Visualized macrophage dynamics and significance of S100A8 in obese fat.

Chronic low-grade inflammation of adipose tissue plays a crucial role in the pathophysiology of obesity. Immunohistological microscopic analysis in obese fat tissue has demonstrated the infiltration of several immune cells such as macrophages, but dynamics of immune cells have not been fully elucidated and clarified. Here, by using intravital multiphoton imaging technique, to our knowledge for the first time, we analyzed and visualized the inflammatory processes in adipose tissue under high-fat and high-sucrose (HF/HS) diet with lysozyme M-EGFP transgenic (LysM(EGFP)) mice whose EGFP was specifically expressed in the myelomonocytic lineage. Mobility of LysM(EGFP)-positive macrophages was shown to be activated just 5 d after HF/HS diet, when the distinct hypertrophy of adipocytes and the accumulation of macrophages still have not become prominent. Significant increase of S100A8 was detected in mature adipocyte fraction just 5 d after HF/HS diet. Recombinant S100A8 protein stimulated chemotactic migration in vitro and in vivo, as well as induced proinflammatory molecules, both macrophages and adipocytes, such as TNF-α and chemokine (C-C motif) ligand 2. Finally, an antibody against S100A8 efficiently suppressed the HF/HS diet-induced initial inflammatory change, i.e., increased mobilization of adipose LysM(EGFP)-positive macrophages, and ameliorated HF/HS diet-induced insulin resistance. In conclusion, time-lapse intravital multiphoton imaging of adipose tissues identified the very early event exhibiting increased mobility of macrophages, which may be triggered by increased expression of adipose S100A8 and results in progression of chronic inflammation in situ.

Pioglitazone suppresses neuronal and muscular degeneration caused by polyglutamine-expanded androgen receptors.

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by the expansion of a CAG repeat in the androgen receptor (AR) gene. Mutant AR has been postulated to alter the expression of genes important for mitochondrial function and induce mitochondrial dysfunction. Here, we show that the expression levels of peroxisome proliferator-activated receptor-γ (PPARγ), a key regulator of mitochondrial biogenesis, were decreased in mouse and cellular models of SBMA. Treatment with pioglitazone (PG), an activator of PPARγ, improved the viability of the cellular model of SBMA. The oral administration of PG also improved the behavioral and histopathological phenotypes of the transgenic mice. Furthermore, immunohistochemical and biochemical analyses demonstrated that the administration of PG suppressed oxidative stress, nuclear factor-κB (NFκB) signal activation and inflammation both in the spinal cords and skeletal muscles of the SBMA mice. These findings suggest that PG is a promising candidate for the treatment of SBMA.

High serum C1q-binding adiponectin levels in male patients with acute coronary syndrome.

BACKGROUND: The complement system is part of the immune system in acute coronary syndrome (ACS). Adiponectin has anti-atherogenic and anti-inflammatory properties. Adiponectin and C1q form a protein complex in blood, and serum C1q binding adiponectin (C1q-APN) can be measured. We investigated the comparative evaluation of serum C1q-APN levels in males with ACS, stable angina pectoris (SAP) versus controls. METHODS: The study subjects were 138 Japanese patients who underwent diagnostic coronary angiography. Blood total adiponectin (Total-APN), C1q-APN and C1q were measured by enzyme-linked immunosorbent assays. Patients were divided into three groups according to the clinical condition: ACS (n = 78), SAP (n = 41) or normal coronary (NC, n = 19) groups. RESULTS: Serum C1q levels were significantly higher in the ACS group (54.9±1.2 µg/mL) than in the NC group (48.0±2.5 µg/mL). Although serum Total-APN levels were significantly lower in the SAP and ACS groups, compared with the NC group (7.0±0.5, 7.2±0.3, 10.6±2.0 µg/mL, respectively), serum C1q-APN levels were significantly higher in the ACS group than in the NC and SAP groups (112.1±4.1, 66.3±4.4, 65.7±2.9 units/mL, respectively). CONCLUSIONS: Patients with ACS had higher serum C1q-APN levels. TRIAL REGISTRATION: UMIN000002997.

A pilot three-month sitagliptin treatment increases serum adiponectin level in Japanese patients with type 2 diabetes mellitus--a randomized controlled trial START-J study.

