5'-Adenosine monophosphate-activated protein kinase (AMPK) is a master regulator of energy homeostasis in eukaryotes. Despite three decades of investigation, the biological roles of AMPK and its potential as a drug target remain incompletely understood, largely because of a lack of optimized pharmacological tools. We developed MK-8722, a potent, direct, allosteric activator of all 12 mammalian AMPK complexes. In rodents and rhesus monkeys, MK-8722-mediated AMPK activation in skeletal muscle induced robust, durable, insulin-independent glucose uptake and glycogen synthesis, with resultant improvements in glycemia and no evidence of hypoglycemia. These effects translated across species, including diabetic rhesus monkeys, but manifested with concomitant cardiac hypertrophy and increased cardiac glycogen without apparent functional sequelae.

Dipeptidyl peptidase IV (DP-IV), a member of the prolyl oligopeptidase family of peptidases, is involved in the metabolic inactivation of a glucose-dependent insulinotropic hormone, glucagon-like peptide 1 (GLP-1), and other incretin hormones. Here, we investigated the impact of DP-IV deficiency on body weight control and insulin sensitivity in mice. Whereas WT mice displayed accelerated weight gain and hyperinsulinemia when fed a high-fat diet (HFD), mice lacking the gene encoding DP-IV (DP-IV ؊͞؊ ) are refractory to the development of obesity and hyperinsulinemia. Pair-feeding and indirect calorimetry studies indicate that reduced food intake and increased energy expenditure accounted for the resistance to HFD-induced obesity in the DP-IV ؊͞؊ mice. Ablation of DP-IV also is associated with elevated GLP-1 levels and improved metabolic control in these animals, resulting in improved insulin sensitivity, reduced pancreatic islet hypertrophy, and protection against streptozotocin-induced loss of ␤ cell mass and hyperglycemia. Together, these observations suggest that chronic deletion of DP-IV gene has significant impact on body weight control and energy homeostasis, providing validation of DP-IV inhibition as a viable therapeutic option for the treatment of metabolic disorders related to diabetes and obesity.

This study demonstrates that blocking glucagon signalling by targeted Gcgr gene deletion leads to an improvement in metabolic control in this mouse model.

Obesity and insulin resistance are major risk factors for a number of metabolic disorders, such as type 2 diabetes mellitus. Insulin has been suggested to function as one of the adiposity signals to the brain for modulation of energy balance. Administration of insulin into the brain reduces food intake and body weight, and mice with a genetic deletion of neuronal insulin receptors are hyperphagic and obese. However, insulin is also an anabolic factor; when administered systemically, pharmacological levels of insulin are associated with body weight gain in patients. In this study, we investigated the efficacy and feasibility of small molecule insulin mimetic compounds to regulate key parameters of energy homeostasis. Central intracerebroventricular (i.c.v.) administration of an insulin mimetic resulted in a dose-dependent reduction of food intake and body weight in rats, and altered the expression of hypothalamic genes known to regulate food intake and body weight. Oral administration of a mimetic in a mouse model of high-fat diet-induced obesity reduced body weight gain, adiposity and insulin resistance. Thus, insulin mimetics have a unique advantage over insulin in the control of body weight and hold potential as a novel anti-obesity treatment.

An increased contribution of de novo lipogenesis (DNL) may play a role in cases of dyslipidemia and adipose accretion; this suggests that inhibition of fatty acid synthesis may affect clinical phenotypes. Since it is not clear whether modulation of one step in the lipogenic pathway is more important than another, the use of tracer methods can provide a deeper level of insight regarding the control of metabolic activity. Although [H]water is generally considered a reliable tracer for quantifying DNL in vivo (it yields a homogenous and quantifiable precursor labeling), the relatively long half-life of body water is thought to limit the ability of performing repeat studies in the same subjects; this can create a bottleneck in the development and evaluation of novel therapeutics for inhibiting DNL. Herein, we demonstrate the ability to perform back-to-back studies of DNL using [H]water. However, this work uncovered special circumstances that affect the data interpretation, i.e., it is possible to obtain seemingly negative values for DNL. Using a rodent model, we have identified a physiological mechanism that explains the data. We show that one can use [H]water to test inhibitors of DNL by performing back-to-back studies in higher species [i.e., treat nonhuman primates with platensimycin, an inhibitor of fatty acid synthase]; studies also demonstrate the unsuitability of [C]acetate.