Vasopressin V1a and V1b receptor modulators: a patent review (2012 – 2014)

Vasopressin receptor antagonists: a patent summary (2018-2022)

INTRODUCTION

Arginine-vasopressin hormone (AVP) is a key regulator in many essential physiological processes. The effect of AVP is mediated through three receptors within the body, these are the G protein-coupled vasopressin receptors, namely V1a, V1b (also called V3), and V2. Numerous studies investigated the role of these receptors in certain pathological conditions; therefore, stimulation or inhibition of these receptors may be a treatment option in these diseases.

AREAS COVERED

In this manuscript, the authors summarize recent patent activity (2018-2022) associated with vasopressin receptor antagonists (selective V1a or V2, and dual-acting V1a/V2), focusing mostly on chemical structures, their modifications, and potential clinical applications. Patent search was carried out using SciFinder, Espacenet, Patentscope, Cortellis Competitive Intelligence, and Derwent Innovation databases.

EXPERT OPINION

In recent years, vasopressin receptor antagonists have been in the spotlight of drug discovery, especially V1a selective molecules. Publishing balovaptan as a possible treatment for autism spectrum disorder (ASD), greatly increased the interest in CNS-acting vasopressin antagonists. In addition, peripherally active selective V2 and dual-acting V1a/V2 antagonists have also been developed. Although clinical trials were unsuccessful in many cases, there is still potential in the research of vasopressin receptor antagonists as shown by several currently ongoing clinical trials.

Synthesis and Characterization of New V1A Antagonist Compounds: The Separation of Four Atropisomeric Stereoisomers

A new class of selective vasopressin receptor 1A (V_1A) antagonists was identified, where "methyl-scan" was performed around the benzene ring of the 5-hydroxy-triazolobenzazepine core. This led to the synthesis of two 10-methyl derivatives, each possessing a chiral axis and a stereogenic center. The four atropisomeric stereoisomers (involving two enantiomer pairs and atropisomeric diastereomers) could be successfully isolated and spectroscopically characterized. According to the in vitro pharmacological profiles of the compounds, the human V_1A receptor has a strong preference toward the isomers having an aR axial chirality, the most active isomer being the aR,5S isomer. Furthermore, the structure-activity relationships obtained for the isomers and for the newly synthesized analogues could be tentatively explained by an in silico study.

Discovery of New Heterocyclic Ring Systems as Novel and Potent V1A Receptor Antagonists

Autism spectrum disorder is a neurodevelopmental disease with increasing occurrence. Recent studies focus on the development of novel V_1A receptor antagonists which can influence the core symptoms of autism through the AVP pathway. In this study, we describe the synthesis of new heterocyclic ring systems. These are a novel class of brain-penetrating V_1A antagonists with improved metabolic stability and in vivo potency. The efficacy of the compounds was strongly influenced by the position of the chlorine atom, suggesting halogen bond formation between the ligands and the V_1A receptor.

Tolvaptan attenuated brain edema in experimental intracerebral hemorrhage

Arginine-vasopressin (AVP) is believed to be positively correlated with the brain edema formation, but the underlying mechanism is still unclear. In this study, we explored the role of the V2 receptors antagonist tolvaptan on brain edema following intracerebral hemorrhage (ICH) with a rat model. Animals were randomly given tolvaptan or vehicle through oral gavage at 12 h, 36 h, and 60 h after ICH surgery. Brain swelling (%), brain water content(BWC), neurological scores, Evans blue fluorescence and blood-brain barrier (BBB) tight junction proteins were measured to evaluate the effect of tolvaptan in ICH. We found that tolvaptan alleviated the brain swelling (%), decreased the BWC growth, and attenuated the neurological deficits after ICH (p < 0.05, vs vehicle). What's more, tolvaptan increased the expression of ZO-1 and occludin (p < 0.05, vs vehicle), which might be attributed to the down-regulated effects of tolvaptan on MMP-9. These results provided evidence supporting the use of tolvaptan for ICH-induced brain edema. Large animal experiments are required to further explore the efficacy and mechanism of tolvaptan in ICH treatment.

Arginine Vasopressin and Arginine Vasopressin Receptor 1b Involved in Electroacupuncture-Attenuated Hypothalamic-Pituitary-Adrenal Axis Hyperactivity in Hepatectomy Rats

Objective

The study aims to know the effect of electroacupuncture (EA) in maintenance of the homeostasis of the neuroendocrine system in hepatectomy rats and the involvement of arginine vasopressin (AVP) signaling in hypothalamus after EA was observed.

Materials and Methods

Rats were randomly assigned to four groups, including the intact group, model group, sham‐EA group, and EA group. EA was given during the perioperative period at the Zusanli (ST36) and Sanyinjiao (SP6) points after hepatectomy. The serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels were detected via radioimmunoassay. The expression of AVP, arginine vasopressin receptor 1a (AVPR1a), arginine vasopressin receptor 1b (AVPR1b), and glucocorticoid receptor (GR) was detected by Western blot after surgery.

Results

Compared with the intact group, the ACTH and CORT levels in the serum of model group were increased, whereas the ACTH and CORT levels were decreased in the EA group compared with the model group. Moreover, AVP and AVPR1b protein levels in the pituitary gland were increased in the model group and decreased in the EA group. Further, a distinct increase in the AVP and AVPR1a protein levels was observed in the model group, whereas they were significantly decreased in the EA group. Blockade of AVPR1b by nelivaptan reduced the increase of ACTH and CORT. D [Leu⁴, Lys⁸] vasopressin can inhibit the effect of EA in rectification of the hyperactivity of the hypothalamic‐pituitary‐adrenal (HPA) axis.

Conclusions

EA application at ST36 and SP6 can ameliorate the hyperactivity of the HPA axis via AVP signaling during the perioperative period.