Circulating levels of neuropeptides (CGRP, VIP, NPY) in patients with fulminant hepatic failure

Neuropeptide Y inhibits biliary hyperplasia of cholestatic rats by paracrine and autocrine mechanisms

Neuropeptide Y (NPY) exerts its functions through six subtypes of receptors (Y₁-Y₆). Biliary homeostasis is regulated by several factors through autocrine/paracrine signaling. NPY inhibits cholangiocarcinoma growth; however, no information exists regarding the autocrine/paracrine role of NPY on biliary hyperplasia during cholestasis. The aims of this study were to determine: 1) the expression of NPY and Y₁-Y₅ in cholangiocytes and 2) the paracrine/autocrine effects of NPY on cholangiocyte proliferation. Normal or bile duct ligation (BDL) rats were treated with NPY, neutralizing anti-NPY antibody, or vehicle for 7 days. NPY and NPY receptor (NPYR) expression was assessed in liver sections and isolated cholangiocytes. NPY secretion was assessed in serum and bile from normal and BDL rats, as well as supernatants from normal and BDL cholangiocytes and normal rat cholangiocyte cell line [intrahepatic normal cholangiocyte culture (NRICC)]. We evaluated intrahepatic bile ductal mass (IBDM) in liver sections and proliferation in cholangiocytes. With the use of NRICC, the effects of NPY or anti-NPY antibody on cholangiocyte proliferation were determined. The expression of NPY and all NPYR were increased after BDL. NPY levels were lower in serum and cholangiocyte supernatant from BDL compared with normal rats. NPY secretion from NRICC was detected at both the basolateral and apical domains. Chronic NPY treatment decreased proliferating cellular nuclear antigen (PCNA) expression and IBDM in BDL rats. Administration of anti-NPY antibody to BDL rats increased cholangiocyte proliferation and IBDM. NPY treatment of NRICC decreased PCNA expression and increased the cell cycle arrest, whereas treatment with anti-NPY antibody increased proliferation. Therapies targeting NPY-mediated signaling may prove beneficial for the treatment of cholangiopathies.

Progress in understanding the role of vasoactive intestinal polypeptide in the pathogenesis of digestive diseases

Vasoactive intestinal polypeptide (VIP) is not only a gastrointestinal hormone but also a neuropeptide. It is an important brain-gut peptide that relates to many disciplines such as physiology, biochemistry, cell biology, molecular biology, neurology, and immunology. It is distributed in the liver, biliary tract, pancreas, and gastrointestinal tract, and has close relationship with digestive diseases. In pathological states, VIP was degraded slowly. Once its content and receptor sensitivity change, multiple diseases, especially secretory function disorders of the digestive system, may be caused. This article summarizes the characteristics and functions of VIP as well as its relationship with the pathogenesis of digestive diseases.

Roles of vascular mediators in the pathogenesis of hepatopulmonary syndrome in rats

AIM: To explore the roles of endothelin-1 (ET-1), nitric oxide (NO) and calcitonin gene-related peptide (CGRP) in the pathogenesis of hepatopulmonary syndrome (HPS) in rats.

METHODS: Thirty-two male Wistar rats were randomly and averagely divided into 4 groups: sham operation group, common bile duct ligation (CBDL) 3-wk group, CBDL 4-wk group and CBDL 5-wk group. HPS model was induced by CBDL. Liver function and pathological changes of liver and lung were observed. The concentrations of ET-1 and CGRP in plasma, liver and lung tissues were detected by radioimmunoassay (RIA) and the NO content in serum, liver and lung tissues was measured with nitrate reductase method.

RESULTS: During the pathogenesis of HPS, liver was damaged with inflammation and fibrous hyperplasia. Fibrosis caused the formation of false lobules. Lung structural alterations such as alveolar capillary dilation and angiogenesis, thickened alveolar septa and decreased alveolar capacity were observed. The levels of ET-1, NO and CGRP in plasma, liver and lung tissues were gradually increased from the 3rd to 5th wk after CBDL, which were positively correlated with alanine aminotransferase level (plasma, ET-1: r = 0.9889, P = 0.0111; NO: r = 0.9935, P = 0065; CGRP: r = 0.9714, P = 0.0286; liver tissue: r = 0.9969, P = 0.0035; r = 0.9993, P = 0.0070; r = 0.9507, P = 0.0493; lung tissue: r = 0.9939, P = 0.0061; r = 0.9991, P = 0.0009; r = 0.9557, P = 0.0443).

CONCLUSION: The levels of ET-1, NO and CGRP in plasma, liver and lung are increased markedly during the process of HPS formation, suggesting that vascular mediators such as ET-1, NO and CGRP may play important roles in the pathogenesis of HPS.

Role of the nitric oxide pathway and the endocannabinoid system in neurogenic relaxation of corpus cavernosum from biliary cirrhotic rats

BACKGROUND AND PURPOSE

Relaxation of corpus cavernosum, which is mediated by nitric oxide (NO) released from non-adrenergic non-cholinergic (NANC) neurotransmission, is critical for inducing penile erection and can be affected by many pathophysiological conditions. However, the peripheral effect of liver cirrhosis on erectile function is as yet unknown. The aim of the present study was to investigate the effect of biliary cirrhosis on NANC-mediated relaxation of rat corpus cavernosum and the possible roles of endocannabinoid and nitric oxide systems in this model.

EXPERIMENTAL APPROACH

Cirrhosis was induced by bile duct ligation. Controls underwent sham operation. Four weeks later, strips of corpus cavernosum were mounted in a standard organ bath and NANC-mediated relaxations were obtained by applying electrical field stimulation.

