ABSTRACT
In this paper, we describe the discovery and optimization of a new chemotype of isoform selective PI3Kγ inhibitors. Starting from an HTS hit, potency and physicochemical properties could be improved to give compounds such as 15, which is a potent and remarkably selective PI3Kγ inhibitor with ADME properties suitable for oral administration. Compound 15 was advanced into in vivo studies showing dose-dependent inhibition of LPS-induced airway neutrophilia in rats when administered orally.
Subject(s)
Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Phosphoinositide-3 Kinase Inhibitors , Adenosine Triphosphate/metabolism , Administration, Oral , Animals , Binding Sites , Biological Availability , Crystallography, X-Ray , Dogs , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical/methods , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/pharmacokinetics , Humans , Isoenzymes , Leukocyte Disorders/chemically induced , Leukocyte Disorders/drug therapy , Lipopolysaccharides/toxicity , Phosphatidylinositol 3-Kinases/chemistry , Phosphatidylinositol 3-Kinases/metabolism , Phthalimides/chemistry , Rats , Structure-Activity RelationshipABSTRACT
Relaxin family peptide receptor 3 (RXFP3) is a G-protein coupled receptor mainly expressed in the brain and involved in appetite regulation. Previous studies in lean Wistar rats during the light phase have shown that the chimeric peptide R3(BΔ23-27)R/I5 suppresses food intake stimulated by an RXFP3 agonist, but has no effect on food intake when administered alone. We wanted to further investigate if R3(BΔ23-27)R/I5 on its own is able to antagonize the basal tone of the relaxin-3/RXFP3 system and therefore characterized the pharmacology of R3(BΔ23-27)R/I5 in vivo and in vitro. R3(BΔ23-27)R/I5 was intracerebroventricularly (ICV) injected in diet induced obese (DIO) Wistar rats and food intake was automatically measured during the dark phase when feeding drive is high. In our hands, R3(BΔ23-27)R/I5 alone did not have a significant effect on food intake during 24h following administration. Consistent with previous results, relaxin-3 stimulated food intake in satiated lean rats. R3(BΔ23-27)R/I5 was characterized in vitro using [(35)S]-GTPγS binding and cAMP assays, both assessing Gαi-protein mediated signalling, and dynamic mass redistribution (DMR) assays capturing the integrated cell response. R3(BΔ23-27)R/I5 showed partial agonist activity in all three functional assays. Thus, since R3(BΔ23-27)R/I5 displays partial RXFP3 agonist properties in vitro, further in vivo studies including additional tool compounds are needed to address if antagonizing relaxin-3/RXFP3 basal tone is a therapeutically relevant mechanism to regulate food intake and body weight.
Subject(s)
Anti-Obesity Agents/pharmacology , Peptides/pharmacology , Receptors, G-Protein-Coupled/agonists , Receptors, Peptide/agonists , Recombinant Proteins/pharmacology , Animals , Anti-Obesity Agents/therapeutic use , Diet, High-Fat/adverse effects , Drive , Eating/drug effects , Eating/psychology , Male , Obesity/drug therapy , Obesity/etiology , Obesity/physiopathology , Obesity/psychology , Peptides/therapeutic use , Rats , Rats, Wistar , Recombinant Proteins/therapeutic useABSTRACT
The metabotropic glutamate receptor 5 (mGluR5) has been suggested to modulate energy balance. For example, mGluR5 antagonists inhibit food intake in rodents and mGluR5 knockout mice resist diet-induced obesity. However, nonspecific effects can reduce food intake. Thus, to further support the role of mGluR5 in feeding behaviour, we evaluated if the mGluR5 agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG) would induce the opposite effect, i.e. increased food intake in rats. Intracerebroventricularly injected CHPG (0.5-1.5 micromol) induced a dose-dependent stimulation of food intake (349% increase at 2 h with 1.5 micromol). The mGluR5 antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (10 mg/kg intraperitoneally) reduced 24 h food intake, without altering CHPG-induced feeding. These findings further support a physiologically relevant role of mGluR5 in appetite regulation.
