Metabolic syndrome: comparison of the two commonly used animal models

Rosiglitazone and bezafibrate modulate gene expression in a rat model of non-alcoholic fatty liver disease--a historical prospective

Background

Genetic factors implicated in the pathogenesis of non-alcoholic fatty liver disease are poorly understood. Our aim was to characterize three genes involved in a rat model of non-alcoholic fatty liver disease and investigate the effect of rosiglitazone and bezafibrate.

Method

Five rats were fed a chow diet (controls) and 18 a fructose-enriched diet (FED) for 5 weeks: 6 were administered rosiglitazone and 6 bezafibrate during the last 2 weeks and 6 were not treated at all. Livers were examined by reverse transcription-PCR for the genes encoding peroxisome proliferator-activated receptors (PPAR), PPAR-α, PPAR-γ, and Mn superoxide dismutase2 (Mn SOD2). Western blot was used for proteins levels.

Result

The FED rats showed a decrease in mRNA of MnSOD2, PPAR-α, and PPAR-γ (3, 3.5 fold, and 27%, respectively) (p<0.05). The 3 genes normalized in response to rosiglitazone and bezafibrate. The proteins of MnSOD2, PPAR-α and PPAR-γ in the FED rats decreased (2.5, 2, and 2.2, respectively) (p<0.05). Following administration of rosiglitazone, proteins of MnSOD2, PPAR-α and PPAR-γ in the FED rats increased (reaching 1.5-fold, a 20% increase and normalization, respectively), (p<0.05). Administration of bezafibrate to the FED rats restored the proteins of 3 genes to baseline.

Conclusion

A consistent reduction in hepatic expression of MnSOD2, PPAR-α and PPAR-γ in the FED rats compared with controls was observed. Administration of either rosiglitazone or bezafibrate to the FED rats restored these genes to a pre-morbid state.

Role of T regulatory lymphocytes in the pathogenesis of high-fructose diet-induced metabolic syndrome

We recently showed that T regulatory lymphocytes (Treg), which are immune suppressors of inflammatory responses, play a role blunting the development of hypertension-induced injury. Treg are unchanged or decreased in children with metabolic syndrome, and therefore, their role in metabolic syndrome remains unclear. We hypothesized that Treg number or function would be depressed in a high-fructose diet-induced metabolic syndrome-like model in rats. Sprague-Dawley rats were fed normal chow or a high-fructose diet for 5 weeks. The high-fructose diet-induced a 3.8-fold increase in plasma triglycerides and a 14% reduction in high-density lipoprotein cholesterol (P<0.001). The high-fructose diet increased reactive oxygen species in aorta and periaortic adipose tissue 2.8-fold (P<0.05), and reduced nicotinamide adenine dinucleotide phosphate oxidase activity 1.9-fold in aorta, and 2.5-fold in the heart (P<0.05). It also increased plasma nitric oxide metabolite levels 6.4-fold (P<0.001). Western blots showed that the high-fructose diet increased ≥2.3-fold vascular and in platelet endothelial cell adhesion molecule 1 in aorta (P<0.01). It did not affect monocyte/macrophage aortic infiltration but caused a 2.4-fold increase in collagen deposition in the aortic media (P<0.01). No change in plasma interleukin-10 was detected. The percentage of spleen CD4+ CD25- and Treg (CD4+ CD25(high)) cells was unaltered by the high-fructose diet. However, cultured Treg from high-fructose diet-fed rats secreted 62% less interleukin-10 than control cells (P<0.05), suggesting a decreased Treg function, which could play a role in the development of cardiovascular complications of the metabolic syndrome.

Apoptosis of endothelial progenitor cells in a metabolic syndrome experimental model

Aim:

This study tests the hypothesis postulating that metabolic syndrome induced by chronic administration of fructose to spontaneously hypertensive rats (FFHR) generates impairment in vascular repair by endothelial progenitor cells (EPC).

Materials and Methods:

To characterize the vascular adverse environment present in this experimental model we measured: NAD(P)H oxidase activity, eNOS activity, presence of apoptosis in the arterial wall, all these parameters were most affected in the FFHR group. Also, we found decreased level and proliferative capacity of EPC measured by flow cytometry and colonies forming units assay in cultured cells, respectively, in both groups treated with fructose; FFHR (SHR fructose fed rats) and FFR (WKY fructose fed rats) compared with their controls; SHR and WKY.

