scholarly journals Immunochemical studies with soluble and mitochondrial pyruvate carboxylase activities from rat tissues

1970 ◽  
Vol 119 (4) ◽  
pp. 735-742 ◽  
Author(s):  
F. J. Ballard ◽  
R. W. Hanson ◽  
Lea Reshef

1. Pyruvate carboxylase (EC 6.4.1.1), purified from rat liver mitochondria to a specific activity of 14 units/mg, was used for the preparation of antibodies in rabbits. 2. Tissue distribution studies showed that pyruvate carboxylase was present in all rat tissues that were tested, with considerable activities both in gluconeogenic tissues such as liver and kidney and in tissues with high rates of lipogenesis such as white adipose tissue, brown adipose tissue, adrenal gland and lactating mammary gland. 3. Immunochemical titration experiments with the specific antibodies showed no differences between the inactivation of pyruvate carboxylase from mitochondrial or soluble fractions of liver, kidney, mammary gland, brown adipose tissue or white adipose tissue. 4. The antibodies were relatively less effective in reactions against pyruvate carboxylase from sheep liver than against the enzyme from rat tissues. 5. Pyruvate carboxylase antibodies did not inactivate either propionyl-CoA carboxylase or acetyl-CoA carboxylase from rat liver. 6. It is concluded that pyruvate carboxylase in lipogenic tissues is similar antigenically to the enzyme in gluconeogenic tissues and that the soluble activities of pyruvate carboxylase detected in many rat tissues do not represent discrete enzymes but are the result of mitochondrial damage during tissue homogenization.

1970 ◽  
Vol 118 (1) ◽  
pp. 171-179 ◽  
Author(s):  
W. N. Aldridge ◽  
B. W. Street

1. The binding of trimethyltin and triethyltin to rat liver mitochondria was determined and the results were analysed by the method of Scatchard (1949). 2. One binding site (site 1) has the correct characteristics for the site to which trimethyltin and triethyltin are attached when they inhibit oxidative phosphorylation. For each compound the concentration of site 1 is 0.8nmol/mg of protein and the ratios of their affinity constants are the same as the ratio of the concentrations inhibiting oxidative phosphorylation. 3. Binding site 1 is present in a fraction derived from mitochondria containing only 15% of the original protein. In this preparation ultrasonication rapidly destroyed site 1. 4. Dimethyltin and diethyltin do not prevent binding of triethyltin to rat liver mitochondria, whereas triethyl-lead does. 5. Trimethyltin and triethyltin bind to mitochondria from brown adipose tissue and the results indicate a binding site 1 similar to that in rat liver mitochondria. 6. The advantages and limitations of this approach to the study of inhibitors are discussed.


1988 ◽  
Vol 254 (2) ◽  
pp. 539-546 ◽  
Author(s):  
C M Oller do Nascimento ◽  
D H Williamson

1. The effects of starvation and refeeding on the disposal of oral [14C]triolein between 14CO2 production and 14C-lipid accumulation in tissues of virgin rats, lactating rats and lactating rats with pups removed were studied. 2. Starvation (24 h) increased 14CO2 production in lactating rats and lactating rats with pups removed to values found in virgin rats. This increase was accompanied by decreases in 14C-lipid accumulation in mammary gland and pups of lactating rats and in white and brown adipose tissue of lactating rats with pups removed. 3. Short-term (2 h) refeeding ad libitum decreased 14CO2 production in lactating rats and lactating rats with pups removed, and restored the 14C-lipid accumulation in mammary glands plus pups and in white and brown adipose tissue respectively 4. Insulin deficiency induced with mannoheptulose inhibited the restoration of 14C-lipid accumulation in white adipose tissue on refeeding of lactating rats with pups removed, but did not prevent the restoration of 14C-lipid accumulation in mammary gland. 5. Changes in the activity of lipoprotein lipase in mammary gland and white adipose tissue paralleled the changes in 14C-lipid accumulation in these tissues. 6. It is concluded that 14C-lipid accumulation in mammary gland may not be affected by changes in plasma insulin concentration and that it is less sensitive to starvation than is lipogenesis or lactose synthesis. This has the advantage that the milk lipid content can still be maintained from hepatic very-low-density lipoprotein for a period after withdrawal of food. The major determinant of the disposal of oral 14C-triolein appears to be the total tissue activity of lipoprotein lipase. When this is high in mammary gland (fed lactating rats) or white adipose tissue (fed lactating rats with pups removed), less triacylglycerol is available for the muscle mass and consequently less is oxidized.


