ABSTRACT
Diacylglycerol acyltransferase-1 (DGAT1) is a potential therapeutic target for treatment of obesity and related metabolic diseases. However, the degree of DGAT1 inhibition required for metabolic benefits is unclear. Here we show that partial DGAT1 deficiency in mice suppressed postprandial triglyceridemia, led to elevations in glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) only following meals with very high lipid content, and did not protect from diet-induced obesity. Maximal DGAT1 inhibition led to enhanced GLP-1 and PYY secretion following meals with physiologically relevant lipid content. Finally, combination of DGAT1 inhibition with dipeptidyl-peptidase-4 (DPP-4) inhibition led to further enhancements in active GLP-1 in mice and dogs. The current study suggests that targeting DGAT1 to enhance postprandial gut hormone secretion requires maximal inhibition, and suggests combination with DPP-4i as a potential strategy to develop DGAT1 inhibitors for treatment of metabolic diseases.
Subject(s)
Diacylglycerol O-Acyltransferase/genetics , Gastrointestinal Hormones/metabolism , Gastrointestinal Tract/metabolism , Postprandial Period , Animals , Base Sequence , Diacylglycerol O-Acyltransferase/deficiency , Diacylglycerol O-Acyltransferase/metabolism , Diet , Dipeptidyl Peptidase 4/genetics , Dipeptidyl Peptidase 4/metabolism , Dogs , Enzyme Activation , Female , Gastric Emptying/genetics , Gene Dosage , Gene Expression Regulation , Gene Order , Genotype , Glucagon-Like Peptide 1/metabolism , Lipid Metabolism , Male , Mice , Mice, Knockout , Molecular Sequence Data , Triglycerides/bloodABSTRACT
Mitochondrial dysfunction is increasingly associated with disease states. These organelles, responsible for adenosine triphosphate production, have been targeted for improved function in such diseases as Parkinson's, Alzheimer's, type 2 diabetes, and sarcopenia. In addition, the importance of determining if a clinical drug candidate adversely effects mitochondria function, which could lead to overt toxicity, has been recognized. Hence, assays that measure mitochondria activity have become essential in early stage drug development. Limitations of current assays that measure mitochondria membrane potential have prohibited the high-throughput performance necessary to screen current chemical space. Here, we describe a homogeneous assay to measure mitochondria membrane potential that can utilize either adherent or suspension cell types. The assay has been miniaturized to 1,536-well plate format, and was used to perform a fully automated robotic high-throughput screen of a small molecule chemical library.
Subject(s)
Biological Assay/methods , Membrane Potential, Mitochondrial/drug effects , Membrane Potentials/drug effects , Mitochondria/drug effects , Animals , CHO Cells , Carbonyl Cyanide m-Chlorophenyl Hydrazone/metabolism , Coloring Agents/metabolism , Cricetinae , Drug Evaluation, Preclinical/methods , Drug-Related Side Effects and Adverse Reactions/metabolism , High-Throughput Screening Assays , Humans , Jurkat Cells , Luminescent Measurements , Miniaturization , Mitochondria/metabolism , Proton Ionophores/metabolism , Rhodamines/metabolism , Time FactorsABSTRACT
Design, syntheses and structure-activity relationships of N-acetylated piperazine privileged structures containing MC4R agonist compounds were described. The most potent derivatives were low nM MC4R selective full agonists. Several compounds from the series had modest pharmacokinetic properties.
Subject(s)
Ligands , Receptor, Melanocortin, Type 4/agonists , Animals , Humans , Piperazine , Piperazines/chemical synthesis , Piperazines/chemistry , Piperazines/pharmacokinetics , Rats , Rats, Sprague-Dawley , Receptor, Melanocortin, Type 4/metabolism , Structure-Activity RelationshipABSTRACT
SAR about the piperidine core in a series of MC4R agonists is described. A number of alkyl substituents that furnish compounds with good affinity and functional potency are reported.
Subject(s)
Alkanes/pharmacology , Piperidines/chemistry , Piperidines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Receptor, Melanocortin, Type 4/metabolism , Alkanes/chemical synthesis , Alkanes/chemistry , Amides/chemistry , Humans , Molecular Structure , Nitriles/chemistry , Piperidines/chemical synthesis , Structure-Activity Relationship , Tetrazoles/chemistryABSTRACT
A novel isoquinuclidine containing selective melanocortin subtype-4 receptor small molecule agonist, 3 (RY764), is reported. Its in vivo characterization revealed mechanism-based food intake reduction and erectile activity augmentation in rodents.