Results:

The fructose-fed groups FFR and SHR also showed an incremented number of apoptotic (annexinV+/7AADdim) EPC measured by flow cytometry that returns to almost normal values after eliminating fructose administration.

Conclusion:

Our findings suggest that increased apoptosis levels of EPC generated in this experimental model could bein part the underlying cause for the impaired vascular repair by in EPC.

Effect of dietary blueberry pomace on selected metabolic factors associated with high fructose feeding in growing Sprague-Dawley rats

An experiment was conducted to study the protective effect of feeding extruded and unextruded blueberry pomace (BBP) on selected metabolic parameters associated with metabolic syndrome in a model of high fructose (HF)-fed growing Sprague-Dawley rats. Treatments were as follows: (1) control (modified AIN-based diet); (2) HF diet (AIN diet with 58% fructose); (3) HF diet with 1.5% unextruded BBP; (4) HF diet with 1.5% extruded BBP; (5) HF diet with 3% unextruded BBP; and (6) HF diet with 3% extruded BBP. Compared with the control, HF feeding increased fasting plasma insulin and fasting and postprandial plasma triglycerides as well as homeostatic scores of insulin resistance and β-cell function, but not weight gain, diet intake and efficiency, abdominal fat, oral glucose tolerance, and fasting and postprandial plasma glucose, cholesterol, and leptin levels. Inclusion of unextruded or extruded BBP was effective in minimizing or ameliorating the fructose-induced metabolic anomalies, except postprandial plasma triglycerides, especially at 3% of the diet. In addition, unextruded or extruded BBP at 3% of the diet was also able to reduce plasma cholesterol and abdominal fat relative to the HF control, which may impart additional health benefits. Compared with the control, inclusion of unextruded or extruded BBP at both 1.5% and 3% resulted in lower total fat weight, and animals fed a diet supplemented with 3% unextruded BBP in fasting state or 3% unextruded BBP in fed state had lower leptin levels than the control. This is the first study demonstrating the beneficial effects of feeding blueberry pomace on health.

Oligonucleotide microarray analysis of dietary-induced hyperlipidemia gene expression profiles in miniature pigs

Background

Hyperlipidemia animal models have been established, but complete gene expression profiles of the transition from normal lipid levels have not been obtained. Miniature pigs are useful model animals for gene expression studies on dietary-induced hyperlipidemia because they have a similar anatomy and digestive physiology to humans, and blood samples can be obtained from them repeatedly.

Methodology

Two typical dietary treatments were used for dietary-induced hyperlipidemia models, by using specific pathogen-free (SPF) Clawn miniature pigs. One was a high-fat and high-cholesterol diet (HFCD) and the other was a high-fat, high-cholesterol, and high-sucrose diet (HFCSD). Microarray analyses were conducted from whole blood samples during the dietary period and from white blood cells at the end of the dietary period to evaluate the transition of expression profiles of the two dietary models.

Principal Findings

Variations in whole blood gene expression intensity within the HFCD or the HFCSD group were in the same range as the controls provide with normal diet at all periods. This indicates uniformity of dietary-induced hyperlipidemia for our dietary protocols. Gene ontology- (GO) based functional analyses revealed that characteristics of the common changes between HFCD and HFCSD were involved in inflammatory responses and reproduction. The correlation coefficient between whole blood and white blood cell expression profiles at 27 weeks with the HFCSD diet was significantly lower than that of the control and HFCD diet groups. This may be due to the effects of RNA originating from the tissues and/or organs.

Conclusions

No statistically significant differences in fasting plasma lipids and glucose levels between the HFCD and HFCSD groups were observed. However, blood RNA analyses revealed different characteristics corresponding to the dietary protocols. In this study, whole blood RNA analyses proved to be a useful tool to evaluate transitions in dietary-induced hyperlipidemia gene expression profiles in miniature pigs.

Blunted blood pressure response and elevated plasma adiponectin levels in female Sprague Dawley rats

BACKGROUND

Premenopausal women have lower blood pressure (BP) levels than men of similar age. Adiponectin has been shown to play a role in the pathogenesis of hypertension. The aim of the present study was to compare the effect of various stress stimuli on BP and plasma adiponectin levels in male and female Sprague Dawley (SD) rats.

METHODS

In three experimental models of hypertension, fructose-enriched diet, high salt diet, or L-NAME, were administered for up to 4 weeks. BP, metabolic parameters, and plasma adiponectin were measured at baseline and during the studies. The fructose diet protocol was repeated in female rats for 2 weeks with the addition of testosterone injections or vehicle.

