Adiponectin, an adipocytokine, has been identified in adipose tissue, and its receptors are widely distributed in many tissues, including the liver. The present study was performed to clarify the role of adiponectin in lipopolysaccharide (LPS)-induced liver injury using KK-Ay obese mice. We analyzed the effects of adiponectin pretreatment on liver injury induced by d-galactosamine/LPS (GalN/LPS) in KK-Ay obese mice. GalN/LPS treatment induced significant increases in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the blood, apoptotic and necrotic changes in hepatocytes, and/or showed a high degree of lethality. The GalN/LPS-induced liver injury was more pronounced in KK-Ay obese mice than in lean controls. Pretreatment with adiponectin ameliorated the GalN/LPS-induced elevation of serum AST and ALT levels and the apoptotic and necrotic changes in hepatocytes, resulting in a reduction in lethality. In addition, pretreatment with adiponectin attenuated the GalN/LPS-induced increases in serum and hepatic tumor necrosis factor α (TNF-α) levels and increased peroxisome proliferator-activated receptor (PPAR) α messenger RNA expression in the liver. Furthermore, abdominal macrophages from KK-Ay obese mice pretreated with adiponectin in vitro exhibited decreased LPS-induced TNF-α production compared with controls. Finally, adiponectin pretreatment also ameliorated TNF-α-induced liver injury. In conclusion, these findings suggest that adiponectin prevents LPS-induced hepatic injury by inhibiting the synthesis and/or release of TNF-α of KK-Ay obese mice. (Hepatology 2004;40:177-184.)

Apelin, the endogenous ligand of the APJ receptor, has been identified in a variety of tissues, including stomach, heart, skeletal muscle, and white adipose tissue. We sought to clarify the effects of apelin on body adiposity and the expression of uncoupling proteins (UCPs) in C57BL/6 mice. Treatment with ip apelin at a dose of 0.1 μmol/kg·d for 14 d decreased the weight of white adipose tissue and serum levels of insulin and triglycerides, compared with controls, without influencing food intake. Apelin treatment also decreased body adiposity and serum levels of insulin and triglycerides in obese mice fed a high-fat diet. Apelin increased the serum adiponectin level and decreased that of leptin. Additionally, apelin treatment increased mRNA expression of UCP1, a marker of peripheral energy expenditure, in brown adipose tissue (BAT) and of UCP3, a regulator of fatty acid export, in skeletal muscle. In addition, immunoblot bands and relative densities of UCP1 content in BAT were also higher in the apelin group than controls. Furthermore, apelin treatment increased body temperature and O₂ consumption and decreased the respiratory quotient. In conclusion, apelin appears to regulate adiposity and lipid metabolism in both lean and obese mice. In addition, apelin regulates insulin resistance by influencing the circulating adiponectin level, the expression of BAT UCP1, and energy expenditure in mice.

Histamine H₁ receptors (H₁-Rs) are found in peripheral tissues and in regions of the hypothalamus that are concerned with regulating body composition. In the present study, we investigated the detailed mechanisms of histamine H₁-Rs in the development of obesity. Histamine H₁-R knockout (H1KO) mice gradually developed mature-onset obesity, which was accompanied by hyperphagia and decreased expression of uncoupling protein-1 (UCP-1) mRNA. Both younger nonobese (12-week-old) and older obese (48-week-old) H1KO mice exhibited impairment of the responsiveness to the leptin. In addition, disruption of the diurnal rhythm of feeding occurred before the onset of obesity in H1KO mice. Correction of these abnormal feeding rhythms by means of scheduled feeding caused a reduction in obesity and associated metabolic disorders in H1KO mice. Furthermore, central administration of a histamine H₁-R agonist affected feeding behavior, body weight, and c-fos-like immunoreactivity in the hypothalamus. Taken together, these findings suggest that histamine H₁-Rs are crucial for the regulation of feeding rhythm and in mediating the effects of leptin. Early disruption of H₁-R-mediated functions in H1KO mice may lead to hyperphagia and decreased expression of UCP-1 mRNA, which may contribute to the development of obesity in these animals. In addition, centrally acting histamine H₁-R may be a novel therapeutic target for the treatment of obesity and related metabolic disorders.

Anti‐programmed cell death‐1 (PD‐1) antibodies are regarded as a risk factor for insulin‐dependent diabetes mellitus as a side‐effect. While a small number of cases have been reported, evidence remains limited. This is the first report of an Asian patient developing insulin‐dependent diabetes during anti‐PD‐1 therapy. A 55‐year‐old euglycemic woman receiving nivolumab for malignant melanoma showed abrupt onset of ketonuria, and elevated levels of plasma glucose (580 mg/dL) and hemoglobin A1c (7.0%). Over the next 2 weeks, serum C‐peptide levels fell below the limit of detection. Islet autoantibodies were negative, and the patient showed a human leukocyte antigen haplotype associated with type 1 diabetes. Anti‐PD‐1 therapy can cause rapid onset of insulin‐dependent diabetes, possibly because of inappropriate activation of T cells. Human leukocyte antigen haplotypes might be related to the onset of this disease. Physicians should be aware of this serious adverse event and carry out routine blood glucose testing during anti‐PD‐1 therapy.

To examine the peripheral and central roles of adiponectin in energy intake and expenditure, we investigated the effects of adiponectin on food intake, adiposity, sympathetic nerve activity (SNA), and mRNA expressions of uncoupling protein (UCP) in the brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle in agouti yellow (A^y/a) obese mice. Intraperitoneal administration of adiponectin (1.5 mg/kg for 7 days) attenuated body weight gain and reduced visceral adiposity in A^y/a obese mice compared with PBS-treated controls. In addition, adiponectin treatment increased the expression of UCP1 mRNA in BAT, UCP2 mRNA in WAT, and UCP3 mRNA in skeletal muscle compared with PBS-treated A^y/a controls. Acute peripheral administration of adiponectin (1.5 mg/kg, one injection) also increased SNA in the BAT accompanied by an increase in rectal temperature. Finally, these above responses as well as expression of c-Fos–like immunohistochemistry in the hypothalamus were not induced by central application of adiponectin (0–15 μg/kg). Taken together, adiponectin effectively regulated visceral adiposity, SNA, and UCP mRNA expression peripherally, suggesting that this substance can be used as a therapeutic tool, administered peripherally, in the treatment of visceral obesity and related metabolic disorders.