Novel oxytocin receptor agonists and antagonists: a patent review (2002 - 2013)

Emotional and cognitive changes in chronic kidney disease

Chronic kidney disease (CKD) leads to cognitive impairment and emotional changes. However, the precise mechanism underlying the crosstalk between the kidneys and the nervous system is not fully understood. Inflammation and cerebrovascular disease can influence the development of depression in CKD. CKD is one of the strongest risk factors for cognitive impairment. Moreover, cognitive impairment occurs in CKD as patients experience the dysregulation of several brain functional domains due to damage caused to multiple cortical regions and to subcortical modulatory neurons. The differences in structural brain changes between CKD and non-CKD dementia may be attributable to the different mechanisms that occur in CKD. The kidney and brain have similar anatomical vascular systems, which may be susceptible to traditional risk factors. Vascular factors are assumed to be involved in the development of cognitive impairment in patients with CKD. Vascular injury induces white matter lesions, silent infarction, and microbleeds. Uremic toxins may also be directly related to cognitive impairment in CKD. Many uremic toxins, such as indoxyl sulfate, are likely to have an impact on the central nervous system. Further studies are required to identify therapeutic targets to prevent changes in the brain in patients with CKD.

Oxytocin and Related Peptide Hormones: Candidate Anti-Inflammatory Therapy in Early Stages of Sepsis

Sepsis is a potentially life-threatening systemic inflammatory syndrome characterized by dysregulated host immunological responses to infection. Uncontrolled immune cell activation and exponential elevation in circulating cytokines can lead to sepsis, septic shock, multiple organ dysfunction syndrome, and death. Sepsis is associated with high re-hospitalization and recovery may be incomplete, with long term sequelae including post-sepsis syndrome. Consequently, sepsis continues to be a leading cause of morbidity and mortality across the world. In our recent review of human chorionic gonadotropin (hCG), we noted that its major properties including promotion of fertility, parturition, and lactation were described over a century ago. By contrast, the anti-inflammatory properties of this hormone have been recognized only more recently. Vasopressin, a hormone best known for its anti-diuretic effect, also has anti-inflammatory actions. Surprisingly, vasopressin's close cousin, oxytocin, has broader and more potent anti-inflammatory effects than vasopressin and a larger number of pre-clinical studies supporting its potential role in limiting sepsis-associated organ damage. This review explores possible links between oxytocin and related octapeptide hormones and sepsis-related modulation of pro-inflammatory and anti-inflammatory activities.

Oxytocin in the Male Reproductive Tract; The Therapeutic Potential of Oxytocin-Agonists and-Antagonists

In this review, the role of oxytocin and oxytocin-like agents (acting via the oxytocin receptor and belonging to the oxytocin-family) in the male reproductive tract is considered. Previous research (dating back over 60 years) is revised and connected with recently found aspects of the role oxytocin plays in male reproductive health. The local expression of oxytocin and its receptor in the male reproductive tract of different species is summarized. Colocalization and possible crosstalk to other agents and receptors and their resulting effects are discussed. The role of the newly reported oxytocin focused signaling pathways in the male reproductive tract, other than mediating contractility, is critically examined. The structure and effect of the most promising oxytocin-agonists and -antagonists are reviewed for their potential in treating male disorders with origins in the male reproductive tract such as prostate diseases and ejaculatory disorders.

Quantification of receptor activation by oxytocin and vasopressin in endocytosis-coupled bioluminescence reduction assay using nanoKAZ

Oxytocin (OXT) and arginine vasopressin (AVP) are structurally similar neuropeptide hormones that function as neurotransmitters in the brain, and have opposite key roles in social behaviors. These peptides bind to their G protein-coupled receptors (OXTR and AVPRs), inducing calcium ion-dependent signaling pathways and endocytosis of these receptors. Because selective agonists and antagonists for these receptors have been developed as therapeutic and diagnostic agents for diseases such as psychiatric disorders, facile methods are in demand for the evaluation of selectivity between these receptors. In this study, we developed a quantitative assay for OXT- and AVP-induced endocytosis of their receptors. The mutated Oplophorus luciferase, nanoKAZ, was fused to OXTR and AVPRs to enable rapid quantification of agonist-induced endocytosis by bioluminescence reduction. Agonist stimulation significantly decreases bioluminescence of nanoKAZ-fused receptors in living cells. Using this system, we evaluated clinically used OXTR antagonist atosiban and a reported pyrazinyltriazole derivative, hereby designated as PF13. Atosiban acted as an antagonist of AVPR1a, as well as an agonist for AVPR1b, whereas PF13 antagonized OXTR more selectively than atosiban, as reported previously. This paper shows a strategy for quantification of agonist-induced endocytosis of OXTR and AVPRs, and confirms its potent utility in the evaluation of agonists and antagonists.

Molecular modeling and docking studies of the oxytocin receptor

Aim: Low oxytocin (OT) level is involved in a number of psychiatric diseases, indicating that OT could be used to aid treating these disorders. OT itself is unable to cross the blood–brain barrier, and development of new small nonpeptide drugs targeting the OT receptor (OXTR) may be beneficial for treating mental disorders. Results & methodology: Three OXTR models were constructed based on crystallized homologous proteins (Protein Data Bank [PDB]: 2Y00, PDB: 4BVN and PDB: 4LDE). The abilities of the models to discriminate between true binders and decoys were analyzed using receiver operating characteristics curves, and the 4LDE-based model gave the best result. Conclusion: The present study demonstrates that the 4LDE-based model may be suitable as a tool for the development of novel drugs targeting OXTR.

Flexible analogues of WAY-267,464: Synthesis and pharmacology at the human oxytocin and vasopressin 1a receptors

A previously identified, non-peptidic oxytocin (OT) receptor agonist WAY-267,464 (1) and nine novel derivatives (3, 4a-7a, 4b-7b) were synthesised and evaluated in vitro with the aim of systematically exploring hydrogen bonding interactions and ligand flexibility. All analogues were subjected to competition radioligand binding assays at human oxytocin (OT) and arginine vasopressin 1a (V1a) receptors. Physiological activity was determined using whole cell IP1 accumulation assays. Under these conditions, WAY-267,464 had higher affinity for the V1a receptor compared to the OT receptor (8.5x more selective) with poor functional selectivity (2x selective for OT receptor agonism over V1a receptor antagonism). Methylation of the resorcinol moiety (3) reversed the OT receptor pharmacological profile, removing agonist activity and inducing antagonist activity, without altering V1a receptor pharmacology. All flexible tethered derivatives removed OT receptor affinity and activity resulting in the generation of highly selective V1a receptor ligands.