Hemodynamic Mechanisms Initiating Salt-Sensitive Hypertension in Rat Model of Primary Aldosteronism.

Few studies have investigated the hemodynamic mechanism whereby primary hyperaldosteronism causes hypertension. The traditional view holds that hyperaldosteronism initiates hypertension by amplifying salt-dependent increases in cardiac output (CO) by promoting increases in sodium retention and blood volume. Systemic vascular resistance (SVR) is said to increase only as a secondary consequence of the increased CO and blood pressure. Recently, we investigated the primary hemodynamic mechanism whereby hyperaldosteronism promotes salt sensitivity and initiation of salt-dependent hypertension. In unilaterally nephrectomized male Sprague-Dawley rats given infusions of aldosterone or vehicle, we found that aldosterone promoted salt sensitivity and initiation of salt-dependent hypertension by amplifying salt-induced increases in SVR while decreasing CO. In addition, we validated mathematical models of human integrative physiology, derived from Guyton's classic 1972 model - Quantitative Cardiovascular Physiology-2005 and HumMod-3.0.4. Neither model accurately predicted the usual changes in sodium balance, CO, and SVR that normally occur in response to clinically realistic increases in salt intake. These results demonstrate significant limitations with the hypotheses inherent in the Guyton models. Together these findings challenge the traditional view of the hemodynamic mechanisms that cause salt-sensitive hypertension in primary aldosteronism. Key words: Aldosterone, Blood pressure, Salt, Sodium, Rat.

Lysosomal sequestration of weak base drugs, lysosomal biogenesis, and cell cycle alteration.

Lysosomes, now known to take part in multiple cellular functions, also respond to various stress stimuli. These include biogenesis in response to nanomolar concentrations of hydrophobic weak-base anticancer drugs. However, since lysosomal stress mediated by accumulation of weak-base drugs at such concentrations has never been proven and these drugs have diverse effects on malignant cells, we investigated whether the interpretation of the data was true. We found that lysosomal accumulation of the drugs daunorubicin, doxorubicin, mitoxantrone, symadex, chloroquine, clomipramine and sunitinib alone, was insufficient to induce lysosomal alkalization i.e., lysosomal stress-mediated biogenesis at nanomolar concentrations. Instead, we found that some of the drugs used induced G2 phase arrest and lysosomal biogenesis that is associated with activation of transcription factor EB (TFEB). Similarly, cantharidin, a control compound that does not belong to the weak base drugs, induced cell cycle arrest in the G2 phase associated with TFEB-driven lysosomal biogenesis. Overall none of the tested drugs caused stress-induced lysosomal biogenesis at nanomolar concentrations. However, daunorubicin, doxorubicin, mitoxantrone, symadex and cantharidin induced a massive block in the G2 phase of the cell cycle which is naturally associated with TFEB-driven lysosomal biogenesis.

High cysteine diet reduces insulin resistance in SHR-CRP rats.

Increased plasma total cysteine (tCys) has been associated with obesity and metabolic syndrome in human and some animal studies but the underlying mechanisms remain unclear. In this study, we aimed at evaluating the effects of high cysteine diet administered to SHR-CRP transgenic rats, a model of metabolic syndrome and inflammation. SHR-CRP rats were fed either standard (3.2 g cystine/kg diet) or high cysteine diet (HCD, enriched with additional 4 g L-cysteine/kg diet). After 4 weeks, urine, plasma and tissue samples were collected and parameters of metabolic syndrome, sulfur metabolites and hepatic gene expression were evaluated. Rats on HCD exhibited similar body weights and weights of fat depots, reduced levels of serum insulin, and reduced oxidative stress in the liver. The HCD did not change concentrations of tCys in tissues and body fluids while taurine in tissues and body fluids, and urinary sulfate were significantly increased. In contrast, betaine levels were significantly reduced possibly compensating for taurine elevation. In summary, increased Cys intake did not induce obesity while it ameliorated insulin resistance in the SHR-CRP rats, possibly due to beneficial effects of accumulating taurine.

Changes in expression of lysosomal membrane proteins in leucocytes of cancer patients treated with tyrosine kinase inhibitors.

