Anatomy of efferent hepatic nerves

Olanzapine Modulate Lipid Metabolism and Adipose Tissue Accumulation via Hepatic Muscarinic M3 Receptor-Mediated Alk-Related Signaling

Olanzapine is an atypical antipsychotic drug and a potent muscarinic M3 receptor (M3R) antagonist. Olanzapine has been reported to cause metabolic disorders, including dyslipidemia. Anaplastic lymphoma kinase (Alk), a tyrosine kinase receptor well known in the pathogenesis of cancer, has been recently identified as a key gene in the regulation of thinness via the regulation of adipose tissue lipolysis. This project aimed to investigate whether Olanzapine could modulate the hepatic Alk pathway and lipid metabolism via M3R. Female rats were treated with Olanzapine and/or Cevimeline (an M3R agonist) for 9 weeks. Lipid metabolism and hepatic Alk signaling were analyzed. Nine weeks' treatment of Olanzapine caused metabolic disturbance including increased body mass index (BMI), fat mass accumulation, and abnormal lipid metabolism. Olanzapine treatment also led to an upregulation of Chrm3, Alk, and its regulator Ptprz1, and a downregulation of Lmo4, a transcriptional repressor of Alk in the liver. Moreover, there were positive correlations between Alk and Chrm3, Alk and Ptprz1, and a negative correlation between Alk and Lmo4. However, cotreatment with Cevimeline significantly reversed the lipid metabolic disturbance and adipose tissue accumulation, as well as the upregulation of the hepatic Alk signaling caused by Olanzapine. This study demonstrates evidence that Olanzapine may cause metabolic disturbance by modulating hepatic Alk signaling via M3R, which provides novel insight for modulating the hepatic Alk signaling and potential interventions for targeting metabolic disorders.

The Sympathetic-Immune Milieu in Metabolic Health and Diseases: Insights from Pancreas, Liver, Intestine, and Adipose Tissues

Sympathetic innervation plays a crucial role in maintaining energy balance and contributes to metabolic pathophysiology. Recent evidence has begun to uncover the innervation landscape of sympathetic projections and sheds light on their important functions in metabolic activities. Additionally, the immune system has long been studied for its essential roles in metabolic health and diseases. In this review, the aim is to provide an overview of the current research progress on the sympathetic regulation of key metabolic organs, including the pancreas, liver, intestine, and adipose tissues. In particular, efforts are made to highlight the critical roles of the peripheral nervous system and its potential interplay with immune components. Overall, it is hoped to underscore the importance of studying metabolic organs from a comprehensive and interconnected perspective, which will provide valuable insights into the complex mechanisms underlying metabolic regulation and may lead to novel therapeutic strategies for metabolic diseases.

The Hepatic Nerves Regulated Inflammatory Effect in the Process of Liver Injury: Is Nerve the Key Treating Target for Liver Inflammation?

Liver injury is a common pathological basis for various liver diseases. Chronic liver injury is often an important initiating factor in liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Currently, hepatitis A and E infections are the most common causes of acute liver injury worldwide, whereas drug toxicity (paracetamol overdose) in the USA and part of Western Europe. In recent years, chronic liver injury has become a common disease that harms human health. Meanwhile, the main causes of chronic liver injury are viral hepatitis (B, C) and long-term alcohol consumption worldwide. During the process of liver injury, massive inflammatory cytokines are stimulated by these hazardous factors, leading to a systemic inflammatory response syndrome, followed by a compensatory anti-inflammatory response, which causes immune cell dysfunction and sepsis, subsequent multi-organ failure. Cytokine release and immune cell infiltration-mediated aseptic inflammation are the most important features of the pathobiology of liver failure. From this perspective, diminishing the onset and progression of liver inflammation is of clinical importance in the treatment of liver injury. Although many studies have hinted at the critical role of nerves in regulating inflammation, there largely remains undetermined how hepatic nerves mediate immune inflammation and how the inflammatory factors released by these nerves are involved in the process of liver injury. Therefore, the purpose of this article is to summarize previous studies in the field related to hepatic nerve and inflammation as well as future perspectives on the aforementioned questions. Our findings were presented in three aspects: types of nerve distribution in the liver, how these nerves regulate immunity, and the role of liver nerves in hepatitis and liver failure.

Interventional metabology: A review of bariatric arterial embolization and endovascular denervation for treating metabolic disorders

The rising prevalence of metabolic disorders such as obesity and type 2 diabetes mellitus (T2DM) poses a major challenge to global health. Existing therapeutic approaches have limitations, and there is a need for new, safe, and less invasive treatments. Interventional metabolic therapy is a new addition to the treatment arsenal for metabolic disorders. This review focuses on two interventional techniques: bariatric arterial embolization (BAE) and endovascular denervation (EDN). BAE involves embolizing specific arteries feeding ghrelin-producing cells to suppress appetite and promote weight loss. EDN targets nerves that regulate metabolic organs to improve glycemic control in T2DM patients. We describe the current state of these techniques, their mechanisms of action, and the available safety and effectiveness data. We also propose a new territory called "Interventional Metabology" to encompass these and other interventional approaches to treating metabolic disorders.

Downregulation of Bmal1 Expression in Celiac Ganglia Protects against Hepatic Ischemia-Reperfusion Injury

Hepatic ischemia-reperfusion injury (HIRI) significantly contributes to liver dysfunction following liver transplantation and hepatectomy. However, the role of the celiac ganglion (CG) in HIRI remains unclear. Adeno-associated virus was used to silence Bmal1 expression in the CG of twelve beagles that were randomly assigned to the Bmal1 knockdown group (KO-Bmal1) and the control group. After four weeks, a canine HIRI model was established, and CG, liver tissue, and serum samples were collected for analysis. The virus significantly downregulated Bmal1 expression in the CG. Immunofluorescence staining confirmed a lower proportion of c-fos⁺ and NGF⁺ neurons in TH⁺ cells in the KO-Bmal1 group than in the control group. The KO-Bmal1 group exhibited lower Suzuki scores and serum ALT and AST levels than the control group. Bmal1 knockdown significantly reduced liver fat reserve, hepatocyte apoptosis, and liver fibrosis, and it increased liver glycogen accumulation. We also observed that Bmal1 downregulation inhibited the hepatic neurotransmitter norepinephrine, neuropeptide Y levels, and sympathetic nerve activity in HIRI. Finally, we confirmed that decreased Bmal1 expression in CG reduces TNF-α, IL-1β, and MDA levels and increases GSH levels in the liver. The downregulation of Bmal1 expression in CG suppresses neural activity and improves hepatocyte injury in the beagle model after HIRI.

The density of hepatic autonomic innervation differs between compensatory and direct hyperplasia rat models

To contribute to the knowledge of the autonomic innervation in liver regeneration, here we investigate the distribution of tyrosine hydroxylase (TH)- and choline acetyltransferase (ChAT)-like immunoreactive (LI) nerve fibers, to indicate noradrenergic and cholinergic nerves, respectively, in rats under different conditions of liver damage and repair. By immunohistochemistry and assessment of nerve fiber density, three models of induced hepatic regeneration were examined: the carbon tetrachloride (CCl₄ ) intoxication, with two treatment periods of 14 weeks and 18 weeks; the partial hepatectomy (PH); the thyroid hormone (T3) treatment. TH- and ChAT-LI nerve fibers were detectable mostly in the portal spaces, the TH-LI ones occurring only around blood vessels while the ChAT-LI nerve fibers were also associated with secretory ducts. The density of TH-like immunoreactivity in the portal areas decreased after the CCl₄ 14 weeks treatment and PH and increased after T3. By contrast, ChAT-LI nerve fibers appeared particularly abundant around the neoductal elements in the CCl₄ rats and were rare to absent in the PH and T3-treated groups. The ChAT-LI nerve fiber density within the portal areas revealed an increase in the CCl₄ -treated rats while showing no change in the PH and T3-treated rats. The changes in the density of perivascular TH- and ChAT-containing nerve fibers suggest a finely tuned autonomic modulation of hepatic blood flow depending on the type of subacute/chronic induced hyperplasia, while the characteristic occurrence of the periductal cholinergic innervation after the CCl₄ treatment implies a selective parasympathetic role in regulating the physiopathological regenerative potential of the rat liver.

