Nagase Analbuminemic Rats Research Articles

Investigating the Impact of Albumin on the Liver Uptake of Pitavastatin and Warfarin in Nagase Analbuminemic Rats.

Albumin has been suggested to enhance the hepatic uptake of organic anion-transporting polypeptide (Oatp) substrates in various in vitro as well as liver perfusion models. However, it is not known whether the interplay between albumin and Oatp substrates is an experimental artifact or if this interaction occurs in vivo. The objective of this work was to investigate the hepatic uptake of warfarin and pitavastatin, which are both extensively bound to albumin but only pitavastatin being an Oatp substrate. Experiments were conducted in Nagase analbuminemic rats (NAR) which exhibit reduced albumin levels compared with F344 (wild type, WT). The fraction unbound (f u) was 140- and 10-fold greater in NAR plasma for warfarin and pitavastatin, respectively, whereas no meaningful differences were observed with tissue binding. In vitro, pitavastatin uptake into hepatocytes reconstituted in WT plasma was 17- and 3-fold greater than when reconstituted in buffer or NAR plasma, respectively. In vivo, the free tissue-to-free plasma ratios (K p,u,u) from brain and liver in intact WT and NAR were not significantly different for warfarin. Contrarily, liver K p,u,u of pitavastatin was 6-fold higher in WT animals, which corresponded to a 2.3-fold reduction in free plasma and 2.6-fold increase in free liver exposure. These results suggest that the enhanced hepatic uptake by albumin is not necessarily an experimental artifact but is also a relevant phenomenon in vivo. This work raises the possibility that other plasma proteins may also effect the function of additional drug transporters, and that modulating plasma protein binding may exhibit meaningful clinical relevance in the disposition of drugs. SIGNIFICANCE STATEMENT: The interplay between albumin and Oatp substrates has been reported in hepatocytes and in liver perfusion studies, but the in vivo relevance of this interaction has yet to be elucidated. Using NAR and its corresponding WT animal, this study demonstrates that albumin may indeed enhance the hepatic uptake of pitavastatin in intact animals. In vivo demonstration of this interplay not only provides further justification for continued investigation into this particular mechanism but also raises the possibility that other plasma proteins may affect additional drug transporters and that modulating plasma protein binding may exhibit meaningful clinical relevance in the disposition of drugs.

The impact of plasma protein binding on the tissue distribution of warfarin - investigation in nagase analbuminemic rats (NAR)

The impact of plasma protein binding on the tissue distribution of warfarin - investigation in nagase analbuminemic rats (NAR)

注意欠陥/多動性障害(AD/HD)動物モデルとしての無アルブミンラットに関する検討

注意欠陥/多動性障害(AD/HD)動物モデルとしての無アルブミンラットに関する検討

The Protective Effect of Transplanting Liver Cells Into the Mesentery on the Rescue of Acute Liver Failure After Massive Hepatectomy.

Postoperative liver failure is one of the most critical complications following extensive hepatectomy. Although transplantation of allogeneic hepatocytes is an attractive therapy for posthepatectomy liver failure, transplanting cells via the portal veins typically causes portal vein embolization. The embolization by transplanted cells would be lethal in patients who have undergone massive hepatectomy. Thus, transplant surgeons need to select extrahepatic sites as transplant sites to prevent portal vein embolization. We aimed to investigate the mechanism of how liver cells transplanted into the mesentery protect recipient rats from acute liver failure after massive hepatectomy. We induced posthepatectomy liver failure by 90% hepatectomy in rats. Liver cells harvested from rat livers were transplanted into the mesenteries of hepatectomized rats. Twenty percent of the harvested cells, which consisted of hepatocytes and nonparenchymal cells, were transplanted into each recipient. The survival rate improved significantly in the liver cell transplantation group compared to the control group 7 days after hepatectomy (69 vs. 7%). Histological findings of the transplantation site, in vivo imaging system study findings, quantitative polymerase chain reaction assays of the transplanted cells, and serum albumin measurements of transplanted Nagase analbuminemic rats showed rapid deterioration of viable transplanted cells. Although viable transplanted cells deteriorated in the transplanted site, histological findings and an adenosine-5'-triphosphate (ATP) assay showed that the transplanted cells had a protective effect on the remaining livers. These results indicated that the paracrine effects of transplanted liver cells had therapeutic effects. The same protective effects were observed in the hepatocyte transplantation group, but not in the liver nonparenchymal cell transplantation group. Therefore, this effect on the remnant liver was mainly due to the hepatocytes among the transplanted liver cells. We demonstrated that transplanted liver cells protect the remnant liver from severe damage after massive hepatectomy.

