The Adiponectin Receptor Agonist AdipoRon Ameliorates Diabetic Nephropathy in a Model of Type 2 Diabetes.

Adiponectin exerts renoprotective effects against diabetic nephropathy (DN) by activating the AMP-activated protein kinase (AMPK)/peroxisome proliferative-activated receptor-α (PPARα) pathway through adiponectin receptors (AdipoRs). AdipoRon is an orally active synthetic adiponectin receptor agonist. We investigated the expression of AdipoRs and the associated intracellular pathways in 27 patients with type 2 diabetes and examined the effects of AdipoRon on DN development in male C57BLKS/J db/db mice, glomerular endothelial cells (GECs), and podocytes. The extent of glomerulosclerosis and tubulointerstitial fibrosis correlated with renal function deterioration in human kidneys. Expression of AdipoR1, AdipoR2, and Ca2+/calmodulin-dependent protein kinase kinase-ß (CaMKKß) and numbers of phosphorylated liver kinase B1 (LKB1)- and AMPK-positive cells significantly decreased in the glomeruli of early stage human DN. AdipoRon treatment restored diabetes-induced renal alterations in db/db mice. AdipoRon exerted renoprotective effects by directly activating intrarenal AdipoR1 and AdipoR2, which increased CaMKKß, phosphorylated Ser431LKB1, phosphorylated Thr172AMPK, and PPARα expression independently of the systemic effects of adiponectin. AdipoRon-induced improvement in diabetes-induced oxidative stress and inhibition of apoptosis in the kidneys ameliorated relevant intracellular pathways associated with lipid accumulation and endothelial dysfunction. In high-glucose-treated human GECs and murine podocytes, AdipoRon increased intracellular Ca2+ levels that activated a CaMKKß/phosphorylated Ser431LKB1/phosphorylated Thr172AMPK/PPARα pathway and downstream signaling, thus decreasing high-glucose-induced oxidative stress and apoptosis and improving endothelial dysfunction. AdipoRon further produced cardioprotective effects through the same pathway demonstrated in the kidney. Our results show that AdipoRon ameliorates GEC and podocyte injury by activating the intracellular Ca2+/LKB1-AMPK/PPARα pathway, suggesting its efficacy for treating type 2 diabetes-associated DN.

MiR-323 Inhibits Prostate Cancer Vascularization Through Adiponectin Receptor.

BACKGROUND/AIMS: The current treatments fail to provide satisfactory cure for aggressive prostate cancers (PCs). Hence, further comprehension of PC metastasis is highly appreciated for improving the levels of therapy. We have previously shown that Adiponectin reduces the levels of vascular endothelial growth factor A (VEGF-A) in PCs to suppress tumor-associated neovascularization, possibly through AMPK/mTor signaling. Here, we studied the regulation of Adiponectin signaling in PCs. METHODS: We analyzed the levels and correlation of Adiponectin receptor 1 (AdipoR1) and microRNA-323 (miR-323) in the PC specimen, compared to the paired normal prostate tissue. We analyzed the binding of miR-323 to the 3'UTR of AdipoR1 mRNA and its effects on AdipoR1 translation by bioinformatics analysis and by luciferase-reporter assay, respectively. We modified miR-323 levels in PC cells, and examined the effects on the expression of AdipoR1 and VEGF-A, as well as on vessel formation in a human umbilical vein endothelial cells (HUVECs) transwell collagen gel assay. RESULTS: We detected significantly lower levels of AdipoR1 and significantly higher levels of miR-323 in PC specimen. Moreover, the levels of AdipoR1 and miR-323 are inversely correlated. Moreover, miR-323 was found to bind to the 3'UTR of AdipoR1 mRNA to inhibit its translation. Overexpression of miR-323 in PC cells decreased AdipoR1 protein levels, whereas inhibition of miR-323 increased AdipoR1 protein levels, without affecting AdipoR1 transcripts. Moreover, overexpression of miR-323 increased the levels of VEGF-A and the vessel formation by HUVECs, while inhibition of miR- 323 decreased the levels of VEGF-A and the vessel formation by HUVECs. CONCLUSION: Our data demonstrate that miR-323 may increase VEGF-A-mediated cancer vascularization in PC cells through AdipoR1 suppression.

