Alpha6-containing GABA receptors - Novel targets for the treatment of schizophrenia.

α6-containing GABA receptors (α6GABARs) are strongly expressed in cerebellar granule cells and are of central importance for cerebellar functions. The cerebellum not only is involved in regulation of motor activity, but also in regulation of thought, cognition, emotion, language, and social behavior. Activation of α6GABARs enhances the precision of sensory inputs, enables rapid and coordinated movement and adequate responses to the environment, and protects the brain from information overflow.

Why Can Modulation of α6-Containing GABA Receptors Reduce the Symptoms of Multiple Neuropsychiatric Disorders?

α6-containing GABA receptors (α6GABARs) are strongly expressed in cerebellar granule cells, where they mediate a correctly timed and precise coordination of all muscle groups that execute behavior and protect the brain from information overflow. Recently, it was demonstrated that positive modulators with a high selectivity for α6GABARs (α6-modulators) can reduce the symptoms of multiple neuropsychiatric disorders in respective animal models to an extent comparable with established clinical therapeutics. Here, these incredible findings are discussed and explained.

The Concise Guide to PHARMACOLOGY 2023/24: Ion channels.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.

Cerebellar α6GABA Receptors as a Therapeutic Target for Essential Tremor: Proof-of-Concept Study with Ethanol and Pyrazoloquinolinones.

Ethanol has been shown to suppress essential tremor (ET) in patients at low-to-moderate doses, but its mechanism(s) of action remain unknown. One of the ET hypotheses attributes the ET tremorgenesis to the over-activated firing of inferior olivary neurons, causing synchronic rhythmic firings of cerebellar Purkinje cells. Purkinje cells, however, also receive excitatory inputs from granule cells where the α6 subunit-containing GABA receptors (α6GABARs) are abundantly expressed.

Targeting α6GABA receptors as a novel therapy for schizophrenia: A proof-of-concept preclinical study using various animal models.

GABA receptors containing α6 subunits (α6GABARs) in the cerebellum have -been implicated in schizophrenia. It was reported that the GABA synthesizing enzymes were downregulated whereas α6GABARs were upregulated in postmortem cerebellar tissues of patients with schizophrenia and in a rat model induced by chronic phencyclidine (PCP). We have previously demonstrated that pyrazoloquinolinone Compound 6, an α6GABAR-highly selective positive allosteric modulator (PAM), can rescue the disrupted prepulse inhibition (PPI) induced by methamphetamine (METH), an animal model mimicking the sensorimotor gating deficit based on the hyper-dopaminergic hypothesis of schizophrenia.

GABA receptors in GtoPdb v.2021.3.

The GABA receptor is a ligand-gated ion channel of the Cys-loop family that includes the nicotinic acetylcholine, 5-HT and strychnine-sensitive glycine receptors. GABA receptor-mediated inhibition within the CNS occurs by fast synaptic transmission, sustained tonic inhibition and temporally intermediate events that have been termed 'GABA, slow' [45]. GABA receptors exist as pentamers of 4TM subunits that form an intrinsic anion selective channel.

Nivolumab versus sorafenib in advanced hepatocellular carcinoma (CheckMate 459): a randomised, multicentre, open-label, phase 3 trial.

Background: Single-agent nivolumab showed durable responses, manageable safety, and promising survival in patients with advanced hepatocellular carcinoma in the phase 1-2 CheckMate 040 study. We aimed to investigate nivolumab monotherapy compared with sorafenib monotherapy in the first-line setting for patients with advanced hepatocellular carcinoma.

Methods: In this randomised, open-label, phase 3 trial done at medical centres across 22 countries and territories in Asia, Australasia, Europe, and North America, patients at least 18 years old with histologically confirmed advanced hepatocellular carcinoma not eligible for, or whose disease had progressed after, surgery or locoregional treatment; with no previous systemic therapy for hepatocellular carcinoma, with Child-Pugh class A and Eastern Cooperative Oncology Group performance status score of 0 or 1, and regardless of viral hepatitis status were randomly assigned (1:1) via an interactive voice response system to receive nivolumab (240 mg intravenously every 2 weeks) or sorafenib (400 mg orally twice daily) until disease progression or unacceptable toxicity.

Morphometric Analysis of Mast Cells in Tumor Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation.

Tumor-infiltrating immune cells are relevant prognostic and immunotherapeutic targets in hepatocellular carcinoma (HCC). Mast cells play a key role in allergic response but may also be involved in anticancer immunity. Digital morphometric analysis of patient tissue sections has become increasingly available for clinical routine and provides unbiased quantitative data.

