Induced Lipid Deposition Research Articles

FXR-mediated inhibition of autophagy contributes to FA-induced TG accumulation and accordingly reduces FA-induced lipotoxicity

BackgroundExcessive dietary fat intake induces lipid deposition and contributes to the progress of nonalcoholic fatty liver disease (NAFLD). However, the underlying mechanisms are still unclear.MethodsYellow catfish were given two experimental diets with dietary lipid levels of 11.3 and 15.4%, respectively, for 56 days, and the contents of triglyceride (TG), nonesterified free fatty acids (NEFA) and bile acid (BA), RNA-seq, enzymatic activities and mRNA expression were deteremined in the liver tissues. Hepatocytes from yellow catfish liver tissues were isolated and cultured. Fatty acids (FA) (palmitic acid: OA, oleic acid =1:1), pathway inhibitors (MA, autophagy inhibitor; guggulsterone, FXR inhibitor) and agonist (rapamyicn, autophagy agonist; GW4064, FXR agonist) were used to incubate the cells. TG and NEFA contents, ultrastructural observation, autophagic vesicles and intracellular LD,apoptosis,western blot and Co-IP, and Immunofluorescence analysis, enzymatic activities and Q-PCR were decided.ResultsUsing RNA sequencing, we found that high fat diets induced changes in expression of many genes associated with the pathways of lipid metabolism and autophagy. The mRNA profiles of the differentially expressed genes (DEG) indicated that high dietary fat-induced lipid deposition was predominantly influenced by the inhibition of autophagy. Using primary hepatocytes, we found that fatty acids (FA) suppressed autophagy, which in turn reduced cellular free FA level by decreasing triglyceride (TG) breakdown. Moreover, our study indicated that farnesoid X receptor (FXR)-cyclic AMP-responsive element-binding protein (CREB) axis was the pivotal physiological switch regulating FA-induced changes of autophagy and lipid metabolism, which represented cellular defenses against FA-induced lipotoxicity.ConclusionThis discovery may provide new targets for treating pathological changes involved in the dysfunction of autophagy and metabolism, including NAFLD.AmrG3KeYnpRNJADevGhfpFVideo Graphical abstract

The effect and mechanism of dietary monocalcium phosphate restriction on hepatic lipid deposition and immune status in obscure puffer, Takifugu obscurus

A 12-week chronic feeding trial was conducted to determine the effect and mechanism of dietary monocalcium phosphate (CaH2PO4) restriction on hepatic lipid deposition and immune status in obscure puffer, Takifugu obscurus. Fish with an initial mean weight of 7.21 ± 0.05 g were fed a phosphorus (P)-sufficient diet (P6, diet supplemented with 0.6% P) or P-deficient diet (P0, diet supplemented without P). Sampling occurred at weeks 3, 6, 9 and 12, respectively. During the feeding trial, fish fed the P0 diet showed poor growth performance, reduced feed intake, whole body P and ash as well as vertebrae P contents, which are signs of P deficiency. Dietary P restriction increased hepatic vacuoles and lipid droplets, lipid content of whole body and liver, viscerosomatic and hepatosomatic indices, whereas reduced whole body protein content and lipolytic enzyme activities, including carnitine palmitoyltransferase 1 (CPT-1) and lipoprotein lipase (LPL). But peroxisome proliferators-activated receptor α (pparα) mRNA level was up-regulated by dietary P deficiency on week 3, and then down-regulated on weeks 6, 9 and 12. Meanwhile, dietary P deficiency increased hepatic mRNA expressions of 6-phosphogluconate dehydrogenase (6pgd), malic enzyme (me), acetyl-CoA carboxylase (acc)-α and acc-β, while decreased cpt-1 and fatty acid binding protein (fabp). Additionally, dietary P deficiency decreased the mRNA level of complement 3 (c3) while increased heat shock proteins (HSPs, including hsp90 and hsp70) on weeks 9 and 12. Dietary P restriction also induced apoptosis by up-regulating the mRNA levels of caspase-3, caspase-8 and caspase-9 and down-regulating the levels of B-cell lymphoma 2 (bcl-2) and Bax inhibitor-1 (bi-1). In conclusion, our study indicated that dietary P deficiency induced lipid deposition and impaired the immune status of obscure puffer.