Perineural invasion is a prognostic factor in stage II colorectal cancer but not a treatment indicator for traditional chemotherapy: a retrospective cohort study

BACKGROUND

Perineural invasion (PNI) is considered a risk factor of survival but does not yet inform treatment decisions, and has not been studied separately in stage II colorectal cancer (CRC) patients whose postoperative traditional chemotherapy is controversial. This cohort study aimed to assess the association of PNI with basic clinicopathological features and patient outcomes after curative resection and the effects of PNI on responses to adjuvant chemotherapy in stage II CRC.

METHODS

The clinical data of 371 stage II CRC patients who underwent curative-intent surgery at the National Cancer Center/Cancer Hospital in 2014 were retrospectively reviewed. The adjuvant chemotherapy data were acquired from follow-up information. PNI status was examined, and the overall survival (OS) and disease-free survival (DFS) rates were analyzed.

RESULTS

PNI was detected in 82 of the 371 patients (22.1%) and was closely correlated with preoperative serum carcinoembryonic antigen (CEA) levels (P=0.030), gross tumor type (P=0.010), tumor differentiation (P=0.010), p stage (P<0.001), and extramural vascular invasion (EMVI) (P<0.001). The median follow-up time was 71 months. The 5-year OS was 84.1% and 96.5% (P<0.001), and the 5-year DFS was 75.6% and 91.3% (P<0.001) for PNI-positive (+) and PNI-negative (-) patients, respectively. The multivariate regression analyses identified PNI as an independent negative prognostic factor for DFS [hazard ratio (HR): 2.95; 95% confidence interval (CI), 1.546-5.626; P=0.001] and OS (HR: 3.966; 95% CI, 1.642-9.575; P=0.002). Among PNI (+) patients, DFS and OS were positively correlated with CEA levels (P=0.005 and P=0.004, respectively). Postoperative chemotherapy failed to improve DFS (P=0.480 and P=0.267, respectively) and OS (P=0.940 and P=0.077, respectively) regardless of whether the patients were PNI positive or not.

CONCLUSIONS

In stage II CRC patients, PNI was a poor independent predictor for DFS and OS. Among PNI (+) patients, CEA levels were positively correlated with DFS and OS. Traditional postoperative adjuvant chemotherapy does not improve outcomes of PNI (+) patients. Therefore, as to the active role of PNI and vacancy for treatment in allusion to PNI, follow-up of PNI (+) patients with elevated CEA level should be strengthened and further research on drug conducted on PNI deserve to be carried on.

Development of the nervous system in mouse liver

BACKGROUND

The role of the hepatic nervous system in liver development remains unclear. We previously created functional human micro-hepatic tissue in mice by co-culturing human hepatic endodermal cells with endothelial and mesenchymal cells. However, they lacked Glisson’s sheath [the portal tract (PT)]. The PT consists of branches of the hepatic artery (HA), portal vein, and intrahepatic bile duct (IHBD), collectively called the portal triad, together with autonomic nerves.

AIM

To evaluate the development of the mouse hepatic nervous network in the PT using immunohistochemistry.

METHODS

Liver samples from C57BL/6J mice were harvested at different developmental time periods, from embryonic day (E) 10.5 to postnatal day (P) 56. Thin sections of the surface cut through the hepatic hilus were examined using protein gene product 9.5 (PGP9.5) and cytokeratin 19 (CK19) antibodies, markers of nerve fibers (NFs), and biliary epithelial cells (BECs), respectively. The numbers of NFs and IHBDs were separately counted in a PT around the hepatic hilus (center) and the peripheral area (periphery) of the liver, comparing the average values between the center and the periphery at each developmental stage. NF-IHBD and NF-HA contacts in a PT were counted, and their relationship was quantified. SRY-related high mobility group-box gene 9 (SOX9), another BEC marker; hepatocyte nuclear factor 4α (HNF4α), a marker of hepatocytes; and Jagged-1, a Notch ligand, were also immunostained to observe the PT development.

RESULTS

HNF4α was expressed in the nucleus, and Jagged-1 was diffusely positive in the primitive liver at E10.5; however, the PGP9.5 and CK19 were negative in the fetal liver. SOX9-positive cells were scattered in the periportal area in the liver at E12.5. The Jagged-1 was mainly expressed in the periportal tissue, and the number of SOX9-positive cells increased at E16.5. SOX9-positive cells constructed the ductal plate and primitive IHBDs mainly at the center, and SOX-9-positive IHBDs partly acquired CK19 positivity at the same period. PGP9.5-positive bodies were first found at E16.5 and HAs were first found at P0 in the periportal tissue of the center. Therefore, primitive PT structures were first constructed at P0 in the center. Along with remodeling of the periportal tissue, the number of CK19-positive IHBDs and PGP9.5-positive NFs gradually increased, and PTs were also formed in the periphery until P5. The numbers of NFs and IHBDs were significantly higher in the center than in the periphery from E16.5 to P5. The numbers of NFs and IHBDs reached the adult level at P28, with decreased differences between the center and periphery. NFs associated more frequently with HAs than IHBDs in PTs at the early phase after birth, after which the number of NF-IHBD contacts gradually increased.

CONCLUSION

Mouse hepatic NFs first emerge at the center just before birth and extend toward the periphery. The interaction between NFs and IHBDs or HAs plays important roles in the morphogenesis of PT structure.

A Spatial Model of Hepatic Calcium Signaling and Glucose Metabolism Under Autonomic Control Reveals Functional Consequences of Varying Liver Innervation Patterns Across Species

Rapid breakdown of hepatic glycogen stores into glucose plays an important role during intense physical exercise to maintain systemic euglycemia. Hepatic glycogenolysis is governed by several different liver-intrinsic and systemic factors such as hepatic zonation, circulating catecholamines, hepatocellular calcium signaling, hepatic neuroanatomy, and the central nervous system (CNS). Of the factors regulating hepatic glycogenolysis, the extent of lobular innervation varies significantly between humans and rodents. While rodents display very few autonomic nerve terminals in the liver, nearly every hepatic layer in the human liver receives neural input. In the present study, we developed a multi-scale, multi-organ model of hepatic metabolism incorporating liver zonation, lobular scale calcium signaling, hepatic innervation, and direct and peripheral organ-mediated communication between the liver and the CNS. We evaluated the effect of each of these governing factors on the total hepatic glucose output and zonal glycogenolytic patterns within liver lobules during simulated physical exercise. Our simulations revealed that direct neuronal stimulation of the liver and an increase in circulating catecholamines increases hepatic glucose output mediated by mobilization of intracellular calcium stores and lobular scale calcium waves. Comparing simulated glycogenolysis between human-like and rodent-like hepatic innervation patterns (extensive vs. minimal) suggested that propagation of calcium transients across liver lobules acts as a compensatory mechanism to improve hepatic glucose output in sparsely innervated livers. Interestingly, our simulations suggested that catecholamine-driven glycogenolysis is reduced under portal hypertension. However, increased innervation coupled with strong intercellular communication can improve the total hepatic glucose output under portal hypertension. In summary, our modeling and simulation study reveals a complex interplay of intercellular and multi-organ interactions that can lead to differing calcium dynamics and spatial distributions of glycogenolysis at the lobular scale in the liver.