A Novel Approach to Ultrasound-Mediated Tissue Decellularization and Intra-Hepatic Cell Delivery in Rats

Liver transplantation is the mainstay of treatment for end stage liver diseases, including metabolic and congenital liver diseases. The number of suitable donor organs is, however, limited, and a whole-liver transplant requires complex surgery. Cell therapy, such as intra-portal hepatocytes transplantation, has been considered as a bridging therapy to liver transplantation but has shown a mixed clinical outcome with limited success, including low level of engraftment of transplanted hepatocytes. Here, we report a novel cell delivery technique in a rat model by creating a cavity inside the liver parenchyma by non-invasive high intensity focused ultrasound histotripsy. Our in vivo experimental results together with histologic observations show that direct injection of cells inside the cavity can facilitate successful uptake, proliferation and integration of the transplanted hepatocytes in the recipient liver. We were able to restore the plasma albumin level to 50% of the normal level in Nagase analbuminemic rats (serum albumin level of the Nagase rats was initially nil) by cell therapy after high intensity focused ultrasound–mediated histotripsy. We believe that this novel technique would enable the delivery of a large number of cells into the liver to restore liver function, particularly as a treatment for metabolic liver diseases. This novel method of intra-hepatic hepatocyte transplantation might be an invaluable tool for cell therapy in the future.

Fetal liver cell-containing hybrid organoids improve cell viability and albumin production upon transplantation

Cell transplantation is a potential alternative for orthotopic liver transplantation because of the chronic donor shortage. Functional liver tissue is needed for cell transplantations. However, large functional liver tissue is difficult to construct because of the high oxygen consumption of hepatocytes. In our previous study, we developed a novel method to generate hybrid organoids. In this study, we used fetal liver cells (FLCs) to construct a hybrid organoid. Nucleus numbers, angiogenesis, and albumin production were measured in transplanted samples. Higher cell viability and larger liver tissue was found in FLC-containing samples than in hepatocyte-containing samples. Furthermore, the therapeutic efficiency of FLC-containing samples was evaluated by transplantation into Nagase analbuminemia rats. As a result, an increase in albumin concentration was found in rat blood. In summary, transplantation of a FLC-containing hybrid organoid is a potential approach for cell transplantation.

Pharmacokinetics and pharmacodynamics of mycophenolic acid in Nagase analbuminemic rats: Evaluation of protein binding effects using the modeling and simulation approach

This study aimed to examine the pharmacokinetics and pharmacodynamics of mycophenolic acid (MPA) in Nagase analbuminemic rats (NARs) to evaluate the effect of protein binding on the associated inosine-5ʹ-monophosphate dehydrogenase (IMPDH) activity. Free fractions of MPA in the control rats and NARs were 2.09 and 24.8%, respectively. Pharmacokinetic and pharmacodynamic parameters simultaneously obtained by the nonlinear mixed effects modeling program NONMEM explained reasonably well the concentrations of MPA and MPA glucuronide as well as IMPDH activity in both rats. NARs showed a higher clearance and a smaller volume of distribution based on the free MPA concentration than the controls did, besides the increase in free fraction. The half-maximal inhibitory concentration based on free MPA was estimated as 163 ng/mL for both rats. Simulations based on the obtained pharmacokinetic and pharmacodynamic parameters showed that the area under the IMPDH activity-time curve decreased non-linearly according to the increase in free fraction of MPA. In conclusion, the experimental data obtained from NARs followed by the modeling and simulation approach quantitatively clarified that the free MPA concentration was suitable for the biomarker of immunosuppressive effect of MPA. Dose adjustments based on the total MPA may cause unnecessary overexposure to MPA in patients with hypoalbuminemia.

Examination of behavioral validity of Nagase analbuminemic rats as an animal model of ADHD

Examination of behavioral validity of Nagase analbuminemic rats as an animal model of ADHD

Effects of edaravone, a radical scavenger, on hepatocyte transplantation.