Concentration-dependent effects of 17β-estradiol and bisphenol A on lipid deposition, inflammation and antioxidant response in male zebrafish (Danio rerio)

Environmental estrogenic compounds are important pollutants, which are widely distributed in natural water bodies. They produce various adverse effects on fish, but their concentration-dependent toxicities in fish metabolism and health are not fully understood. This study investigated the effects of 17β-estradiol (E2) and bisphenol A (BPA) at low and high concentrations on lipid deposition, inflammation and antioxidant response in male zebrafish. We measured fish growth parameters, gonad development, lipid contents and the activities of inflammatory and antioxidant enzymes, as well as their mRNA expressions. All E2 and BPA concentrations used increased body weight, damaged gonad structure and induced feminization in male zebrafish. The exposure of zebrafish to E2 and BPA promoted lipid accumulation by increasing total fat, liver triglycerides and free fatty acid contents, and also upregulated lipogenic genes expression, although they decreased total cholesterol content. Notably, zebrafish exposed to low concentrations of E2 (200 ng/L) and BPA (100 μg/L) had higher lipid synthesis and deposition compared to high concentrations (2000 ng/L and 2000 μg/L, respectively). However, the high concentrations of E2 and BPA increased inflammation and antioxidant response. Furthermore, BPA caused greater damage to fish gonad development and more severe lipid peroxidation compared to E2. Overall, the results suggest that the toxic effects of E2 and BPA on zebrafish are concentration-dependent such that, the relative low concentrations used induced lipid deposition, whereas the high ones caused adverse effects on inflammation and antioxidant response.

Inflammation Induces Lipid Deposition in Kidneys by Downregulating Renal PCSK9 in Mice with Adriamycin-Induced Nephropathy.

BackgroundPrevious studies of human and animal models indicate that inflammation alters lipid metabolism. The pro-protein convertase subtilisin kexin type 9 (PCSK9) plays an important role in lipid metabolism.Material/MethodsWe examined the effect of inflammation on PCSK9 expression and lipid deposition in the kidneys of mice with Adriamycin-induced nephropathy.ResultsThe results indicated an increased expression of inflammatory cytokines and lipid deposition over 12 weeks. During this time, the expression of PCSK9 and its transcriptional activator (hepatocyte nuclear factor 1α, HNF1α) decreased, and the expression of the low-density lipoprotein receptor (LDLR) and its transcriptional activator (sterol regulatory element binding protein-2, SREBP-2) increased. Exogenous inflammation appeared to further aggravate this process.ConclusionsOur mouse model of nephropathy suggests that a key step in the inflammation-induced deposition of lipids in the kidneys is the downregulation renal PCSK9 expression.

611-P: Berberine Prevented High-Fat Diet-Induced Metabolic Disorders via Inhibition of Whole Lipid Metabolism

Berberine, an alkaloid extracted from coptis and phellodendron, is known to alleviate lipid metabolism disorders, but the precise molecular mechanism remains unknown. This study aimed to investigate whether berberine regulated lipid metabolism by mitochondrial complex I suppression. In this study, the mitochondrial complex I inhibitor rotenone was used parallel to explore whether the lipid-lowering action of BBR was related to complex I. B6 mice were fed with high-fat diet (HFD) with or without berberine or rotenone for 20 weeks. Obesity, hepatic steatosis and insulin resistance were induced by HFD and reversed by berberine. Additionally, berberine reduced HFD induced complex I-dependent oxidative phosphorylation of gut and liver, citrate synthase activity, mtDNA copy number and ATP synthesis in liver. It also inhibited lipid synthesis, fatty acid uptake and oxidation. Furthermore, berberine increased the length and decreased the density of mitochondria to facilitate mitochondrial fusion. Berberine promoted the intestinal lipid excretion as well as reduced the abundance and diversity of gut microbiota remarkably. Nevertheless, no changes in metabolism and mitochondrial function of the recipient mice were observed after transplantation of fecal microbiota from the berberine treated mice. In vitro, berberine normalized oleic acid induced lipid deposition of mouse primary hepatocytes significantly. Oleic acid decreased AMPK activity, which was activated by berberine. The lipid-lowering effects of berberine were unaffected in the presence of compound C, an AMPK inhibitor. In all experiments, rotenone showed similar effects as berberine except for the little alteration of gut bacteria. In conclusion, these results suggested that mitochondrial complex I of gut and liver is the target of berberine. Berberine and rotenone alleviates obesity and hepatic steatosis independently of gut microbiota and AMPK activity. Disclosure M. Yu: None. M. Alimujiang: None. J. Yin: None. Funding National Natural Science Foundation of China (81670790)