Hepatic Nervous System in Development, Regeneration, and Disease

The liver is innervated by autonomic and sensory fibers of the sympathetic and parasympathetic nervous systems that regulate liver function, regeneration, and disease. Although the importance of the hepatic nervous system in maintaining and restoring liver homeostasis is increasingly appreciated, much remains unknown about the specific mechanisms by which hepatic nerves both influence and are influenced by liver diseases. While recent work has begun to illuminate the developmental mechanisms underlying recruitment of nerves to the liver, evolutionary differences contributing to species-specific patterns of hepatic innervation remain elusive. In this review, we summarize current knowledge on the development of the hepatic nervous system and its role in liver regeneration and disease. We also highlight areas in which further investigation would greatly enhance our understanding of the evolution and function of liver innervation.

Endovascular Celiac Denervation for Glycemic Control in Patients with Type 2 Diabetes Mellitus

PURPOSE

To investigate the safety and effects of catheter-based endovascular denervation (EDN) at the celiac artery, and the abdominal aorta around celiac artery on glycemic control in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

With a novel catheter system, EDN was conducted at the celiac artery along with the abdominal aorta around the celiac artery in patients with T2DM whose hemoglobin A1c (HbA1c) was >7.5%. The primary outcome was HbA1c at 6-month. Other outcomes included safety, oral glucose tolerant test (OGTT), homeostasis-model assessment of insulin resistance (HOMA-IR), fasting plasma glucose (FPG), 2-hour postprandial plasma glucose (2hPG), and C-peptide test.

RESULTS

A total of 11 subjects were included for analysis. The technical success was 100% and no severe treatment-related adverse events or major complications were observed. Both HbA1c and HOMA-IR were significantly reduced at 6 months (9.9 vs. 8.0 %, P = 0.005; 13.3 vs. 6.0, P = 0.016). Decreases in FPG and 2hPG were observed (227.2 vs. 181.8 mg/dL, P < 0.001; 322.2 vs. 205.2 mg/dL, P = 0.001). C-peptide test indicated improved beta-cell function (area under curve [AUC] 0.23 vs. 0.28 pmol/mL, P =0.046). A reduction of daily insulin injection (P = 0.02) and improvement of liver function (alanine aminotransferase, P = 0.014; γ-glutamyl transpeptidase, P = 0.021) were also observed.

CONCLUSION

EDN at the celiac artery and the abdominal aorta around celiac artery elicited a clinically significant improvement in glycemic control and insulin resistance in patients with T2DM, with good tolerability as 6-month follow-up demonstrated.

Decreased risk of liver and intrahepatic cancer in non-H. pylori-infected perforated peptic ulcer patients with truncal vagotomy: a nationwide study

The vagal nervous system is central to the physiological responses and systemic diseases of the liver. We evaluated the subsequent risk of liver and intrahepatic cancer (HCC/ICC) in non-H. pylori (HP)-infected perforated peptic ulcer (PPU) patients with and without vagotomy. Hospitalized PPU patients who underwent simple closure or truncal vagotomy/pyloroplasty (TVP) in the National Health Insurance Research Database from 2000 to 2008 were enrolled. The exclusion criteria included: (1) Multiple surgeries for PPU were received at the same admission; (2) Any cancer history; (3) Previous peptic ulcer-associated surgery; (4) HP infection history; (5) Viral hepatitis infection history; (6) Follow-up duration < 1 year; and (7) Age < 18 years. The risks of developing HCC/ICC in PPU patients with and without vagotomy were assessed at the end of 2013. To balance the baseline condition between groups, we used the propensity score matched method to select study subjects. Cox proportional hazard regression was used to estimate the hazard ratio and 95% confidence interval (CI) of HCC/ICC. Before propensity score matching, 675 simple suture patients and 54 TVP patients had HCC/ICC, which corresponded to incidences of 2.11 and 0.88 per 1000 person-years, respectively. After propensity score matching, 145 simple suture patients and 54 TVP patients experienced HCC/ICC, which corresponded to incidences of 1.45 and 0.88 per 1000 person-years, respectively. The TVP patients had a 0.71 (95% CI 0.54-0.95)- and 0.69 (95% CI 0.49-0.97)-fold risk of developing HCC/ICC compared to simple suture patients before and after propensity score matching. Our findings reported that, in the Asian population, TVP decreases the risk of HCC/ICC in non-HP-infected PPU patients compared to simple closure patients. However, further studies are warranted.

Sympathetic innervation of the mouse kidney and liver arising from prevertebral ganglia

The sympathetic nervous system (SNS) plays a crucial role in the regulation of renal and hepatic functions. Although sympathetic nerves to the kidney and liver have been identified in many species, specific details are lacking in the mouse. In the absence of detailed information of sympathetic prevertebral innervation of specific organs, selective manipulation of a specific function will remain challenging. Despite providing major postganglionic inputs to abdominal organs, limited data are available about the mouse celiac-superior mesenteric complex. We used tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DbH) reporter mice to visualize abdominal prevertebral ganglia. We found that both the TH and DbH reporter mice are useful models for identification of ganglia and nerve bundles. We further tested if the celiac-superior mesenteric complex provides differential inputs to the mouse kidney and liver. The retrograde viral tracer, pseudorabies virus (PRV)-152 was injected into the cortex of the left kidney or the main lobe of the liver to identify kidney-projecting and liver-projecting neurons in the celiac-superior mesenteric complex. iDISCO immunostaining and tissue clearing were used to visualize unprecedented anatomical detail of kidney-related and liver-related postganglionic neurons in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia compared with TH-positive neurons. Kidney-projecting neurons were restricted to the suprarenal and aorticorenal ganglia, whereas only sparse labeling was observed in the celiac-superior mesenteric complex. In contrast, liver-projecting postganglionic neurons were observed in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia, suggesting spatial separation between the sympathetic innervation of the mouse kidney and liver.

Vagal afferent fibers contribute to the anti-inflammatory reactions by vagus nerve stimulation in concanavalin A model of hepatitis in rats

Background

Increasing number of studies provide evidence that the vagus nerve stimulation (VNS) dampens inflammation in peripheral visceral organs. However, the effects of afferent fibers of the vagus nerve (AFVN) on anti-inflammation have not been clearly defined. Here, we investigate whether AFVN are involved in VNS-mediated regulation of hepatic production of proinflammatory cytokines.

Methods

An animal model of hepatitis was generated by intraperitoneal (i.p.) injection of concanavalin A (ConA) into rats, and electrical stimulation was given to the hepatic branch of the vagus nerve. AFVN activity was regulated by administration of capsaicin (CAP) or AP-5/CNQX and the vagotomy at the hepatic branch of the vagus nerve (hVNX). mRNA and protein expression in target tissues was analyzed by RT-PCR, real-time PCR, western blotting and immunofluorescence staining. Hepatic immune cells were analyzed by flow cytometry.

Results

TNF-α, IL-1β, and IL-6 mRNAs and proteins that were induced by ConA in the liver macrophages were significantly reduced by the electrical stimulation of the hepatic branch of the vagus nerve (hVNS). Alanine transaminase (ALT) and aspartate transaminase (AST) levels in serum and the number of hepatic CD4⁺ and CD8⁺ T cells were increased by ConA injection and downregulated by hVNS. CAP treatment deteriorated transient receptor potential vanilloid 1 (TRPV1)-positive neurons and increased caspase-3 signals in nodose ganglion (NG) neurons. Concomitantly, CAP suppressed choline acetyltransferase (ChAT) expression that was induced by hVNS in DMV neurons of ConA-injected animals. Furthermore, hVNS-mediated downregulation of TNF-α, IL-1β, and IL-6 expression was hampered by CAP treatment and similarly regulated by hVNX and AP-5/CNQX inhibition of vagal feedback loop pathway in the brainstem. hVNS elevated the levels of α7 nicotinic acetylcholine receptors (α7 nAChR) and phospho-STAT3 (Tyr705; pY-STAT3) in the liver, and inhibition of AFVN activity by CAP, AP-5/CNQX and hVNX or the pharmacological blockade of hepatic α7 nAChR decreased STAT3 phosphorylation.