Serum adiponectin is associated with worsened overall survival in a prospective cohort of hepatocellular carcinoma patients.

BACKGROUND: Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. The rise in metabolic syndrome has contributed to this trend. Adipokines, such as adiponectin, are associated with prognosis in several cancers, but have not been well studied in HCC. METHODS: We prospectively enrolled 140 patients with newly diagnosed or recurrent HCC with Child-Pugh (CP) class A or B cirrhosis. We examined associations between serum adipokines, clinicopathological features of HCC, and time to death. We also examined a subset of tumors with available pathology for tissue adiponectin receptor (AR) expression by immunohistochemistry. RESULTS: The median age of subjects was 62 years; 79% were men, 59% had underlying hepatitis C, and 36% were diabetic. Adiponectin remained a significant predictor of time to death (hazard ratio 1.90; 95% confidence interval 1.05-3.45; p = 0.03) in a multivariable adjusted model that included age, alcohol history, CP class, stage, and serum α-fetoprotein level. Cytoplasmic AR expression (AR1 and AR2) in tumors trended higher in those with higher serum adiponectin levels and in those with diabetes mellitus, but the association was not statistically significant. CONCLUSIONS: In this hypothesis-generating study, we found the serum adiponectin level to be an independent predictor of overall survival in a diverse cohort of HCC patients. IMPACT: Understanding how adipokines affect the HCC outcome may help develop novel treatment and prevention strategies.

Endometria from Obese PCOS Women with Hyperinsulinemia Exhibit Altered Adiponectin Signaling.

Hyperandrogenemia, hyperinsulinemia, and obesity affect 60-70% of patients with Polycystic Ovarian Syndrome (PCOS), who exhibit an altered endometrial insulin signaling. The aim of the study was to evaluate whether hyperandrogenism, hyperinsulinism, and obesity present in PCOS patients impair the endometrial adiponectin signaling pathway. The ex vivo study was conducted on 27 samples from lean (n=9), obese (n=9), and obese-PCOS (n=9) patients. The in vitro assays were performed in immortalized human endometrial stromal cells stimulated with testosterone, insulin, or testosterone plus insulin. Serum steroid-hormones, adiponectin, glucose, and insulin; body mass index, free androgen index, ISI-Composite, and HOMA were evaluated in the 3 groups. Ex vivo and in vitro gene expression and protein content of adiponectin, AdipoR1, AdipoR2, and APPL1 were determined. Adiponectin serum levels were decreased in obese-PCOS patients compared to lean (78%) and obese (54%) controls (p<0.05). AdipoR1 protein and gene expression were increased in obese group vs. obese-PCOS and lean groups (2-fold, p<0.05). In turn, AdipoR2 protein and mRNA content was similar between the 3 groups. APPL1 protein levels were reduced in endometria from both obese groups, compared to lean group (6-fold, p<0.05). Testosterone plus insulin stimulation of T-HESC and St-T1b leads to a reduction of adiponectin, AdipoR1, AdipoR2, and APPL1 protein content in both endometrial cell lines (p<0.05), whereas, in the presence of testosterone or insulin alone, protein levels were similar to basal. Therefore, endometrial adiponectin-signaling pathway is impaired in hyperandrogenemic and hyperinsulinemic obese-PCOS patients, corroborated in the in vitro model, which could affect endometrial function and potentially the implantation process.

[Serum adipokines and their receptors in endometrial and colon cancer patients: relationship with tumor invasion and metastasis].

