Neuronal Lipoprotein Lipase Deficiency alters Neuronal Function and Hepatic Metabolism

2020 ◽  
Author(s):  
Kimberley Bruce ◽  
Hong Wang ◽  
Evgenia Dobrinskikh ◽  
Ivan A Rudenko ◽  
Hong Gao ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Tca Cycle ◽  
Hepatic Metabolism ◽  
Hepatic Function ◽  
Molecular Characteristics ◽  
Fluorescence Lifetime Imaging ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid Accumulation ◽  
Glucose And Lipid Metabolism ◽  
Neuronal Metabolism

Abstract Background: The autonomic regulation of hepatic metabolism offers a novel target for the treatment of non-alcoholic fatty liver disease (NAFLD). However, the molecular characteristics of neurons that regulate the brain-liver axis remain unclear. Since mice lacking neuronal lipoprotein lipase (LPL) develop perturbations in neuronal lipid-sensing and systemic energy balance, we reasoned that LPL may be a component of pre-autonomic neurons involved in the regulation of hepatic metabolism. Methods: Measures of glucose homeostasis in mice homozygous (NEXLPL-/-) and heterozygous (NEXLPL+/-) for neuronal LPL deficiency were compared to that of WT mice. A detailed analysis of hepatic glucose and lipid metabolism was also determined in NEXLPL+/- at 6-18 mo. To determine the effect of neuronal LPL deficiency on neuronal physiology, liver-related neurons were identified in the paraventricular nucleus (PVN) of the hypothalamus using the transsynaptic retrograde tracer PRV-152. In addition, we used Fluorescence Lifetime Imaging Microscopy (FLIM) as a novel method to visualize changes in neuronal metabolism following LPL-depletion directly in the PVN. Results: Here we show that despite obesity, mice with reduced neuronal LPL also show improved glucose tolerance and reduced hepatic lipid accumulation with aging, concomitant with reduced hepatic lipogenic gene expression (e.g. SCD1 and FADS2). Retroviral tracing and patch clamp studies revealed reduced inhibitory post-synaptic currents in liver-related neurons lacking LPL. Quantification of the free versus bound Nicotinamide Adenine Dinucleotide (NADH) and Flavin Adenine Dinucleotide (FAD), revealed that LPL loss resulted in altered substrate utilization characterized by increased glucose utilization and TCA cycle flux. These findings were recapitulated by analysis of global metabolites from hypothalamic cell lines either deficient in, or over-expressing, LPL. Conclusions: Our data suggest that LPL is a novel feature of liver–related preautonomic neurons in the PVN. Moreover, LPL loss is sufficient to alter neuronal metabolism and function, leading to changes in systemic glucose metabolism including improved hepatic function with age.

scholarly journals Neuronal Lipoprotein Lipase Deficiency Alters Neuronal Function and Hepatic Metabolism

2020 ◽  
Author(s):  
Kimberley D. Bruce ◽  
Hong Wang ◽  
Evgenia Dobrinskikh ◽  
Ivan Rudenko ◽  
Hong Gao ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Tca Cycle ◽  
Hepatic Metabolism ◽  
Molecular Characteristics ◽  
Fluorescence Lifetime Imaging ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid Accumulation ◽  
Novel Target ◽  
And Function ◽  
Neuronal Physiology

The autonomic regulation of hepatic metabolism offers a novel target for the treatment of non-alcoholic fatty liver disease (NAFLD). However, the molecular characteristics of neurons that regulate the brain-liver axis remain unclear. Since mice lacking neuronal lipoprotein lipase (LPL) develop perturbations in neuronal lipid-sensing and systemic energy balance, we reasoned that LPL might be a component of pre-autonomic neurons involved in the regulation of hepatic metabolism. Here we show that despite obesity, mice with reduced neuronal LPL (NEXCreLPLflox [LPL KD]) show improved glucose tolerance and reduced hepatic lipid accumulation with aging compared to WT controls (LPLflox). To determine the effect of LPL deficiency on neuronal physiology, liver-related neurons were identified in the paraventricular nucleus (PVN) of the hypothalamus using the transsynaptic retrograde tracer PRV-152. Patch-clamp studies revealed reduced inhibitory post-synaptic currents in liver-related neurons of LPL KD mice. Fluorescence Lifetime Imaging Microscopy (FLIM) was used to visualize metabolic changes in LPL-depleted neurons. Quantification of the free vs. bound Nicotinamide Adenine Dinucleotide (NADH) and Flavin Adenine Dinucleotide (FAD) revealed increased glucose utilization and TCA cycle flux in LPL-depleted neurons compared to controls. Global metabolomics from hypothalamic cell lines either deficient in, or over-expressing, LPL recapitulated these findings. Our data suggest that LPL is a novel feature of liver–related preautonomic neurons in the PVN. Moreover, LPL loss is sufficient to cause changes in neuronal substrate utilization and function, which may precede changes in hepatic metabolism.