Comparison of effects of dietary‐specific fatty acids on growth and lipid metabolism in Nile tilapia

The dominant fatty acids (FAs) in oils are often used to explain different nutritional effects of dietary oils in fish. However, the amounts of dominant FAs among oils are different, and the nutritional roles of these important FAs in fish have not been precisely compared at similar levels in feeding trials. In the present study, different amounts of palmitic acid were added to safflower oil (SO), olive oil (OO) and fish oil (FO) to obtain comparable amounts (about 550 g/kg of total FAs) of 18:2n‐6, 18:1n‐9 and 20:5n‐3 + 22:6n‐3 and subsequently fed to Nile tilapia (11.1 ± 0.01 g) for 8 weeks. The results showed similar growth among groups but FO group obtained lower fat deposition, serum ALT and AST activities, compared to OO. Lipogenesis‐related gene expressions were higher in OO group than FO group in liver, muscle and adipose tissue, but there were only few differences in these genes between SO and FO groups. Lipid catabolism genes in FO group were higher than OO and SO groups in adipose tissue, but not in muscle, and the significantly higher expressions of CPT1b and PPARα were only observed in liver. Overall, dietary 18:2n‐6, 20:5n‐3 and 22:6n‐3 were beneficial to normal growth and lipid metabolism, whereas high amount of 18:1n‐9 induced lipid deposition and liver damage in Nile tilapia.

Bisphenol A, but not Bisphenol S, exposure increases lipid deposition by acting on the PI3K pathway in vivo

Bisphenol A (BPA) is an endocrine disrupter present in many daily products including food and beverage packaging. BPA exposure has been linked to many disorders in humans including cancer, neurological disorders, diabetes and obesity and has therefore been declared toxic and a partial ban is in effect in several countries. Recently the plastic industry has come with a bisphenol analog as a substitute for BPA in BPA free products: BPS. However to date, little is known regarding the toxicity of BPS in vivo. In this study, we used the zebrafish as a vertebrate model to understand the mechanism of action of BPA and BPS in lipid usage during embryogenesis. Zebrafish embryos exposed to the extreme low dose 1 nM BPA (over 6,000‐fold lower than the accepted human daily exposure), have a 65% increase in lipid deposition. Interestingly, BPS exposure, at the same concentration, has no effect on lipid deposition. BPA is classified as an estrogenic compound however, pharmacological blockage of the nuclear estrogen receptors does not suppress the induced lipid deposition. To identify which pathway might be involved in this increased lipid deposition, we performed a full embryo lipidomic analysis. This revealed that BPA exposed embryos had a dramatic increase of diacylglycerol (DAG) and Phosphatidylinositol (PI) lipids. Strikingly, lipidomic analysis of BPS exposed embryos showed a decrease of DAGs and PIs. This is the first study to demonstrate a phenotypical difference between BPA and BPS at similar doses. Double exposure of BPA and LY294002, a strong inhibitor of phosphoinositide 3‐kinases, abolishes the BPA induced increase in lipid deposition and lipid usage. At the molecular level, BPA exposure increases the expression of key enzymes of the PI3K pathway such as: cdipt, plcb3, vps34p and p110. Our study allows us to propose a model in which BPA, but not BPS, at very low concentration can activate the PI3K pathway leading to an accumulation of lipid during embryogenesis in an estrogen receptors independent manner. Our results confirm that, at least in terms a of lipid usages, BPS is safer than BPA exposure and support the ban on BPA from consumer merchandise.Support or Funding InformationThis project was supported by an Australian Diabetes Research Trust (DART) research grant to YGThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Swertiamarin decreases lipid accumulation dependent on 3-ketoacyl-coA thiolase

Natural compounds are important resources for drug discovery. Using Caenorhabditis elegans (C. elegans) models, we screened active natural compounds with lipid lowering effects. Swertiamarin was found as a potent candidate to reduce lipid content in C. elegans. Using RNAi screening, we were able to demonstrate that kat-1 (ketoacyl thiolase-1) is necessary for the lipid lowering effect of swertiamarin. Furthermore, the activity of swertiamarin was verified in high fat diet induced obese mice. Consistent with the results in C. elegans, swertiamarin ameliorated high fat diet induced lipid deposition and hyperlipidemia. These results indicate that swertiamarin exerts lipid-lowering effects through kat-1 regulation and could serve as a possible therapeutic option to improve hyperlipidemia induced comorbidities.

