Growth hormone but not gonadal steroids influence lipoprotein lipase and hepatic lipase activity in hypophysectomized rats

1994 ◽  
Vol 140 (2) ◽  
pp. 203-209 ◽  
Author(s):  
K Vikman-Adolfsson ◽  
J Oscarsson ◽  
P Nilsson-Ehle ◽  
S Edén
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Hepatic Lipase ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Male Rats ◽  
Lipoprotein Lipase Activity ◽  
Peripheral Tissues ◽  
Hepatic Lipase Activity ◽  
Hypophysectomized Rats

Abstract Lipoprotein lipase and hepatic lipase are involved in the degradation and cellular uptake of lipids in peripheral tissues and the liver. These enzymes seem to be influenced by gonadal steroids in the rat as well as in man. Since gonadal steroids have been shown to influence the secretory pattern of GH and since the effect of gonadal steroids on several metabolic functions may be dependent upon their effects on GH secretion, the present study was undertaken to investigate the developmental regulation of heparin-releasable lipoprotein lipase and hepatic lipase activities in female and male rats, and to study the effects of gonadal steroids and different modes of GH administration to hypophysectomized rats on these enzyme activities. Female and male Sprague–Dawley rats from 20 to 65 days of age were studied. Hypophysectomy was performed at 50 days of age and these rats were given replacement therapy with thyroxine and cortisone. Groups of hypophysectomized rats were treated with either oestradiol valerate (0·1 mg/kg per day) or testosterone enanthate (1 mg/kg per day). Bovine GH (1 mg/kg per day) was given to groups of hypophysectomized rats either by two daily subcutaneous injections or by continuous infusion using osmotic minipumps. Hormone treatment was given for 1 week. Lipoprotein lipase and hepatic lipase activities were measured in heparinized plasma. There was no difference in lipoprotein lipase activity between male and female rats at 20 to 45 days of age. Lipoprotein lipase activity decreased between 45 and 65 days of age in male rats but not in females and, at 65 days of age, lipoprotein lipase activity was higher in females compared with males. Hepatic lipase activity increased from 20 to 45 days of age in both female and male rats but at 45 and 65 days of age it was higher in female than in male rats. Hypophysectomy decreased lipoprotein lipase and hepatic lipase activity in female rats. Neither oestradiol nor testosterone treatment had any effects in hypophysectomized rats. Treatment with bovine GH increased both lipoprotein lipase and hepatic lipase activities irrespective of its mode of administration and these effects were not influenced by additional treatment with oestradiol or testosterone. After the last injection of GH, lipoprotein lipase activity was increased for 12 h. Hepatic lipase activity was increased at 2 and 4 h after the last GH injection but after 12 h the activity had decreased, indicating that the time-course for the effects of GH on lipoprotein lipase and hepatic lipase may be different. It is concluded that GH markedly influences post-heparin lipoprotein lipase and hepatic lipase activities. The lack of effects of gonadal steroids on these activities in hypophysectomized rats suggests that the gonadal steroids influence these lipases via their influence on GH release. Journal of Endocrinology (1994) 140, 203–209

scholarly journals Post-Heparin Triacylglycerol Lipases in Ovine Plasma

1988 ◽  
Vol 41 (2) ◽  
pp. 215
Author(s):  
RK Tume ◽  
RF Thornton ◽  
G WJohnson
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipolytic Activity ◽  
Hepatic Lipase ◽  
Significant Proportion ◽  
Lipolytic Enzyme ◽  
Free Fatty Acid Concentration ◽  
Lipoprotein Lipase Activity ◽  
Hepatic Lipase Activity ◽  
Heparin Plasma

