Altered hepatic fatty acid metabolism in endotoxicosis: effect of L-carnitine on survival

1989 ◽  
Vol 256 (1) ◽  
pp. E31-E38 ◽  
Author(s):  
N. Takeyama ◽  
D. Takagi ◽  
N. Matsuo ◽  
Y. Kitazawa ◽  
T. Tanaka

The activities of palmitoyl-coenzyme A (CoA) synthetase, carnitine acetyltransferase (CAT), and carnitine palmitoyltransferase (CPT) and the levels of ketone bodies, reduced coenzyme A (CoASH), carnitine, and their esters, which are involved in fatty acid metabolism, in rat liver and plasma were measured after the administration of Escherichia coli lipopolysaccharide (LPS). We also studied the effect of L-carnitine treatment before LPS administration on survival and on hepatic fatty acid metabolism. The activities of CAT and CPT and the concentrations of ketone bodies, CoA, and carnitine derivatives (except for malonyl-CoA) declined in the liver after LPS administration. The activity of palmitoyl-CoA synthetase was changed little after LPS administration, and the level of hepatic malonyl-CoA increased significantly, suggesting that LPS causes activated fatty acids to undergo esterification and lipogenesis rather than oxidation. Treatment of rats with L-carnitine before LPS greatly increased the survival rate, but did not affect enzymes that metabolize fatty acids, CoA, or carnitine derivatives in the liver. Further studies are necessary to elucidate the mechanism of the effect of carnitine on post-LPS survival.

2001 ◽  
Vol 280 (1) ◽  
pp. R183-R190 ◽  
Author(s):  
Robert H. Lane ◽  
David E. Kelley ◽  
Elisa M. Gruetzmacher ◽  
Sherin U. Devaskar

Multiple adult morbidities are associated with intrauterine growth retardation (IUGR) including dyslipidemia. We hypothesized that uteroplacental insufficiency and subsequent IUGR in the rat would lead to altered hepatic fatty acid metabolism. To test this hypothesis, we quantified hepatic mRNA levels of acetyl-CoA carboxylase (ACC), carnitine palmitoyltransferase (CPTI), the β-oxidation-trifunctional protein (HADH), fasting serum triglycerides, and hepatic malonyl-CoA levels at different ages in control and IUGR rats. Fetal gene expression of all three enzymes was decreased. Juvenile gene expression of CPTI and HADH continued to be decreased, whereas gene expression of ACC was increased. Serum triglycerides were unchanged. A sex-specific response was noted in the adult rats. In males, serum triglycerides, hepatic malonyl-CoA levels, and ACC mRNA levels were significantly increased, and CPTI and HADH mRNA levels were significantly decreased. In contrast, the female rats demonstrated no significant changes in these variables. These results suggest that uteroplacental insufficiency leads to altered hepatic fatty acid metabolism that may contribute to the adult dyslipidemia associated with low birth weight.


1981 ◽  
Vol 198 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Victor A. Zammit

1. The concentrations of malonyl-CoA, glycerol 3-phosphate, non-esterified carnitine, acid-soluble and acid-insoluble acylcarnitines, acetoacetate, 3-hydroxybutyrate and acid-insoluble acyl-CoA were measured in rapidly-frozen liver samples from fed or starved (24h) virgin, pregnant (19–20 days), lactating (2, 10–12 and 18–20 days) and weaned (for 24h, on 10th day of lactation) rats. The activities of total and N-ethylmaleimide-sensitive and -insensitive glycerophosphate acyltransferase (acyl-CoA:sn-glycerol 3-phosphate O-acyltransferase; EC 2.3.1.15) were also measured. 2. The concentration of malonyl-CoA was significantly higher in liver of fed pregnant, mid- and late-lactating rats than in liver of fed virgin rats. After starvation for 24h hepatic malonyl-CoA concentrations were higher in mid-lactating rats and lower in pregnant and weaned rats than in virgin animals. 3. After starvation for 24h the hepatic concentrations of glycerol 3-phosphate, ketone bodies, acid-soluble acylcarnitines and the value for the [3-hydroxybutyrate]/[acetoacetate] ratio were all highest in pregnant rats, intermediate in virgin, 2-day lactating and weaned animals and lowest in mid- and late-lactating rats. The concentrations of acid-insoluble acylcarnitines also increased most in pregnant rats, after starvation. The concentration of acid-insoluble acyl-CoA increased equally after starvation in virgin and pregnant animals but did not increase significantly in all other animals studied. 4. The total concentration of carnitine was similar in livers of fed virgin, pregnant and 2-day lactating animals but fell markedly by the 10th day of lactation and remained low in late-lactating animals. The concentration of non-esterified carnitine followed the same pattern. After starvation for 24h the hepatic concentration of non-esterified carnitine decreased significantly in virgin, pregnant and 2-day lactating animals, but remained unchanged in mid- and late-lactating or weaned animals. 5. The activities of N-ethylmaleimide-sensitive and -insensitive glycerophosphate acyltransferase both increased significantly in livers of mid-lactating animals. After starvation for 24h the activity of the N-ethylmaleimide-insensitive O-acyltransferase decreased in livers of virgin, pregnant and mid-lactating animals, whereas the activity of the N-ethylmaleimide-sensitive O-acyltransferase was unchanged in virgin animals but decreased markedly in livers of pregnant and lactating rats. 6. The results are discussed in relation to the importance of different metabolic parameters in the regulation of long-chain acyl-CoA metabolism in the liver.