Lysosomal sequestration of weak base drugs has been identified as one of the stress-related mechanisms that trigger in vitro lysosomal biogenesis controlled by transcription factor EB (TFEB). Whether such mechanism can induce lysosomal biogenesis in vivo is unknown. In this study, we addressed the question whether prolonged treatment with sunitinib (SUN) in patients with advanced renal cell carcinoma (n = 22) and with imatinib (IM) in those with gastrointestinal stromal tumor (n = 6) could induce lysosomal biogenesis in leukocytes. Lysosomal biogenesis was monitored using immunoblotting of three lysosomal membrane proteins: lysosome-associated membrane proteins 1 and 2 (LAMP1 and LAMP2) and vacuolar H+-ATPase, B2 subunit (ATP6V1B2). Present results indicate that prolonged treatment with SUN affects LAMP1 and LAMP2 expression only marginally in most patients. In contrast, changes in ATP6V1B2 expression were marked and resembled irregular oscillations. Very similar changes in the expression of lysosomal membrane proteins were also found in IM-treated patients. Conclusion: prolonged treatment of cancer patients with SUN and IM did not induce leucocyte lysosomal biogenesis but dramatically affected expression of ATP6V1B2.

Conplastic strains for identification of retrograde effects of mitochondrial dna variation on cardiometabolic traits in the spontaneously hypertensive rat.

Mitochondrial retrograde signaling is a pathway of communication from mitochondria to the nucleus. Recently, natural mitochondrial genome (mtDNA) polymorphisms (haplogroups) received increasing attention in the pathophysiology of human common diseases. However, retrograde effects of mtDNA variants on such traits are difficult to study in humans. The conplastic strains represent key animal models to elucidate regulatory roles of mtDNA haplogroups on defined nuclear genome background. To analyze the relationship between mtDNA variants and cardiometabolic traits, we derived a set of rat conplastic strains (SHR-mtBN, SHR-mtF344 and SHR-mtLEW), harboring all major mtDNA haplotypes present in common inbred strains on the nuclear background of the spontaneously hypertensive rat (SHR). The BN, F344 and LEW mtDNA differ from the SHR in multiple amino acid substitutions in protein coding genes and also in variants of tRNA and rRNA genes. Different mtDNA haplotypes were found to predispose to various sets of cardiometabolic phenotypes which provided evidence for significant retrograde effects of mtDNA in the SHR. In the future, these animals could be used to decipher individual biochemical components involved in the retrograde signaling.

Can image analysis provide evidence that lysosomal sequestration mediates daunorubicin resistance?

Altered intracellular distribution of weak base anticancer drugs owing to lysosomal sequestration is one purported mechanism contributing to chemotherapy resistance. This has often been demonstrated with the example of daunorubicin (DNR), chemotherapy with its characteristic red fluorescence used to trace it in cellular compartments. Here we addressed the question whether image analysis of DNR fluorescence can reflect its real intracellular distribution. We observed that the relationship between the intensity of the DNR fluorescence and its concentration in water solutions with or without proteins is far from linear. In contrast, nucleic acids, RNA and DNA in particular, dramatically diminish the DNR fluorescence, however, the intensity was proportional to the amount. Therefore, image analysis reflects the composition of different cell compartments (i.e., the presence of proteins and nucleic acids) rather than the actual concentration of DNR in these compartments. In line with these results, we observed highly fluorescent lysosomes and low fluorescent nucleus in sensitive cancer cells treated with low DNR concentrations, a fluorescence pattern thought to be found only in resistant cancer cells. Importantly, LC/MS/MS analysis of extracts from sensitive cells treated with DNR or DNR in combination with an inhibitor of vacuolar ATPase, concanamycin A, indicated that lysosomal accumulation of DNR increased with increasing extracellular concentration. However, even the highest lysosomal accumulation of DNR failed to reduce its extralysosomal concentration and thus change the cell sensitivity to the drug. In conclusion, our results strongly suggest that DNR fluorescence within cells does not indicate the real drug distribution. Further they suggested that lysosomal sequestration of DNR can hardly contribute to its resistance in cancer cells in vitro.

N-acetylcysteine dual and antagonistic effect on cadmium cytotoxicity in human leukemia cells.

Although cadmium (Cd2+) is unable to form reactive oxygen species (ROS) directly, many of its adverse effects are connected to increased ROS generation resulting in cell death. In support of this supposition, a large number of studies have shown protective effects of antioxidants such as N-acetylcysteine (NAC) against cadmium induced cytotoxicity. Here, we describe the cytotoxic effects of Cd2+ on human leukemia U937 and K562 cells that were not mediated by oxidative stress. Surprisingly, we observed that addition of low concentrations of NAC can drastically potentiate cadmium cytotoxicity solely via ROS production. However, all adverse effects of the metal were prevented by NAC at high concentrations. Detailed analysis indicated that the protective effect of NAC was mediated by its ability to form stable complex with cadmium [Cd(NAC)2]. In conclusion, NAC exhibits dual and antagonistic effects on Cd2+ cytotoxicity in human leukemia cells.

