Effect of the novel histamine H4 receptor antagonist SENS-111 on spontaneous nystagmus in a rat model of acute unilateral vestibular loss

[Research advances in the mechanism of vestibular compensation and treatment]

Unlike other sensory systems, since the vestibular system maintains the tension balance of the entire system in a"push-pull" mode, local dysfunction in the system will cause the balance of the entire system to collapse. Unilateral peripheral vestibular dysfunction will cause severe vestibular symptoms, but it can recover spontaneously within a few days to several weeks. This phenomenon is called "vestibular compensation"（VC）. Since the peripheral vestibular impact in most cases is irreversible, it is widely believed that the central mechanism plays a key role in the vestibular compensation process. Static symptom is fully compensated within a few weeks, which is in parallel with the restored balance in the resting discharge of the vestibular nucleus on both sides; the incomplete compensation of dynamic deficits takes longer and is achieved mainly through the mechanism of sensory substitution and behavioral substitution. Here we briefly reviewed the mechanism of vestibular compensation and treatment in order to provide an insight into further study and clinical treatment strategies.

Pharmacological Treatment of Acute Unilateral Vestibulopathy: A Review

There have been few investigations on the epidemiology, etiology, and medical management of acute unilateral vestibulopathy (AUV). Short-term pharmaceutical resolutions include vestibular symptomatic suppressants, anti-emetics, and some cause-based therapies. Anticholinergics, phenothiazines, antihistamines, antidopaminergics, benzodiazepines, and calcium channel antagonists are examples of vestibular suppressants. Some of these medications may show their effects through multiple mechanisms. In contrast, N-acetyl-L-leucine, Ginkgo biloba, and betahistine improve central vestibular compensation. Currently, AUV pathophysiology is poorly understood. Diverse hypotheses have previously been identified which have brought about some causal treatments presently used. According to some publications, acute administration of anti-inflammatory medications may have a deleterious impact on both post-lesional functional recovery and endogenous adaptive plasticity processes. Thus, some authors do not recommend the use of corticosteroids in AUV. Antivirals are even more contentious in the context of AUV treatment. Although vascular theories have been presented, no verified investigations employing anti-clotting or vasodilator medications have been conducted. There are no standardized treatment protocols for AUV to date, and the pharmacological treatment of AUV is still questionable. This review addresses the most current developments and controversies in AUV medical treatment.

Synthesis of benzo[f][1,2]thiazepine 1,1-dioxides based on the visible-light-mediated aza Paternò-Büchi reaction of benzo[d]isothiazole 1,1-dioxides with alkenes

A new two-step, one-pot synthesis of benzo[f][1,2]thiazepine 1,1-dioxides was developed, which contains a visible-light mediated aza Paternò-Büchi reaction of benzo[d]isothiazole 1,1-dioxides with alkenes and a Lewis acid catalyzed ring-expansion of azetidine. In this work, the mechanism of the aza Paternò-Büchi reaction was also investigated.

Chemical Probes for Histamine Receptor Subtypes

Ligands with different properties and different selectivity are highly needed for in vitro and in vivo studies on the (patho)physiological influence of the chemical mediator histamine and its receptor subtypes. A selection of well-described ligands for the different receptor subtypes and different studies is shown with a particular focus on affinity and selectivity. In addition, compounds with radioactive or fluorescence elements will be presented with their beneficial use for other species or different investigations.

Inertial Measurement of Head Tilt in Rodents: Principles and Applications to Vestibular Research

Inertial sensors are increasingly used in rodent research, in particular for estimating head orientation relative to gravity, or head tilt. Despite this growing interest, the accuracy of tilt estimates computed from rodent head inertial data has never been assessed. Using readily available inertial measurement units mounted onto the head of freely moving rats, we benchmarked a set of tilt estimation methods against concurrent 3D optical motion capture. We show that, while low-pass filtered head acceleration signals only provided reliable tilt estimates in static conditions, sensor calibration combined with an appropriate choice of orientation filter and parameters could yield average tilt estimation errors below 1.5∘ during movement. We then illustrate an application of inertial head tilt measurements in a preclinical rat model of unilateral vestibular lesion and propose a set of metrics describing the severity of associated postural and motor symptoms and the time course of recovery. We conclude that headborne inertial sensors are an attractive tool for quantitative rodent behavioral analysis in general and for the study of vestibulo-postural functions in particular.

Histamine-4 Receptor: Emerging Target for the Treatment of Neurological Diseases

A major challenge in the field of the biogenic amine histamine is the search for new-generation histamine receptor specific drugs. Daniel Bovet and Sir James Black received their Nobel Prizes for Medicine for their work on histamine-1 receptor (H₁R) and H₂R antagonists to treat allergies and gastrointestinal disorders. The first H₃R-targeting drug to reach the market was approved for the treatment of the neurological disorder narcolepsy in 2018. The antagonists for the most recently identified histamine receptor, H₄R, are currently under clinical evaluation for their potential therapeutic effects on inflammatory diseases such as atopic dermatitis and pruritus. In this chapter, we propose that H₄R antagonists are endowed with prominent anti-inflammatory and immune effects, including in the brain. To substantiate this proposition, we combine data from transcriptional analyses of postmortem human neurodegenerative disease brain samples, human genome-wide association studies (GWAS), and translational animal model studies. The results prompt us to suggest the potential involvement of the H₄R in various neurodegenerative diseases and how manipulating the H₄R may create new therapeutic opportunities in central nervous system diseases.

Challenges in the development and exploitation of new therapeutic options targeting the histaminergic system

LINKED ARTICLES

This article is part of a themed section on New Uses for 21st Century Antihistamines. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

Effect of the novel histamine H4 receptor antagonist SENS-111 on spontaneous nystagmus in a rat model of acute unilateral vestibular loss

BACKGROUND AND PURPOSE

Histamine H₄ receptors are expressed in the peripheral vestibular system, and their selective inhibition improves vertigo symptoms in rats with unilateral vestibular lesions. The effects of SENS-111, a selective oral H₄ receptor antagonist with high affinity to both animal and human receptors, on vertigo symptoms was evaluated in a translational in vivo model of unilateral vestibular loss.

EXPERIMENTAL APPROACH

Pharmacokinetics of SENS-111 in rats was determined to aid dose selection for efficacy testing. Vestibular lesions were induced in rats by unilateral transtympanic injection of kainic acid. The effect of SENS-111 (10 or 20 mg·kg^-1 ) on spontaneous nystagmus was evaluated compared with placebo vehicle using video-nystagmography, and the effective dose was compared with those of similar drugs used clinically, as single agents or combined with SENS-111.

KEY RESULTS

Doses were selected for plasma exposure were consistent with published phase 1 results from healthy volunteers. SENS-111 of 10 mg·kg^-1 gave a 21-22% reduction in nystagmus at 1 hr post-administration, whereas a loss of efficacy was seen with 20 mg·kg^-1 . Compared with SENS-111, meclizine and methylprednisolone had minimal effects on nystagmus as single agents, and meclizine abolished the effect of SENS-111 when combined with SENS-111. All evaluated drugs were well tolerated.

CONCLUSIONS AND IMPLICATIONS

The exposure-efficacy relationship for improved spontaneous nystagmus seen with SENS-111 in this in vivo model is consistent with phase 1 clinical results and provides preclinical support for pharmacokinetic/pharmacodynamic modelling and selection of effective clinical drug concentrations.

LINKED ARTICLES

This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.