1989 ◽  
Vol 258 (1) ◽  
pp. 273-278 ◽  
Author(s):  
C M Oller do Nascimento ◽  
V Ilic ◽  
D H Williamson

1. The effects of various treatments to alter either plasma prolactin (bromocryptine administration or removal of litter) or the metabolic activity of the mammary gland (unilateral or complete teat sealing) on the disposal of oral [14C]lipid between 14CO2 production and [14C]lipid accumulation in tissues of lactating rats were studied. In addition, the rates of lipogenesis in vivo were measured in mammary gland, brown and white adipose tissue and liver. 2. Bromocryptine administration lowered plasma prolactin, but did not alter [14C]lipid accumulation in mammary gland or in white and brown adipose tissue. 3. In contrast, complete sealing of teats results in no change in plasma prolactin, but a 90% decrease in [14C]lipid accumulation in mammary gland and a 4-fold increase in white and brown adipose tissue. The rate of lipogenesis in mammary gland was decreased by 95%, but there was no change in the rate in white and brown adipose tissue. Unilateral sealing of teats resulted in a decrease in [14C]lipid accumulation in white adipose tissue. 4. Removal of the litter for 24 h (low prolactin) produced a similar pattern to complete teat sealing, except that there was a 6-fold increase in lipogenesis in white adipose tissue. Re-suckling for 5 h increased plasma prolactin, but did not alter the response seen in litter-removed lactating rats. 5. Changes in lipoprotein lipase activity and in plasma insulin paralleled the reciprocal changes in [14C]lipid accumulation in white and brown adipose tissue and in mammary gland. 6. It is concluded that the plasma insulin is more important than prolactin in regulating lipid deposition in adipose tissue during lactation, and that any effects of prolactin must be indirect.


Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 308 ◽  
Author(s):  
Hyo-Geun Lee ◽  
Yu An Lu ◽  
Xining Li ◽  
Ji-Min Hyun ◽  
Hyun-Soo Kim ◽  
...  

Obesity is a serious metabolic syndrome characterized by high levels of cholesterol, lipids in the blood, and intracellular fat accumulation in adipose tissues. It is known that the suppression of adipogenic protein expression is an effective approach for the treatment of obesity, and regulates fatty acid storage and transportation in adipose tissues. The 60% ethanol extract of Grateloupia elliptica (GEE), a red seaweed from Jeju Island in Korea, was shown to exert anti-adipogenic activity in 3T3-L1 cells and in mice with high-fat diet (HFD)-induced obesity. GEE inhibited intracellular lipid accumulation in 3T3-L1 cells, and significantly reduced expression of adipogenic proteins. In vivo experiments indicated a significant reduction in body weight, as well as white adipose tissue (WAT) weight, including fatty liver, serum triglycerides, total cholesterol, and leptin contents. The expression of the adipogenic proteins, SREBP-1 and PPAR-γ, was significantly decreased by GEE, and the expression of the metabolic regulator protein was increased in WAT. The potential of GEE was shown in WAT, with the downregulation of PPAR-γ and C/EBP-α mRNA; in contrast, in brown adipose tissue (BAT), the thermogenic proteins were increased. Collectively, these research findings suggest the potential of GEE as an effective candidate for the treatment of obesity-related issues via functional foods or pharmaceutical agents.


Obesity ◽  
2018 ◽  
Vol 26 (3) ◽  
pp. 547-558 ◽  
Author(s):  
Zhuolun Song ◽  
Xavier Revelo ◽  
Weijuan Shao ◽  
Lili Tian ◽  
Kejing Zeng ◽  
...  

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