Hepatocyte transplantation (HTx) has yielded significant improvements in liver function and survival in experimentally induced acute liver failure and liver-based metabolic disease. However, transplantation is inefficient, and it is thought that transplanted hepatocytes have a shortened lifespan because of inflammation involving excess nitric oxide (NO). The present study aimed to clarify whether edaravone, a free radical scavenger used to treat ischemic stroke, could reduce ischemic changes in hepatocyte-transplanted livers. Edaravone (3 mg/kg) was administered intravenously 24 h before HTx to Nagase analbuminemic rats (NARs). Hepatocytes were isolated, and 30 × 10(6) cells were injected in a 1.0-ml volume directly into the spleens of NARs. All experimental groups studied received FK506 to control rejection. Animals in Group A received medium-only; Group B received HTx only; and Group C received HTx and edaravone. Forty-eight hours after transplantation, the hepatocytes from animals were isolated and analyzed for staining with propidium iodide- and annexin-V using flow cytometry. Liver sections were also studied by immunostaining for albumin, and TUNEL. Peripheral blood serum albumin levels were measured on post-transplant days 0, 3, 5, 7, 10 and 14 using ELISA. The edaravone-treated animals demonstrated an increased number of engrafted donor hepatocytes in the liver. The edaravone-treated liver sections also contained fewer TUNEL-positive cells and animals that received edaravone had higher serum albumin levels post-transplantation. Hepatocytes were also found to have increased in numbers 2 weeks following treatment with edaravone. Edaravone administration during HTx can suppress apoptosis near the transplanted cells, increasing engraftment. These studies indicate its potential usefulness for future clinical application.

Pharmacokinetics of drugs in mutant Nagase analbuminemic rats and responses to select diuretics

To report (1) the pharmacokinetics of drugs that are mainly metabolized via hepatic cytochrome P450s (CYPs) or mainly excreted via the urine and bile, (2) the mechanism for the urinary excretion of drugs (such as glomerular filtration or renal active secretion or re-absorption), and (3) the diuretic effect of some loop diuretics in mutant Nagase analbuminaemic rats (NARs), an animal model for human familial analbuminaemia based on the pharmacokinetics of drugs reported in the literatures. In NARs, the changes in the time-averaged non-renal clearances (CL(NR)s) of drugs that are mainly metabolized via CYPs were explained in terms of changes in the hepatic intrinsic clearance (mainly because of changes in CYPs), free (unbound) fractions of drugs in the plasma (fp) and hepatic blood-flow rate (QH) depending on the hepatic excretion ratios of drugs. The CL(NR) changes of drugs mainly metabolized via hepatic CYPs can be sufficiently explained by the three earlier mentioned factors. The plasma albumin (furosemide) or globulin (azosemide, bumetanide and torasemide) binding affects their diuretic effects.

Effect of albumin on transthyretin and amyloidogenic transthyretin Val30Met disposition and tissue deposition in familial amyloidotic polyneuropathy

AimsTransthyretin (TTR)-related familial amyloidotic polyneuropathy (FAP) is characterized by the systemic accumulation of amyloid fibrils caused by amyloidogenic. Our previous studies demonstrated that albumin played a role in the inhibition of TTR amyloid-formation. The aim of this study was to evaluate the effect of albumin on TTR disposition and tissue deposition in vivo. Main methodsFor pharmacokinetic studies, recombinant wild-type TTR (rTTR) and recombinant amyloidogenic TTR Val30Met (rATTR V30M) were labeled with iodine and administered to Sprague–Dawley rats and analbuminemia rats (NAR: Nagase Analbuminemia Rats). The deposition of ATTR V30M was also analyzed by immunohistochemistry in the transgenic (Tg) rats possessing a human ATTR V30M gene (ATTR V30M Tg rats) and NAR possessing a human ATTR V30M gene (ATTR V30M Tg NAR). Key findingsThe presence of albumin had no effect on the tissue distribution of either rTTR or rATTR V30M. However, more ATTR V30M was deposited in the hearts, stomachs and small intestines of ATTR V30M Tg NAR rats, compared to ATTR V30M Tg rats. SignificanceAlthough the disposition of TTR and ATTR V30M was unaffected by the presence of albumin, the deposition of ATTR V30M in some organs was apparently increased in the absence of albumin compared to the presence of albumin. These results show that albumin would contribute to suppressing the tissue deposition of TTR in pathogenesis of FAP, but does not affect the disposition of TTR.