Conclusions

Our data indicate that the activity of AFVN contributes to hepatic anti-inflammatory responses mediated by hVNS in ConA model of hepatitis in rats.

Peripheral Innervation in the Regulation of Glucose Homeostasis

Precise regulation of circulating glucose is crucial for human health and ensures a sufficient supply to the brain, which relies almost exclusively on glucose for metabolic energy. Glucose homeostasis is coordinated by hormone-secreting endocrine cells in the pancreas, as well as glucose utilization and production in peripheral metabolic tissues including the liver, muscle, and adipose tissue. Glucose-regulatory tissues receive dense innervation from sympathetic, parasympathetic, and sensory fibers. In this review, we summarize the functions of peripheral nerves in glucose regulation and metabolism. Dynamic changes in peripheral innervation have also been observed in animal models of obesity and diabetes. Together, these studies highlight the importance of peripheral nerves as a new therapeutic target for metabolic disorders.

Pituitary adenylate cyclase-activating peptide: Potential roles in the pathophysiology and complications of cirrhosis

Pituitary adenylate cyclase-activating peptide (PACAP) is a ubiquitous neuropeptide with diverse functions throughout the organism. Most abundantly investigated for its role in several neurological disorders as well as in circadian rhythms, other fields of medicine, including cardiology, have recently shown interest in the role of PACAP and its potential as a biomarker. Timely diagnosis and treatment of cirrhosis and its complications is a considerable challenge for health services world-wide and development of new areas of research is warranted. Direct and indirect evidence exists of PACAP involvement in the cascade of pathological events and processes ultimately leading to cirrhosis and its complications, but its exact role remains to be determined. Studies have documented PACAP involvement in immune function, metabolism, local vasoconstriction and dilatation and systemic vascular decompensation and there is ongoing research of a possible role in liver reperfusion injury. Considering these reports, PACAP could theoretically exude influence on the disease course of cirrhosis through the hypothalamus-pituitary-adrenal axis, chronic inflammation, fibrogenesis, vasodilation and reduced vascular resistance. The paucity of literature on the specific topic of PACAP and cirrhosis reflects complex mechanisms and difficulty in accurate measurements and sample taking. This does not detract from the need to further characterize and elucidate the role PACAP plays in the underdiagnosed and undertreated condition of cirrhosis.

Space of Disse: a stem cell niche in the liver

Recent evidence indicates that the plasticity of preexisting hepatocytes and bile duct cells is responsible for the appearance of intermediate progenitor cells capable of restoring liver mass after injury without the need of a stem cell compartment. However, mesenchymal stem cells (MSCs) exist in all organs and are associated with blood vessels which represent their perivascular stem cell niche. MSCs are multipotent and can differentiate into several cell types and are known to support regenerative processes by the release of immunomodulatory and trophic factors. In the liver, the space of Disse constitutes a stem cell niche that harbors stellate cells as liver resident MSCs. This perivascular niche is created by extracellular matrix proteins, sinusoidal endothelial cells, liver parenchymal cells and sympathetic nerve endings and establishes a microenvironment that is suitable to maintain stellate cells and to control their fate. The stem cell niche integrity is important for the behavior of stellate cells in the normal, regenerative, aged and diseased liver. The niche character of the space of Disse may further explain why the liver can become an organ of extra-medullar hematopoiesis and why this organ is frequently prone to tumor metastasis.

Acupuncture stimulation attenuates TNF-α production via vagal modulation in the concanavalin A model of hepatitis

Background:

A growing body of evidence shows that neuronal activity is involved in modulating the efficacy of acupuncture therapy. However, it has been seldom investigated whether neuronal activity following acupuncture stimulation is effective at regulating hepatic inflammation.

Objective:

Using the concanavalin A (ConA) model of hepatitis, we investigated the regulation of inflammatory cytokine tumor necrosis factor (TNF)-α in the liver tissue and the blood after acupuncture stimulation at ST36.

Methods:

Mice were subjected to ConA injection, acupuncture stimulation at ST36 by manual acupuncture (MA) or electroacupuncture (EA) procedures, and vagotomy (VNX). Liver tissue and blood were collected for TNF-α analysis. TNF-α mRNA was analyzed by real-time polymerase chain reaction (PCR), and TNF-α, CD11b, CD68, and Erk1/2 proteins were analyzed by Western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay.

Results:

TNF-α mRNA and protein were induced in CD11b-positive hepatic cells and the plasma at 6–24 h after ConA injection. The application of MA or EA was very effective at attenuating the production of TNF-α. Anti-inflammatory effects of acupuncture were greatly suppressed by VNX in ConA-injected animals, suggesting the requirement of vagus nerve activity in acupuncture-mediated anti-inflammatory responses. Electrical stimulation of the sciatic nerve (SNS) resulted in an anti-inflammatory effect similar to acupuncture stimulation. In parallel with TNF-α, production of phospho-Erk1/2, which was induced in the liver tissue, was downregulated by MA and EA in liver cells.

Conclusion:

The regulatory effects of acupuncture stimulation on inflammatory responses in the liver may be modulated through the activation of the vagus nerve pathway.

Clinical anatomy of the anterior and posterior hepatic plexuses, including relations with the pancreatic plexus: A cadaver study

The poor prognosis after surgery for pancreatic cancer or extrahepatic bile duct cancer has mainly been attributed to early lymph node metastasis, as well as a high frequency of perineural invasion along the peripancreatic neural plexuses or extrahepatic bile duct plexus. However, there has been no detailed morphological description of the anterior and posterior hepatic plexuses (AHP and PHP). In addition, the concepts of the pancreatic plexus and PHP are confused by surgeons. To assess the relations of the pancreatic plexus and hepatic plexuses from the morphological, developmental, and clinical perspectives, these plexuses were dissected in 24 cadavers. The PHP was found to be completely independent of the AHP. The PHP ran behind the portal vein, with most nerve fibers ascending along the bile duct to the gallbladder and the liver or descending to the distal common bile duct and duodenal papilla. Some branches of the PHP contributed to the pancreatic plexus, corresponding to pancreatic head plexus I as defined by the Japan Pancreas Society. The differences between the PHP and pancreatic head plexus I should be understood, even though liver function is not obviously affected after PHP excision for pancreatic head cancer. Further study is needed to determine whether there are functional differences between the AHP and PHP. Clin. Anat., 33:630-636, 2020. © 2019 Wiley Periodicals, Inc.

Vagus nerve regulates the phagocytic and secretory activity of resident macrophages in the liver

The gastrointestinal (GI) tract harbors commensal microorganisms as well as invasive bacteria, toxins and other pathogens and, therefore, plays a pivotal barrier and immunological role against pathogenic agents. The vagus nerve is an important regulator of the GI tract-associated immune system, having profound effects on inflammatory responses. Among GI tract organs, the liver is a key site of immune surveillance, as it has a large population of resident macrophages and receives the blood drained from the guts through the hepatic portal circulation. Although it is widely accepted that the hepatic tissue is a major target for vagus nerve fibers, the role of this neural circuit in liver immune functions is still poorly understood. Herein we used in vivo imaging techniques, including confocal microscopy and scintigraphy, to show that vagus nerve stimulation increases the phagocytosis activity by resident macrophages in the liver, even on the absence of an immune challenge. The activation of this neural circuit in a non-lethal model of sepsis optimized the removal of bacteria in the liver and resulted in the production of anti-inflammatory and pro-regenerative cytokines. Our findings provide new insights into the neural regulation of the immune system in the liver.

Intercellular calcium waves integrate hormonal control of glucose output in the intact liver

Key points

Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown.

We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production.

The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production.

The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.