scholarly journals Neuronal Lipoprotein Lipase Deficiency Alters Neuronal Function and Hepatic Metabolism

Metabolites ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 385
Author(s):  
Kimberley D. Bruce ◽  
Evgenia Dobrinskikh ◽  
Hong Wang ◽  
Ivan Rudenko ◽  
Hong Gao ◽  
...  
Keyword(s):  
Lipoprotein Lipase ◽  
Tca Cycle ◽  
Hepatic Metabolism ◽  
Molecular Characteristics ◽  
Fluorescence Lifetime Imaging ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid Accumulation ◽  
Novel Target ◽  
And Function ◽  
Neuronal Physiology

The autonomic regulation of hepatic metabolism offers a novel target for the treatment of non-alcoholic fatty liver disease (NAFLD). However, the molecular characteristics of neurons that regulate the brain-liver axis remain unclear. Since mice lacking neuronal lipoprotein lipase (LPL) develop perturbations in neuronal lipid-sensing and systemic energy balance, we reasoned that LPL might be a component of pre-autonomic neurons involved in the regulation of hepatic metabolism. Here, we show that, despite obesity, mice with reduced neuronal LPL (NEXCreLPLflox (LPL KD)) show improved glucose tolerance and reduced hepatic lipid accumulation with aging compared to wilt type (WT) controls (LPLflox). To determine the effect of LPL deficiency on neuronal physiology, liver-related neurons were identified in the paraventricular nucleus (PVN) of the hypothalamus using the transsynaptic retrograde tracer PRV-152. Patch-clamp studies revealed reduced inhibitory post-synaptic currents in liver-related neurons of LPL KD mice. Fluorescence lifetime imaging microscopy (FLIM) was used to visualize metabolic changes in LPL-depleted neurons. Quantification of free vs. bound nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) revealed increased glucose utilization and TCA cycle flux in LPL-depleted neurons compared to controls. Global metabolomics from hypothalamic cell lines either deficient in or over-expressing LPL recapitulated these findings. Our data suggest that LPL is a novel feature of liver-related preautonomic neurons in the PVN. Moreover, LPL loss is sufficient to cause changes in neuronal substrate utilization and function, which may precede changes in hepatic metabolism.

Dietary raffinose ameliorates hepatic lipid accumulation induced by cholic acid via modulation of enterohepatic bile acid circulation in rats

2021 ◽  
pp. 1-26
Author(s):  
Kenta Maegawa ◽  
Haruka Koyama ◽  
Satoru Fukiya ◽  
Atsushi Yokota ◽  
Koichiro Ueda ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Bile Acid ◽  
Cholic Acid ◽  
Lipid Accumulation ◽  
Enterohepatic Circulation ◽  
Control Diet ◽  
Hepatic Triglyceride ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation

