Purified Chickpea or Lentil Proteins Impair VLDL Metabolism and Lipoprotein Lipase Activity in Epididymal Fat, but Not in Muscle, Compared to Casein, in Growing Rats

Background: It is well known that the legume proteins have a lowering effect on plasma cholesterol and triacylglycerols (TG) concentrations compared to animal proteins. The protein itself, as well as non-protein constituents, naturally present in legumes may be implicated.

Aim Of The Study: The effects of various dietary purified legumes proteins compared to casein, were determined on plasma TG level, VLDL concentration and composition. Moreover, lipoprotein lipase (LPL) activity in epididymal fat, gastrocnemius and heart was investigated to evaluate in these tissues their capacity to release free fatty acids from their TG substrate and the liver capacity to stock the TG.

Methods: Weaning male Wistar rats were fed ad libitum one of the following diets: 200 g/kg diet of purified proteins of lentil (L), or chickpea (CP) or casein (CAS). At day 28, VLDL were isolated from plasma sample by a single ultracentrifugation flotation. Hepatic lipase and LPL activity in epididymal fat, gastrocnemius and heart were measured by using glycerol tri [9-10(n)-(3)H] oleate emulsion as substrate.

Results: Compared with CAS diet, the CP and L protein diets exhibited similar cholesterolemia, but lower triglyceridemia (1.9-fold and 2.5-fold) and VLDL particle number, as measured by their reduced contents of TG and apolipoproteins. CP and L protein diets reduced liver TG and cholesterol by 31 and 45%, respectively compared to CAS diet. Furthermore, LPL activity in adipose tissue of rats fed CP or L was 1.6-fold lower than that of rats fed CAS. There was no significant difference in heart and gastrocnemius LPL activities with the three proteins. In contrast, hepatic lipase activity was higher in rats fed CP and L diets.

Conclusion: The low food efficiency ratio of purified CP and L proteins related to CAS is associated with decreased plasma VLDL and adipose tissue LPL activity. The low liver TG concomitant with reduced TG and apolipoproteins contents of VLDL confirm that hypotriglyceridemia is essentially due to impaired synthesis, exportation and transport of TG by VLDL which prevent lipid storage in adipose tissue.