Mifepristone potentiates etoposide toxicity in Hep G2 cells by modulating drug transport.

Etoposide is a well-known and widely used anticancer drug that displays several side effects. In addition, tumors often acquire resistance to this drug. Our aim is to develop a combination therapy that would augment toxicity of etoposide in malignant cells. Based on literature and our experiments, we selected mifepristone (RU486) as a potential supporting molecule that is able to enhance etoposide toxicity against cancer cells. All experiments were performed with Hep G2 cells, a well-known and described human hepatocellular carcinoma cell line. By using xCELLigence system, we demonstrated that mifepristone enhances toxicity of etoposide in a dose dependent manner with concomitant caspase-3 activity. We evaluated upregulation of Bax because mifepristone was demonstrated to modulate proapoptotic Bax protein expression. Our data show only weak and not statistically significant increase of Bax expression. On the other hand, we show that mifepristone increases etoposide toxicity via inhibition of ABC transporters, coupled with significant increase of intracellular etoposide concentration. In conclusion, we demonstrate that mifepristone has a synergistic effect with etoposide treatment in the Hep G2 cells and that the effect is related to ABC transporters inhibition.

Acute toxic effects of telmisartan in spontaneously hypertensive rats fed a high fructose diet.

Telmisartan is an angiotensin receptor blocker (ARB) and a selective peroxisome proliferator activated receptor gamma (PPARG) modulator. Recently, we tested metabolic effects of telmisartan (5 mg/kg body weight) in spontaneously hypertensive rats (SHR) fed a diet containing 60 % fructose, a widely used model of the metabolic syndrome. Surprisingly, we observed acute toxic effects of telmisartan. Rats lost body weight rapidly and died within 2 to 3 weeks due to bleeding into the upper gastrointestinal tract. SHR fed a high fructose diet and treated with telmisartan exhibited rapid decrease in blood pressure when compared to the SHR fed a high fructose diet and treated with valsartan. Concentrations of both unconjugated telmisartan and telmisartan glucuronide in the liver of SHR rats fed a high fructose diet were approximately 4 fold higher when compared to Brown Norway (BN) rats fed the same diet. Plasma concentrations of unconjugated telmisartan in the SHR were about 5 fold higher when compared to BN rats while plasma levels of telmisartan glucuronide were similar between the strains. Testing of other rat strains, diets, and the ARB valsartan showed that toxic effects of telmisartan in combination with high fructose diet are specific for the SHR. These results are consistent with the possibility that in some circumstances, SHR are predisposed to telmisartan toxicity possibly because of a genetically determined disturbance in telmisartan metabolism.

Dissecting the role of Folr1 and Folh1 genes in the pathogenesis of metabolic syndrome in spontaneously hypertensive rats.

Increased levels of plasma cysteine predispose to obesity and metabolic disturbances. Our recent genetic analyses in spontaneously hypertensive rats (SHR) revealed mutated Folr1 (folate receptor 1) on chromosome 1 as a quantitative trait gene associated with reduced folate levels, hypercysteinemia and metabolic disturbances. The Folr1 gene is closely linked to the Folh1 (folate hydrolase 1) gene which codes for an enzyme involved in the hydrolysis of dietary polyglutamyl folates in the intestine. In the current study, we obtained evidence that Folh1 mRNA of the BN (Brown Norway) origin is weakly but significantly expressed in the small intestine. Next we analyzed the effects of the Folh1 alleles on folate and sulfur amino acid levels and consecutively on glucose and lipid metabolism using SHR-1 congenic sublines harboring either Folr1 BN and Folh1 SHR alleles or Folr1 SHR and Folh1 BN alleles. Both congenic sublines when compared to SHR controls, exhibited significantly reduced folate clearance and lower plasma cysteine and homocysteine levels which was associated with significantly decreased serum glucose and insulin concentrations and reduced adiposity. These results strongly suggest that, in addition to Folr1, the Folh1 gene also plays an important role in folate and sulfur amino acid levels and affects glucose and lipid metabolism in the rat.

Genetically determined folate deficiency is associated with abnormal hepatic folate profiles in the spontaneously hypertensive rat.