KEY RESULTS

The NANC-mediated relaxation was enhanced in corporal strips from cirrhotic animals. Anandamide potentiated the relaxations in both groups. Either AM251 (CB(1) antagonist) or capsazepine (vanilloid VR(1) antagonist), but not AM630 (CB(2) antagonist), prevented the enhanced relaxations of cirrhotic strips. Either the non-selective NOS inhibitor L-NAME or the selective neuronal NOS inhibitor L-NPA inhibited relaxations in both groups, but cirrhotic groups were more resistant to the inhibitory effects of these agents. Relaxations to sodium nitroprusside (NO donor) were similar in tissues from the two groups.

CONCLUSIONS AND IMPLICATIONS

Cirrhosis potentiates the neurogenic relaxation of rat corpus cavernosum probably via the NO pathway and involving cannabinoid CB(1) and vanilloid VR(1) receptors.

The validity of a hyperventilation test for an investigation of autonomic failure: assessment in patients with multiple system atrophy and Parkinson's disease

Although heart rate (HR) responses to hyperventilation (HV) have been used as a cardiovascular autonomic function test, autonomic involvement during HV remains uncertain. To clarify the relationship between autonomic activity and cardiovascular changes during HV, we compared cardiovascular responses during HV among subjects with different autonomic function, namely 16 patients with probable multiple system atrophy (MSA), 16 with possible MSA, 28 with Parkinson's disease (PD) and 28 healthy controls. Abnormalities of cardiovascular responses to head-up postural change and the Valsalva maneuver were definitely present in the order of probable MSA, possible MSA and PD, and abnormal HR and blood pressure (BP) responses during HV were observed in probable MSA and possible MSA, but not in PD. Unlike the significant difference in standard cardiovascular autonomic function tests, the HR and BP responses during HV were equivalent between probable and possible MSA. These findings suggest that cardiovascular control during HV may be affected not only by autonomic activity but also by other factors.

Therapy of intracranial hypertension in patients with fulminant hepatic failure

Severe intracranial hypertension (IH) in the setting of fulminant hepatic failure (FHF) carries a high mortality and is a challenging disease for the critical care provider. Despite considerable improvements in the understanding of the pathophysiology of cerebral edema during liver failure, therapeutic maneuvers that are currently available to treat this disease are limited. Orthotopic liver transplantation is currently the only definitive therapeutic strategy that improves outcomes in patients with FHF. However, many patients die prior to the availability of donor organs, often because of cerebral herniation. Currently, two important theories prevail in the understanding of the pathophysiology of IH during FHF. Ammonia and glutamine causes cytotoxic cerebral injury while cerebral vasodilation caused by loss of autoregulation increases intracranial pressure (ICP) and predisposes to herniation. Although ammonia-reducing strategies are limited in humans, modulation of cerebral blood flow seems promising, at least during the early stages of hepatic encephalopathy. ICP monitoring, transcranial Doppler, and jugular venous oximetry offer valuable information regarding intracranial dynamics. Induced hypothermia, hypertonic saline, propofol sedation, and indomethacin are some of the newer therapies that have been shown to improve survival in patients with severe IH. In this article, we review the pathophysiology of IH in patients with FHF and outline various therapeutic strategies currently available in managing these patients in the critical care setting.

Serum calcitonin gene-related peptide levels in untreated prostate cancer patients

BACKGROUND

The role of calcitonin gene-related peptide (CGRP) in prostate cancer has not been fully understood. Moreover, the serum CGRP level in prostate cancer patients has never been reported. We measured the serum CGRP levels in untreated prostate cancer patients to elucidate its clinical significance.

MATERIALS AND METHODS

We used 36 serum samples from prostate cancer patients. All patients had never received any treatment. Serum CGRP was measured by immunoradiometric assay, and we analysed the association between serum CGRP level and clinicopathological factors.

RESULTS

Serum CGRP levels in the patients with higher clinical stages and histological grade were significantly higher than in those with lower stages and grade, respectively. But the levels did not correlate with the patient's age, liver or renal functions, serum prostate-specific antigen levels.

CONCLUSION

Serum CGRP levels were significantly elevated in the patients with high grade or high stage untreated prostate cancer patients. Measurement of the serum CGRP may be a useful predictor of staging or grading of prostate cancer in the untreated prostate cancer patients.

Cerebral Blood Flow in Fulminant Hepatitis

Fulminant hepatic failure (FHF) is often complicated with cerebral edema, intracranial hypertension, and coma. Cytotoxic and vasogenic factors have been recognized in the etiology of cerebral edema. One of the main causes seems to be the accumulation of glutamine in astrocytes, which is produced from ammonia and the excitatory neurotransmitter glutamate. Ammonia is detoxified within the brain in astrocytes, where it increases the osmotic pressure for water. Ammonia-induced astrocytic water accumulation seems to act as an integrative trigger for the development of intracranial hypertension. While cerebral blood flow is sometimes reduced in the first stage of FHF, as compensatory cerebral vasoconstriction to reduce mean arterial pressure, it later increases as hyperammonemia decreases cerebral arteriolar tone. Despite vasodilation in the systemic and splanchnic beds at early stages of the disease, cerebral vessel resistance may increase, so that cerebral perfusion pressure may be preserved. When cerebral vascular tone is no longer effective in the course of illness, vasodilation gradually develops and rapidly becomes poorly responsive to carbon dioxide stimulation, which signifies loss of autoregulatory tone and cerebral hyperemia develops. Prolonged excessive flow may lead to brain swelling, vasogenic edema, and intracerebral hemorrhage. Brain edema further aggravates the critically reduced cerebral perfusion and is responsible for the high mortality.