BACKGROUND: The dipeptidyl-peptidase-IV (DPP-4) inhibitors, including sitagliptin, are used for the treatment of type 2 diabetes mellitus (T2DM). Adiponectin, an adipocyte-derived circulating protein, has anti-atherosclerotic and anti-diabetic properties and is effectively elevated in bloodstream by thiazolidinediones, an insulin sensitizer. However, the effect of sitagliptin treatment on serum adiponectin level in T2DM has not fully elucidated in Japanese T2DM patients. The aim of the present study was to examine the effect of sitagliptin treatment on serum adiponectin levels in T2DM subjects. METHODS: Twenty-six consecutive Japanese T2DM outpatients were recruited between April 2011 and March 2013, and randomized into the control (conventional treatment, n = 10) group and sitagliptin treatment group (n = 16). Serum adiponectin was measured by enzyme-linked immunosorbent assay. RESULTS: Indices of glycemic control, such as hemoglobin A1c, glycated albumin, and 1.5-anhydro-D-glucitol, were significantly improved after the three-month treatment in both the control and sitagliptin groups. Serum adiponectin level was significantly increased in sitagliptin group from 6.7 ± 0.8 to 7.4 ± 1.0 µg/mL without change of body mass index (p = 0.034), while serum adiponectin level was not altered in the control group (p = 0.601). CONCLUSION: In Japanese T2DM patients, serum adiponectin level was elevated by three-month treatment with sitagliptin without change of body weight. TRIAL REGISTRATION: UMIN000004721.

Serum C1q- binding adiponectin in maintenance hemodialysis patients.

BACKGROUND: Patients on maintenance hemodialysis (HD) have much higher levels of adiponectin (Total-APN). Adiponectin and C1q form a protein complex in human blood, and serum C1q-binding adiponectin (C1q-APN) can be measured. We recently reported that C1q-APN/Total-APN ratio rather than Total-APN correlated with atherosclerosis in diabetics. However, the characteristics of C1q-APN in HD patients remain unclear. The preset study investigated the characteristics of the adiponectin parameters including C1q-APN and also to clarify the relationship between various serum adiponectin parameters and atherosclerotic cardiovascular diseases (ACVD) in HD patients. METHODS: The single cross-sectional study subjects were 117 Japanese patients (males/females = 61/56) on regular HD. Blood Total-APN, high molecular weight-adiponectin (HMW-APN), C1q-APN and C1q concentrations were measured by enzyme-linked immunosorbent assays. ACVD were defined as stroke, coronary and peripheral artery diseases, thoracic and abdominal aneurysms. RESULTS: Stepwise regression analysis identified high-density lipoprotein-cholesterol (HDL-C) as the only significant and independent determinant of C1q-APN in males, and duration of HD as the only significant and independent determinant of C1q-APN in females. Stepwise regression analysis identified uric acid, low-density lipoprotein-cholesterol and triglyceride as significant and independent determinants of C1q-APN/Total-APN ratio in males, and leukocyte count and HDL-C as significant and independent determinants of C1q-APN/Total-APN ratio in females. Multiple logistic regression analysis identified inorganic phosphorus and C1q-APN or C1q-APN/C1q ratio as significant determinants of ACVD. CONCLUSIONS: Low serum C1q-APN and C1q-APN/C1q ratio, but not C1q-APN/Total-APN ratio, correlated with ACVD in HD patients. TRIAL REGISTRATION: ClinicalTrials.gov: UMIN http://000004318.

High circulating levels of S100A8/A9 complex (calprotectin) in male Japanese with abdominal adiposity and dysregulated expression of S100A8 and S100A9 in adipose tissues of obese mice.

S100A8/A9 complex, calprotectin, which serves as an endogenous ligand for immune pathways, is associated with atherosclerosis. These proteins are reported to have several functions such as activating NADPH oxidase, binding toll-like receptor 4 and associated with the receptor for advanced glycation end-products. We recently reported S100A8 mRNA was highly expressed in mouse white adipose tissues and differentiated 3T3-L1 adipocytes. However, regulation of S100A9 expression in murine adipose tissue remains to be elucidated. The results of our studies in male Japanese, obese and control mice and cultured cells showed: (1) serum levels of S100A8/A9 complex, calprotectin, correlated with visceral fat area, body mass index, subcutaneous fat area, and leukocyte count in 500 Japanese men, and (2) higher mRNA expression levels of S100A8 in mature adipocyte fraction and S100A9 in stromal vascular cell fraction of obese mice, compared with those of lean mice. Overexpression of S100A8 and S100A9 in obese adipose tissue may be involved, at least partly, in not only high circulating levels of S100A8/A9 complex in abdominal obesity but also adipose and systemic tissue inflammation.