Subject(s)
Aza Compounds/pharmacology , Eating/drug effects , Penile Erection/drug effects , Piperazines/pharmacology , Piperidines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Animals , Aza Compounds/chemical synthesis , Humans , Male , Microsomes, Liver/metabolism , Piperazines/chemistry , Piperidines/chemical synthesis , Protein Binding , Quinuclidines/chemistry , Rats , Rats, Sprague-Dawley , Rodentia , Structure-Activity Relationship , Time FactorsABSTRACT
We report the discovery and optimization of substituted 2-piperazinecarboxamides as potent and selective agonists of the melanocortin subtype-4 receptor. The 5- and 6-alkylated piperazine compounds exhibit low bioactivation potential as measured by covalent binding in microsome preparations.
Subject(s)
Piperazines/chemistry , Piperazines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Humans , Piperazines/metabolism , Receptor, Melanocortin, Type 4/metabolism , Structure-Activity RelationshipABSTRACT
We report the discovery and optimization of substituted 2-piperazinecarboxamides as potent and selective agonists of the melanocortin subtype-4 receptor. Further in vivo development of lead agonist, MB243, is disclosed.
Subject(s)
Piperazines/pharmacology , Piperidines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Animals , Dogs , Erectile Dysfunction/drug therapy , Haplorhini , Male , Mice , Obesity/drug therapy , Piperazines/chemistry , Piperazines/pharmacokinetics , Piperazines/therapeutic use , Piperidines/chemistry , Piperidines/pharmacokinetics , Piperidines/therapeutic use , RatsABSTRACT
The melanocortin 4 receptor (MC4-R) is a Galpha s-coupled receptor known to increase cAMP production following agonist stimulation. We demonstrate that the mitogen-activated protein kinases p42 (ERK2) and p44 (ERK1) are also activated by MC4-R following treatment with the MC4-R agonist NDP-alpha-MSH in stably transfected CHO-K1 cells. This time- and dose-dependent response is abolished by the MC4-R antagonist SHU-9119. p42/p44 MAPK activation is blocked by the phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002 but not by the protein kinase A (PKA) inhibitor Rp-cAMPS, indicating that that signal activating the p42/p44 MAPK pathway is conveyed through inositol triphosphate.
Subject(s)
Mitogen-Activated Protein Kinase 3/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Receptor, Melanocortin, Type 4/antagonists & inhibitors , Androstadienes/pharmacology , Animals , CHO Cells , Cells, Cultured , Chromones/pharmacology , Cricetinae , Cyclic AMP/analogs & derivatives , Cyclic AMP/pharmacology , Cyclic AMP-Dependent Protein Kinases/pharmacology , Enzyme Activation , Enzyme Inhibitors/pharmacology , Melanocyte-Stimulating Hormones/pharmacology , Morpholines/pharmacology , Protein Kinase Inhibitors/pharmacology , Receptor, Melanocortin, Type 4/metabolism , Signal Transduction , WortmanninABSTRACT
The discovery and optimization of a new class of non-peptidyl, pyridazinone derived melanocortin subtype-4 receptor agonists is disclosed.
Subject(s)
Pyridazines/chemical synthesis , Pyridazines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Animals , Binding Sites , Humans , Indicators and Reagents , Kinetics , Mice , Molecular Conformation , Pyridazines/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
By using a combination of genetic, pharmacological, and anatomical approaches, we show that the melanocortin 4 receptor (MC4R), implicated in the control of food intake and energy expenditure, also modulates erectile function and sexual behavior. Evidence supporting this notion is based on several findings: (i) a highly selective non-peptide MC4R agonist augments erectile activity initiated by electrical stimulation of the cavernous nerve in wild-type but not Mc4r-null mice; (ii) copulatory behavior is enhanced by administration of a selective MC4R agonist and is diminished in mice lacking Mc4r; (iii) reverse transcription (RT)-PCR and non-PCR based methods demonstrate MC4R expression in rat and human penis, and rat spinal cord, hypothalamus, brainstem, pelvic ganglion (major autonomic relay center to the penis), but not in rat primary corpus smooth muscle cavernosum cells; and (iv) in situ hybridization of glans tissue from the human and rat penis reveal MC4R expression in nerve fibers and mechanoreceptors in the glans of the penis. Collectively, these data implicate the MC4R in the modulation of penile erectile function and provide evidence that MC4R-mediated proerectile responses may be activated through neuronal circuitry in spinal cord erectile centers and somatosensory afferent nerve terminals of the penis. Our results provide a basis for the existence of MC4R-controlled neuronal pathways that control sexual function.