Increased levels of plasma cysteine are associated with obesity and metabolic disturbances. Our recent genetic analyses in spontaneously hypertensive rats (SHR) revealed a mutated Folr1 (folate receptor 1) as the quantitative trait gene associated with diminished renal Folr1 expression, lower plasma folate levels, hypercysteinemia, hyperhomocysteinemia and metabolic disturbances. To further analyse the effects of the Folr1 gene expression on folate metabolism, we used mass spectrometry to quantify folate profiles in the plasma and liver of an SHR-1 congenic strain, with wild type Folr1 allele on the SHR genetic background, and compared them with the SHR strain. In the plasma, concentration of 5-methyltetrahydrofolate (5mTHF) was significantly higher in SHR-1 congenic rats compared to SHR (60+/-6 vs. 42+/-2 nmol/l, P<0.01) and 5mTHF monoglutamate was the predominant form in both strains (>99 % of total folate). In the liver, SHR-1 congenic rats showed a significantly increased level of 5mTHF and decreased concentrations of dihydrofolate (DHF), tetrahydrofolate (THF) and formyl-THF when compared to the SHR strain. We also analysed the extent of folate glutamylation in the liver. Compared with the SHR strain, congenic wild-type Folr1 rats had significantly higher levels of 5mTHF monoglutamate. On the other hand, 5mTHF penta- and hexaglutamates were significantly higher in SHR when compared to SHR-1 rats. This inverse relationship of rat hepatic folate polyglutamate chain length and folate sufficiency was also true for other folate species. These results strongly indicate that the whole body homeostasis of folates is substantially impaired in SHR rats compared to the SHR-1 congenic strain and might be contributing to the associated metabolic disturbances observed in our previous studies.

The effect of zinc and/or vitamin E supplementation on biochemical parameters of selenium-overdosed rats.

The normotensive (Wistar) and spontaneously hypertensive (SHR) rats were examined to assess the response of the organism to selenium (Se) overdose. Moreover, the effect of zinc (Zn) and vitamin E, i.e. dietary components interacting in many biochemical processes with Se, on the Se uptake was evaluated. The control group was fed an untreated diet, and the diets of two other groups were overdosed with Se in the form of sodium selenite (9 mg/kg) and supplemented with Zn (13 mg/kg). Two experimental groups were fed a diet supplemented with Zn (13 mg/kg) and Se at an adequate level (0.009 mg/kg); a half of the animals was supplemented with vitamin E. The results showed significant differences in the Se contents between the rat strains in case of Se-overdosed groups, where in the liver and kidney tissue Se contents of SHR rats exceeded 3- and 7-fold the normotensive ones. The Se uptake was altered by the vitamin E; no effect of Zn was observed. Activities of antioxidant enzymes were determined in the animal tissues indicating different patterns according to rat strain, tissue analysed, and administered Se dose. Thus, Se overdose, for instance, via an incorrectly prepared dietary supplement, can result in serious imbalances of the biochemical status of the animals.

Mutant Wars2 gene in spontaneously hypertensive rats impairs brown adipose tissue function and predisposes to visceral obesity.

Brown adipose tissue (BAT) plays an important role in lipid and glucose metabolism in rodents and possibly also in humans. Identification of genes responsible for BAT function would shed light on underlying pathophysiological mechanisms of metabolic disturbances. Recent linkage analysis in the BXH/HXB recombinant inbred (RI) strains, derived from Brown Norway (BN) and spontaneously hypertensive rats (SHR), identified two closely linked quantitative trait loci (QTL) associated with glucose oxidation and glucose incorporation into BAT lipids in the vicinity of Wars2 (tryptophanyl tRNA synthetase 2 (mitochondrial)) gene on chromosome 2. The SHR harbors L53F WARS2 protein variant that was associated with reduced angiogenesis and Wars2 thus represents a prominent positional candidate gene. In the current study, we validated this candidate as a quantitative trait gene (QTG) using transgenic rescue experiment. SHR-Wars2 transgenic rats with wild type Wars2 gene when compared to SHR, showed more efficient mitochondrial proteosynthesis and increased mitochondrial respiration, which was associated with increased glucose oxidation and incorporation into BAT lipids, and with reduced weight of visceral fat. Correlation analyses in RI strains showed that increased activity of BAT was associated with amelioration of insulin resistance in muscle and white adipose tissue. In summary, these results demonstrate important role of Wars2 gene in regulating BAT function and consequently lipid and glucose metabolism.