Lipoprotein lipase and hepatic lipase have been shown to be present in the post-heparin plasma of sheep. Intravenous injection of heparin into sheep produced a rapid increase in the free fatty acid concentration and lipolytic enzyme activity of the plasma, both peaking within 5-15 min and then falling to pre-heparin levels within 30-60 min. Lipolytic activity was not detected in plasma before heparin treatment. Two distinct lipolytic activities were separated from the plasma by chromatography on heparin-Sepharose 6B. Lipoprotein lipase was identified on the basis that the lipolytic activity was dependent upon the addition of plasma, inhibited by 1M NaCI, and inhibited by a specific antiserum against lipoprotein lipase. The second lipolytic activity of plasma was identified as hepatic lipase, as it was not dependent upon plasma for activity, nor was it inhibited by 1M NaCI or antiserum against lipoprotein lipase. Its properties were identical to the lipase extracted from the liver of sheep. Lipoprotein-lipase activity, but not hepatic-lipase activity, was dependent upon the nutritional state of the sheep at the time of heparin injection. However, hepatic lipase comprised a significant proportion of the total lipolytic activity.

Two methods compared for measuring lipase activity in plasma after heparin administration.

1984 ◽  
Vol 30 (9) ◽  
pp. 1568-1570 ◽  
Author(s):  
C Ehnholm ◽  
E A Nikkilä ◽  
P Nilsson-Ehle
Keyword(s):  
Human Plasma ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Hepatic Lipase ◽  
Gum Arabic ◽  
Systematic Difference ◽  
Enzymic Activity ◽  
Specific Substrate ◽  
Hepatic Lipase Activity ◽  
Heparin Administration

Abstract We compared two methods for the direct selective measurement of hepatic lipase and lipoprotein lipase activities in human plasma after intravenous administration of heparin. Except for the emulsifier (gum arabic vs lecithin), the two assay media for hepatic lipase are essentially similar. Results for hepatic lipase by these two assays correlate well (r = 0.99). The assays for lipoprotein lipase in the two procedures differ in the way that hepatic lipase activity is eliminated (immunological inhibition vs a specific substrate emulsion), and also with regard to the emulsifier. The substrate emulsion stabilized by gum arabic (immunological assay) consistently yielded about three times higher enzymic activity than the specific substrate stabilized by lecithin. Experiments in which purified enzymes were used demonstrated that this systematic difference can be accounted for by the different emulsifiers. The satisfactory correlation (r = 0.92) between the two lipoprotein lipase assays, however, demonstrates that they measure the same enzymic activity.

scholarly journals Effect of protamine on lipoprotein lipase and hepatic lipase in rats

1994 ◽  
Vol 304 (3) ◽  
pp. 959-966 ◽  
Author(s):  
M Hultin ◽  
G Olivecrona ◽  
T Olivecrona
Keyword(s):  
Endothelial Cell ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Binding Sites ◽  
Hepatic Lipase ◽  
Lipoprotein Lipase Activity ◽  
Cell Surfaces ◽  
Intravenous Injections

The polycation protamine impedes the catabolism of triglyceride-rich lipoproteins and this has been suggested to be due to intravascular inactivation of lipoprotein lipase. We have made intravenous injections of protamine to rats and found that both lipoprotein lipase and hepatic lipase activities were released to plasma. The effect of protamine was more short-lived than that obtained by injection of heparin. The release of hepatic lipase by protamine was as effective as the release by heparin, while the amount of lipoprotein lipase released by protamine was only about one-tenth of that released by heparin. This was not due to inactivation of lipoprotein lipase, since injection of an excess of heparin 10 min after injection of protamine released as much lipoprotein lipase activity to plasma as in controls. The results in vivo differed from those obtained in model experiments in vitro. Protamine was able to almost quantitatively release both lipoprotein lipase and hepatic lipase from columns of heparin-agarose. The displacement was dependent on the total amount of protamine that had passed over the column, indicating that it was due to occupation by protamine of all available binding sites. Our results in vivo showed that the binding sites for lipoprotein lipase were not blocked as efficiently as those for hepatic lipase, indicating that the binding structures were not identical. It was concluded that the impaired turnover of lipoproteins by protamine probably was due to prevention of binding of the lipoproteins to endothelial cell surfaces rather than to impaired lipase function.

