scholarly journals Control of hepatic triacylglycerol synthesis. Diurnal variations in hepatic phosphatidate phosphohydrolase activity and in the concentrations of circulating insulin and corticosterone in rats

1979 ◽  
Vol 180 (2) ◽  
pp. 441-443 ◽  
Author(s):  
A M Knox ◽  
R G Sturton ◽  
J Cooling ◽  
D N Brindley
Keyword(s):  
Peak Concentration ◽  
Dark Period ◽  
Serum Insulin ◽  
Diurnal Variations ◽  
Male Rats ◽  
Serum Corticosterone ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Hepatic Triacylglycerol

Male rats were kept for 14 days with alternating 12h periods of light and darkness. The hepatic activity of soluble phosphatidate phosphohydrolase and the concentration of serum insulin were maximum at about 2h after dark. The peak concentration of serum corticosterone occurred 2h before the dark period. It is proposed that corticosterone is partly responsible for the increased phosphohydrolase activity, and that this enables the liver to increase its capacity to synthesize triacylglycerols during the period of maximum feeding.

scholarly journals Effects of phenobarbital upon triacylglycerol metabolism in the rabbit

1980 ◽  
Vol 192 (1) ◽  
pp. 165-175 ◽  
Author(s):  
D M Goldberg ◽  
M W Roomi ◽  
A Yu ◽  
D A K Roncari
Keyword(s):  
Enzyme Induction ◽  
Microsomal Enzyme ◽  
Gamma Glutamyltransferase ◽  
Triacylglycerol Metabolism ◽  
Triacylglycerol Synthesis ◽  
Triacylglycerol Content ◽  
Phosphatidate Phosphohydrolase ◽  
Hepatic Triacylglycerol ◽  
Microsomal Enzyme Induction

1. The association between hepatic microsomal enzyme induction and triacylglycerol metabolism was examined in fasting male rabbits (2kg body wt.) injected intra-peritoneally with 50 mg of phenobarbital per kg for 10 days. 2. Occurrence of enzyme induction was established by a significant increase in hepatic aminopyrine N-demethylase activity and cytochrome P-450 content, as well as a doubling of microsomal protein per g of liver and a 54% increase in liver weight. Parallel increments in hepatic gamma-glutamyltransferase (EC 2.3.2.2) activity occurred; these were more pronounced in the whole homogenate than in the microsomes, which only accounted for 12.5% of the total enzyme activity in the controls and 17.0% in the animals given phenobarbital. Increased activity of gamma-glutamyltransferase activity was also observed in the blood serum of the test animals. 3. The rabbits given phenobarbital manifested increased hepatic triacylglycerol content and the triacylglycerol concentration of blood serum was also elevated. These changes were accompanied by a significantly enhanced ability of cell-free fractions of liver from the test animals (postmitochondrial supernatant and microsomal fractions) to synthesize glycerolipids in vitro from sn-[14C] glycerol 3-phosphate and fatty acids, when expressed per whole liver. Relative to the protein content of the fraction, glycerolipid synthesis in vitro was significantly decreased in the microsomes, presumably consequent upon the dramatic increase in their total protein content, whereas no change occurred in the postmitochondrial supernatant, possibly due to the protective effect of cytosolic factors present in this fraction and known to enhance glycerolipid synthesis. 4. Microsomal phosphatidate phosphohydrolase accounted for 85% of the total liver activity of this enzyme and its specific activity was 20-fold higher than that of the cytosolic phosphatidate phosphohydrolase (EC 3.1.3.4), when each was measured under optimal conditions. A significant increase in the activity of both enzymes per whole liver occurred in the rabbits given phenobarbital. A closer correlation between hepatic triacylglycerol content and and microsomal phosphatidate phosphohydrolase, as well as the above observation, suggest that this, rather than the cytosolic enzyme, may be rate-limiting for triacylglycerol synthesis in rabbit liver. 5. Significant correlations were observed between the various factors of hepatic microsomal-enzyme induction (aminopyrine N-demethylase and gamma-glutamyltransferase activity as well as cytochrome P-450 content) and hepatic triacylglycerol content, suggesting that that microsomal enzyme induction may promote hepatic triacylglycerol synthesis and consequently hypertriglyceridaemia in the rabbit.

