Adriforant is a functional antagonist of histamine receptor 4 and attenuates itch and skin inflammation in mice.

Background: Histamine has been postulated to play a role in atopic dermatitis via histamine receptor 4, mediating pruritic and inflammatory effects. The H4R antagonist adriforant (PF-3893787 or ZPL389) indicated clinical efficacy in a Ph2a study in atopic dermatitis. Preclinical investigations of adriforant had been scarce as experiments in transfectants with H4R from several species suggested partial agonism, not seen in human cells.

Discovery and Optimization of Novel SUCNR1 Inhibitors: Design of Zwitterionic Derivatives with a Salt Bridge for the Improvement of Oral Exposure.

G-protein-coupled receptor SUCNR1 (succinate receptor 1 or GPR91) senses the citric cycle intermediate succinate and is implicated in various pathological conditions such as rheumatoid arthritis, liver fibrosis, or obesity. Here, we describe a novel SUCNR1 antagonist scaffold discovered by high-throughput screening. The poor permeation and absorption properties of the most potent compounds, which were zwitterionic in nature, could be improved by the formation of an internal salt bridge, which helped in shielding the two opposite charges and thus also the high polarity of zwitterions with separated charges.

Structural basis of species-selective antagonist binding to the succinate receptor.

The tricarboxylic acid cycle intermediate succinate is involved in metabolic processes and plays a crucial role in the homeostasis of mitochondrial reactive oxygen species. The receptor responsible for succinate signalling, SUCNR1 (also known as GPR91), is a member of the G-protein-coupled-receptor family and links succinate signalling to renin-induced hypertension, retinal angiogenesis and inflammation. Because SUCNR1 senses succinate as an immunological danger signal-which has relevance for diseases including ulcerative colitis, liver fibrosis, diabetes and rheumatoid arthritis-it is of interest as a therapeutic target.

Blunted 5-HT receptor-mediated responses and antidepressant-like behavior in mice lacking the GABA but not GABA subunit isoforms.

Rationale: There is accumulating evidence for a role of GABA receptors in depression. GABA receptors are heterodimers of GABA and GABA receptor subunits. The predominant GABA subunit isoforms are GABA and GABA.

Antidepressants influence somatostatin levels and receptor pharmacology in brain.

This study investigated how the administration (acute and chronic) of the antidepressants citalopram and desmethylimipramine (DMI) influences somatostatin (somatotropin release inhibitory factor, SRIF) levels and SRIF receptor density (sst(1-5)) in rat brain. Animals received either of the following treatments: (1) saline for 21 days (control group), (2) saline for 20 days and citalopram or DMI for 1 day (citalopram or DMI acute groups), (3) citalopram or DMI for 21 days (citalopram or DMI chronic groups). Somatostatin levels were determined by radioimmunoassay.