Effects of different dietary soybean oil levels on growth, lipid deposition, tissues fatty acid composition and hepatic lipid metabolism related gene expressions in blunt snout bream (Megalobrama amblycephala) juvenile

Soybean oil (SO) is widely used in freshwater aqua-feeds in China. However, little information is available about the effects of dietary SO levels on lipid deposition and hepatic lipid metabolism in fish. This study evaluated effects of different dietary soybean oil (SO) levels on growth performance, lipid deposition, tissues fatty acid compositions and hepatic lipid metabolism related gene expressions in blunt snout bream (Megalobrama amblycephala). Fish (average weight 0.34±0.01g) were fed five experimental diets containing 0% (0%SO), 20% (20%SO), 32% (32%SO), 56% (56%SO) and 100% (100%SO) SO in dietary lipid, and a diet containing 100% fish oil (100%FO). The body weight gain of fish fed 20%SO and 100%FO diets were significantly higher than in the other groups. Hepatic lipid content increased with incremental dietary SO level. The percentages of 18:2n−6 in the liver and muscle significantly increased with increasing dietary SO level. In the fish fed 56%SO and 100%SO diets 20:4n−6 content significantly increased in the liver and muscle suggesting the capacity of blunt snout bream to convert C18 fatty acids (PUFAs) to C20/22 fatty acids. However, increasing dietary SO level up-regulated acyl-CoA delta-9 desaturase and down-regulated peroxisome proliferator-activated receptors-α and -β, which might be responsible for the high 18:2n−6 content. It is suggested that supplementation of 20% soybean oil (8% lipid in diet) could improve blunt snout bream juvenile growth. However, an excess of 18:2n−6 in SO supplemented diets modified the expressions of lipid metabolism-related genes which induced lipid deposition. Statement of relevanceThe present study was conducted to evaluated the effects of different dietary soybean oil (SO) levels on growth performance, lipid deposition, tissues fatty acid compositions and hepatic lipid metabolism related gene expressions in blunt snout bream (M. amblycephala). Fish (average weight 0.34±0.01g) were fed five experimental diets containing the following inclusion levels of SO: 0% (0%SO), 20% (20%SO), 32% (32%SO), 56% (56%SO) and 100% (100%SO) in dietary lipid, and a diet contained 100% fish oil (100%FO) was also used here. The percentages of 18:2n−6 in the liver and muscle significantly increased with increasing dietary SO level, and the fish fed 56%SO and 100%SO diets significantly increased 20:4n−6 contents in the liver and muscle, suggesting blunt snout bream has the capacity to convert C18 fatty acids (PUFAs) to C20/22 fatty acids. However, increasing dietary SO level up-regulated acyl-CoA delta-9 desaturase and down-regulated peroxisome proliferator-activated receptors-α and -β, which might be related associated with high level of 18:2n−6 in SO. It suggested that supplementation of 20% soybean oil (8% lipid in diet) could improve growth of blunt snout bream juvenile. However, an excess of 18:2n−6 in SO would modify the expressions of lipid metabolism-related genes, which induced lipid deposition in fish.

Dietary fenofibrate reduces hepatic lipid deposition by regulating lipid metabolism in yellow catfish Pelteobagrus fulvidraco exposed to waterborne Zn.