The aim of the study was to investigate the serum adipokine levels and expression of adipokine receptors (AdipoR1, AdipoR2) in patients with endometrial and colon cancer in relation with the main clinical morphological parameters (tumor invasion, lymph node involvement). The study included 60 endometrial cancer patients with I-II Stage and 31 patients with colon cancer (T2-4N0-2M0). Serum adipokine levels, the level of soluble form of the leptin receptor (sOb-R) and AdipoR1 and AdipoR2 expression were evaluated with ELISA. In endometrial cancer serum leptin and adiponectin levels were associated not only with metabolic disorders but also with cervical invasion. In colon cancer serum leptin level was associated with lymph node involvement. The data obtained showed the potential implication of serum adipokines into tumor invasion and metastasis. In both sites intratumoral levels of AdipoR1 H AdipoR2 were not associated with the presence of metabolic syndrome. The AdipoR1 level was related with myometrial invasion. In colon cancer patients, AdipoR1 and AdipoR2 expressions were associated with lymph node involvement, and AdipoR1 expression was correlated with tumor size. The obtained results demonstrated involvement of adipose tissue hormones (leptin and adiponectin) and adiponectin receptors (AdipoR1 and AdipoR2) in tumor growth, invasion and lymphogenic metastasis.

Gene expression profiling in melasma in Korean women.

BACKGROUND: There has been a paucity of data about the difference in gene expression between melasma lesional skin and normal adjacent one. OBJECTIVE: Our aim was to identify novel genes involved in the pathogenesis of melasma. METHODS: We performed a microarray analysis and confirmed the results on quantitative real-time polymerase chain reaction (qRT-PCR) in Korean women with melasma. RESULTS: There were 334 genes whose degree of expression showed a significant difference between melasma lesional skin and normal adjacent one. Of these, five were confirmed on qRT-PCR. In melasma lesional skin, there were down-regulation of genes involved in the PPAR signaling pathway and up-regulation of genes involved in neuronal component and the functions of stratum corneum barrier. CONCLUSION: This result suggests that the pathogenesis of melasma might be associated with novel genes involved in the above signaling pathway in Korean women.

Expression of adiponectin and its receptors in the porcine hypothalamus during the oestrous cycle.

Adiponectin is a hormonal link between obesity and reproduction, and its actions are mediated by two types of receptors: adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2). This study compares the expression levels of adiponectin and adiponectin receptor mRNAs and proteins in selected areas of the porcine hypothalamus responsible for GnRH production and secretion: the mediobasal hypothalamus (MBH), pre-optic area (POA) and stalk median eminence (SME). The tissue samples were harvested on days 2-3, 10-12, 14-16 and 17-19 of the oestrous cycle. Adiponectin mRNA expression in MBH was significantly lower on days 14-16, whereas in SME, the most pronounced gene expression was found on days 2-3 of the cycle (p < 0.05). Adiponectin protein in MBH was most abundant on days 17-19 and in POA on days 2-3 (p < 0.05). Adiponectin protein expression in SME was at similar level throughout the most of the cycle with a statistically significant drop (p < 0.05) on days 14-16. AdipoR1 gene expression in POA was potentiated on days 2-3 and 10-12 of the oestrous cycle (p < 0.05). In SME, the highest AdipoR1 mRNA expression was noted on days 2-3 (p < 0.05). The concentrations of the AdipoR1 protein in POA were similar throughout the luteal phase (days 2-14 of the cycle), and they decreased on days 17-19 (p < 0.05). In SME, AdipoR1 protein expression peak occurred on days 2-3 (p < 0.05). The expression patterns of the AdipoR2 gene in MBH, POA and SME revealed the highest mRNA levels on days 2-3 of the cycle (p < 0.05). The highest content of AdipoR2 protein in MBH was reported on days 2-3 (p < 0.05), while in POA on days 17-19 and in SME on days 10-12 and 14-16 (p < 0.05). This study demonstrated that adiponectin and adiponectin receptor mRNAs and proteins are present in the porcine hypothalamus and that their expression levels are determined by the pig's endocrine status related to the oestrous cycle.

CORRELATION OF LEPTIN AND ADIPONECTIN RECEPTOR EXPRESSION WITH CLINICOPATHOLOGICAL PARAMETERS IN COLORECTAL CARCINOMA - A CROSS-SECTIONAL PROSPECTIVE STUDY.