Abstract

Glucogenic hormones, including catecholamines and vasopressin, induce frequency‐modulated cytosolic Ca²⁺ oscillations in hepatocytes, and these propagate as intercellular Ca²⁺ waves via gap junctions in the intact liver. We investigated the role of co‐ordinated Ca²⁺ waves as a mechanism for integrating multiple endocrine and neuroendocrine inputs to control hepatic glucose production in perfused rat liver. Sympathetic nerve stimulation elicited localized Ca²⁺ increases that were restricted to hepatocytes in the periportal zone. During perfusion with subthreshold vasopressin, sympathetic stimulation converted asynchronous Ca²⁺ signals in a limited number of hepatocytes into co‐ordinated intercellular Ca²⁺ waves that propagated across entire lobules. A similar synergism was observed between physiological concentrations of glucagon and vasopressin, where glucagon also facilitated the recruitment of hepatocytes into a Ca²⁺ wave. Hepatic glucose production was significantly higher with intralobular Ca²⁺ waves. We propose that inositol 1,4,5‐trisphosphate (IP₃)‐dependent Ca²⁺ signalling gives rise to an excitable medium across the functional syncytium of the hepatic lobule, co‐ordinating and amplifying the metabolic responses to multiple hormonal inputs.

Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown.

We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production.

The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production.

The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.

A comparative study of subsequent liver cirrhosis risk in non-Helicobacter pylori-infected peptic ulcer patients with and without vagotomy: An Asian population cohort study

OBJECTIVES

Hepatic parasympathetic nerves branch off the vagus nerve. The vagal and hepatic nervous systems are important in liver physiological processes and some diseases such as diabetes, obesity, and liver cirrhosis. We were interested in vagal nerve integrity and subsequent diseases in peptic ulcer patients. Herein, we used National Health Insurance database in Taiwan and retrospectively assessed the risk of developing liver cirrhosis in peptic ulcer patients with and without complications by surgical treatments.

METHODS

A cohort of 357 423 peptic ulcer patients without Helicobacter pylori, hepatitis B/C virus infection, and alcoholism from 2001 to 2008 was established. A randomly selected cohort of 357 423 people without peptic ulcer that matched by age, gender, comorbidities, and index year was used for comparison. The risks of developing liver cirrhosis were assessed both in cohorts and in peptic ulcer patients with and without vagotomy at the end of 2011.

RESULTS

Peptic ulcer patients were with higher incidence of liver cirrhosis than those without peptic ulcer (2.63 vs 0.96 per 1000 person-years) and with a 2.79-fold adjusted hazard ratio (HR) (95% confidence interval = 2.66-2.93) based on the multivariable Cox proportional hazards regression analysis. Comparing with different peptic ulcer management strategies, the HR value for subsequent liver cirrhosis risk was the lowest in vagotomy group (HR = 0.46, 95% confidence interval = 0.33-0.64).

CONCLUSIONS

Peptic ulcer patients have an increased risk of developing liver cirrhosis. Moreover, there were association of vagotomy and decreased risk of subsequent liver cirrhosis in complicated peptic ulcer patients. However, further studies are warranted.

Biliary epithelium: A neuroendocrine compartment in cholestatic liver disease

Hepatic fibrosis is characterized by abnormal accumulation of extracellular matrix (ECM) that can lead to ductopenia, cirrhosis, and even malignant transformation. In this review, we examine cholestatic liver diseases characterized by extensive biliary fibrosis such as primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC), polycystic liver disease (PLD), and MDR2-/- and BDL mouse models. Following biliary injury, cholangiocytes, the epithelial cells that line the bile ducts, become reactive and adopt a neuroendocrine phenotype in which they secrete and respond to neurohormones and neuropeptides in an autocrine and paracrine fashion. Emerging evidence indicates that cholangiocytes influence and respond to changes in the ECM and stromal cells in the microenvironment. For example, activated myofibroblasts and hepatic stellate cells are major drivers of collagen deposition and biliary fibrosis. Additionally, the liver is richly innervated with adrenergic, cholinergic, and peptidergic fibers that release neurohormones and peptides to maintain homeostasis and can be deranged in disease states. This review summarizes how cholangiocytes interact with their surrounding environment, with particular focus on how autonomic and sensory regulation affects fibrotic pathophysiology.

Newly recognized extratumoral features of colorectal cancer challenge the current tumor-node-metastasis staging system

One of the most common malignant tumors in humans, colorectal cancer has been extensively studied during the past few decades. Staging colorectal cancer allows clinicians to obtain precise prognostic information and apply specific treatment procedures. Apart from remote metastases, the depth of tumor infiltration and lymph node involvement have traditionally been recognized as the most important factors predicting outcome. Variations in the molecular signature of colorectal cancer have also revealed differences in phenotypic aggressiveness and therapeutic response rates. This article presents a review of the extratumoral environment in colorectal surgery.

Autonomic Nervous System and the Liver

The liver is innervated by both the sympathetic and the parasympathetic nerve systems. These nerves are derived from the splanchnic and vagal nerves that surround the portal vein, hepatic artery, and bile duct. The afferent fiber delivers information regarding osmolality, glucose level, and lipid level in the portal vein to the central nervous system (CNS). In contrast, the efferent fiber is crucial in the regulation of metabolism, blood flow, and bile secretion. Furthermore, liver innervation has been associated with hepatic fibrosis, regeneration, and circadian rhythm. Knowledge of these mechanisms can be applied for potential liver disease treatment.

Central Insulin Action Activates Kupffer Cells by Suppressing Hepatic Vagal Activation via the Nicotinic Alpha 7 Acetylcholine Receptor

Central insulin action activates hepatic IL-6/STAT3 signaling, which suppresses the gene expression of hepatic gluconeogenic enzymes. The vagus nerve plays an important role in this centrally mediated hepatic response; however, the precise mechanism underlying this brain-liver interaction is unclear. Here, we present our findings that the vagus nerve suppresses hepatic IL-6/STAT3 signaling via α7-nicotinic acetylcholine receptors (α7-nAchR) on Kupffer cells, and that central insulin action activates hepatic IL-6/STAT3 signaling by suppressing vagal activity. Indeed, central insulin-mediated hepatic IL-6/STAT3 activation and gluconeogenic gene suppression were impeded in mice with hepatic vagotomy, pharmacological cholinergic blockade, or α7-nAchR deficiency. In high-fat diet-induced obese and insulin-resistant mice, control of the vagus nerve by central insulin action was disturbed, inducing a persistent increase of inflammatory cytokines. These findings suggest that dysregulation of the α7-nAchR-mediated control of Kupffer cells by central insulin action may affect the pathogenesis of chronic hepatic inflammation in obesity.

Acetylcholine induces fibrogenic effects via M2/M3 acetylcholine receptors in non-alcoholic steatohepatitis and in primary human hepatic stellate cells

BACKGROUND

The parasympathetic nervous system (PNS), via neurotransmitter acetylcholine (ACh), modulates fibrogenesis in animal models. However, the role of ACh in human hepatic fibrogenesis is unclear.

AIMS

We aimed to determine the fibrogenic responses of human hepatic stellate cells (hHSC) to ACh and the relevance of the PNS in hepatic fibrosis in patients with non-alcoholic steatohepatitis (NASH).

METHODS

Primary hHSC were analyzed for synthesis of endogenous ACh and acetylcholinesterase and gene expression of choline acetyltransferase and muscarinic ACh receptors (mAChR). Cell proliferation and fibrogenic markers were analyzed in hHSC exposed to ACh, atropine, mecamylamine, methoctramine, and 4-diphenylacetoxy-N-methylpiperidine methiodide. mAChR expression was analyzed in human NASH scored for fibrosis.

RESULTS

We observed that hHSC synthesize ACh and acetylcholinesterase and express choline acetyltransferase and M1-M5 mAChR. We also show that M2 was increased during NASH progression, while both M2 and M3 were found upregulated in activated hHSC. Furthermore, endogenous ACh is required for hHSC basal growth. Exogenous ACh resulted in hHSC hyperproliferation via mAChR and phosphoinositide 3-kinase and Mitogen-activated protein kinase kinase (MEK) signaling pathways, as well as increased fibrogenic markers.