Proteinuria decreases tissue lipoprotein receptor levels resulting in altered lipoprotein structure and increasing lipid levels

Rats with nephrotic syndrome (NS) have a fivefold increase in lipids and a similar decrease in triglyceride-rich lipoprotein (TRL) clearance. Lipoprotein lipase (LPL) is reduced both in NS and in the Nagase analbuminemic rat. These rats have nearly normal triglyceride levels and TRL clearance, suggesting that reduction in LPL alone is insufficient to cause increased TRL levels. Apolipoprotein E (apoE) was decreased in lipoprotein fractions in NS, but not in analbuminemia. Here we tested whether decreased apoE binding to lipoproteins in NS contributes to hyperlipidemia by decreasing their affinity for lipoprotein receptors. Plasma apoE was increased 60% in both NS and analbuminemia compared with control (CTRL) as a result of a 60% decreased apoE clearance. Very-low-density lipoprotein and high-density lipoprotein in NS had significantly less apoE per mole of phospholipid compared with analbuminemia or CTRL and significantly greater lipid content; however, apoE binding did not differ by lipoprotein class or group. There was a significant reduction of receptors for lipoproteins in nearly all tissues in NS compared with CTRL and analbuminemia. Thus, apoE within lipoprotein fractions was reduced by dilution resulting from expansion of the lipid fraction due to decreased lipolysis and not to differing affinity for apoE. Decreased lipoprotein receptors result from proteinuria and contribute to hyperlipidemia in NS.

Abstract 135: Alubuminuria Causes Disorder of Cytochrome P450 Metabolism of Arachidonic Acid in the Kidney of Nephrotic Rats

Alubuminuria is an aggravating factor for chronic kidney disease. Fatty acids bound to albumin are overloaded to the proximal tubules in alubuminuria and contribute to tubulointerstitial damage. It is known not only the β-oxidation ability but the ability of cytochrome P450 (CYP) metabolism of arachidonic acid (AA) is high in the kidney. Epoxyeicosatrienoic acids synthesized primarily by CYP2C and 20-hydroxyeicosatetraenoic acid synthesized by CYP4A affect tubular function and renal circulation. However, it isn’t clear CYP metabolism of AA would change in alubuminuria. The study tested changes of CYP metabolism of AA in the kidney of nephrotic rats. Sprague-Dawley rat (SD) and Nagase Analbuminemic rat (NAR) with inherited hypoalbuminemia were used and nephrotic syndrome was induced by Puromycin Aminonucleoside (PAN; 100 mg/kg, iv). Rats were randomly divided into four groups; (1) SD group; (2) SD treated with PAN group (PAN group); (3) NAR group; (4)NAR treated with PAN group (NAR+PAN group). Rats were killed on the 14th day and urinary 8OHdG, a marker of oxidative stress in the kidney, and urinary NAG, a marker of proximal tubular cell damage, were measured. The protein level of enzymes in the kidney was analyzed by Western blot and immunohistochemistry. Compared with the SD group, albuminuria, 8OHdG and NAG increased respectively to 847%, 154% and 903% in the PAN group, and Western blot showed the protein levels of CYP2C23 and CYP4A decreased to 45% and 49% without change of the protein level of PPARα, a nuclear receptor regulating fatty acid metabolism, in the PAN group. Immunohistochemistry showed the localization of CYP2C23 and CYP4A in the proximal tubule and confirmed the results by Western blot. Otherwise, we could find no difference in albuminuria, tubulointerstitial damage and the protein level of CYP2C23 between the NAR group and the NAR+PAN group. Compared with the NAR group, the protein level of CYP4A decreased to 68% in the NAR+PAN group. Alubuminuria caused tubulointerstitial damage and decreased the expressions of CYP2C23 and CYP4A in the nephrotic kidney. This study suggested the disorder of CYP metabolism of AA would affect renal circulation in alubuminuria and CYP4A would be affected by anything except alubuminuria in PAN rats.