Modulation by phenobarbital of lipolytic activity in postheparin plasma and tissues of the rat

1982 ◽  
Vol 60 (11) ◽  
pp. 1077-1083 ◽  
Author(s):  
David M. Goldberg ◽  
M. Waheed Roomi ◽  
Alex Yu
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Lipolytic Activity ◽  
Sodium Dodecyl ◽  
Male Rats ◽  
Lipoprotein Lipase Activity ◽  
Protamine Sulphate ◽  
Triacylglycerol Lipase ◽  
Postheparin Lipolytic Activity

Male rats injected with phenobarbital at a dose of 100 mg/kg for 5 days manifested increased postheparin lipolytic activity of fasting plasma. Inhibition studies with protamine sulphate, 1 M NaCl, and sodium dodecyl sulphate revealed that the activities of both lipoprotein lipase and hepatic triacylglycerol lipase were increased in the postheparin plasma of the drug-treated rats. Adipose tissue lipoprotein lipase activity was also increased in the phenobarbital-treated rats. The triacylglycerol lipase activity elutable by heparin from liver slices and the residual activity of liver microsomes increased significantly in the drug-treated rats. Lipoprotein lipase of cardiac muscle and red skeletal muscle was unaltered by phenobarbital treatment. The increased postheparin lipolytic activity of fasting phenobarbital-treated rats seems to be accountable through increased lipoprotein lipase activity of adipose tissue and increased triacylglycerol lipase activity of liver, both of which may contribute to the lowered fasting concentrations of serum triacylglycerol mediated by the drug, as previously reported.

Heparin-Released Plasma Lipases in Chronic Renal Failure and after Renal Transplantation

1979 ◽  
Vol 57 (2) ◽  
pp. 155-165 ◽  
Author(s):  
G. A. Crawford ◽  
E. Savdie ◽  
J. H. Stewart
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Hepatic Lipase ◽  
Elevated Serum ◽  
Soya Bean ◽  
Renal Transplant Recipients ◽  
Hepatic Lipase Activity ◽  
Female Patients

1. Post-heparin plasma from normal subjects, patients with chronic renal failure and recipients of renal allografts were subjected to affinity chromatography on heparin—agarose (Sepharose 4B) columns to separate two fractions representing hepatic lipase and lipoprotein lipase respectively. 2. The optimum conditions for assay of each fraction were determined for both normal and uraemic plasma. 3. Normal males had activities of hepatic lipase which were higher, and activities of lipoprotein lipase which were lower, than normal females. There was no consistent relationship to age for either enzyme. 4. Thirty patients with chronic renal failure untreated by dialysis had significantly elevated serum triacylglycerol concentrations, and significantly lowered lipoprotein lipase activities when compared with control groups with similar ages for each sex. However, only in uraemic males was hepatic lipase activity significantly reduced. 5. In a study of female patients with chronic renal failure, there were no significant differences in activities of hepatic lipase or lipoprotein lipase or concentrations of serum triacylglycerols between eight patients receiving dialysis treatment and eight untreated by dialysis. 6. Although serum triacylglycerol concentrations were raised in the group of 15 renal transplant recipients, lipase activities were not diminished. The only significant change was elevation of hepatic lipase activity in female graft recipients. 7. No relationship was found between the enzyme activities and fasting serum triacylglycerol concentrations in any group. However, there was a weak inverse correlation between serum creatinine and hepatic lipase in female patients from both renal failure and transplant groups. 8. Similar results were obtained when the enzymes were assayed with, as substrate, a laboratory-prepared emulsion of 14C-labelled triolein in water with soya-bean lecithin as emulsifier, or commercially prepared soya-bean oil in water, emulsified with egg-yolk lecithin and containing glycerol (Intralipid).

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