BACKGROUND: Colorectal carcinoma (CRC) is one of the common carcinomas with a rising incidence of metastasis due to its advanced stage of presentation. The existing biomarkers such as CEA (Carcinoembryonic antigen) etc., for prognosis, have low sensitivity and specificity. Hence a need for a newer definitive biomarker. Obesity is the leading cause of CRC. Leptin and adiponectin secreted by adipose tissue have been studied as potential biomarkers in the field of CRC. The present study helps to understand the association of leptin and adiponectin receptors with clinicopathological parameters. OBJECTIVE: To correlate the various clinicopathological parameters with the tissue expression of leptin and adiponectin receptors in CRC. METHODS: It is a cross-sectional prospective study conducted at a tertiary care hospital. Formalin fixed paraffin blocks of all radical resection CRC cases were collected and immunohistochemistry (IHC)was carried out on tumor tissue for leptin and adiponectin receptor. Tumor characteristics and clinical parameters were collected from the hospital medical records. Pearson's correlation coefficient test was used. RESULTS: Immunohistochemistry was performed on 60 cases of CRC. Significant positive correlation of leptin was observed with size, lymph node metastasis, advanced stage, and grade of tumor (P<0.05). A significant correlation between adiponectin receptor and CRC was observed concerning age, stage, lymph node metastasis, distant metastasis and grade of tumor. CONCLUSION: Positive expression of leptin and negative expression of adiponectin receptors in CRC helps to predict the risk of metastasis.

The adipose tissue production of adiponectin is increased in end-stage renal disease.

Adiponectin has antidiabetic properties, and patients with obesity, diabetes, and insulin resistance have low plasma adiponectin levels. However, although kidney disease is associated with insulin resistance, adiponectin is elevated in end-stage renal disease. Here we determine whether adipose tissue production of adiponectin is increased in renal disease in a case-control study of 36 patients with end-stage renal disease and 23 kidney donors. Blood and tissue samples were obtained at kidney transplantation and donation. The mean plasma adiponectin level was significantly increased to 15.6 mg/ml in cases compared with 8.4 mg/ml in controls. Plasma levels of the inflammatory adipokines tumor necrosis factor α, interleukin 6, and high-sensitivity C-reactive protein were significantly higher in cases compared with controls. Adiponectin mRNA and protein expression in visceral and subcutaneous fat were significantly higher in cases than controls, while adiponectin receptor-1 mRNA expression was significantly increased in peripheral blood cells, muscle, and adipose tissue in cases compared with controls. Thus, our study suggests that adipose tissue production of adiponectin contributes to the high plasma levels seen in end-stage renal disease.

Adiponectin regulates functions of gingival fibroblasts and periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Adiponectin is a cytokine constitutively produced by adipocytes and exhibits multiple biological functions by targeting various cell types. However, the effects of adiponectin on primary gingival fibroblasts and periodontal ligament cells are still unexplored. Therefore, we investigated the effects of adiponectin on gingival fibroblasts and periodontal ligament cells. MATERIAL AND METHODS: The expression of adiponectin receptors (AdipoR1 and AdipoR2) on human gingival fibroblasts (HGFs), mouse gingival fibroblasts (MGFs) and human periodontal ligament (HPDL) cells was examined using RT-PCR and western blotting. HGFs and MGFs were stimulated with interleukin (IL)-1ß in the presence or absence of adiponectin, and the expression of IL-6 and IL-8 at both mRNA and protein levels was measured by real-time PCR and ELISA, respectively. Furthermore, small interfering RNAs (siRNAs) in MGFs were used to knock down the expression of mouse AdipoR1 and AdipoR2. The effects of adiponectin on the expression of alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2) genes were evaluated by real-time PCR. Mineralized nodule formation of adiponectin-treated HPDL cells was revealed by Alizarin Red staining. RESULTS: AdipoR1 and AdipoR2 were expressed constitutively in HGFs, MGFs and HPDL cells. Adiponectin decreased the expression of IL-6 and IL-8 in IL-1ß-stimulated HGFs and MGFs. AdipoR1 siRNA in MGFs revealed that the effect of adiponectin on reduction of IL-6 expression was potentially mediated via AdipoR1. Adiponectin-treated HPDL cells promoted the expression of ALP and Runx2 mRNAs and up-regulated ALP activity. Furthermore, adiponectin enhanced mineralized nodule formation of HPDL cells. CONCLUSION: Our observations demonstrate that adiponectin exerts anti-inflammatory effects on HGFs and MGFs, and promotes the activities of osteoblastogenesis of HPDL cells. We conclude that adiponectin has potent beneficial functions to maintain the homeostasis of periodontal health, improve periodontal lesions, and contribute to wound healing and tissue regeneration.

