The quantitation of lipoprotein lipase mRNA in biopsies of human adipose tissue, using the polymerase chain reaction, and the effect of increased consumption of n-3 polyunsaturated fatty acids

Abstract

Objective: To examine the effects of the consumption of ®sh oils on the gene expression of lipoprotein lipase (LPL, EC 3.1.1.34) in human adipose tissue. In order to measure LPL mRNA in adipose tissue samples obtained by needle biopsy from human volunteers a competitive, reverse transcriptase PCR (RT-PCR) protocol was developed. Design: A randomised controlled, single blind cross over dietary study which compared the effects of a low level n-3 polyunsaturated fatty acids (PUFA) using normal foods enriched with eicosapentaenoic (EPA) and docosahexaenoic (DHA) (test diet), with non-enriched but otherwise identical foods (control). The diets were consumed for a period of 22 d with a wash out period of 5 months between the diets. Setting: Free-living individuals associated with the University of Surrey. Subjects: Six male subjects with a mean ( AE sd) age of 51.2 AE 3.6 y were recruited. Major Outcome Measures: Pre-and postprandial blood samples were taken for the measurement of triacylglycerol (TAG), postheparin LPL activity and adipose tissue samples for the measurement of LPL mRNA levels. Results: Mean LPL expression values were 4.12 6 10 5 molecules of LPL mRNA per ng total RNA on the control diet and 4.60 6 10 5 molecules of LPL mRNA per ng total RNA on the n-3 PUFA enriched (test) diet. There was no signi®cant difference between the levels of LPL expression following each diet, consistent with the lack of change in TAG levels in response to increased dietary n-3 PUFA intake. However, the change in LPL expression (Test ± Control diet) correlated signi®cantly with the change in fasting TAG levels (P 0.03, R À0.87 and R 2 0.75) and with the total area under the TAG-time response curve (P 0.003, R À0.96 and R 2 0.92) in individuals. Conclusions: These ®ndings, although based on a small number of subjects, suggest that LPL expression may be a determinant of plasma TAG levels. The development of this methodology should allow further elucidation of the effects of dietary manipulation and disease processes on lipid clearance and regulation in human subjects. Sponsorship: This work was funded by BBSRC.

Dietary long-chain n-3 PUFAs increase LPL gene expression in adipose tissue of subjects with an atherogenic lipoprotein phenotype

“…This study set out to substantiate earlier findings from our laboratory that showed positive effects of fish oil on the pre-translational regulation of LPL gene expression in the epididymal fatpads of rats (12). In a follow-up study on a small group of normal, healthy male subjects (n ϭ 6), the level of AT-LPL mRNA was shown to increase in four out of six subjects in response to fish oil (13). Furthermore, changes in the level of AT-LPL mRNA were inversely associated with changes in fasting plasma TG and postprandial lipemia (AUC), suggesting that LPL gene expression may control longer-term changes in the handling of exogenous and endogenous TG.…”

“…This was performed using the multi-specific internal standard or competitor, published by Laville et al (19), kindly donated by Professor Hubert Vidal. The production of this competitor from the vector has been previously described by Murphy et al (13). RT-PCR utilized oligonucleotide primers that amplify both the competitor and the target RNA in the same reaction, producing cDNA products of different sizes, 267 bp and 227 bp, respectively.…”

Fish oil — How does it reduce plasma triglycerides?

“…1c) and of CD36, the major FA membrane transporter [106, 107]. Similarly, although FO upregulates postprandial LpL expression in human adipose tissue [108], suggestive of increased FA uptake by adipose, no effect on body weight has been seen in multiple studies. Indeed, a few small clinical trials have reported weight loss [109-111].…”

Dietary PUFA and the metabolic syndrome in Indian Asians living in the UK

“…This reduction has been observed in patients consuming a LC n-3 PUFA-rich meal when compared with those receiving a saturated fatty acid-rich meal (Zampelas et al 1994). Murphy et al (1999) investigated the effects of fish oil on gene expression of LPL in human adipose tissue, and reported increased LPL mRNA expression following consumption of a LC n-3 PUFA-enriched diet when compared with a non-enriched diet. Increased fatty acid oxidation and reduced fatty acid synthesis decrease fatty acid availability for TAG synthesis and incorporation into lipoproteins, while increased LPL activity in response to fish oil treatment may accelerate clearance of TAG from the circulation (Weber & Raederstorff, 2000).…”