RESULTS

Females, in contrast to males, did not develop fructose-induced hypertension. Total plasma triglycerides (TGs) were half in females at baseline (P < 0.001) and a third at 4 weeks (P < 0.05). Plasma insulin levels were 23% lower in females than in males at baseline (P < 0.05) and 42% lower after 4 weeks of fructose-enriched diet (P = 0.001). Plasma adiponectin levels were 65% higher in females than in males at baseline (P = 0.001) and 45% higher after 4 weeks of fructose-enriched diet (P < 0.05). Furthermore, female rats showed blunted BP response and elevated plasma adiponectin in the salt-induced and L-NAME-induced hypertension models. Testosterone injection to female rats reduced plasma adiponectin and reversed the blunted BP response.

CONCLUSIONS

Elevated plasma adiponectin levels, perhaps due to lack of suppression by testosterone, are associated with a blunting of BP response in female compared to male SD rats.

Impairments in the intrinsic contractility of mesenteric collecting lymphatics in a rat model of metabolic syndrome

Numerous studies on metabolic syndrome (MetSyn), a cluster of metabolic abnormalities, have demonstrated its profound impact on cardiovascular and blood microvascular health; however, the effects of MetSyn on lymphatic function are not well understood. We hypothesized that MetSyn would modulate lymphatic muscle activity and alter muscularized lymphatic function similar to the impairment of blood vessel function associated with MetSyn, particularly given the direct proximity of the lymphatics to the chronically inflamed adipose depots. To test this hypothesis, rats were placed on a high-fructose diet (60%) for 7 wk, and their progression to MetSyn was assessed through serum insulin and triglyceride levels in addition to the expression of metabolic and inflammatory genes in the liver. Mesenteric lymphatic vessels were isolated and subjected to different transmural pressures while lymphatic pumping and contractile parameters were evaluated. Lymphatics from MetSyn rats had significant negative chronotropic effects at all pressures that effectively reduced the intrinsic flow-generating capacity of these vessels by ∼50%. Furthermore, lymphatics were remodeled to a significantly smaller diameter in the animals with MetSyn. Wire myograph experiments demonstrated that permeabilized lymphatics from the MetSyn group exhibited a significant decrease in force generation and were less sensitive to Ca(2+), although there were no significant changes in lymphatic muscle cell coverage or morphology. Thus, our data provide the first evidence that MetSyn induces a remodeling of collecting lymphatics, thereby effectively reducing their potential load capabilities and impairing the intrinsic contractility required for proper lymph flow.

Early endocrine and molecular changes in metabolic syndrome models

The twenty-first century arrived in the middle of a global epidemic of metabolic syndrome (MS) and type 2 diabetes mellitus (DM2). It is generally accepted that an excess of nutrients linked to a low physical activity triggers the problem. However, the molecular features that interact to develop the MS are not clear. In an effort to understand and control them, they have been extensively studied, but this goal has not been achieved yet. Nonhuman animal models have been used to explore diet and genetic factors in which experimental conditions are controlled. For example, only one factor in the diet, such as fats or carbohydrates can be modified to better understand a single change that would be impossible in humans. Most of the studies have been done in rodents. However, it is difficult to directly compare them, because experiments are different in more than one variable; genetic strains, amount, and the type of fat used in the diet and sex. Thus, the only possible criteria of comparison are the relevance of the observed changes. We review different animal models and add some original observations on short-term changes in metabolism and beta cells in our own model of adult Wistar rats that are not especially prone to get fat or develop DM2, treated with 20% sucrose in drinking water. One early change observed in pancreatic beta cells is the increase in GLUT2 expression that is located to the membrane of the cells. This change could partially explain the presence of insulin hypersecretion and hyperinsulinemia in these rats. Understanding early changes that lead to MS and in time to pancreatic islet exhaustion is an important biomedical problem that may contribute to learn how to prevent or even reverse MS, before developing DM2.