scholarly journals The effects of cortisol, corticotropin and thyroxine on the synthesis of glycerolipids and on the phosphatidate phosphohydrolase activity in rat liver

1978 ◽  
Vol 176 (3) ◽  
pp. 777-784 ◽  
Author(s):  
Helen P. Glenny ◽  
David N. Brindley
Keyword(s):  
Body Weight ◽  
Body Weight Gain ◽  
Relative Rate ◽  
Male Rats ◽  
Very Low Density Lipoproteins ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Ethanol Feeding ◽  
Enzyme Adaptation ◽  
Subtotal Hepatectomy

1. Male rats were injected daily for 5 days with 0.15m-NaCl, corticotropin, cortisol or l-thyroxine and the rates of glycerolipid synthesis were measured in the livers after intraportal injection of [14C]palmitate and [3H]glycerol. 2. Injection of all three hormones decreased the rates of body-weight gain. 3. Cortisol treatment increased the weight of the liver relative to body weight. 4. Thyroxine treatment increased the relative rate of triacylglycerol synthesis from [3H]glycerol and decreased the relative accumulation of 3H and 14C in diacylglycerol. It did not significantly alter the accumulation of these isotopes in phosphatidate nor the activity of the soluble phosphatidate phosphohydrolase in the total liver. However, this activity increased by 1.5-fold when expressed relative to the soluble protein of the liver. The increased triacylglycerol synthesis appears to be related to a general increase in the turnover of fatty acids in the liver. 5. Treatment with cortisol and corticotropin increased the relative rate of triacylglycerol synthesis from [3H]glycerol, decreased the accumulation of 3H in phosphatidate and increased the flux of both isotopes from phosphatidate to diacylglycerol. This appeared to be caused by the increased activity of the soluble phosphatidate phosphohydrolase that was observed in the livers of the cortisol-treated rats. 6. It is proposed that cortisol could be directly or indirectly involved in increasing the activity of hepatic phosphatidate phosphohydrolase in starvation, diabetes, laparotomy, subtotal hepatectomy, liver damage, ethanol feeding and in obesity. This enzyme adaptation could contribute to the potential of the liver to increase its synthesis and accumulation of triacylglycerols or to secrete very-low-density lipoproteins.

scholarly journals The involvement of phosphatidate phosphohydrolase and phospholipase A activities in the control of hepatic glycerolipid synthesis. Effects of acute feeding with glucose, fructose, sorbitol, glycerol and ethanol

1978 ◽  
Vol 174 (2) ◽  
pp. 667-670 ◽  
Author(s):  
R G Sturton ◽  
P H Pritchard ◽  
L Y Han ◽  
D N Brindley
Keyword(s):  
Single Dose ◽  
Microsomal Fraction ◽  
Phospholipase A ◽  
Stomach Tube ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Glycerolipid Synthesis ◽  
Significant Change ◽  
Hepatic Triacylglycerol

Rats were fed by stomach tube with a single dose of glucose, sorbitol, fructose, glycerol or ethanol of equivalent energy contents or with 0.15 M-NaCl. They were killed 6 h later and the relative rates of phosphatidate deacylation and dephosphorylation measured in the microsomal and supernatant fractions of the livers. Treatment with sorbitol, fructose, glycerol and ethanol increased phosphohydrolase activities in the microsomal and supernatant fractions. The only significant change in deacylase activity was an increase in the microsomal fraction produced by ethanol. It is proposed that hepatic triacylglycerol synthesis is partly controlled by the balance between phosphatidate phosphohydrolase and phospholipase A-type activities.

scholarly journals Effects of chronic modification of dietary fat and carbohydrate on the insulin, corticosterone and metabolic responses of rats fed acutely with glucose, fructose or ethanol

1981 ◽  
Vol 200 (2) ◽  
pp. 275-283 ◽  
Author(s):  
David N. Brindley ◽  
June Cooling ◽  
Helen P. Glenny ◽  
Susan L. Burditt ◽  
I. Sarah McKechnie
Keyword(s):  
Dietary Fat ◽  
Corn Oil ◽  
Male Rats ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Corticosterone Response ◽  
Pelleted Diet ◽  
Increased Activity ◽  
Lard Diet ◽  
Starch Diet