Adiponectin and its receptors in chronic hepatitis B patients with metabolic syndrome in China.

BACKGROUND/AIMS: Adiponectin can initiate a broad range of metabolic and immunological effects. Little is known about the role of adiponectin in hepatitis B related liver disease and metabolic syndrome (MS). METHODOLOGY: We studied 138 patients with untreated chronic hepatitis B (CHB), who were from Beijing Ditan hospital in 2005 to 2009. According to MS, two groups (65 with MS vs. 73 without MS) were established. They were compared with characteristics and stained immunohistochemically for adiponectin and adiponectin receptor2 (adipoR2). RESULTS: In the group of CHB patients with MS, the levels of LDH, γ-GT, FPG, FINS, HOMA-IR, HOMA-ß, TG and HBeAg positive were significantly higher than those in the group without MS (p<0.05). Liver steatosis in the group with MS is significantly more severe than that in the group without MS (p<0.001). With binary logistic regression analyses, BMI and HOMA-IR showed independent predictors to MS in patients with CHB. In patients with chronic HBV, the insulin sensitizing adipokine adiponectin and its receptor AdipoR2 was associated with diabetes in patients with CHB and MS. CONCLUSIONS: Our findings showed the CHB patients with MS may be presence of more severe steatosis. MS in CHB patients may be closely correlated with insulin resistance and less effect of viruses. Reduced hepatic expression of adiponectin and adipoR2 might be of pathophysiological relevance in CHB patients with MS.

Mechanisms underlying the anti-proliferative actions of adiponectin in human breast cancer cells, MCF7-dependency on the cAMP/protein kinase-A pathway.

Obesity is a risk factor for breast cancer, and low blood concentrations of adiponectin are associated with high incidence and poor prognosis of breast cancer. However, the molecular mechanisms underlying such inhibitory effects of adiponectin remain to be defined. By using MCF7 cells, we investigated the mechanisms underlying the inhibitory effects of adiponectin on breast cancer cells, particularly in the context of opposing IGF-1-induced proliferation. We found that adiponectin, at 20 and 40 µg/ml, reduced MCF7 cell growth in the absence and presence of IGF-1. These inhibitory effects were primarily the result of the significant increase of cells at G(1)/G(0) phase and concomitant decrease of cells at S phase. In addition, the percentage of apoptotic cells increased more than two-fold. Within 30-min of adiponectin addition, the phosphorylation of AMPKα was sharply elevated, and the level of IGF-1-activated Akt was decreased. Prolonged exposure to adiponectin resulted in reduction of cyclin D1 and cyclin E2 expression. Adiponectin also increased intracellular levels of cAMP and the activity of protein kinase-A (PKA). The inhibitors of PKA completely abolished the adiponectin's effects on cell growth. In conclusion, our studies revealed an important cellular mechanism underlying the relationship between reduced adiponectin concentrations and breast cancer development.

Nobiletin alleviates high-fat diet-induced nonalcoholic fatty liver disease by modulating AdipoR1 and gp91phox expression in rats.