Effects of coenzyme Q10 and α-lipoic acid supplementation in fructose fed rats

This study was conducted to investigate the effects of α-lipoic acid and coenzyme Q10 on plasma levels of lipids, asymmetric dimethylarginine, oxidative stress in fructose fed rats which provide a model of dietary-induced insulin resistance and to evaluate vascular changes developing in these rats by histologically. Male Sprague Dawley rats were used in this study. The animals were divided into 4 groups. Group 1 did not receive any medication and served as a control. Group 2 received a regular diet and water ad libitum and fructose was administered as % 10 solution in drinking water. Group 3 received α-lipoic acid (100 mg/kg/day) i.p. for 5 weeks and Group 4 received coenzyme Q10 (10 mg/kg/day) i.p. for 5 weeks. For determination of plasma asymmetric dimethylarginine, glutathione and malondialdehyde levels, high-performance liquid chromatography system was used. Homeostatic model assessment as a measure of insulin resistance was calculated. Lipid profile measurements were determined using enzymatic assay on an Auto analyzer. The high fructose diet was significantly associated with an increase in levels of plasma LDL, VLDL and total cholesterol and decrease in level of HDL cholesterol. Plasma asymmetric dimethylarginine, malondialdehyde and glutathione levels were also increase in these rats. α-lipoic acid or coenzyme Q10 supplementation was found to have some positive effect on these parameters. These findings were also demonstrated by morphological observation of the aorta. We demonstrated that administration of α-lipoic acid and coenzyme Q10 notably suppresses oxidative and nitrative stress, hyperinsulinemia, insulin resistance developing in fructose fed rats, a model of metabolic syndrome (MS). These positive effects of α-lipoic acid or coenzyme Q10 can be attributed to its antioxidant activity.

The relation between dietary fructose, dietary fat and leptin responsiveness in rats

Others reported that rats fed a high-fructose diet for 6 months were leptin resistant. We tested peripheral and/or central leptin responses in rats fed fructose for shorter time periods. Rats fed a diet containing 60% energy (% kcal) fructose and 10% kcal fat diet for 21 days had the same serum triglycerides (TG), gained less weight than controls, decreased their food intake and weight gain in response to central injections of 0.5 or 1.0 ug leptin, but were resistant to an i.p. injection of 2.0 mg leptin/kg. An i.p. injection of 1 mg leptin/kg increased phosphorylation of hypothalamic signal transducer and activator of transcription 3 (PSTAT3) implying resistance was not a failure of leptin to cross the blood brain barrier. The effects of dietary fructose were compared with those of dietary fat. Rats fed a 10%kcal fructose and 30%kcal fat diet for 39 days were leptin resistant whereas rats fed a 40%kcal fructose and 30%kcal fat diet responded to i.p. leptin. Another monosaccharide, glucose, replicated the effects of fructose in the 30% kcal fat diet. Surprisingly, none of the rats showed a reliable response to third ventricle leptin and peripheral leptin failed to stimulate hypothalamic PSTAT3 although it did increase PSTAT3 in the brainstem of rats fed the 40%kcal fructose or glucose diets. Thus a high-fructose, low-fat diet induces peripheral leptin resistance in less than 4 weeks, but high dietary concentrations of fructose or glucose prevent peripheral leptin resistance in rats fed a high-fat diet.

Chronic cola drinking induces metabolic and cardiac alterations in rats

AIM

To investigate the effects of chronic drinking of cola beverages on metabolic and echocardiographic parameters in rats.

METHODS

Forty-eight male Wistar rats were divided in 3 groups and allowed to drink regular cola (C), diet cola (L), or tap water (W) ad libitum during 6 mo. After this period, 50% of the animals in each group were euthanized. The remaining rats drank tap water ad libitum for an additional 6 mo and were then sacrificed. Rat weight, food, and beverage consumption were measured regularly. Biochemical, echocardiographic and systolic blood pressure data were obtained at baseline, and at 6 mo (treatment) and 12 mo (washout). A complete histopathology study was performed after sacrifice.

RESULTS

After 6 mo, C rats had increased body weight (+7%, P < 0.01), increased liquid consumption (+69%, P < 0.001), and decreased food intake (-31%, P < 0.001). C rats showed mild hyperglycemia and hypertriglyceridemia. Normoglycemia (+69%, P < 0.01) and sustained hypertriglyceridemia (+69%, P < 0.01) were observed in C after washout. Both cola beverages induced an increase in left ventricular diastolic diameter (C: +9%, L: +7%, P < 0.05 vs W) and volumes (diastolic C: +26%, L: +22%, P < 0.01 vs W; systolic C: +24%, L: +24%, P < 0.05 vs W) and reduction of relative posterior wall thickness (C: -8%, L: -10%, P < 0.05 vs W). Cardiac output tended to increase (C: +25%, P < 0.05 vs W; L: +17%, not significant vs W). Heart rate was not affected. Pathology findings were scarce, related to aging rather than treatment.