Hyperinsulinemia correlates with low levels of plasma B-type natriuretic peptide in Japanese men irrespective of fat distribution.

BACKGROUND: B-type natriuretic peptide (BNP), a member of the natriuretic peptide family, is a cardiac-derived secretory hormone with natriuretic, diuretic, and vasorelaxant activities. Intraabdominal fat accumulation is associated with atherosclerotic cardiovascular diseases and cardiac dysfunction. Circulating BNP levels are relatively low (within the normal limits) in obesity and the metabolic syndrome. However, the relationship between plasma BNP levels and visceral fat accumulation in general population has not been reported. The present study analyzed the relationships between plasma BNP levels and various clinical variables, including insulin, visceral and subcutaneous fat area (VFA and SFA, respectively), in normal Japanese men. METHODS: The study (Victor-J study) subjects were consecutive 500 Japanese male workers, who underwent a health checkup and were measured VFA and SFA by computed tomography. RESULTS: Age-adjusted simple linear regression analysis showed that log-BNP correlated positively with HDL-cholesterol, and negatively with VFA, log-immunoreactive insulin (IRI), log-triglyceride, and LDL-cholesterol, but not body mass index or SFA. Stepwise multiple regression analysis identified log-IRI and HDL-cholesterol as significant determinants of log-BNP. Subjects with IRI ≥5.5 µIU/mL had lower plasma BNP levels than those with IRI < 5.5 µIU/mL, irrespective of obesity (body mass index, cutoff value 25 kg/m2), visceral fat accumulation (VFA, cutoff value 100 cm2) and subcutaneous fat accumulation (SFA, cutoff value 128 cm2). CONCLUSIONS: Our study showed that hyperinsulinemia correlated with low levels of plasma BNP in general men, irrespective of fat distribution. TRIAL REGISTRATION: UMIN 000004318.

Characteristics of sleep-disordered breathing in Japanese patients with acromegaly.

Sleep-disordered breathing (SDB), especially sleep apnea-hypopnea syndrome (SAS), is often observed in patients with active acromegaly. This complication is a risk factor for cardiovascular disease and associated with increased morbidity and mortality in acromegaly. However there is little information on SDB in Japanese patients with acromegaly. We investigated the prevalence of SDB and association between the severity of SDB and various features and biomarkers in Japanese patients with acromegaly. Twenty-four Japanese patients with active acromegaly underwent overnight cardiorespiratory monitoring, hormonal assays and cephalometric measurements on X-ray. A high prevalence of SDB was detected in acromegaly (87.5%). Log apnea-hypopnea index (AHI) correlated positively with soft palate length / body height (X-ray) (r=0.44, p=0.043), but not with log growth hormone levels and insulin-like growth factor type-1 standard deviation scores, size of pituitary adenoma, disease duration, body mass index, waist circumference, estimated visceral fat area, heel pad thickness / height, tongue thickness/ height, or oropharyngeal dimension/ height. In conclusion, our study demonstrated a high prevalence of SDB in Japanese patients with acromegaly, and its severity correlated with soft palate length. Based on the high incidence of SDB identified in the present study, we recommend that all patients with acromegaly are routinely screened for SDB for early diagnosis and treatment.

Diet-induced insulin resistance in mice lacking adiponectin/ACRP30.

Here we investigated the biological functions of adiponectin/ACRP30, a fat-derived hormone, by disrupting the gene that encodes it in mice. Adiponectin/ACRP30-knockout (KO) mice showed delayed clearance of free fatty acid in plasma, low levels of fatty-acid transport protein 1 (FATP-1) mRNA in muscle, high levels of tumor necrosis factor-alpha (TNF-alpha) mRNA in adipose tissue and high plasma TNF-alpha concentrations. The KO mice exhibited severe diet-induced insulin resistance with reduced insulin-receptor substrate 1 (IRS-1)-associated phosphatidylinositol 3 kinase (PI3-kinase) activity in muscle. Viral mediated adiponectin/ACRP30 expression in KO mice reversed the reduction of FATP-1 mRNA, the increase of adipose TNF-alpha mRNA and the diet-induced insulin resistance. In cultured myocytes, TNF-alpha decreased FATP-1 mRNA, IRS-1-associated PI3-kinase activity and glucose uptake, whereas adiponectin increased these parameters. Our results indicate that adiponectin/ACRP30 deficiency and high TNF-alpha levels in KO mice reduced muscle FATP-1 mRNA and IRS-1-mediated insulin signaling, resulting in severe diet-induced insulin resistance.