Nitric oxide-dependent bradycardia in mutant analbuminemic rats

Nagase analbuminemic rats (NAR) are natural mutant Sprague-Dawley rats which do not express albumin due to a single splice mutation in the albumin gene. We accidentally discovered that NAR have a significant bradycardia compared with wild type Sprague-Dawley rats, and the present study was carried out to investigate the mechanism of bradycardia in analbuminemic rats. In vitro studies showed that the basal spontaneous beating rate of isolated atria is similar in NAR compared with wild type animals. However, the chronotropic responsiveness of isolated atria to cholinergic stimulation was markedly increased in NAR, an effect which was prevented by incubation with a nitric oxide synthase (NOS) or guanylyl cyclase inhibitor. NAR had a significant increase in plasma nitrite/nitrate concentrations. Administration of a NOS inhibitor for 5 days normalized heart rate in NAR. The level of NOS isoforms, caveolin-1 and caveolin-3 expression in the atria was assessed by real time PCR. There was no significant difference in the expression of NOS isoforms or caveolin-3 in NAR compared with wild type controls. However, NAR exhibited a significant decrease in caveolin-1 expression in the atria. Since caveolin-1 is known to inhibit endothelial NOS activity in cardiomyocytes, we suggest that decreased caveolin-1 levels may have a role in increased nitric oxide production in NAR. Our data suggest that a NOS/cGMP-dependent mechanism might be involved in increased responsiveness to vagal stimulation and bradycardia in analbuminemic condition.

Disorder of fatty acid metabolism in the kidney of PAN-induced nephrotic rats

Proteinuria is considered to play an essential role in the progression of tubulointerstitial damage, which causes end-stage renal disease. Fatty acid-binding albumins are filtered through glomeruli and reabsorbed into proximal tubular epithelial cells (PTECs). However, the role of fatty acid metabolism associated with albuminuria in the development of tubulointerstitial damage remains unclear. Thus, the present study was designed to determine the changes of fatty acid metabolism in the nephrotic kidney. To induce nephrotic syndrome, Sprague-Dawley rats (SDRs) and Nagase analbuminemic rats (NARs) with inherited hypoalbuminemia were treated with a single injection of puromycin aminonucleoside (PAN). In SDRs, PAN treatment induced massive proteinuria and albuminuria and caused tubular damage, apoptosis, and lipid accumulation in PTECs. Among the enzymes of fatty acid metabolism, expressions of medium-chain acyl-CoA dehydrogenase (MCAD) and cytochrome P-450 (CYP)4A significantly decreased in PTECs of PAN-treated SDRs. Expressions of peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α and estrogen-related receptor (ERR)α also significantly decreased, without changes in the expression of PPAR-α. In NARs, PAN treatment induced proteinuria but not albuminuria and did not cause tubular damage, apoptosis, or lipid accumulation. Expressions of MCAD, PGC-1α, or ERRα did not change in the kidney cortex of PAN-treated NARs, but the expression of CYP4A significantly decreased. These results indicate that massive albuminuria causes tubular damage and lipid accumulation with the reduction of MCAD, CYP4A, PGC-1α, and ERRα in PTECs.

OC-068 Albumin is central in mediating the cardio-renal dysfunction of cirrhosis: a study in analbuminaemic rats

IntroductionAlbumin is a multifunctional protein which is reduced in concentration and function in liver disease. Albumin infusion prevents and improves renal dysfunction in patients with advanced liver failure but the...

577 ALBUMIN IS CENTRAL IN MEDIATING THE CARDIO-RENAL DYSFUNCTION OF CIRRHOSIS: A STUDY IN ANALBUMINAEMIC RATS

Introduction Albumin is a multifunctional protein which is reduced in concentration and function in liver disease. Albumin infusion prevents and improves renal dysfunction in patients with advanced liver failure but the mechanisms of its beneficial properties are unclear. We hypothesised that albumin is central in the maintenance of cardio-renal function in cirrhosis and albumin impairment worsens outcome. In order to answer this question we investigated analbuminaemic rats, characterised by lack of albumin but with normal protein concentration, following induction of cirrhosis with bile duct ligation (BDL). Methods Male Sprague-Dawley (SD) and Nagase analbuminaemic (NAR) rats were studied 6 weeks after BDL or sham surgery (n=6 sham-SD, 8 sham-NAR, 7 SD-BDL, 7 NAR-BDL). Rats underwent systemic mean arterial pressure (MAP) and portal pressure (PP) assessment under terminal anaesthesia. Plasma and urine were collected for measurements of renal function and protein profile. Plasma renin activity (PRA) was measured as a marker of cardio-renal dysfunction. Urinary neopterin, a marker of macrophage activation was assessed. Results NARs showed plasma total protein concentration similar to SD despite lack of albumin before (72±15 vs 82±8) and after BDL (67±7 vs 75±22). After BDL both groups of animals showed histological evidence of severe liver damage, though the NARs showed a significantly worse systemic haemodynamics with lower MAP (p=0.01), evidence of renal dysfunction indicated by higher plasma creatinine and higher PRA (p Conclusion A lack of albumin was associated with a raised PRA and a marked deterioration in systemic haemodynamics and renal function after liver injury (BDL), despite normal total plasma protein concentration. This worsened outcome in the absence of albumin strongly supports the central role of albumin in maintenance of cardio-renal function in liver failure and may indicate that albumin plays a crucial role in moderating inflammation. Competing interests None declared.