Nobiletin, one of the polymethoxylated flavonoids isolated from citrus peels, is reported to possess various biological activities. The current study investigates the effect and possible mechanisms of nobiletin on nonalcoholic fatty liver disease (NAFLD) in high-fat diet (HFD)-fed rats. Male Sprague-Dawley rats were administrated with HFD and fructose (15%) in drinking water for 16 weeks to induce NAFLD. HFD-fed rats were treated with nobiletin (20 or 40 mg/kg/day) or vehicle for the last 4 weeks. Treatment of HFD-fed rats with nobiletin significantly reduced systolic blood pressure, adiposity, hyperlipidemia, insulin resistance, hepatic lipids content, NAFLD activity score and liver fibrosis. Nobiletin significantly increased plasma adiponectin levels, together with up-regulation of liver adiponectin receptor 1 (AdipoR1) expression. Additionally, decreased malondialdehyde levels and increased superoxide dismutase activity in plasma and hepatic tissue, consistent with down-regulation of liver NADPH oxidase subunit gp91phox expression, were also observed after nobiletin treatment. Furthermore, high dose of nobiletin exhibited higher therapeutic effect as a compared to low dose. These findings suggest that nobiletin alleviates HFD-induced NAFLD and metabolic dysfunction in rats. There might be an association between the observed inhibitory effect of nobiletin on NAFLD and modulation of AdipoR1 and gp91phox.

Up-regulation of cell cycle arrest protein BTG2 correlates with increased overall survival in breast cancer, as detected by immunohistochemistry using tissue microarray.

BACKGROUND: Previous studies have shown that the ADIPOR1, ADORA1, BTG2 and CD46 genes differ significantly between long-term survivors of breast cancer and deceased patients, both in levels of gene expression and DNA copy numbers. The aim of this study was to characterize the expression of the corresponding proteins in breast carcinoma and to determine their correlation with clinical outcome. METHODS: Protein expression was evaluated using immunohistochemistry in an independent breast cancer cohort of 144 samples represented on tissue microarrays. Fisher's exact test was used to analyze the differences in protein expression between dead and alive patients. We used Cox-regression multivariate analysis to assess whether the new markers predict the survival status of the patients better than the currently used markers. RESULTS: BTG2 expression was demonstrated in a significantly lower proportion of samples from dead patients compared to alive patients, both in overall expression (P = 0.026) and cell membrane specific expression (P = 0.013), whereas neither ADIPOR1, ADORA1 nor CD46 showed differential expression in the two survival groups. Furthermore, a multivariate analysis showed that a model containing BTG2 expression in combination with HER2 and Ki67 expression along with patient age performed better than a model containing the currently used prognostic markers (tumour size, nodal status, HER2 expression, hormone receptor status, histological grade, and patient age). Interestingly, BTG2 has previously been described as a tumour suppressor gene involved in cell cycle arrest and p53 signalling. CONCLUSIONS: We conclude that high-level BTG2 protein expression correlates with prolonged survival in patients with breast carcinoma.

Expression levels of adiponectin receptors and periodontitis.

BACKGROUND AND OBJECTIVE: We recently showed that adiponectin, an adipocyte-derived cytokine, may function as a negative regulator of the Toll-like receptor signaling pathway and of osteoclast formation in periodontal disease. In this study, we investigated whether the expression levels of adiponectin receptors (AdipoR1 and AdipoR2) are related to the presence of periodontitis. MATERIAL AND METHODS: We initially examined, using RT-PCR, the expression of the AdipoR1 and AdipoR2 genes at the mRNA level in several oral tissues of C57BL mice. Next, we investigated (using real-time PCR assays) whether inflammatory cytokines, such as tumor necrosis factor-alpha, could affect the expression levels of these genes in human gingival fibroblasts. Lastly, we compared the expression levels of these receptor proteins in gingival tissues between two healthy subjects and five patients with severe periodontal disease using western blotting analysis. RESULTS: The AdipoR1 and AdipoR2 receptors were ubiquitously expressed in the oral tissues of mice. We observed that treatment with tumor necrosis factor-alpha could significantly reduce the expression levels of both AdipoR1 and AdipoR2 genes in human gingival fibroblasts. Moreover, we found that the expression of both receptors was lower in periodontal tissues from patients with severe periodontitis than in patients with healthy periodontal tissues. CONCLUSION: These observations suggest that adiponectin may not function efficiently in sites of periodontal disease because of a decrease in the number of its receptors, and this probable dysfunction may play a role in worsening periodontitis in patients.