Fenofibrate is known to possess lipid-lowering effects by regulation of gene transcription involved in lipid metabolism. Waterborne Zn exposure induces lipid deposition in yellow catfish Pelteobagrus fulvidraco. Thus, the present working hypothesis is that dietary fenofibrate addition will reduce hepatic lipids in yellow catfish exposed to waterborne Zn. To this end, juvenile yellow catfish were exposed to 0.04 (control), 0.35 mg/L waterborne Zn, 0.15% dietary fenofibrate, and 0.35 mg Zn/l + 0.15% dietary fenofibrate for 8 weeks. Growth performance, lipid deposition and metabolism in the liver were determined. Dietary fenofibrate promoted growth performance and reduced hepatic lipid content of yellow catfish exposed to waterborne Zn. However, these effects did not appear in fish in normal water. The lipid-lowering effect of fenofibrate on fish exposed to waterborne Zn was associated with increased lipolysis, as indicated by increased CPT I activities and expression of lipolytic genes PPARα, CPT IA, ATGL and HSL, and with reduced lipogenesis as indicated by reduced activities of G6PD, 6PGD, ME and ICDH. Dietary fenofibrate significantly increased mRNA levels of FAS, LPL and ACCα, but reduced mRNA levels of ACCβ and PPARγ in fish exposed to waterborne Zn. Pearson correlations between transcriptional factors expression, and activities and expression of several enzymes were observed, indicating that changes at the molecular and enzymatic levels may underlie the patterns of lipid metabolism and accordingly affect hepatic fat storage. Taken together, our results suggest that the lipid-lowering effect of fenofibrate was attributed, in part, to the down-regulation of lipogenesis and up-regulation of fatty acid oxidation.

Hepatic SIRT1 Attenuates Hepatic Steatosis and Controls Energy Balance in Mice by Inducing Fibroblast Growth Factor 21

The hepatocyte-derived hormone fibroblast growth factor 21 (FGF21) is a hormone-like regulator of metabolism. The nicotinamide adenine dinucleotide-dependent deacetylase SIRT1 regulates fatty acid metabolism through multiple nutrient sensors. Hepatic overexpression of SIRT1 reduces steatosis and glucose intolerance in obese mice. We investigated mechanisms by which SIRT1 controls hepatic steatosis in mice. Liver-specific SIRT1 knockout (SIRT1 LKO) mice and their wild-type littermates (controls) were divided into groups that were placed on a normal chow diet, fasted for 24 hours, or fasted for 24 hours and then fed for 6 hours. Liver tissues were collected and analyzed by histologic examination, gene expression profiling, and real-time polymerase chain reaction assays. Human HepG2 cells were incubated with pharmacologic activators of SIRT1 (resveratrol or SRT1720) and mitochondrion oxidation consumption rate and immunoblot analyses were performed. FGF21 was overexpressed in SIRT1 LKO mice using an adenoviral vector. Energy expenditure was assessed by indirect calorimetry. Prolonged fasting induced lipid deposition in livers of control mice, but severe hepatic steatosis in SIRT1 LKO mice. Gene expression analysis showed that fasting up-regulated FGF21 in livers of control mice but not in SIRT1 LKO mice. Decreased hepatic and circulating levels of FGF21 in fasted SIRT1 LKO mice were associated with reduced hepatic expression of genes involved in fatty acid oxidation and ketogenesis, and increased expression of genes that control lipogenesis, compared with fasted control mice. Resveratrol or SRT1720 each increased the transcriptional activity of the FGF21 promoter (-2070/+117) and levels of FGF21 messenger RNA and protein in HepG2 cells. Surprisingly, SIRT1 LKO mice developed late-onset obesity with impaired whole-body energy expenditure. Hepatic overexpression of FGF21 in SIRT1 LKO mice increased the expression of genes that regulate fatty acid oxidation, decreased fasting-induced steatosis, reduced obesity, increased energy expenditure, and promoted browning of white adipose tissue. SIRT1-mediated activation of FGF21 prevents liver steatosis caused by fasting. This hepatocyte-derived endocrine signaling appears to regulate expression of genes that control a brown fat-like program in white adipose tissue, energy expenditure, and adiposity. Strategies to activate SIRT1 or FGF21 could be used to treat fatty liver disease and obesity.

The Critical Role of AKT2 in Hepatic Steatosis Induced by PTEN Loss

Insulin signaling in the liver leads to accumulation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3). Deletion of the phosphatase Pten (phosphatase and tensin homologue deleted on chromosome 10) reduces PIP3 levels and leads to fatty liver development. The purpose of this study was to investigate the mechanisms underlying lipogenesis that result from PIP3 accumulation using liver Pten-deletion mice. To explore the role of AKT2, the major liver AKT isoform in steatosis induced by deletion of Pten, we created mice lacking both Pten and Akt2 in hepatocytes and compared the effect of deleting Akt2 and Pten in the double mutants to the Pten deletion mice alone. Hepatic lipid accumulation was significantly reduced in mice lacking both PTEN and AKT2, as compared with Pten mutant mice alone. This effect was due to the role of AKT2 in maintaining expression of genes involved in de novo lipogenesis. We showed that lipid accumulation in the double mutant hepatocytes was partially reversed by expression of constitutive active FOXO1, a transcription factor downstream of AKT not dependent on inhibition of atypical protein kinase C. In summary, this study delineated regulation of lipid metabolism by PI3K signaling pathway by showing that AKT mediates PIP3 accumulation (mimicked by PTEN loss) induced lipid deposition in the liver and provided an important molecular mechanism for insulin-regulated hepatic lipogenesis.