CONCLUSION

This experimental model may prove useful to investigate the consequences of high consumption of soft drinks.

Two unhealthy dietary habits featuring a high fat content and a sucrose-containing beverage intake, alone or in combination, on inducing metabolic syndrome in Wistar rats and C57BL/6J mice

To establish animal models with diet-induced metabolic disorders similar to human metabolic syndrome, 2 unhealthy dietary habits featuring a high fat content and a sucrose-containing beverage intake, alone or in combination, were tested on Wistar rats and C57BL/6J mice. The 2 dietary habits were, respectively, simulated by feeding a high-fat diet (regimen A) or additionally providing 30% sucrose (wt/vol) in the drinking water (regimen B). Using a 2 x 2 factorial design, 4 groups of animals were fed chow diet plus plain water (group C), high-fat diet (30% [wt/wt] fat) plus plain water (group A), chow diet plus sucrose in drinking water (group B), and high-fat diet plus sucrose in drinking water (group AB) for 26 weeks. In Wistar rats, regimen B caused a significant increase in visceral fat; serum levels of lipids, glucose, insulin, and uric acid; insulin resistance; and blood pressure, whereas regimen A only caused a significant increase in visceral fat and serum insulin levels (P < .05). In contrast, regimen A induced a full array of metabolic syndrome in C57BL/6J mice; but regimen B only caused slight obesity and hyperlipidemia. In both Wistar rats and C57BL/6J mice, there were no additive effects of the 2 regimens, indicated by significant interactions between regimens A and B on the metabolic indexes measured. These results show that, in terms of inducing metabolic syndrome, Wistar rats are more responsive to sucrose water regimen, whereas C57BL/6J mice are more responsive to the high-fat diet regimen.

Effects of hypoxia-inducible factor-1alpha overexpression in pregnant mice: possible implications for preeclampsia and intrauterine growth restriction

Preeclampsia and intrauterine growth restriction (IUGR) are pregnancy-specific disorders that share a common pathophysiology. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that plays an important role in placental development. HIF-1α is elevated in preeclamptic placentas and induces soluble vascular endothelial growth factor receptor-1 (sFLT-1), a central factor in preeclampsia and IUGR pathogenesis. Our objective was to investigate the effects of HIF-1α overexpression on pregnancy in mice. C57BL/6J pregnant mice were systemically administered either adenovirus expressing stabilized HIF-1α (cytomegalovirus [CMV]-HIF), luciferase control (CMV-Luc), or saline on gestational day 8. Pregnant mice overexpressing HIF-1α had significantly elevated blood pressure and proteinuria compared with pregnant controls. HIF-1α mice showed fetal IUGR, decreased placental weights, and histopathological placental abnormalities compared with control mice. Glomerular endotheliosis, the hallmark lesion of preeclampsia, was demonstrated in the kidneys of these mice relative to the normal histology in control mice. Moreover, liver enzyme levels were significantly elevated, whereas complete blood counts revealed significant anemia and thrombocytopenia in CMV-HIF mice compared with controls. Blood smears confirmed microangiopathic hemolytic anemia in CMV-HIF mice, consistent with HELLP (hemolysis, elevated liver enzymes, and low platelets)-like syndrome. CMV-HIF mice showed elevation in serum sFLT-1 and soluble endoglin, providing a mechanistic explanation for the observations. Collectively, our results suggest a possible role for HIF-1α in the pathogenesis of both preeclampsia and IUGR.

Contribution of animal models to the understanding of the metabolic syndrome: a systematic overview

The metabolic syndrome (MetS) is one of the most important challenges to public health and biomedical research. Animal models of MetS, such as leptin-deficient obese mice, obese spontaneously hypertensive rats, JCR: LA-cp rats and the Ossabaw and Göttingen minipigs, have contributed to our understanding of the pathophysiological basis and the development of novel therapies. For a complex disease syndrome, no animal model can be expected to serve all needs of research. Although each animal model has limitations and strengths, used together in a complementary fashion, they are essential for research on the MetS and for rapid progress in understanding the aetiology and pathogenesis towards a cure. The purpose of this review is to assess how current animal models contributed to our knowledge of the human MetS, and to systematically evaluate the strengths and weaknesses of the currently available 78 animal models from 11 species.