Expression of adiponectin and its receptors in livers of morbidly obese patients with non-alcoholic fatty liver disease.

BACKGROUND AND AIM: Obesity is one of the risk factors for non-alcoholic fatty liver disease (NAFLD) and a common disease that comprises simple steatosis and non-alcoholic steatohepatitis (NASH), and can eventually lead to liver cirrhosis. Adiponectin is an adipocyte-derived protein that has anti-obesity, antidiabetic and anti-inflammatory properties, and is considered to possess a hepatoprotective function. Its role in the development and progression of NAFLD in morbidly obese patients is unknown. In this study, we examined the expression levels of adiponectin and its receptors in liver biopsies of morbidly obese patients and then determined whether there was an association with the disease severity. METHODS: Liver biopsies from 30 morbidly obese patients (18 NASH vs 12 steatosis) were analyzed. The needle core biopsies were subjected to routine histological examination and stained immunohistochemically for adiponectin, adiponectin receptor I (adipoRI) and receptor II (adipoRII). RESULTS: The two groups were comparable with respect to body mass index, age and gender distribution. The expression of adiponectin decreased in liver biopsies with NASH as compared to those with simple steatosis (1.61 +/- 0.70 vs 2.25 +/- 0.75, P = 0.028). Spearman's rank correlation coefficient analysis showed that the staining intensity of adiponectin negatively correlated with the grade of inflammation (r = -0.368, P = 0.045) and stage of fibrosis (r = -0.380, P = 0.038). There was no significant difference in expression of adipoRI and adipoRII between the two groups. CONCLUSION: These findings indicate that decreased liver adiponectin expression may play a role in the development and progression of NAFLD, from simple steatosis to NASH, in morbidly obese patients.

Feline adiponectin: molecular structures and plasma concentrations in obese cats.

Adiponectin is an adipokine that is specifically expressed in adipose tissues, directly sensitizes the body to insulin via specific receptors and its decreased plasma concentration is responsible for insulin resistance in obese humans. Diabetes is an important problem also in veterinary medicine, and feline diabetes is very similar to human type 2 diabetes, in which obesity is an important risk factor. In the present study, We obtained cDNA clones corresponding to feline adiponectin and adiponectin receptor 1 (AD-R1), whose nucleotide and deduced amino acid sequences were highly identical to those of other species, especially, the extra-cellular domain of feline AD-R1 was almost identical to that of human AD-R1. Adiponectin mRNA was exclusively detected in the adipose tissue, but AD-R1 was in all tissues tested in this study. Next, plasma samples were collected from 22 cats visiting veterinary practices. They were divided to 2 groups based on a five-point scale body condition score (BCS), such as normal group (BCS ranged from 2.5 through 3.5) and obese group (BCS ranged from 4.0 through 5.0). Plasma adiponectin in obese cats (7.2 +/- 1.5 microg/ml) was significantly lower than that of normal cats (18.0 +/- 3.2 microg/ml). These results suggest that adiponectin may be responsible for insulin function also in the cat, and it can be a target molecule for treatment of obesity and diabetes in cats.

Expression of adiponectin receptors in the brain of adult zebrafish and mouse: Links with neurogenic niches and brain repair.