Chloroquine Induced Lipid Deposition in the Lateral Geniculate Body and Superior Colliculus of Adult Wistar Rats

The effect of administration of chloroquine on lipid deposition was studied in intracranial visual relay centers. Adult Wistar rats (38) weighing averagely 200g were randomly assigned into treatment (28) and control (10) groups. The rats in the treatment groups received 2mg/kg body weight of chloroquine phosphate in distilled water for 13 days. The rats were sacrificed on days 1,3,5,7,9,11 and 13. The lateral geniculate body and the superior colliculus were dissected out and frozen. Frozen sections were stained with Sudan Black B. Results obtained showed that prolonged administration ofchloroquine caused increased and diffused lipid deposition in these tissues especially on the 13th day treatment group. This lipid deposition may interfere with the normal functions of these visual relay centers.

Inhibitory Effect of Triterpenoid Saponins from the Leaves ofIlex kudingchaon Aggregated LDL-Induced Lipid Deposition in Macrophages

We have investigated the inhibitory effect of triterpenoid saponins from the leaves of Ilex kudingcha C. J. Tseng on aggregated low-density lipoprotein (LDL)-induced lipid deposition in macrophages. A cell-based screening model was initially applied on aggregated LDL (aggLDL)-induced lipid deposition on macrophages to test the inhibitory effects of the 12 triterpenoid saponins from this plant. Eight of these compounds inhibited the formation of foam cells and reduced intracellular total cholesterol and triglyceride contents. Structure-activity relationship analysis showed the essential role of the delta-lactone ring for the biological activity. The promoter action of the OH group at the C-12 position, the number of monosaccharides in the sugar chain and the rhamnose at the terminal of the sugar chain is also discussed.

Secretory group II phospholipase A2 in human atherosclerotic plaques

Atherosclerotic plaques exhibit a series of features that are similar to those of chronic inflammation. Based on the fact that during inflammation several cell types synthesize and secrete a group II phospholipase A2 (PLA2), an immunohistochemical study was undertaken to explore whether this enzyme can be identified in human atherosclerotic lesions. Tissue specimens obtained from 13 patients who had undergone arteriectomy and three specimens with advanced atherosclerotic plaques obtained at autopsy were analyzed and compared to arteries free of atherosclerosis. The results showed that in all areas with atherosclerotic lesions, a staining with monoclonal antibodies raised against group II PLA2 was evident. In normal arteries without thickened intima, this immunostaining was completely negative. With the use of specific monoclonal antibodies against macrophages (anti-KP-1) and smooth muscle cells (anti-α-actin), PLA2-positive cells were identified as foam cells mainly derived from macrophages. In addition to these cells, other regions of the thickened intima gave a partially positive reaction with anti-PLA2 antibodies, but could not be stained with either anti-KP-1 or anti-α-actin. Some of these regions were localized on edges of calcification and cell necrosis. Other PLA2-positive regions seem to be associated with extracellular matrix structures. In summary, the findings of this study may be regarded as further evidence to support the link between atherosclerosis and chronic inflammatory processes. In view of the fact that the in vitro modification of lipoproteins by PLA2-treatment induces lipid deposition in macrophages, the results of this study suggest that group II PLA2 may actively be involved in the formation of foam cells in vivo.

Predilection of experimental arterial aneurysms for dietary-induced lipid deposition

In 14 stock rabbits experimental aneurysms (saccular, fusiform or berry) were produced on the common carotid artery or the aorta by microvascular surgery using a modification of the venous pouch technique. The animals were given a cholesterol-rich diet at varying times postoperatively to determine the susceptibility of the experimental aneurysmal walls to dietary-induced lipid deposition. The experimental aneurysms all exhibited a pronounced predilection for dietary-induced lipid deposition, greater than that of the host artery or the contralateral vein. The results demonstrate the importance of haemodynamic stress in the localization of dietary induced lipid deposition.