CONCLUSION

We show that ACh regulates hHSC activation via M2 and M3 mAChR involving the phosphoinositide 3-kinase and MEK pathways in vitro. Finally, we provide evidence that the PNS may be involved in human NASH fibrosis.

Central insulin-mediated regulation of hepatic glucose production [Review]

Insulin controls hepatic glucose production (HGP) and maintains glucose homeostasis through the direct action of hepatic insulin receptors, as well as the indirect action of insulin receptors in the central nervous system. Insulin acts on insulin receptors in the hypothalamic arcuate nucleus, activates ATP-sensitive potassium channels in a phosphoinositide 3-kinase (PI3K)-dependent manner, induces hyperpolarization of the hypothalamic neurons, and regulates HGP via the vagus nerve. In the liver, central insulin action augments IL-6 expression in Kupffer cells and activates STAT3 transcription factors in hepatocytes. Activated STAT3 suppresses the gene expression of gluconeogenic enzymes, thereby reducing HGP. It has become evident that nutrients such as glucose, fatty acids, and amino acids act upon the hypothalamus together with insulin, affecting HGP. On the other hand, HGP control by central insulin action is impeded in obesity and impeded by insulin resistance due to disturbance of PI3K signaling and inflammation in the hypothalamus or inhibition of STAT3 signaling in the liver. Although the mechanism of control of hepatic gluconeogenic gene expression by central insulin action is conserved across species, its importance in human glucose metabolism has not been made entirely clear and its elucidation is anticipated in the future.

Innervation of Extrahepatic Biliary Tract, With Special Reference to the Direct Bidirectional Neural Connections of the Gall Bladder, Sphincter of Oddi and Duodenum in Suncus murinus, in Whole-Mount Immunohistochemical Study

Sphincter of Oddi dysfunction is one of the most important symptoms in post-cholecystectomy syndrome. Using either electrical or mechanical stimulation and retrogradely transported neuronal dyes, it has been demonstrated that there are direct neural pathways connecting gall bladder and the sphincter of Oddi in the Australian opossum and the golden hamster. In the present study, we employed whole-mount immunohistochemistry staining to observe and verify that there are two different plexuses of the extrahepatic biliary tract in Suncus murinus. One, named Pathway One, showed a fine, irregular but dense network plexus that ran adhesively and resided on/in the extrahepatic biliary tract wall, and the plexus extended into the intrahepatic area. On the other hand, named Pathway Two, exhibiting simple, thicker and straight neural bundles, ran parallel to the surface of the extrahepatic biliary tract and passed between the gall bladder and duodenum, but did not give off any branches to the liver. Pathway Two was considered to involve direct bidirectional neural connections between the duodenum and the biliary tract system. For the first time, morphologically, we demonstrated direct neural connections between gall bladder and duodenum in S. murinus. Malfunction of the sphincter of Oddi may be caused by injury of the direct neural pathways between gall bladder and duodenum by cholecystectomy. From the viewpoint of preserving the function of the major duodenal papilla and common bile duct, we emphasize the importance of avoiding kocherization of the common bile duct so as to preserve the direct neural connections between gall bladder and sphincter of Oddi.

Prognostic value of perineural invasion in colorectal cancer: a meta-analysis

BACKGROUND

The prognostic value of perineural invasion (PNI) in colorectal cancer (CRC) does not reach a consensus.

METHODS

A comprehensive literature search for relevant reports published up to October 2014 was performed using the electronic databases: PubMed, Embase, and Web of Science. The pooled hazard ratio (HR) with 95 % confidence intervals (CI) was used to estimate the prognostic effects.

RESULT

Thirty-eight studies comprising 12,661 CRC patients were analyzed. Our results showed that PNI is significantly associated with poor prognosis in OS (overall survival) (HR = 2.07, 95 % CI = 1.87-2.29, P < 0.01) and DFS (disease-free survival) (HR = 2.23, 95 % CI = 1.79-2.78, P < 0.01). There was no significant prognostic difference in DFS between stage II CRC patients with PNI(+) and stage III patients (HR = 1.67, 95 % CI = 0.53-5.25, P = 0.38). Further subgroup analysis revealed that the significance of the association between PNI and worse prognosis in CRC patients is not affected by many factors, including geographic setting, PNI positive rate, treatment, TNM stage, tumor site, and quality of the study.

CONCLUSIONS

The meta-analysis indicates that PNI is a poor prognostic factor in CRC patients. The postoperative survival of stage II CRC patients with PNI(+) is probably more similar to that of stage III patients. Currently available adjuvant therapy should be considered in stage II CRC patients with PNI(+).

Recent advances in research on nitrergic nerve-mediated vasodilatation

Cerebral vascular resistance and blood flow were widely considered to be regulated solely by tonic innervation of vasoconstrictor adrenergic nerves. However, pieces of evidence suggesting that parasympathetic nitrergic nerve activation elicits vasodilatation in dog and monkey cerebral arteries were found in 1990. Nitric oxide (NO) as a neurotransmitter liberated from parasympathetic postganglionic neurons decreases cerebral vascular tone and resistance and increases cerebral blood flow, which overcome vasoconstrictor responses to norepinephrine liberated from adrenergic nerves. Functional roles of nitrergic vasodilator nerves are found also in peripheral vasculature, including pulmonary, renal, mesenteric, hepatic, ocular, uterine, nasal, skeletal muscle, and cutaneous arteries and veins; however, adrenergic nerve-induced vasoconstriction is evidently greater than nitrergic vasodilatation in these vasculatures. In coronary arteries, neurogenic NO-mediated vasodilatation is not clearly noted; however, vasodilatation is induced by norepinephrine released from adrenergic nerves that activates β1-adrenoceptors. Impaired actions of NO liberated from the endothelium and nitrergic neurons are suggested to participate in cerebral hypoperfusion, leading to brain dysfunction, like that in Alzheimer's disease. Nitrergic neural dysfunction participates in impaired circulation in peripheral organs and tissues and also in systemic blood pressure increase. NO and vasodilator peptides, as sensory neuromediators, are involved in neurogenic vasodilatation in the skin. Functioning of nitrergic vasodilator nerves is evidenced not only in a variety of mammals, including humans and monkeys, but also in non-mammals. The present review article includes recent advances in research on the functional importance of nitrergic nerves concerning the control of cerebral blood flow, as well as other regions, and vascular resistance. Although information is still insufficient, the nitrergic nerve histology and function in vasculatures of non-mammals are also summarized.

Ontogenic development of nerve fibers in human fetal livers: an immunohistochemical study using neural cell adhesion molecule (NCAM) and neuron-specific enolase (NSE)

The aim of the study was to investigate nerve fibers (NF) in human fetal livers. An immunohistochemical study was performed. NF were classified into portal tract innervation (PoI) and parenchymal innervation (PaI). The hilum area showed many Pol NF at 7 GW, and NF increased with gestational week (GW). Direct innervations to biliary epithelium were recognized. In large portal tracts, a few NCAM-positive mesenchymal cells were seen at 8 GW and many mesenchymal cells were noted around 12 GW. Apparent NF emerged around 15 GW, and NF increased with GW. Many NF plexuses were seen in 30-40 GW. In small portal tracts, no NF were seen in 7-10 GW. A few NCAM-positive mesenchymal cells emerged in 11 GW, and they increased thereafter. Apparent NF were seen around 20 GW and NF increased with GW. At term (40 GW), PoI NF were still immature. Ductal plate (DP) was positive for NCAM, NSE, chromogranin and synaptophysin, and direct innervations to DP were seen. The direct innervations to developing bile ducts and peribiliary glands were also seen. PaI NF were first seen at 21 GW and was consistent until 40 GW in which a few NF were seen in PaI. These observations suggest that PoI NF arise from committed portal mesenchyme. PaI NF are very immature at 40 GW. There are direct innervations to bile ducts, peribiliary glands, portal veins, hepatic arteries, and DP.