Abstract Enterohepatic circulation of 12α-hydroxylated (12αOH) bile acid (BA) is enhanced depending on the energy intake in high-fat diet-fed rats. Such BA metabolism can be reproduced using a diet supplemented with cholic acid (CA), which also induces simple steatosis, without inflammation and fibrosis, accompanied by some other symptoms that are frequently observed in the condition of non-alcoholic fatty liver in rats. We investigated whether supplementation of the diet with raffinose (Raf) improves hepatic lipid accumulation induced by the CA-fed condition in rats. After acclimation to the AIN-93-based control diet, male Wistar rats were fed diets supplemented with a combination of Raf (30 g/kg diet) and/or CA (0.5 g/kg diet) for 4 weeks. Dietary Raf normalised hepatic triglyceride levels (two-way ANOVA P<0.001 for CA, P=0.02 for Raf, and P=0.004 for interaction) in the CA-supplemented diet-fed rats. Dietary Raf supplementation reduced hepatic 12αOH BA concentration (two-way ANOVA P<0.001 for CA, P=0.003 for Raf, and P=0.03 for interaction). The concentration of 12αOH BA was reduced in the aortic and portal plasma. Raf supplementation increased acetic acid concentration in the caecal contents (two-way ANOVA P=0.001 as a main effect). Multiple regression analysis revealed that concentrations of aortic 12αOH BA and caecal acetic acid could serve as predictors of hepatic triglyceride concentration (R2=0.55, P<0.001). However, Raf did not decrease the secondary 12αOH BA concentration in the caecal contents as well as the transaminase activity in the CA diet-fed rats. These results imply that dietary Raf normalises hepatic lipid accumulation via suppression of enterohepatic 12αOH BA circulation.

scholarly journals N-Acetyl Cysteine Targets Hepatic Lipid Accumulation to Curb Oxidative Stress and Inflammation in NAFLD: A Comprehensive Analysis of the Literature

Antioxidants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1283
Author(s):  
Phiwayinkosi V. Dludla ◽  
Bongani B. Nkambule ◽  
Sithandiwe E. Mazibuko-Mbeje ◽  
Tawanda M. Nyambuya ◽  
Fabio Marcheggiani ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lipid Accumulation ◽  
Randomized Clinical Trials ◽  
Therapeutic Potential ◽  
Therapeutic Effects ◽  
Metabolic Complications ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation ◽  
Acetyl Cysteine

Impaired adipose tissue function and insulin resistance remain instrumental in promoting hepatic lipid accumulation in conditions of metabolic syndrome. In fact, enhanced lipid accumulation together with oxidative stress and an abnormal inflammatory response underpin the development and severity of non-alcoholic fatty liver disease (NAFLD). There are currently no specific protective drugs against NAFLD, and effective interventions involving regular exercise and healthy diets have proved difficult to achieve and maintain. Alternatively, due to its antioxidant and anti-inflammatory properties, there has been growing interest in understanding the therapeutic effects of N-acetyl cysteine (NAC) against metabolic complications, including NAFLD. Here, reviewed evidence suggests that NAC blocks hepatic lipid accumulation in preclinical models of NAFLD. This is in part through the effective regulation of a fatty acid scavenger molecule (CD36) and transcriptional factors such as sterol regulatory element-binding protein (SREBP)-1c/-2 and peroxisome proliferator-activated receptor gamma (PPARγ). Importantly, NAC appears effective in improving liver function by reducing pro-inflammatory markers such as interleukin (IL)-6 IL-1β, tumour necrosis factor alpha (TNF-α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This was primarily through the attenuation of lipid peroxidation and enhancements in intracellular response antioxidants, particularly glutathione. Very few clinical studies support the beneficial effects of NAC against NAFLD-related complications, thus well-organized randomized clinical trials are still necessary to confirm its therapeutic potential.

Hepatic function in rats after spaceflight: effects on lipids, glycogen, and enzymes

1987 ◽  
Vol 252 (2) ◽  
pp. R222-R226 ◽  
Author(s):  
A. H. Merrill ◽  
E. Wang ◽  
D. P. Jones ◽  
J. L. Hargrove
Keyword(s):  
Specific Activity ◽  
Cytochrome B5 ◽  
Hepatic Metabolism ◽  
Microsomal Protein ◽  
Hepatic Function ◽  
Tyrosine Aminotransferase ◽  
Fatty Acyl ◽  
Blood Cholesterol ◽  
Serine Palmitoyltransferase ◽  
Coa Reductase