Beneficial effects of foot care nursing for people with diabetes mellitus: an uncontrolled before and after intervention study.

AIM: The aim of this study was to assess the effectiveness of a preventative foot care nursing programme for diabetic patients. BACKGROUND: Foot complications are common in diabetic patients and prevention of such complications requires foot care. However, there is little information on the effectiveness of foot care nursing on the incidence and recurrence of diabetic foot. METHODS: We developed a diabetic foot care programme based on the International Working Group on the Diabetic Foot. We studied 88 patients who attended our foot care programme for 2 years, and collected data from April 2005 to March 2009. Patients were divided into four groups according to the risk classification, and received foot care. We evaluated the incidence of foot ulceration or recurrence and non-ulcerated foot condition. Characteristics of the patients were analysed using the paired t-test and McNemar's test, and changes in severity of tinea pedis and grade of callus were analysed using Wilcoxon's signed rank sum test. RESULTS: The programme reduced the severity score of tinea pedis (P < 0·001) and improved callus grade (P < 0·001). All these were evaluated by Wilcoxon's signed rank sum test. None of the patients of risk-group-3 (history of foot ulceration) showed recurrence of callus-related foot ulcers. Six high-risk patients developed foot ulceration during the programme because of minor injury, but the ulcers healed without development of gangrene. CONCLUSION: A nurse-based foot care programme is effective in preventing diabetic foot in diabetic patients.

[Etiology of atherosclerosis--special reference to humoral and neurogenic factors].

Atherosclerotic cardiovascular diseases, currently the leading cause of death and illness in developed countries, will soon become the health problem worldwide. Atherosclerosis, a progressive disease characterized by the accumulation of lipids and fibrous elements in the arteries, constitutes the most important contributor to this growing burden of cardiovascular disease. The vascular endothelium is the inner lining of all blood vessels and serves as an important autocrine and paracrine organ, that regulates vascular wall functions. The vascular components are susceptible to the effect of oxidative stress, inflammation, (adipo)cytokines, neurohumoral factors, sleep disorders, psychogenic stress and other mediators. These vascular systems should maintain vascular homeostasis in the whole body for preventing atherosclerotic cardiovascular diseases.

Reciprocal regulation of natriuretic peptide receptors by insulin in adipose cells.

Atrial- and brain-type natriuretic peptides (ANP and BNP, respectively) have been shown to exert potent lipolytic action in adipocytes. A family of natriuretic peptide receptors (NPRs), NPR-1, NPR-2, and NPR-3, mediates their physiologic effects. NPR-1 and NPR-2 are receptor guanylyl cyclases, while NPR-3 lacks enzymatic activity and functions primarily as a clearance receptor for natriuretic peptides. ANP has a high affinity for NPR-1 and NPR-3 than other natriuretic peptides. There is a possibility that ANP may exhibit its lipolytic effect through the balance of NPR-1 and NPR-3 expressions in adipocytes. However, the regulation of adipose NPRs has not been fully elucidated. We here examined the regulation of mouse adipose NPRs by insulin, an anti-lipolytic hormone. Among the insulin target organs, NPR-1 mRNA levels were higher in white adipose tissue (WAT) than in liver and skeletal muscle. NPR-3 mRNA was expressed most abundantly in WAT. Fasting condition induced NPR-1 mRNA level while suppressed NPR-3 mRNA level in WAT. Administration of streptozotocin resulted in the increase of NPR-1 mRNA level while the decrease of NPR-3 mRNA level in WAT. In ob/ob mice, hyperinsulinemic model, NPR-1 mRNA level was lower whereas NPR-3 mRNA level was higher compared to lean control mice. In 3T3-L1 adipocytes, insulin significantly reduced NPR-1 mRNA level while increased NPR-3 mRNA levels both through phosphatidylinositol 3-kinase (PI3-kinase) pathway. In summary, NPR-1 and NPR-3 were highly expressed in WAT and adipose NPR-1 and NPR-3 were reciprocally regulated by insulin. This study suggests that insulin may efficiently promote lipogenesis partly by reducing the lipolytic action of ANP through the opposite regulation of NPR-1 and NPR-3.