Hypothalamic control of hepatic lipid metabolism via the autonomic nervous system

Our body is well designed to store energy in times of nutrient excess, and release energy in times of food deprivation. This adaptation to the external environment is achieved by humoral factors and the autonomic nervous system. Claude Bernard, in the 19th century, showed the importance of the autonomic nervous system in the control of glucose metabolism. In the 20th century, the discovery of insulin and the development of techniques to measure hormone concentrations shifted the focus from the neural control of metabolism to the secretion of hormones, thus functionally "decapitating" the body. Just before the end of the 20th century, starting with the discovery of leptin in 1994, the control of energy metabolism went back to our heads. Since the start of 21st century, numerous studies have reported the involvement of hypothalamic pathways in the control of hepatic insulin sensitivity and glucose production. The autonomic nervous system is, therefore, acknowledged to be one of the important determinants of liver metabolism and a possible treatment target. In this chapter, we review research to date on the hypothalamic control of hepatic lipid metabolism.

Carvedilol improves ethanol-induced liver injury via modifying the interaction between oxidative stress and sympathetic hyperactivity in rats

AIM

Oxidative stress is a major pathway mediating ethanol hepatotoxicity and liver injury. We previously found that carvedilol, which can block the sympathetic nervous system via β1-, β2- and α1-adrenoreceptors, modifies ethanol-induced production of lipogenesis- and fibrogenesis-related mediators from hepatic stellate cells (HSC). In the present study, we assessed the effects of carvedilol on ethanol-induced liver injury, hepatic insulin resistance, and the interaction between oxidative stress and sympathetic hyperactivity in rats with alcoholic fatty liver disease (AFLD).

METHODS

Male Wistar rats were pair-fed for 49 days and divided into four groups: control and ethanol liquid-diet-fed rats with and without 7-day carvedilol treatment. Rats' sympathetic activity, hepatic oxidative stress, hepatic insulin resistance and liver injury were evaluated based on biochemical analysis, enzyme-linked immunosorbent assay, fluorescence immunohistochemistry, western blot and reverse transcriptase polymerase chain reaction.

RESULTS

Forty-nine days of ethanol consumption induced the increases in circulating noradrenaline metabolite (3-methoxy-4-hydroxyphenylglycol), hepatic noradrenaline and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, the downregulation of hepatic insulin receptor substrate-1 gene expression, and the accumulation of fatty droplets within hepatocytes with the increased hepatic triglyceride and blood alanine aminotransferase levels. All of these changes were modified by carvedilol treatment. 8-OHdG was detected in activated HSC and suppressed by carvedilol treatment based on fluorescence immunohistochemical double-staining analysis.

CONCLUSION

Carvedilol may modify the interaction between the oxidative stress and the sympathetic hyperactivity, and then contribute to attenuating the development of AFLD in rats. Additionally, oxidative stress may be responsible for the activation of HSC during the early stage of alcoholic liver disease.

Hepatic nervous system and neurobiology of the liver

The liver has a nervous system containing both afferent and efferent neurons that are involved in a number of processes. The afferent arm includes the sensation of lipids, glucose, and metabolites (after eating and drinking) and triggers the nervous system to make appropriate physiological changes. The efferent arm is essential for metabolic regulation, modulation of fibrosis and biliary function and the control of a number of other processes. Experimental models have helped us to establish how: (i) the liver is innervated by the autonomic nervous system; and (ii) the cell types that are involved in these processes. Thus, the liver acts as both a sensor and effector that is influenced by neurological signals and ablation. Understanding these processes hold significant implications in disease processes such as diabetes and obesity, which are influenced by appetite and hormonal signals.

The role of gastrointestinal hormones in hepatic lipid metabolism

Hepatocellular accumulation of free fatty acids (FFAs) in the form of triglycerides constitutes the metabolic basis for the development of nonalcoholic fatty liver disease (NAFLD). Recent data demonstrate that excess FFA hepatocyte storage is likely to lead to lipotoxicity and hepatocyte apoptosis. Hence, FFA-mediated hepatocyte injury is a key contributor to the pathogenesis of nonalcoholic steatohepatitis (NASH). Nonalcoholic steatohepatitis, obesity, type 2 diabetes, essential hypertension, and other common medical problems together comprise metabolic syndrome. Evidence suggests that peptide hormones from the L cells of the distal small intestine, which comprise the core of the enteroendocrine system (EES), play two key roles, serving either as incretins, or as mediators of appetite and satiety in the central nervous system. Recent data related to glucagon-like peptide-1 (GLP-1) and other known L-cell hormones have accumulated due to the increasing frequency of bariatric surgery, which increase delivery of bile salts to the hindgut. Bile acids are a key stimulus for the TGR5 receptor of the L cells. Enhanced bile-salt flow and subsequent EES stimulation may be central to elimination of hepatic steatosis following bariatric surgery. Although GLP-1 is a clinically relevant pharmacological analogue that drives pancreatic β-cell insulin output, GLP-1 analogues also have independent benefits via their effects on hepatocellular FFA metabolism. The authors also discuss recent data regarding the role of the major peptides released by the EES, which promote satiety and modulate energy homeostasis and utilization, as well as those that control fat absorption and intestinal permeability. Taken together, elucidating novel functions for EES-related peptides and pharmacologic development of peptide analogues offer potential far-ranging treatment for obesity-related human disease.

Prognostic significance of lymphovascular or perineural invasion in patients with locally advanced colorectal cancer

BACKGROUND

This study was designed to evaluate the prognostic significance of the positivity of lymphovascular (LVI) and perineural invasion (PNI) in patients with locally advanced colorectal cancer.

METHODS

From January 1999 to December 2009, 1,437 consecutive patients who underwent curative surgery for stage II or III colorectal cancer were analyzed. Patients were then categorized into 4 groups: LVI-/PNI- (n = 850), LVI+ only (n = 178), PNI+ only (n = 271), and LVI+/PNI+ (n = 138).

RESULTS

With a median follow-up period of 56 months, the 5-year overall survival rates of patients with LVI-/PNI-, LVI+ only, PNI+ only, and LVI+/PNI+ were 82%, 73%, 71%, and 56%, respectively (P < .001), and the 5-year disease-free survival rates of patients with LVI-/PNI-, LVI+ only, PNI+ only, and LVI+/PNI+ were 80%, 70%, 65%, and 46%, respectively (P < .001). In multivariate analysis, LVI+/PNI+ was an independent prognostic factor for both overall survival (P < .001) and disease-free survival (P < .001).

CONCLUSIONS

Positivity of both LVI and PNI is a strong predictor of overall and disease-free survival in patients with stages II and III colorectal cancer.

Hepatic stem cell niches

Stem cell niches are special microenvironments that maintain stem cells and control their behavior to ensure tissue homeostasis and regeneration throughout life. The liver has a high regenerative capacity that involves stem/progenitor cells when the proliferation of hepatocytes is impaired. In recent years progress has been made in the identification of potential hepatic stem cell niches. There is evidence that hepatic progenitor cells can originate from niches in the canals of Hering; in addition, the space of Disse may also serve as a stem cell niche during fetal hematopoiesis and constitute a niche for stellate cells in adults.

