Indeed, transplantation of BAT to mice has been shown to decrease body weight and improve glucose metabolism and insulin sensitivity23. its associated diseases, especially diabetes type 2, constitute one of the major public health concerns in most developed societies1. Taking only energetics into account, treatment of obesity by reducing caloric intake and increasing energy expenditure should be simple, however most patients fail to achieve or more important- maintain weight loss goals through diet and exercise NBI-98782 alone2. Therefore , pharmacologic and/or surgical treatment options to support patients in the fight against excessive body weight are increasingly sought for. It is currently known that body weight regulation goes beyond simple energetics and that other metabolic, behavioral, neuroendocrine, and autonomic responses play important roles in maintenance of the amount of fat reserves3. Since its rediscovery in adult humans in the late 2000s, brown adipose tissue (BAT) has attracted a lot of attention as a potential target to combat obesity, and stimuli for its activation have been investigated in both animal models and humans414. As part of the mechanisms of adaptive thermogenesis, BAT enables the release of energy as heat instead of storage as energy molecules by dissociation of mitochondrial substrate oxidation from ATP production, a phenomenon mediated by uncoupling protein 1 (UCP-115), which is present in BAT, but not in white adipose tissue (WAT). Most recently, experimental murine studies reported that diet-induced obesity resulted in impaired glucose tolerance, BAT functional hypoxia and subsequent structural whitening that eventually led to a functional shift from thermogenesis toward lipid NBI-98782 storage16, 17. The loss of functional BAT in obesity might be consistent with the lack of BAT response to both insulin and cold stimulation in obese adults18, whereas exposure to cold in young subjects does stimulate BAT activity4. Preserved spontaneously activated BAT was also significantly higher in patients with low fasting plasma glucose levels ( <93 mg/dl) as compared to patients with glucose levels higher than 103 mg/dl19. However , further knowledge about the relationship between type 2 diabetes mellitus and BAT is still very limited. In this study, we aimed to investigate BAT glucose utilization in a well-established genetic rat model of type 2 diabetes20using18F-FDG PET imaging under hyperinsulinemic-euglycemic NBI-98782 clamping conditions. Rats were set under hyperinsulinemic-euglycemic conditions to stimulated BAT glucose consumption by high serum insulin concentrations during the imaging period2123, furthermore the euglycemic status permitted to avoid interference of different plasma glucose concentrations between diabetic and control animals24. == Methods == == Study approval == Animal studies were IL5RA performed in agreement with the Guide for Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No . 85-23, revised 1996) and in compliance with the German law on the protection of animals. Animal protocols were approved by the local Animal Care and Use Committee (Regierung von Unterfranken, Germany). == Small animal18F-FDG-PET/CT imaging == Ten weeks old male Zucker diabetic fatty (ZDF; n = 11) were randomized into NBI-98782 a no-restriction diet (ZDF-ND) group (n = 6) and a mild calorie restriction (ZDF-CR) group (n = 5), male Zucker lean (ZL) rats served as controls (n = 6) (Charles River, Wilmington, USA). All animal received waterad libitum. Diet intervention consisted in 3 weeks of: standard foodad libitumto ZL lean rats (daily food intake of 20. 29 1 . 97 g); Purina 5008 (protein 23%, fat 6. 5%, carbohydrates 58. 5%, fiber 4% and ash 8%; as recommended by the supplier)ad libitumto ZDF-ND rats (daily food intake of 36. 25 5. 8 g) and 20 g of Purina 5008 per day (the same weight of food ZL lean consumed per day) to ZDF-CR rats, respectively. At 13 weeks of age, ZDF-ND rats (average weight, 356 24 g), ZDF-CR rat (average weight, 354 50 g) and controls (average weight, 290 25 g) underwent18F-FDG-PET at room temperature (23 C) using a dedicated small animal PET scanner (Inveon;.