NPY) enhances bile secretion through vagal pathways in animal models. NPY nerve fibers and receptors are localized in the dorsal vagal complex (DVC), and retrograde tracing techniques have shown that hepatic vagal nerves are projected mainly from the left DVC. However, nothing is known about the central sites of action for NPY to elicit bile secretion. The medullary sites of the action for NPY were investigated in this study. METHODS: The bile duct was cannulated in urethane-anesthetized and bile acid-compensated rats. After measuring basal secretion, NPY was microinjected into the DVC and bile response was observed for 100 minutes. Either left or right cervical vagotomy or hepatic branch vagotomy was performed 2 hours before the peptide. RESULTS: Microinjection of NPY (7-30 pmol) into the left DVC, but not the right DVC, dose-dependently increased bile acid-independent and bicarbonate-dependent bile secretion. Stimulation of bile secretion by NPY was eliminated by left cervical and hepatic branch vagotomy but not by right cervical vagotomy. CONCLUSIONS: NPY acts in the left DVC to stimulate bile acid-independent and bicarbonate-dependent bile secretion through the left cervical and hepatic vagus; these findings suggest that neuropeptides may act in the specific brain nuclei to regulate hepatic function.

Increase of sulfated ursodeoxycholic acid in the serum and urine of patients with chronic liver disease after ursodeoxycholic acid therapy.

The present study was undertaken in order to investigate the influence of ursodeoxycholic acid (UDCA) on the composition of sulfate-conjugated bile acids in the serum and urine of patients with chronic active hepatitis and compensated liver cirrhosis. After a 12 week UDCA treatment (600 mg/day), total serum bile acid concentration increased two-fold in patients with compensated liver cirrhosis and increased slightly in patients with chronic active hepatitis. The percentage of sulfated bile acids significantly increased in patients with both compensated liver cirrhosis and chronic active hepatitis. UDCA made up 63% of the total serum bile acids in compensated liver cirrhosis and 61% in chronic active hepatitis after UDCA treatment. Of the serum bile acids after UDCA treatment, 35.2 and 53.9% of UDCA was sulfate conjugated in compensated liver cirrhosis and chronic active hepatitis, respectively. Urinary excretion of total bile acid and UDCA after UDCA treatment in compensated liver cirrhosis were higher than in chronic active hepatitis. UDCA made up 68% of the total urinary bile acids in compensated liver cirrhosis and 64% in chronic active hepatitis after UDCA treatment. Of the urinary bile acids after UDCA treatment, 51.8 and 54.8% of UDCA was sulfate conjugated in compensated liver cirrhosis and chronic active hepatitis, respectively. UDCA treatment for compensated liver cirrhosis was less effective than for chronic active hepatitis. We found that sulfate conjugation is one of the major metabolic pathways for UDCA after UDCA treatment in chronic liver diseases.

Rapid gastric emptying and pathological changes of vagus nerve in the spontaneously diabetic Chinese hamster.

To estimate autonomic neuropathy in the spontaneously diabetic Chinese hamster, which is an established strain for the non-obese non-insulin-dependent diabetes mellitus model, gastric emptying and morphometric analysis of the vagus nerve were studied in 12-month-old spontaneously diabetic Chinese hamsters (duration of diabetes was 9 months). Gastric emptying was determined by the phenol red method. Vagus was obtained from just above the diaphragm. Morphometric analysis of myelinated fibers was performed light-microscopically using semi-thin sections and unmyelinated fibers were studied electron-microscopically using ultra-thin sections. Gastric emptying of spontaneously diabetic Chinese hamster was significantly increased compared with control (86.6 +/- 1.9 vs. 51.2 +/- 3.4, P < 0.01). Myelinated fibers of the spontaneously diabetic Chinese hamster were not different from control animals, while the size of unmyelinated fibers in the spontaneously diabetic Chinese hamster was significantly decreased. These data suggest that pathological changes in unmyelinated fibers, which consist mainly of afferent fibers, might play a role in gastric motor dysfunction in the spontaneously diabetic Chinese hamster.

Central neuropeptide Y enhances bile secretion through vagal and muscarinic but not nitric oxide pathways in rats.

Neuropeptide Y (NPY) acts in the central nervous system to regulate gastrointestinal functions in rats and dogs. The effects of intracisternal injection of NPY on bile secretion and biliary components were investigated in urethane-anesthetized rats with bile duct cannula. Intracisternal NPY (0.02-0.12 nmol) dose-dependently increased bile secretion by 9.2-19.5%. The secretory response occurred within the first 20-40 min and lasted for the 120-min observation period. Intravenous injection of NPY (0.12 nmol) did not modify bile secretion under identical conditions. Biliary bile acid, phospholipid, and cholesterol secretion were not modified by intracisternal injection of NPY (0.12 nmol), whereas bicarbonate was increased by 19.0 +/- 1.7% from 40 to 120 min after NPY injection. Cervical cord transection at the C6 level, acute bilateral adrenalectomy (-120 min), or injection of NG-nitro-L-arginine methyl ester (10 mg/kg, IV, -15 min), an inhibitor of nitric oxide biosynthesis, did not alter intracisternal NPY (0.12 nmol)-induced stimulation of bile secretion. Atropine (2.0 mg/kg, IP, -30 min) and bilateral cervical vagotomy (-120 min) completely abolished the stimulatory effect of intracisternal NPY (0.12 nmol) on bile secretion. These findings indicate that NPY acts in the brain to stimulate bicarbonate-dependent bile secretion through vagal and muscarinic pathways and suggest that peptides in the central nervous system may be involved in the vagal regulation of bile secretion.