The localization of substance P in brain regions that coordinate stress responses and receive convergent monoaminergic innervation suggested that substance P antagonists might have psychotherapeutic properties. Like clinically used antidepressant and anxiolytic drugs, substance P antagonists suppressed isolation-induced vocalizations in guinea pigs. In a placebo-controlled trial in patients with moderate to severe major depression, robust antidepressant effects of the substance P antagonist MK-869 were consistently observed. In preclinical studies, substance P antagonists did not interact with monoamine systems in the manner seen with established antidepressant drugs. These findings suggest that substance P may play an important role in psychiatric disorders.

OBJECTIVEOxyntomodulin (OXM) is a glucagon-like peptide 1 (GLP-1) receptor (GLP1R)/glucagon receptor (GCGR) dual agonist peptide that reduces body weight in obese subjects through increased energy expenditure and decreased energy intake. The metabolic effects of OXM have been attributed primarily to GLP1R agonism. We examined whether a long acting GLP1R/GCGR dual agonist peptide exerts metabolic effects in diet-induced obese mice that are distinct from those obtained with a GLP1R-selective agonist.RESEARCH DESIGN AND METHODSWe developed a protease-resistant dual GLP1R/GCGR agonist, DualAG, and a corresponding GLP1R-selective agonist, GLPAG, matched for GLP1R agonist potency and pharmacokinetics. The metabolic effects of these two peptides with respect to weight loss, caloric reduction, glucose control, and lipid lowering, were compared upon chronic dosing in diet-induced obese (DIO) mice. Acute studies in DIO mice revealed metabolic pathways that were modulated independent of weight loss. Studies in Glp1r−/− and Gcgr−/− mice enabled delineation of the contribution of GLP1R versus GCGR activation to the pharmacology of DualAG.RESULTSPeptide DualAG exhibits superior weight loss, lipid-lowering activity, and antihyperglycemic efficacy comparable to GLPAG. Improvements in plasma metabolic parameters including insulin, leptin, and adiponectin were more pronounced upon chronic treatment with DualAG than with GLPAG. Dual receptor agonism also increased fatty acid oxidation and reduced hepatic steatosis in DIO mice. The antiobesity effects of DualAG require activation of both GLP1R and GCGR.CONCLUSIONSSustained GLP1R/GCGR dual agonism reverses obesity in DIO mice and is a novel therapeutic approach to the treatment of obesity.

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Structural modifications requiring novel synthetic chemistry were made to the morpholine acetal human neurokinin-1 (hNK-1) receptor antagonist 4, and this resulted in the discovery of 2-(R)-(1-(R)-3, 5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluoro)phenyl-4-(3-ox o-1 ,2,4-triazol-5-yl)methyl morpholine (17). This modified compound is a potent, long-acting hNK-1 receptor antagonist as evidenced by its ability to displace [125I]Substance P from hNK-1 receptors stably expressed in CHO cells (IC50 = 0.09 +/- 0.06 nM) and by the measurement of the rates of association (k1 = 2.8 +/- 1.1 x 10(8) M-1 min-1) and dissociation (k-1 = 0.0054 +/- 0.003 min-1) of 17 from hNK-1 expressed in Sf9 membranes which yields Kd = 19 +/- 12 pM and a t1/2 for receptor occupancy equal to 154 +/- 75 min. Inflammation in the guinea pig induced by a resiniferatoxin challenge (with NK-1 receptor activation mediating the subsequent increase in vascular permeability) is inhibited in a dose-dependent manner by the oral preadmininstration of 17 (IC50 (1 h) = 0.008 mg/kg; IC90 (24 h) = 1.8 mg/kg), indicating that this compound has good oral bioavailbility and peripheral duration of action. Central hNK-1 receptor stimulation is also inhibited by the systemic preadministration of 17 as shown by its ability to block an NK-1 agonist-induced foot tapping response in gerbils (IC50 (4 h) = 0.04 +/- 0.006 mg/kg; IC50 (24 h) = 0.33 +/- 0.017 mg/kg) and by its antiemetic actions in the ferret against cisplatin challenge. The activity of 17 at extended time points in these preclinical animal models sets it apart from earlier morpholine antagonists (such as 4), and the piperidine antagonists 2 and 3 and could prove to be an advantage in the treatment of chronic disorders related to the actions of Substance P. In part on the basis of these data, 17 has been identified as a potential clinical candidate for the treatment of peripheral pain, migraine, chemotherapy-induced emesis, and various psychiatric disorders.

The ratio of GLP-1/glucagon receptor (GLP1R/GCGR) co-agonism that achieves maximal weight loss without evidence of hyperglycemia was determined in diet-induced obese (DIO) mice chronically treated with GLP1R/GCGR co-agonist peptides differing in their relative receptor agonism. Using glucagon-based peptides, a spectrum of receptor selectivity was achieved by a combination of selective incorporation of GLP-1 sequences, C-terminal modification, backbone lactam stapling to stabilize helical structure, and unnatural amino acid substitutions at the N-terminal dipeptide. In addition to α-amino-isobutyric acid (Aib) substitution at position two, we show that α,α'-dimethyl imidazole acetic acid (Dmia) can serve as a potent replacement for the highly conserved histidine at position one. Selective site-specific pegylation was used to further minimize enzymatic degradation and provide uniform, extended in vivo duration of action. Maximal weight loss devoid of any sign of hyperglycemia was achieved with a co-agonist comparably balanced for in vitro potency at murine GLP1R and GCGR. This peptide exhibited superior weight loss and glucose lowering compared to a structurally matched pure GLP1R agonist, and to co-agonists of relatively reduced GCGR tone. Any further enhancement of the relative GCGR agonist potency yielded increased weight loss but at the expense of elevated blood glucose. We conclude that GCGR agonism concomitant with GLP1R agonism constitutes a promising approach to treatment of the metabolic syndrome. However, the relative ratio of GLP1R/GCGR co-agonism needs to be carefully chosen for each species to maximize weight loss efficacy and minimize hyperglycemia.