PRETRANSLATIONAL REGULATION OF THE EXPRESSION OF THE LIPOPROTEIN-LIPASE (EC 3.1.1.34) GENE BY DIETARY FATTY-ACIDS IN THE RAT

Although there have been a number of studies of effects of diet and ho rmones on lipoprotein lipase (EC 3.1.1.34; LPL) activity and levels of LPL mRNA (Raynolds et al. 1990), there have been no studies which hav e investigated effects of different dietary fatty acids on LPL gene ex pression. In the present study male Wistar Albino rats were pair-fed d iets containing 50 g fat/kg of different fatty acid composition for 2 weeks. The diets fed were (1) a mixed oil (450 g saturated fatty acids , 420 g monounsaturated fatty acids, 130 g polyunsaturated fatty acids /kg; n 8), (2) maize oil (n 8), or (3) fish oil (n 8). Animals were ki lled, RNA was extracted from liver and perirenal and epididymal fat pa ds, and analysed by 'Northern methodology'. Samples were hybridized to a human cDNA probe for LPL (Gotoda et al. 1989). Two transcripts were identified in epididymal and perirenal adipose tissue which were appr oximately 3.7 and 1.7 kb in size. The results suggested that (1) fish oil-fed animals had significantly greater production of LPL mRNA in ep ididymal adipose tissue compared with maize oil-fed animals (P < 0.05) , (2) maize oil-fed animals had significantly greater production of LP L mRNA in perirenal fat compared with the other dietary groups (P < 0. 05), (3) expression in the liver was not significant. Rats fed on a fi sh oil diet had significantly reduced plasma triacylglycerol concentra tions compared with the mixed-oil group (P < 0.05), but there were no significant differences in plasma cholesterol. The differences in LPL could not be explained directly by the changes in plasma immunoreactiv e-insulin and glucose-dependent insulinotrophic polypeptide levels in the three groups.