Clinically relevant interactions of anti-apoptotic Bcl-2 protein inhibitors with ABC transporters.

In this work we studied clinically relevant interactions between the BH3 mimetics and the ABCB1 and ABCG2 transporters. We observed that the intracellular levels of ABT-263 and ABT-199, but not ABT-737, might be reduced by ABCB1 or ABCG2. Importantly, this effect was proportional to the transporter expression level. High transporter expression levels decreased the intracellular levels of ABT-263 and ABT-199 substantially. Low transporter expression levels, which are clinically relevant, affected the intracellular level of ABT-263 slightly but significantly, however, they failed to decrease the intracellular level of ABT-199 below the control level in parental cells. Our results further revealed that ABT-263 did not inhibit the ABCB1 mediated transport, however, it partially inhibited the ABCG2 mediated transport at clinically relevant concentrations. In contrast, ABT-199 inhibited partially the ABCB1 mediated transport and it fully inhibited the ABCG2 mediated transport at clinically relevant concentrations. Importantly, cells expressing higher drug transporters levels required higher concentrations of ABT-263 or ABT-199 to achieve certain inhibition of substrate efflux. CONCLUSIONS: Antiproliferative effects of ABT-263 and ABT-199 might be reduced by ABCB1 or ABCG2, however, this effect depends on transporter expression levels. Since the expression levels of ABCB1 and ABCG2 are rarely high in clinical samples, their contribution to the overall resistance to ABT-263 or ABT-199 is probably low. Inhibition study revealed that ABT-199, but not ABT-263, fully inhibited low expression level of ABCG2. Our data suggest that ABT-199 should be evaluated beyond its original application as an inhibitor of the ABCG2 transporter in clinical settings.

Effects of transgenic expression of dopamine beta hydroxylase (Dbh) gene on blood pressure in spontaneously hypertensive rats.

The spontaneously hypertensive rat (SHR) is the most widely used animal model of essential hypertension and left ventricular hypertrophy. Catecholamines play an important role in the pathogenesis of both essential hypertension in humans and in the SHR. Recently, we obtained evidence that the SHR harbors a variant in the gene for dopamine beta hydroxylase (Dbh) that is associated with reduced adrenal expression of Dbh mRNA and reduced DBH enzymatic activity which correlated negatively with blood pressure. In the current study, we used a transgenic experiment to test the hypothesis that reduced Dbh expression predisposes the SHR to hypertension and that augmentation of Dbh expression would reduce blood pressure. We derived 2 new transgenic SHR-Dbh lines expressing Dbh cDNA under control of the Brown Norway (BN) wild type promoter. We found modestly increased adrenal expression of Dbh in transgenic rats versus SHR non-transgenic controls that was associated with reduced adrenal levels of dopamine and increased plasma levels of norepinephrine and epinephrine. The observed changes in catecholamine metabolism were associated with increased blood pressure and left ventricular mass in both transgenic lines. We did not observe any consistent changes in brainstem levels of catecholamines or of mRNA levels of Dbh in the transgenic strains. Contrary to our initial expections, these findings are consistent with the possibility that genetically determined decreases in adrenal expression and activity of DBH do not represent primary determinants of increased blood pressure in the SHR model.

Hepatotoxic effects of fenofibrate in spontaneously hypertensive rats expressing human C-reactive protein.

Dyslipidemia and inflammation play an important role in the pathogenesis of cardiovascular and liver disease. Fenofibrate has a well-known efficacy to reduce cholesterol and triglycerides. Combination with statins can ameliorate hypolipidemic and anti-inflammatory effects of fibrates. In the current study, we tested the anti-inflammatory and metabolic effects of fenofibrate alone and in combination with rosuvastatin in a model of inflammation and metabolic syndrome, using spontaneously hypertensive rats expressing the human C-reactive protein transgene (SHR-CRP transgenic rats). SHR-CRP rats treated with fenofibrate alone (100 mg/kg body weight) or in combination with rosuvastatin (20 mg/kg body weight) vs. SHR-CRP untreated controls showed increased levels of proinflammatory marker IL6, increased concentrations of ALT, AST and ALP, increased oxidative stress in the liver and necrotic changes of the liver. In addition, SHR-CRP rats treated with fenofibrate, or with fenofibrate combined with rosuvastatin vs. untreated controls, exhibited increased serum triglycerides and reduced HDL cholesterol, as well as reduced hepatic triglyceride, cholesterol and glycogen concentrations. These findings suggest that in the presence of high levels of human CRP, fenofibrate can induce liver damage even in combination with rosuvastatin. Accordingly, these results caution against the possible hepatotoxic effects of fenofibrate in patients with high levels of CRP.