The inclusion of rats aboard Spacelab 3 (SL-3) allowed analyses of liver lipids, glycogen, hepatic enzymes of cholesterol, glycerolipid and sphingolipid biosynthesis, and other enzyme activities. Glycogen content was markedly elevated in livers from the flight animals compared with controls. Cholesterol was 24% (P less than 0.04) lower in livers from the experimental groups, whereas blood cholesterol was 19% higher (P less than 0.05). The activity of 3-hydroxy-3-methylglutaryl-CoA reductase, the rate-limiting enzyme of steroid biosynthesis, was 80% lower (P less than 0.01). Total phospholipids and sphingolipid levels did not differ significantly. The specific activity of fatty acyl-CoA synthetase, which is responsible for activation of fatty acids, was 37% (P less than 0.05) higher in microsomes from the rats on SL-3; however, since these animals had 25% less microsomal protein (P less than 0.02), there was no difference per gram of liver. The initial enzymes of sphingolipid and glycerolipid biosynthesis were assayed; serine palmitoyltransferase was 40% lower (P less than 0.01), and glycerol 3-phosphate acyltransferase did not differ. Hepatic cytochrome P-450 content decreased by 50% after spaceflight. Enzymes that did not differ significantly between the two groups include cytochrome b5, glutathione S-transferase, tyrosine aminotransferase, aspartate aminotransferase, and cystathionase. These findings suggest that spaceflight alters hepatic metabolism of several classes of compounds.

scholarly journals Hepatic Mitochondrial Oxidative Metabolism and Lipogenesis Synergistically Adapt to Mediate Healthy Embryonic-to-Neonatal Transition in Chicken

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chaitra Surugihalli ◽  
Tom E. Porter ◽  
Angela Chan ◽  
Linda S. Farley ◽  
Meghan Maguire ◽  
...  
Keyword(s):  
Lipid Oxidation ◽  
Metabolic Networks ◽  
Tca Cycle ◽  
Neonatal Development ◽  
Alcoholic Fatty Liver ◽  
Species Production ◽  
Mitochondrial Oxidative Metabolism ◽  
And Oxidative Stress ◽  
Alcoholic Fatty Liver Disease ◽  
Neonatal Transition

AbstractDuring the normal embryonic-to-neonatal development, the chicken liver is subjected to intense lipid burden from high rates of yolk-lipid oxidation and also from the accumulation of the yolk-derived and newly synthesized lipids from carbohydrates. High rates of hepatic lipid oxidation and lipogenesis are also central features of non-alcoholic fatty liver disease (NAFLD) in both rodents and humans, but is associated with impaired insulin signaling, dysfunctional mitochondrial energetics and oxidative stress. However, these adverse effects are not apparent in the liver of embryonic and neonatal chicken, despite lipid burden. Utilizing comprehensive metabolic profiling, we identify that steady induction of hepatic mitochondrial tricarboxylic acid (TCA) cycle and lipogenesis are central features of embryonic-to-neonatal transition. More importantly, the induction of TCA cycle and lipogenesis occurred together with the downregulation of hepatic β-oxidation and ketogenesis in the neonatal chicken. This synergistic remodeling of hepatic metabolic networks blunted inflammatory onset, prevented accumulation of lipotoxic intermediates (ceramides and diacylglycerols) and reduced reactive oxygen species production during embryonic-to-neonatal development. This dynamic remodeling of hepatic mitochondrial oxidative flux and lipogenesis aids in the healthy embryonic-to-neonatal transition in chicken. This natural physiological system could help identify mechanisms regulating mitochondrial function and lipogenesis, with potential implications towards treatment of NAFLD.

Etoposide kinetics in patients with obstructive jaundice.

1990 ◽  
Vol 8 (6) ◽  
pp. 1101-1107 ◽  
Author(s):  
K R Hande ◽  
S N Wolff ◽  
F A Greco ◽  
J D Hainsworth ◽  
G Reed ◽  
...  
Keyword(s):  
Obstructive Jaundice ◽  
Urinary Excretion ◽  
Hepatic Metabolism ◽  
Study Groups ◽  
Hepatic Function ◽  
Volume Of Distribution ◽  
Metabolic Clearance ◽  
Total Clearance ◽  
Dose Reductions ◽  
Made In