Essential Role of Excessive Tryptophan and its Neurometabolites in Fatigue

Serotonin, a neurotransmitter synthesized from tryptophan, has been proposed to play a key role in central fatigue. In this study, we examined whether tryptophan itself and/or its two metabolites, kyneurenic acid (KYNA) and quinolinic acid (QUIN), are involved in central fatigue. Experiments were conducted using Sprague-Dawley rats (SDR) and Nagase analbuminemic rats (NAR). Central fatigue was assessed by treadmill running and a Morris water maze test. Microdialysis was used to collect samples for measurement of extracellular concentration of tryptophan, serotonin and 5-hydroxyindoleacetic acid (5-HIAA) and to infuse test agents. To examine the kinetics of release, synaptosomes in the striatum were prepared in vitro to measure intra- and extrasynaptosomal concentration of tryptophan, serotonin and 5-HIAA. The concentration of tryptophan secreted into the extracellular space of the striatum was higher during fatigue only, and quickly returned to basal levels with recovery from fatigue. Running time to exhaustion was reduced by activation of tryptophan receptors. Time to exhaustion was shorter in NAR, which maintain a higher extracellular level of striatum tryptophan than SDR. Impaired memory performance in a water maze task after tryptophan treatment was attributable to high levels of KYNA and QUIN in the hippocampus acting synergistically on N-methyl-D-aspartic acid receptors. When branched-chain amino acids were administered, tryptophan transport to the extracellular space of the striatum was drastically inhibited. Our findings demonstrate that the increase in fatigue which occurs because of excessively elevated brain tryptophan can be further amplified by the use of synthetic KYNA and QUIN.

Decreased apoE within lipoprotein classes in the nephrotic syndrome is due to diluted apoE pool

Hyperlipidemia in nephrotic syndrome (NS) results from decreased clearance of triglyceride rich lipoproteins (TGLs). VLDL and HDL from NS rats have reduced apolipoprotein E (apoE) content despite increased plasma apoE levels. Lipoprotein lipase (LpL) is decreased in both NS and the Nagase Analbuminemic Rat (NAR). However, NAR have nearly normal lipid levels and TGLs clearance. ApoE, a ligand for the VLDL receptor, is depleted from NS VLDL rats, while normal or increased in NAR VLDL suggesting that the difference in VLDL apoE contributes to defective clearance. It is unknown whether decreased apoE was a consequence of decreased binding to VLDL. Plasma apoE was measured by ELISA. Apo E clearance was measured 7 Control, 7 NS and 9 NAR male rats using 125I labeled apoE. Apo E affinity was measured in 6 Control and 5 NS rats using spin labeled E4 binding with electron spin resonance and nonlinear regression. Apo E levels were significantly greater in plasma NS than in NAR and greater in both than in Control. However, VLDL and HDL from NS had significantly less apoE per mole of PL than those isolated from NAR or Control. ApoE clearance was significantly lower in NS than in NAR and Control, entirely accounting for the increased plasma levels of apoE. Binding of apoE did not differ by lipoprotein class or by group. Decreased apoE within lipoprotein classes in the nephrotic syndrome is due to diluted apoE pool. (Supported by the Department of Veteran's Affairs)

Albumin expression is required for adipocyte differentiation of 3T3-L1 cells

We have previously demonstrated that albumin is directly involved in the formation of cytoplasmic lipid droplets in pancreatic stellate cells and may act as a downstream effector of adipogenic transcription factors, PPAR-γ and C/EBP-α. Here, we investigated the role of albumin in adipocyte differentiation using 3T3-L1 cells. Albumin expression was significantly increased at later stages of adipocyte differentiation, which was accompanied with increased C/EBP-β binding to albumin promoter. Suppression of albumin expression using short-hairpin RNA (shRNA) during differentiation led to a considerable reduction in lipid droplet formation, whereas albumin overexpression was stimulatory. Furthermore, point mutation in its fatty acid-binding sites inhibited lipid droplet formation. Consistent with these in vitro finding, Nagase analbuminemic rats displayed reduced fat accumulation. Therefore, our findings suggest that albumin may play a distinct role in adipocyte differentiation by promoting lipid accumulation.