Gender-related effects on substrate utilization and metabolic adaptation in hairless spontaneously hypertensive rat.

Cold exposure of rats leads to ameliorated glucose and triglyceride utilization with females displaying better adaptation to a cold environment. In the current study, we used hairless rats as a model of increased thermogenesis and analyzed gender-related effects on parameters of lipid and glucose metabolism in the spontaneously hypertensive (SHR) rats. Specifically, we compared hairless coisogenic SHR-Dsg4 males and females harboring mutant Dsg4 (desmoglein 4) gene versus their SHR wild type controls. Two way ANOVA showed significant Dsg4 genotype (hairless or wild type) x gender interaction effects on palmitate oxidation in brown adipose tissue (BAT), glucose incorporation into BAT determined by microPET, and glucose oxidation in skeletal muscles. In addition, we observed significant interaction effects on sensitivity of muscle tissue to insulin action when Dsg4 genotype affected these metabolic traits in males, but had little or no effects in females. Both wild type and hairless females and hairless males showed increased glucose incorporation and palmitate oxidation in BAT and higher tissue insulin sensitivity when compared to wild type males. These findings provide evidence for gender-related differences in metabolic adaptation required for increased thermogenesis. They are consistent with the hypothesis that increased glucose and palmitate utilization in BAT and muscle is associated with higher sensitivity of adipose and muscle tissues to insulin action.

Rosuvastatin ameliorates inflammation, renal fat accumulation, and kidney injury in transgenic spontaneously hypertensive rats expressing human C-reactive protein.

Recently, we derived "humanized" spontaneously hypertensive rats (SHR-CRP) in which transgenic expression of human CRP induces inflammation, oxidative stress, several features of metabolic syndrome and target organ injury. In addition, we found that rosuvastatin treatment of SHR-CRP transgenic rats can protect against pro-inflammatory effects of human CRP and also reduce cardiac inflammation and oxidative damage. In the current study, we tested the effects of rosuvastatin (5 mg/kg) on kidney injury in SHR-CRP males versus untreated SHR-CRP and SHR controls. All rats were fed a high sucrose diet. In SHR-CRP transgenic rats, treatment with rosuvastatin for 10 weeks, compared to untreated transgenic rats and SHR controls, was associated with significantly reduced systemic inflammation which was accompanied with activation of antioxidative enzymes in the kidney, lower renal fat accumulation, and with amelioration of histopathological changes in the kidney. These findings provide evidence that, in the presence of high CRP levels, rosuvastatin exhibits significant anti-inflammatory, anti-oxidative, and renoprotective effects.

Sterol regulatory element binding protein 2 overexpression is associated with reduced adipogenesis and ectopic fat accumulation in transgenic spontaneously hypertensive rats.

It has been reported that the major function of the sterol regulatory element binding protein 2 (SREBP-2) is to activate preferentially cholesterol biosynthesis in liver and adipose tissue rather than fatty acid synthesis. In the current study, we analyzed the effects of overexpression of human dominant-positive SREBP-2 transgene under control of PEPCK promoter in the spontaneously hypertensive rat (SHR) on lipid and glucose metabolism. Transgenic overexpression of SREBP-2 was associated with significantly higher hepatic triglycerides (20.4+/-0.9 vs. 17.0+/-0.05 micromol/g, P<0.05) but not cholesterol (10.6+/-0.4 vs. 10.9+/-0.4 micromol/g) and decreased relative weight of epididymal fat pad (0.73+/-0.03 vs. 0.83+/-0.03, P<0.05). In addition, muscle triglyceride (15.8+/-3.7 vs. 8.5+/-1.2 micromol/g, P<0.001) and cholesterol (3.6+/-0.5 vs. 2.1+/-0.1 micromol/g, P<0.05) concentrations were significantly increased in transgenic rats when compared to SHR controls. Ectopic fat accumulation was associated with significantly increased serum glucose levels (6.4+/-0.1 vs. 5.9+/-0.1 mmol/l, P<0.005) and reduced insulin levels (1.78+/-0.33 vs. 2.73+/-0.37 nmol/l, P<0.05) in transgenic rats. These results provide evidence for important role of SREBP-2 in regulation of lipid and glucose metabolism.