1. Male rats were fed for 14 days on powdered diets containing (by weight) 53% of starch, or on diets in which 20g of starch per 100g of diet was replaced by lard or corn oil. They were then fed acutely by stomach tube with a single dose of glucose, fructose or ethanol of equivalent energy contents, or with 0.15m-NaCl. The serum concentrations of corticosterone, insulin, glucose, glycerol, triacylglycerol and cholesterol were measured up to 6h after this treatment. 2. Feeding saline (0.9% NaCl) acutely to the rats maintained on the three powdered diets produced a small transient increase in circulating corticosterone that was similar to that in rats maintained on the normal 41B pelleted diet. 3. Feeding glucose acutely to the rats on the powdered diets produced peak concentrations of corticosterone that were 2–3-fold higher than those seen in rats maintained on the 41B diet. The duration of this response increased in the order starch diet<lard diet<corn-oil diet. This abnormal corticosterone response to glucose feeding appeared to be responsible for an increased activity in phosphatidate phosphohydrolase in the livers of rats fed the starch and lard diets of 2.9- and 4.9-fold respectively. The latter increase was similar to that produced by ethanol, whereas glucose did not increase the phosphohydrolase activity in the liver of rats maintained on the 41B diet. 4. Feeding fructose acutely produced even more marked increases than glucose in the concentrations of circulating corticosterone in rats given the powdered diets, but unlike glucose did not increase circulating insulin. The duration of the corticosterone response again increased in the order starch diet<lard diet<corn-oil diet. The concentrations of circulating glucose were increased by fructose feeding in rats maintained on these diets, but they were not altered in the rats maintained on the 41B pellets. A prolonged increase in serum corticosterone concentrations was also observed when fructose was fed to rats maintained on pelleted diets enriched with corn oil or beef tallow rather than with starch or sucrose. However, these effects were less marked than those seen with rats fed on the powdered diets. 5. These results are discussed in relation to the mechanism whereby high dietary fat exaggerates the effects of ethanol, fructose and sorbitol in stimulating triacylglycerol synthesis in the liver.

scholarly journals The effect of dietary carbohydrate and fat on the activities of some enzymes responsible for glycerolipid synthesis in rat liver

1978 ◽  
Vol 174 (2) ◽  
pp. 535-541 ◽  
Author(s):  
H P Glenny ◽  
M Bowley ◽  
S L Burditt ◽  
J Cooling ◽  
P H Pritchard ◽  
...  
Keyword(s):  
Corn Oil ◽  
Specific Activity ◽  
Male Rats ◽  
Dihydroxyacetone Phosphate ◽  
Triacylglycerol Synthesis ◽  
Choline Phosphotransferase ◽  
Phosphatidate Phosphohydrolase ◽  
Glycerolipid Synthesis ◽  
Starch Diet

1. Male rats were fed for 14 days on diets containing (by wt.) 53% of starch, or on diets in which 20% of the starch was replaced by sucrose, corn oil or lard. 2. The hepatic activities of the microsomal glycerol phosphate acyltransferase, dihydroxyacetone phosphate acyltransferase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase and choline phosphotransferase, and of the soluble phosphatidate phosphohydrolase, were measured. 3. The soluble phosphatidate phosphohydrolase activity was higher in those rats fed on lard than in those fed on the starch diet. Choline phosphotransferase activity was higher in the rats fed on corn oil than in those fed on the starch diet. 4. The rate of hepatic glycerolipid synthesis was measured in vivo 1 min after injection of [1,3-3H]glycerol and [1-14C]palmitate into the portal veins. 5. The relative rate of phosphatidylcholine synthesis in vivo was increased after feeding with corn oil and the higher specific activity of choline phosphotransferase may contribute to this result. The equivalent rate of triacylglycerol synthesis was increased by feeding with lard rather than corn oil, and the increased activity of phosphatidate phosphohydrolase may partly explain this. The latter changes probably contribute to the increased concentration of triacylglycerol which other authors have observed in the livers and sera of animals fed on saturated and monounsaturated fats.