A high-fructose diet worsens eccentric left ventricular hypertrophy in experimental volume overload

The development of left ventricular (LV) hypertrophy (LVH) can be affected by diet manipulation. Concentric LVH resulting from pressure overload can be worsened by feeding rats with a high-fructose diet. Eccentric LVH is a different type of hypertrophy and is associated with volume overload (VO) diseases. The impact of an abnormal diet on the development of eccentric LVH and on ventricular function in chronic VO is unknown. This study therefore examined the effects of a fructose-rich diet on LV eccentric hypertrophy, ventricular function, and myocardial metabolic enzymes in rats with chronic VO caused by severe aortic valve regurgitation (AR). Wistar rats were divided in four groups: sham-operated on control diet (SC; n = 13) or fructose-rich diet (SF; n = 13) and severe aortic regurgitation fed with the same diets [aortic regurgitation on control diet (ARC), n = 16, and aortic regurgitation on fructose-rich diet (ARF), n = 13]. Fructose-rich diet was started 1 wk before surgery, and the animals were euthanized 9 wk later. SF and ARF had high circulating triglycerides. ARC and ARF developed significant LV eccentric hypertrophy after 8 wk as expected. However, ARF developed more LVH than ARC. LV ejection fraction was slightly lower in the ARF compared with ARC. The increased LVH and decreased ejection fraction could not be explained by differences in hemodynamic load. SF, ARC, and ARF had lower phosphorylation levels of the AMP kinase compared with SC. A fructose-rich diet worsened LV eccentric hypertrophy and decreased LV function in a model of chronic VO caused by AR in rats. Normal animals fed the same diet did not develop these abnormalities. Hypertriglyceridemia may play a central role in this phenomenon as well as AMP kinase activity.

Attenuated alpha-adrenoceptor-mediated arterial and venous constrictions in rat models of diabetes

Diabetes is associated with metabolic and vascular abnormalities. We investigated if arterial and venous constrictions are impaired in rat models of diabetes. Wistar rats (5 weeks old) were fed a normal or high-fructose diet (60% of caloric intake). On Day 14, half of the animals in each diet regimen were given streptozotocin (60 mg/kg, i.v.). On Day 35, plasma insulin and triglyceride were measured, and on Day 42, insulin sensitivity (via hyperinsulinemic euglycemic clamp), and pressor as well as mean circulatory filling pressure (index of venous tone) responses to noradrenaline were determined. The rats treated with streptozotocin or fructose-streptozotocin were hyperglycemic, hypoinsulinemic and insulin resistant, and they also had reduced potency (increased ED(50)) of pressor response and reduced venoconstriction to noradrenaline compared to the two groups not given streptozotocin. Plasma triglyceride was unchanged in streptozotocin-treated rats, moderately increased in fructose-fed rats, and markedly increased in fructose-streptozotocin-treated rats. Hyperglycemia, insulin resistance and alpha-adrenoceptor-mediated venous contractile dysfunction were more pronounced in the group given fructose-streptozotocin than that given streptozotocin alone. The presence of marked hypertriglyceridemia, insulin resistance and vascular dysfunction makes the fructose-streptozotocin-treated rats a suitable model for study of metabolic and vascular abnormalities in advanced type 2 diabetes.

Use of copper and insulin-resistance to accelerate cognitive deficits and synaptic protein loss in a rat Abeta-infusion Alzheimer's disease model

The rat amyloid-beta (Abeta) intracerebroventricular infusion can model aspects of Alzheimer's disease (AD) and has predicted efficacy of therapies such as ibuprofen and curcumin in transgenic mouse models. High density lipoprotein (HDL), a normal plasma carrier of Abeta, is used to attenuate Abeta aggregation within the pump, causing Abeta-dependent toxicity and cognitive deficits within 3 months. Our goal was to identify factors that might accelerate onset of Abeta-dependent deficits to improve efficiency and cost-effectiveness of model. We focused on: 1) optimizing HDL-Abeta preparation for maximal toxicity; 2) evaluating the role of copper, a factor typically in water that can impact oligomer stability; and 3) determining impact of insulin resistance (type II diabetes), a risk factor for AD. In vitro studies were performed to determine doses of copper and methods of Abeta-HDL preparation that maximized toxicity. These preparations when infused resulted in earlier onset of cognitive deficits within 6 weeks post-infusion. Induction of insulin resistance did not exacerbate Abeta-dependent cognitive deficits, but did exacerbate synaptic protein loss. In summary, the newly described in vivo infusion model may be useful cost-effective method for screening for new therapeutic drugs for AD.