2003 ◽  
Vol 90 (5) ◽  
pp. 887-893 ◽  
Author(s):  
Anna M. Giudetti ◽  
Anton C. Beynen ◽  
Arnoldina G. Lemmens ◽  
Gabriele V. Gnoni ◽  
Math J. H. Geelen

In the present study the effects of some C18fatty acids on hepatic fatty acid metabolism have been compared. Male rats were fed cholesterol-free diets containing either C18:0, C18:1cisor C18:1transisomers as the variables. In accordance with previous work, oleic acid in the diet caused an increase in cholesterol concentration in the liver and in the lipoprotein fraction of density (d; kg/l)<1·006. Oleic acid also reduced the triacylglycerol:cholesterol value in this fraction. Surprisingly, the C18:1transisomers diet induced a decrease in the amount of cholesterol in total plasma as well as in the 1·019<d<1·063 lipoprotein fraction. Both oleic acid and C18:1transisomers increased the concentration of triacylglycerols in the liver. The two C18:1fatty acids differently influenced the hepatic activities of carnitine palmitoyltransferase-I and 3-hydroxy-acyl-CoA dehydrogenase; both enzymes were inhibited by C18:1transisomers, while no change was induced by oleic acid. The activity of the citrate carrier was lower in the oleic acid- and C18:1transisomers-fed rats, when compared with the rats fed stearic acid. No diet effects were seen for the activities of acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, citrate synthase and phosphofructokinase. The results are interpreted in that oleic acid raised liver triacylglycerol by reducing the secretion of it with thed<1·006 lipoprotein fraction whereas the C18:1transisomers enhanced liver triacylglycerol by lowering the hepatic oxidation of fatty acids.


2009 ◽  
Vol 34 (3) ◽  
pp. 315-322 ◽  
Author(s):  
Gregory R. Steinberg

During moderate-intensity exercise, fatty acids are the predominant substrate for working skeletal muscle. The release of fatty acids from adipose tissue stores, combined with the ability of skeletal muscle to actively fine tune the gradient between fatty acid and carbohydrate metabolism, depending on substrate availability and energetic demands, requires a coordinated system of metabolic control. Over the past decade, since the discovery that AMP-activated protein kinase (AMPK) was increased in accordance with exercise intensity, there has been significant interest in the proposed role of this ancient stress-sensing kinase as a critical integrative switch controlling metabolic responses during exercise. In this review, studies examining the role of AMPK as a regulator of fatty acid metabolism in both adipose tissue and skeletal muscle during exercise will be discussed. Exercise induces activation of AMPK in adipocytes and regulates triglyceride hydrolysis and esterfication through phosphorylation of hormone sensitive lipase (HSL) and glycerol-3-phosphate acyl-transferase, respectively. In skeletal muscle, exercise-induced activation of AMPK is associated with increases in fatty acid uptake, phosphorylation of HSL, and increased fatty acid oxidation, which is thought to occur via the acetyl-CoA carboxylase-malony-CoA-CPT-1 signalling axis. Despite the importance of AMPK in regulating fatty acid metabolism under resting conditions, recent evidence from transgenic models of AMPK deficiency suggest that alternative signalling pathways may also be important for the control of fatty acid metabolism during exercise.


2020 ◽  
Author(s):  
Ada Admin ◽  
Zhuo Mao ◽  
Mingji Feng ◽  
Zhuoran Li ◽  
Minsi Zhou ◽  
...  

ETV5 is an ETS transcription factor which has been associated with obesity in genomic association studies. However, little is known about the role of ETV5 in hepatic lipid metabolism and non-alcoholic fatty liver disease (NAFLD). In the present study, we found that ETV5 protein expression was increased in diet- and genetic-induced steatotic liver. ETV5 responded to the nutrient status in an mTORC1 dependent manner and in turn regulated mTORC1 activity. Both viral-mediated and genetic depletion of ETV5 in mice led to increased lipid accumulation in the liver. RNA sequencing analysis revealed that PPAR signaling and fatty acid degradation/metabolism pathways were significantly downregulated in ETV5 deficient hepatocytes <i>in vivo</i> and <i>in vitro. </i>Mechanistically, ETV5 could bind to the PPRE region of PPAR downstream genes and enhance its transactivity. Collectively, our study identifies ETV5 as a novel transcription factor for the regulation of hepatic fatty acid metabolism which is required for the optimal β oxidation process. ETV5 may provide a therapeutic target for the treatment of hepatic steatosis.<br>


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