Adiponectin ameliorates hypoxia-induced pulmonary arterial remodeling.

We have demonstrated that adiponectin has anti-atherosclerotic properties. We also reported hypoadiponectinemia and nocturnal reduction in circulating adiponectin concentrations in patients of severe obstructive sleep apnea-hypopnea syndrome (OSAS). OSAS is often complicated with pulmonary hypertension. In this study, we investigated the effect of adiponectin on chronic hypoxia-induced pulmonary arterial remodeling in mice. Exposure of mice to 3-weeks sustained hypoxia (10% O(2)) resulted in significant accumulation of adiponectin in pulmonary arteries. The percentage media wall thickness (%MT), representing pulmonary arterial remodeling, under hypoxic condition, was greater in adiponectin-knockout mice than wild-type mice. Overexpression of adiponectin significantly decreased hypoxia-induced pulmonary arterial wall thickening and right ventricular hypertrophy. These findings demonstrate for the first time that overexpression of adiponectin suppresses the development of hypoxic-induced pulmonary remodeling, and that adiponectin may combat a new strategy for pulmonary vascular changes that underlie pulmonary hypertension in OSAS.

Foxo1 represses expression of musclin, a skeletal muscle-derived secretory factor.

Musclin is a novel skeletal muscle-derived secretory factor, whose mRNA level is markedly regulated by nutritional status. In the present study, we investigated the mechanism of musclin mRNA regulation by insulin. In C2C12 myocytes, insulin-induced upregulation of musclin mRNA was significantly decreased by treatment of phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002, and was abolished in C2C12 myocytes stably expressing a constitutively active Foxo1 (Foxo1-3A), suggesting the involvement of Foxo1 in the regulation of musclin mRNA. Promoter deletion analysis of musclin promoter revealed that the region of -303/-123 is important for the repression of promoter activity by Foxo1. Chromatin immunoprecipitation assay showed that Foxo1 bound to musclin promoter. Musclin mRNA level was markedly downregulated in gastrocnemius muscle of Foxo1 transgenic mice. Our results demonstrated that Foxo1 downregulates musclin mRNA expression both in vitro and in vivo, which should explain insulin-mediated upregulation of this gene in muscle cells.

Correlation of insulin resistance and motor function in spinal and bulbar muscular atrophy.

This study aimed to evaluate various metabolic parameters in patients with spinal and bulbar muscular atrophy (SBMA), to investigate the association between those indices and disease severity, and to explore the underlying molecular pathogenesis. We compared the degree of obesity, metabolic parameters, and blood pressure in 55 genetically confirmed SBMA patients against those in 483 age- and sex-matched healthy control. In SBMA patients, we investigated the correlation between these factors and motor functional indices. SBMA patients had lower body mass index, blood glucose, and Hemoglobin A1c, but higher blood pressure, homeostasis model assessment of insulin resistance (HOMA-IR, a marker of insulin resistance), total cholesterol, and adiponectin levels than the control subjects. There were no differences in visceral fat areas, high-density lipoprotein-cholesterol (HDL-C), or triglyceride levels in two groups. Revised amyotrophic lateral sclerosis functional rating scale (ALSFRS-R) correlated positively with HDL-C, but negatively with HOMA-IR. Through stepwise multiple regression analysis, we identified HOMA-IR as a significant metabolic determinant of ALSFRS-R. In biochemical analysis, we found that decreased expressions of insulin receptors, insulin receptor substrate-1 and insulin receptor-ß, in autopsied muscles and fibroblasts of SBMA patients. This study demonstrates that SBMA patients have insulin resistance, which is associated with the disease severity. The expressions of insulin receptors are attenuated in the skeletal muscle of SBMA, providing a possible pathomechanism of metabolic alterations. These findings suggested that insulin resistance is a metabolic index reflecting disease severity and pathogenesis as well as a potential therapeutic target for SBMA.

Adiponectin specifically increased tissue inhibitor of metalloproteinase-1 through interleukin-10 expression in human macrophages.