Adiponectin and its receptors (adipor) have been initially characterized for their role in lipid and glucose metabolism. More recently, adiponectin signaling was shown to display anti-inflammatory effects and to participate in brain homeostasis and neuroprotection. In this study, we investigated adipor gene expression and its regulation under inflammatory conditions in two complementary models: mouse and zebrafish. We demonstrate that adipor1a, adipor1b, and adipor2 are widely distributed throughout the brain of adult fish, in neurons and also in radial glia, behaving as neural stem cells. We also show that telencephalic injury results in a decrease in adipor gene expression, inhibited by an anti-inflammatory treatment (Dexamethasone). Interestingly, adiponectin injection after brain injury led to a consistent decrease (a) in the recruitment of microglial cells at the lesioned site and (b) in the proliferation of neural progenitors, arguing for a neuroprotective role of adiponectin. In a comparative approach, we investigate Adipor1 and Adipor2 gene distribution in the brain of mice and demonstrated their expression in regions shared with fish including neurogenic regions. We also document Adipor gene expression in mice after middle cerebral artery occlusion and lipopolysaccharide injection. In contrast to zebrafish, these inflammatory stimuli do no impact cerebral adiponectin receptor gene expression in mouse. This work provides new insights regarding adipor expression in the brain of fish, and demonstrates evolutionary conserved distribution of adipor with mouse. This is the first report of adipor expression in adult neural stem cells of fish, suggesting a potential role of adiponectin signaling during vertebrate neurogenesis. It also suggests a potential contribution of inflammation in the regulation of adipor in fish.

Preconditioning with partial caloric restriction confers long-term protection against grey and white matter injury after transient focal ischemia.

Caloric restriction (CR) has been extensively examined as a preventative strategy against aging and various diseases, but CR effects on cerebral ischemia are largely unknown. We subjected C57BL6/J mice to ad libitum food access (LF) or a diet restricted to 70% of ad libitum food access (RF) for two to four weeks followed by 60 min of transient focal ischemia (tFCI). RF for four weeks protected against subsequent tFCI-induced infarct. RF improved sensorimotor function after stroke in the foot fault and corner tests, as well as performance in the Morris water maze test. In addition, RF preserved ischemic white matter tract integrity assessed by histology and compound action potential. Sirt1 and Sirt3 were both upregulated in RF ischemic brain, but heterozygous deletion of Sirt1 or knockout of Sirt3 did not alter the protection induced by RF against ischemic injury. RF induced significant release of adiponectin, a hormone related to glucose metabolism. Knockout of adiponectin decreased RF-induced protection after tFCI. These data demonstrate the novel finding that white matter, as well as neurons, benefit from CR prior to cerebral ischemic injury, and that adiponectin may contribute to these protective effects.

Adiponectin and its receptors are expressed in the chicken testis: influence of sexual maturation on testicular ADIPOR1 and ADIPOR2 mRNA abundance.

Adiponectin is an adipokine hormone that influences glucose utilization, insulin sensitivity, and energy homeostasis by signaling through two distinct receptors, ADIPOR1 and ADIPOR2. While adipose tissue is the primary site of adiponectin expression in the chicken, we previously reported that adiponectin and its receptors are expressed in several other tissues. The objectives of the present study are to characterize adiponectin, ADIPOR1, and ADIPOR2 expressions in the chicken testis and to determine whether sexual maturation affects the abundance of testicular adiponectin, ADIPOR1, and ADIPOR2 mRNAs. By RT-PCR and nucleotide sequencing, testicular adiponectin, ADIPOR1, and ADIPOR2 mRNAs were found to be identical to that expressed in the abdominal fat pad. Using anti-chicken adiponectin, ADIPOR1, or ADIPOR2 antibodies and immunohistochemistry, adiponectin-immunoreactive (ir) and ADIPOR1-ir cells were found exclusively in the peritubular cells as well as in Leydig cells. However, ADIPOR2-ir cells were found in the adluminal and luminal compartments of the seminiferous tubules as well as in interstitial cells. In particular, Sertoli cell syncytia, round spermatids, elongating spermatids, spermatozoa, and Leydig cells showed strong ADIPOR2 immunoreactivity. Using quantitative real-time PCR analyses, testicular ADIPOR1 and ADIPOR2 mRNA abundance were found to be 8.3- and 9-fold higher (P<0.01) in adult chickens compared with prepubertal chickens respectively, suggesting that sexual maturation is likely to be associated with an up-regulation of testicular ADIPOR1 and ADIPOR2 gene expressions. Collectively, our results indicate that adiponectin and its receptors are expressed in the chicken testis, where they are likely to influence steroidogenesis, spermatogenesis, Sertoli cell function as well as spermatozoa motility.