scholarly journals Biosynthesis and secretion of triacylglycerol in rat liver after partial hepatectomy

1991 ◽  
Vol 277 (3) ◽  
pp. 723-728 ◽  
Author(s):  
L B Tijburg ◽  
C B Nyathi ◽  
G W Meijer ◽  
M J H Geelen
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
Diacylglycerol Acyltransferase ◽  
Low Density Lipoproteins ◽  
Plasma Lipoproteins ◽  
Very Low Density Lipoproteins ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Hepatic Triacylglycerol

Partially hepatectomized rats were used to investigate the mechanism of fatty-liver development in the regenerating rat liver. After partial hepatectomy the amount of hepatic triacylglycerol increased by almost 4-fold compared with sham-operated rats. The activities of both cytosolic and microsomal phosphatidate phosphohydrolase were enhanced at 12 h after surgery. The activity of diacylglycerol acyltransferase was increased at a later stage of regeneration. Analysis of plasma lipoproteins showed a significant decrease of lipids associated with very-low-density lipoproteins (VLDL). Relative to control, the rate of hepatic triacylglycerol synthesis from [3H]glycerol in vivo was stimulated at 22 h after partial liver resection. However, secretion of glycerol-labelled triacylglycerol in VLDL was the same in control and hepatectomized rats. In cultures of hepatocytes from hepatectomized donor rats, the concentration of triacylglycerol and the biosynthesis of this lipid from [3H]glycerol or from [3H]oleate were enhanced. The secretion of total triacylglycerol into the medium was not affected, resulting in a net accumulation of intracellular triacylglycerol. The rate of secretion of leucine-labelled apolipoproteins B and E associated with VLDL was similar in cell cultures from hepatectomized and sham-operated rats. The results of this study show that the enhancement of the biosynthesis of triacylglycerol in hepatectomized livers is not accompanied by an increase of the secretion of VLDL.

scholarly journals Neurotoxic Effect of Fipronil in Male Wistar Rats: Ameliorative Effect of L-Arginine and L-Carnitine

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 682
Author(s):  
Yasmina K. Mahmoud ◽  
Ahmed A. Ali ◽  
Heba M. A. Abdelrazek ◽  
Tahany Saleh Aldayel ◽  
Mohamed M. Abdel-Daim ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Histopathological Examination ◽  
Memory Performance ◽  
Elevated Serum ◽  
Corticosterone Level ◽  
Male Rats ◽  
Spatial Learning And Memory ◽  
Serum Corticosterone ◽  
Group I ◽  
Ameliorative Effect

The ameliorative effect of L-arginine (LA) and L-carnitine (LC) against fipronil (FPN)-induced neurotoxicity was explored. In this case, 36 adult male rats were randomly divided into six groups: group I received distilled water, group II received 500 mg/kg LA, group III received 100 mg/kg LC, group IV received 4.85 mg/kg FPN, group V received 4.85 mg/kg FPN and 500 mg/kg LA and group VI received 4.85 mg/kg FPN and 100 mg/kg LC for 6 weeks. Cognitive performance was assessed using Barnes maze (BM). Serum corticosterone, brain total antioxidant capacity (TAC), malondialdehyde (MDA) and dopamine were measured. Histopathology and immunohistochemistry of ionized calcium-binding adaptor (Iba-1), doublecortin (DCX) and serotonin (S-2A) receptors were performed. Fipronil induced noticeable deterioration in spatial learning and memory performance. In addition, FPN significantly (p < 0.05) diminished brain antioxidant defense system and dopamine coincide with elevated serum corticosterone level. Histopathological examination revealed degenerative and necrotic changes. Furthermore, Iba-1 and DCX were significantly expressed in cortex and hippocampus whereas S-2A receptors were significantly lowered in FPN group. However, administration of LA or LC alleviated FPN-induced deteriorations. In conclusion, LA and LC could be prospective candidates for mitigation of FPN-induced neurotoxicity via their antioxidant, anti-inflammatory and neuropotentiating effects.