The kinetics and urinary excretion of etoposide and etoposide glucuronide were determined in 11 patients with obstructive jaundice (bilirubin greater than 2.0 mg/dL) and in 23 patients with normal renal and hepatic function. Mean (+/- SE) measurements of clearance (24.5 +/- 2.06 v 26.5 +/- 2.05 mL/min/m2), half-life (5.7 +/- 0.5 v 6.4 +/- 0.5 hours), and volume of distribution (12.4 +/- 1.1 v 13.7 +/- 1.6 L/m2) were not significantly different in patients with jaundice when compared with controls. Similarly, etoposide kinetics in three patients determined during a period of hyperbilirubinemia were not different from measurements made in the same patients following resolution of their obstructive jaundice. In patients with jaundice, 46% of an administered etoposide dose was excreted in the urine as etoposide compared with 35% in controls (P = .15). Urinary excretion of etoposide glucuronide accounted for 29% of an administered etoposide dose in control patients and 15% in those with hepatic obstruction (P = .03). Biliary etoposide excretion measured in four patients with T-tubes was insignificant (less than 2.0% of an administered dose). The calculated renal clearance of etoposide was 11.5 mL/min/m2 in patients with jaundice and 10.4 mL/min/m2 in controls (P = .53). Respective metabolic clearance was 4.9 and 6.9 mL/min/m2 in these two study groups (P = .13). Although hepatic metabolism of etoposide may be slightly decreased in patients with obstructive jaundice, a modest increase in renal etoposide excretion appears to compensate for this change, so that total clearance is similar in the patients with jaundice when compared with controls. No etoposide dose reductions appear to be needed in treating patients with obstructive jaundice who have normal renal function.

scholarly journals TRIB1 downregulates hepatic lipogenesis and glycogenesis via multiple molecular interactions

2014 ◽  
Vol 52 (2) ◽  
pp. 145-158 ◽  
Author(s):  
Yuumi Ishizuka ◽  
Kazuhiro Nakayama ◽  
Ayumi Ogawa ◽  
Saho Makishima ◽  
Supichaya Boonvisut ◽  
...  
Keyword(s):  
Molecular Interactions ◽  
Molecular Mechanisms ◽  
Protein A ◽  
Proteasome Inhibitors ◽  
Adenovirus Vector ◽  
Hepatic Lipogenesis ◽  
Enhancer Activity ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid Accumulation ◽  
Protein Levels

Mammalian tribbles homolog 1 (TRIB1) regulates hepatic lipogenesis and is genetically associated with plasma triglyceride (TG) levels and cholesterol, but the molecular mechanisms remain obscure. We explored these mechanisms in mouse livers transfected with a TRIB1 overexpression, a shRNA template or a control (LacZ) adenovirus vector. The overexpression of TRIB1 reduced, whereas induction of the shRNA template increased, plasma glucose, TG, and cholesterol and simultaneously hepatic TG and glycogen levels. The involvement of TRIB1 in hepatic lipid accumulation was supported by the findings of a human SNP association study. A TRIB1 SNP, rs6982502, was identified in an enhancer sequence, modulated enhancer activity in reporter gene assays, and was significantly (P=9.39×10−7) associated with ultrasonographically diagnosed non-alcoholic fatty liver disease in a population of 5570 individuals. Transcriptome analyses of mouse livers revealed significant modulation of the gene sets involved in glycogenolysis and lipogenesis. Enforced TRIB1 expression abolished CCAAT/enhancer binding protein A (CEBPA), CEBPB, and MLXIPL proteins, whereas knockdown increased the protein level. Levels of TRIB1 expression simultaneously affected MKK4 (MAP2K4), MEK1 (MAP2K1), and ERK1/2 (MAPK1/3) protein levels and the phosphorylation of JNK, but not of ERK1/2. Pull-down and mammalian two-hybrid analyses revealed novel molecular interaction between TRIB1 and a hepatic lipogenic master regulator, MLXIPL. Co-expression of TRIB1 and CEBPA or MLXIPL reduced their protein levels and proteasome inhibitors attenuated the reduction. These data suggested that the modulation of TRIB1 expression affects hepatic lipogenesis and glycogenesis through multiple molecular interactions.

Lipoprotein lipase liberates free fatty acids to inhibit HCV infection and prevent hepatic lipid accumulation

2016 ◽  
Vol 19 (4) ◽  
pp. e12673 ◽  
Author(s):  
Hung-Yu Sun ◽  
Chun-Chieh Lin ◽  
Pei-Ju Tsai ◽  
Wei-Jen Tsai ◽  
Jin-Ching Lee ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Lipoprotein Lipase ◽  
Lipid Accumulation ◽  
Hcv Infection ◽  
Hepatic Lipid ◽  
Hepatic Lipid Accumulation
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