BACKGROUND: Vascular inflammation and subsequent matrix degradation play an important role in the development of atherosclerosis. We previously reported that adiponectin, an adipose-specific plasma protein, accumulated to the injured artery and attenuated vascular inflammatory response. Clinically, high plasma adiponectin level was associated with low cardiovascular event rate in patients with chronic renal failure. The present study was designed to elucidate the effects of adiponectin on matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in human monocyte-derived macrophages. METHODS AND RESULTS: Human monocyte-derived macrophages were incubated with the physiological concentrations of human recombinant adiponectin for the time indicated. Adiponectin treatment dose-dependently increased TIMP-1 mRNA levels without affecting MMP-9 mRNA levels. Adiponectin also augmented TIMP-1 secretion into the media, whereas MMP-9 secretion and activity were unchanged. Time course experiments indicated that TIMP-1 mRNA levels started to increase at 24 hours of adiponectin treatment and were significantly elevated at 48 hours. Adiponectin significantly increased interleukin-10 (IL-10) mRNA expression at the transcriptional level within 6 hours and significantly increased IL-10 protein secretion within 24 hours. Cotreatment of adiponectin with anti-IL-10 monoclonal antibody completely abolished adiponectin-induced TIMP-1 mRNA expression. CONCLUSIONS: Adiponectin selectively increased TIMP-1 expression in human monocyte-derived macrophages through IL-10 induction. This study identified, for the first time, the adiponectin/IL-10 interaction against vascular inflammation.

Reciprocal association of C-reactive protein with adiponectin in blood stream and adipose tissue.

BACKGROUND: High-sensitive C-reactive protein (hs-CRP) is a well-known risk factor for coronary artery disease (CAD). Recently, we have demonstrated that adiponectin served as an antiatherogenic plasma protein which was secreted specifically from adipocytes. The present study investigated the association between adiponectin and CRP in the blood stream and adipose tissue. METHODS AND RESULTS: We studied a total of 101 male patients, 71 of whom had angiographically documented coronary atherosclerosis. As a control group, 30 patients with normal coronary angiogram were included. The plasma hs-CRP levels were negatively correlated with the plasma adiponectin levels (r=-0.29, P<0.01). The plasma adiponectin concentrations were significantly lower and the hs-CRP levels were significantly higher in the CAD patients compared with control subjects. The mRNA levels of CRP and adiponectin were analyzed by quantitative real-time polymerase chain reaction method. We found that the CRP mRNA was expressed in human adipose tissue. A significant inverse correlation was observed between the CRP and adiponectin mRNA levels in human adipose tissue (r=-0.89, P<0.01). In addition, the CRP mRNA level of white adipose tissue in adiponectin deficient mice was higher than that of wild-type mice. CONCLUSIONS: The reciprocal association of adiponectin and CRP levels in both human plasma and adipose tissue might participate in the development of atherosclerosis.

Coordinated regulation of fat-specific and liver-specific glycerol channels, aquaporin adipose and aquaporin 9.

Plasma glycerol is a major substrate for hepatic gluconeogenesis. Aquaporin adipose (AQPap/7), an adipose-specific glycerol channel, provides fat-derived glycerol into plasma. In the present study, we cloned the coding and promoter regions of mouse aquaporin 9 (AQP9), a liver-specific glycerol channel. Fasting and refeeding of mice increased and decreased hepatic AQP9 mRNA levels, respectively. Insulin deficiency induced by streptozotocin resulted in increased hepatic AQP9 mRNA. These changes in hepatic AQP9 mRNA were accompanied by those of hepatic gluconeogenic mRNAs and plasma glycerol levels. In cultured hepatocytes, insulin downregulated AQP9 mRNA. The AQP9 promoter contained the negative insulin response element TGTTTTC at -496/-502, similar to the promoter of the AQPap/7 gene. In contrast, in insulin-resistant db+/db+ mice, AQPap/7 mRNA in fat and AQP9 mRNA in liver were increased, despite hyperinsulinemia, with high plasma glycerol and glucose levels. Glycerol infusion in the db+/db+ mice augmented hepatic glucose output. Our results indicate that coordinated regulations of fat-specific AQPap/7 and liver-specific AQP9 should be crucial to determine glucose metabolism in physiology and insulin resistance.