Lipoprotein lipase in rats fed fish oil: apparent relationship to plasma insulin levels.
To investigate the role of lipoprotein lipase (LPL) and hepatic lipase in the triacylglycerol lowering effects of fish oil, rats were fed lard (L), corn oil (CO) or menhaden oil (MO) as the primary fat source in otherwise identical diets. After 2 weeks, soleus muscle LPL differed between groups (MO greater than CO greater than L). Hepatic lipase did not differ between CO- and MO-fed rats but was elevated in L-fed rats. Adipose LPL did not differ between diet groups. Total epididymal fat weight was reduced in MO-fed rats. There was a significant positive correlation between adipose tissue weight and plasma free fatty acids. MO-fed rats had lower plasma insulin levels. Insulin was directly correlated with plasma triacylglycerol and glucose, consistent with a hyperinsulinemic, insulin-resistant state in CO- and L-fed rats, and a protective effect with MO feeding. In addition, insulin was directly correlated with adipose LPL. A negative relationship between soleus muscle LPL and insulin approached significance. Soleus muscle LPL was significantly inversely correlated with triacylglycerol. The data indicate that increased skeletal muscle LPL, in response to MO or a MO-induced decrease in insulin, may contribute to the triacylglycerol-lowering effects of fish oil. Decreased fat weight and adipose LPL and increased soleus muscle LPL and decreased plasma triacylglycerol suggest a shift from fat deposition to oxidation with MO feeding. The lack of response of hepatic lipase to MO feeding suggests that this enzyme does not contribute to the fish oil-stimulated lowering of plasma triacylglycerol via hepatic reuptake of very low density lipoproteins or other triacylglycerol-rich lipoproteins.
Baltzell
J K
JK
Department of Research, Baptist Medical Centers, Birmingham, Alabama 35211.
Wooten
J T
JT
Otto
D A
DA
D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002784:Cholesterol / Q000097:blood; D003314:Corn Oil / Q000494:pharmacology; D004041:Dietary Fats / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005395:Fish Oils / Q000494:pharmacology*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D008049:Lipase / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008297:Male; D009132:Muscles / Q000201:enzymology*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D004041:Dietary Fats; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D005395:Fish Oils; D007328:Insulin; D014280:Triglycerides; C033266:Menhaden oil; D003314:Corn Oil; D002784:Cholesterol; D005954:Glucosephosphate Dehydrogenase; D008049:Lipase; D008071:Lipoprotein Lipase; C029310:lard