scholarly journals Effect of Voluntary Exercise Training on Corticosterone Level and Immobility Behavior Induced by Chronic Stress in Rats

2020 ◽  
Vol 6 (3) ◽  
pp. 164-169
Author(s):  
Zahra Entezari ◽  
◽  
Ayyub Babaei ◽  
Saleh Rahmati-Ahmadabad ◽  
◽  
...  
Keyword(s):  
Exercise Training ◽  
Chronic Stress ◽  
Exercise Group ◽  
Voluntary Exercise ◽  
Male Rats ◽  
Depression Symptoms ◽  
Chronic Unpredictable Stress ◽  
Corticosterone Concentration ◽  
Serum Corticosterone ◽  
Immobility Time

Background: Depression is a common mood disorder that in the long-term impairs thoughts, behavior, feelings, and health. Chronic unpredictable stress is one of the factors that can cause depression. Objectives: To investigate the effect of voluntary exercise training on immobility behavior (caused by chronic unpredictable stress) and serum corticosterone concentration. Materials & Methods: A total of 24 male rats were randomly and equally assigned to four groups of healthy-control, healthy-exercise, depressed-control, and depressed-exercise. Depressed-control and depressed-exercise groups were first exposed to three weeks of chronic unpredictable stress. After this period, the exercise groups performed four weeks of voluntary exercise training. Twentyfour hours after the last training session, a forced swim test was taken from the rats and their blood samples were taken 24 hours later. The obtained data were analyzed using a 2-way analysis of variance (significance level: P<0.05). The Pearson correlation coefficient was used to examine the relationship between study variables. All statistical analyses were performed in SPSS v. 22. Results: Chronic stress increased immobility behavior (P=0.001) and serum corticosterone concentration (P=0.001). In contrast, exercise training reduced immobility behavior (P=0.001) and serum corticosterone (P=0.001). The immobility time (P=0.001) and serum corticosterone concentration in the depressed-exercise group were higher than those in the healthy-exercise group (P=0.001). There was a positive correlation between immobility behavior and serum corticosterone concentration (r=0.85 and P=0.001). Conclusion: While the chronic stress increases the immobility behavior and serum corticosterone concentration, voluntary exercise training can reduce immobility behavior and serum corticosterone and adjust some depression symptoms.

Hypothalamic paraventricular nucleus lesions do not prevent anorectic effect of exercise in male rats

1990 ◽  
Vol 259 (3) ◽  
pp. R579-R584 ◽  
Author(s):  
S. Rivest ◽  
D. Richard
Keyword(s):  
Body Weight ◽  
Energy Balance ◽  
Paraventricular Nucleus ◽  
Wistar Rats ◽  
Energy Gain ◽  
Hypothalamic Paraventricular Nucleus ◽  
Male Rats ◽  
Hypothalamic Nucleus ◽  
Serum Corticosterone ◽  
Male Wistar Rats

The effects of a hypothalamic paraventricular nucleus (PVN) lesion on energy balance were investigated in exercise-trained rats. Male Wistar rats weighing initially 250 g were divided into four groups. Two groups of rats underwent a bilateral PVN lesion, whereas the two remaining groups were sham operated. The PVN lesions were done electrolytically. One group from each surgical treatment was exercised, while the other group was kept in sedentary conditions. Rats were exercised on a rodent motor-driven treadmill at moderate intensity, 1 h/day for 21 consecutive days. Food intake and body weight were measured each day during the study. At the end of the treatment period, rats were killed, and carcasses were analyzed for their energy content. Serum corticosterone was measured by a competitive protein-binding assay. Energy gain and energy intake were lower in exercised rats than in sedentary controls, regardless of whether they were sham or PVN lesioned. Concurrently, there was no difference in the energy gain between PVN-lesioned and sham-operated rats, despite the fact that PVN-lesioned rats ended the experiment with a larger body weight than the sham-lesioned animals. Serum corticosterone levels were lower in PVN-lesioned rats than in sham-lesioned rats. In conclusion, the present results indicate that the PVN, the hypothalamic nucleus predominantly controlling the pituitary-adrenal axis activity, is not a prominent structure in the regulation of energy balance in exercised male Wistar rats.

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