Increase of postheparin plasma-lipoprotein-lipase activity in ventromedial-hypothalamic obesity in rats.
Postheparin plasma-lipoprotein lipase (LPL) and hepatic triglyceride lipase (H-TGL) were investigated in rats 1 week after ventromedial-hypothalamic lesions. The enzyme activities were measured using radio-labelled triolein as a substrate. Two lipases were measured separately using specific antiserum prepared against H-TGL. VMH-lesioned rats fed ad lib. showed an increase in plasma LPL with normal H-TGL activity and an elevation of plasma insulin. There was a positive correlation between plasma-LPL activity and insulin levels in VMH-lesioned rats. When rats were examined after overnight fast, VMH-lesioned rats again showed an increase in plasma LPL with normal H-TGL activity and an elevation of plasma insulin. There was also a positive correlation between plasma LPL activity and insulin levels. In order to examine the effect of insulin, rats were treated with daily doses of 3 units of insulin for 1 week. Rats fed ad lib. were insulin treatment showed an increase in plasma LPL with normal H-TGL activity. These results indicate that hyperinsulinemia which was produced by VMH lesions may increase postheparin plasma-LPL activity. We speculate that this increase in plasma-LPL activity mainly reflects that of adipose tissue. The increase of LPL activity can accelerate fat deposition into adipose tissue, contributing to one of the factors causing hypothalamic obesity.
D000273:Adipose Tissue / Q000201:enzymology; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004195:Disease Models, Animal; D005260:Female; D007033:Hypothalamus, Middle / Q000502:physiology; D007106:Immune Sera / Q000494:pharmacology; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D008049:Lipase / Q000097:blood; D008071:Lipoprotein Lipase / Q000097:blood*; D008099:Liver / Q000201:enzymology*; D009765:Obesity / Q000201:enzymology* / Q000209:etiology; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D007106:Immune Sera; D007328:Insulin; D008049:Lipase; D008071:Lipoprotein Lipase