Diabetes confers a vasoprotective role to the neurocompensatory response elicited by carotid balloon injury: consequences on contralateral carotid tone and blood flow

The purpose from this study was to investigate the consequences of sensory neurocompensation to carotid balloon injury in diabetic rats on angiotensin II-induced contraction and basal blood flow in contralateral carotid. Concentration-response curves for angiotensin II and blood flow were obtained in contralateral carotid from non-treated or capsaicin-treated streptozotocin-induced diabetic rats that underwent carotid balloon injury. Diabetes increased angiotensin II-induced contraction and impaired the blood flow in non-operated rat carotid. In diabetic rats, balloon injury led to neointima formation, which reduced the blood flow in ipsilateral carotid. Carotid balloon injury in diabetic rats reduced angiotensin II-induced contraction and restored the blood flow in contralateral carotid when compared to diabetic non-operated rat carotid. Capsaicin inhibited the effects evoked by carotid balloon injury on diabetic rat contralateral carotid. Endothelium removal, PEG-catalase (hydrogen peroxide scavenger) or l-NPA (neuronal nitric oxide synthase, nNOS, inhibitor) increased angiotensin II-induced contraction in contralateral carotid from diabetic operated rats to the levels observed in diabetic non-operated rat carotid. Our findings suggest that carotid balloon injury in diabetic rats elicits a neurocompensation that attenuates the diabetic hyperreactivity to angiotensin II in contralateral carotid by a sensory nerves-dependent mechanism mediated by hydrogen peroxide derived from endothelial nNOS. This sensory mechanism also restored the blood flow in this vessel, compensating the impaired blood flow in diabetic rat ipsilateral carotid. Thus, our major conclusions are that Diabetes confers a vasoprotective significance to the neurocompensation to carotid balloon injury in preventing further damage at carotid cerebral irrigation after angioplasty in diabetic subjects.

Neuropeptide Y in the noradrenergic neurons induces the development of cardiometabolic diseases in a transgenic mouse model

Neuropeptide Y (NPY) is a neuropeptide widely expressed in the brain and a peptide transmitter of sympathetic nervous system (SNS) co-released with noradrenaline (NA) in prolonged stress. Association of a gain-of-function polymorphism in the human NPY gene with dyslipideamia, diabetes and vascular diseases suggests that increased NPY plays a role in the pathogenesis of the metabolic syndrome in humans. In the hypothalamus, NPY plays an established role in the regulation of body energy homeostasis. However, the effects of NPY elsewhere in the brain and in the SNS are less explored. In order to understand the role of NPY co-expressed with NA in the sympathetic nerves and brain noradrenergic neurons, a novel mouse model overexpressing NPY in noradrenergic neurons was generated. The mouse displays metabolic defects such as increased adiposity, hepatosteatosis, and impaired glucose tolerance as well as stress-related hypertension and increased susceptibility to vascular wall hypertrophy. The mouse phenotype closely reflects the findings of the several association studies with human NPY gene polymorphisms, and fits with the previous work on the effects of stress-induced NPY release on metabolism and vasculature. Thus, in addition of promoting feeding and obesity in the hypothalamus, NPY expressed in the noradrenergic neurons in the brain and in the SNS induces the development of cardiometabolic diseases.

Dipeptidylpeptidase--IV, a key enzyme for the degradation of incretins and neuropeptides: activity and expression in the liver of lean and obese rats

Given the scarcity of donors, moderately fatty livers (FLs) are currently being considered as possible grafts for orthotopic liver transplantation (OLT), notwithstanding their poor tolerance to conventional cold preservation. The behaviour of parenchymal and sinusoidal liver cells during transplantation is being studied worldwide. Much less attention has been paid to the biliary tree, although this is considered the Achille's heel even of normal liver transplantation. To evaluate the response of the biliary compartment of FLs to the various phases of OLT reliable markers are necessary. Previously we demonstrated that Alkaline Phosphatase was scarcely active in bile canaliculi of FLs and thus ruled it out as a marker. As an alternative, dipeptidylpeptidase-IV (DPP-IV), was investigated. This ecto-peptidase plays an important role in glucose metabolism, rapidly inactivating insulin secreting hormones (incretins) that are important regulators of glucose metabolism. DPP-IV inhibitors are indeed used to treat Type II diabetes. Neuropeptides regulating bile transport and composition are further important substrates of DPP-IV in the enterohepatic axis. DPP-IV activity was investigated with an azo-coupling method in the liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. Protein expression was studied by immunofluorescence with the monoclonal antibody (clone 5E8). In Wistar rat liver, DPP-IV activity and expression were high in the whole biliary tree, and moderate in sinusoid endothelial cells, in agreement with the literature. Main substrates of DPP-IV in hepatocytes and cholangiocytes could be incretins GLP-1 and GIP, and neuropeptides such as vasoactive intestinal peptide (VIP) and substance P, suggesting that these substances are inactivated or modified through the biliary route. In lean Zucker rat liver the enzyme reaction and protein expression patterns were similar to those of Wistar rat. In obese rat liver the patterns of DPP-IV activity and expression in hepatocytes reflected the morphological alterations induced by steatosis as lipid-rich hepatocytes had scarce activity, located either in deformed bile canaliculi or in the sinusoidal and lateral domains of the plasma membrane. These findings suggest that bile canaliculi in steatotic cells have an impaired capacity to inactivate incretins and neuropeptides. Incretin and/or neuropeptide deregulation is indeed thought to play important roles in obesity and insulin-resistance. No alteration in enzyme activity and expression was found in the upper segments of the biliary tree of obese respect to lean Zucker and Wistar rats. In conclusion, this research demonstrates that DPP-IV is a promising in situ marker of biliary functionality not only of normal but also of fatty rats. The approach, initially devised to investigate the behaviour of the liver during the various phases of transplantation, appears to have a much higher potentiality as it could be further exploited to investigate any pathological or stressful conditions involving the biliary tract (i.e., metabolic syndrome and cholestasis) and the response of the biliary tract to therapy and/or to surgery.

Regulation of hepatic glucose uptake and storage in vivo

In the postprandial state, the liver takes up and stores glucose to minimize the fluctuation of glycemia. Elevated insulin concentrations, an increase in the load of glucose reaching the liver, and the oral/enteral/portal vein route of glucose delivery (compared with the peripheral intravenous route) are factors that increase the rate of net hepatic glucose uptake (NHGU). The entry of glucose into the portal vein stimulates a portal glucose signal that not only enhances NHGU but concomitantly reduces muscle glucose uptake to ensure appropriate partitioning of a glucose load. This coordinated regulation of glucose uptake is likely neurally mediated, at least in part, because it is not observed after total hepatic denervation. Moreover, there is evidence that both the sympathetic and the nitrergic innervation of the liver exert a tonic repression of NHGU that is relieved under feeding conditions. Further, the energy sensor 5'AMP-activated protein kinase appears to be involved in regulation of NHGU and glycogen storage. Consumption of a high-fat and high-fructose diet impairs NHGU and glycogen storage in association with a reduction in glucokinase protein and activity. An understanding of the impact of nutrients themselves and the route of nutrient delivery on liver carbohydrate metabolism is fundamental to the development of therapies for impaired postprandial glucoregulation.

Negative feedforward control of body fluid homeostasis by hepatorenal reflex

The liver, well known for its role in metabolism, clearance and storage can also be regarded as a sensory organ. The liver is an ideal place to monitor the quality and quantity of absorbed substances, because portal blood delivers substances absorbed from the intestine to the liver and these substances circulate in the hepatic vasculature before substances enter the systemic circulation. Sodium (Na(+))-sensitive mechanism exists in the liver; it is stimulated by the increase in Na(+) concentration in the portal vein, and then hepatorenal reflex is triggered. Renal sympathetic nerve activity is reflexively decreased and urinary Na(+) excretion is increased. This Na(+)-sensitive hepatorenal reflex has a significant role in post-prandial natriuresis. However, the long-term role of this reflex in Na(+) homeostasis may be less important, probably because of the desensitization of Na(+)-sensitive mechanisms. Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) is involved in the hepatoportal Na(+)-sensitive mechanism, and NKCC1 expression is reduced if the hepatoportal region is exposed to high Na(+) concentrations for a long time. This situation occurs when animals intake a high-sodium chloride diet for a long time. Liver cirrhosis also impairs the Na(+)-sensitive hepatorenal reflex. Hepatoportal baroreceptor-induced renal sympathetic excitation and the impaired Na(+)-sensitive hepatorenal reflex may partially explain the Na(+) retention in liver cirrhosis.