Cancer and hepatic steatosis.

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and increasing liver disease, which encompasses a variety of liver diseases of different severity. NAFLD can lead to liver cirrhosis with all its complications as well as hepatocellular carcinoma (HCC). Steatosis of the liver is not only related to obesity and other metabolic risk factors, but can also be caused by several drugs, including certain cytotoxic chemotherapeutic agents.

8-Substituted Triazolobenzodiazepines: and Pharmacology in Relation to Structural Docking at the α1 Subunit-Containing GABA Receptor.

In order to develop improved anxiolytic drugs, 8-substituted analogs of triazolam were synthesized in an effort to discover compounds with selectivity for α2/α3 subunit-containing GABA subtypes. Two compounds in this series, XLi-JY-DMH (6-(2-chlorophenyl)-8-ethynyl-1-methyl-4H-benzo [f][1,2,4]triazolo[4,3-a][1,4]diazepine) and SH-TRI-108 [(E)-8-ethynyl-1-methyl-6-(pyridin-2-yl)-4H-benzo [f][1,2,4]triazolo[4,3-a][1,4]diazepine], were evaluated for and properties associated with GABA subtype-selective ligands. In radioligand binding assays conducted in transfected HEK cells containing rat αXβ3γ2 subtypes (X = 1,2,3,5), no evidence of selectivity was obtained, although differences in potency relative to triazolam were observed overall (triazolam > XLi-JY-DMH > SH-TRI-108).

α6GABA Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia.

Migraine is caused by hyperactivity of the trigeminovascular system, where trigeminal ganglia (TG) play an important role. This hyperactivity might originate from an underfunctional GABAergic system in TG. To investigate this possibility, we adapted a mouse model of migraine by inducing migraine-like grimaces in male mice via repeated injections of nitroglycerin (NTG, 10 mg/kg, i.

Immunohistochemical distribution of 10 GABA receptor subunits in the forebrain of the rhesus monkey Macaca mulatta.

GABA receptors are composed of five subunits arranged around a central chloride channel. Their subunits originate from different genes or gene families. The majority of GABA receptors in the mammalian brain consist of two α-, two β- and one γ- or δ-subunit.

Alterations in GABAA Receptor Subunit Expression in the Amygdala and Entorhinal Cortex in Human Temporal Lobe Epilepsy.

The amygdala has long been implicated in the pathophysiology of human temporal lobe epilepsy (TLE). The different nuclei of this complex structure are interconnected and share reciprocal connections with the hippocampus and other brain structures, partly via the entorhinal cortex. Expression of GABAA receptor subunits α1, α2, α3, α5, β2, β2/3, and γ2 was evaluated by immunohistochemistry in amygdala specimens and the entorhinal cortex of 12 TLE patients and 12 autopsy controls.

Structural and Functional Remodeling of Amygdala GABAergic Synapses in Associative Fear Learning.

Associative learning is thought to involve different forms of activity-dependent synaptic plasticity. Although previous studies have mostly focused on learning-related changes occurring at excitatory glutamatergic synapses, we found that associative learning, such as fear conditioning, also entails long-lasting functional and structural plasticity of GABAergic synapses onto pyramidal neurons of the murine basal amygdala. Fear conditioning-mediated structural remodeling of GABAergic synapses was associated with a change in mIPSC kinetics and an increase in the fraction of synaptic benzodiazepine-sensitive (BZD) GABA receptors containing the α2 subunit without altering the intrasynaptic distribution and overall amount of BZD-GABA receptors.

Short- and long-term effects of transarterial chemoembolization on portal hypertension in patients with hepatocellular carcinoma.

Background: Transarterial chemoembolization (TACE) affects hepatic perfusion, and might have an impact on portal pressure in patients with hepatocellular carcinoma (HCC).

Objective: The objective of this article is to report the secondary outcome "hepatic hemodynamics" from the AVATACE trial, a prospective randomized, placebo-controlled trial on the efficacy of conventional TACE in combination with bevacizumab or placebo.

Methods: Hepatic venous pressure gradient (HVPG) was measured at baseline (prior to first TACE), within nine days ("acute effects"), two months ("intermediate effects") and six months ("long-term effects") after the first TACE.

Association of Platelet Count and Mean Platelet Volume with Overall Survival in Patients with Cirrhosis and Unresectable Hepatocellular Carcinoma.

Background: Platelets have been reported to influence tumor biology and may promote metastasis. Traditionally, thrombocytopenia, a hallmark of cirrhosis, was associated with hepatocellular carcinoma (HCC) development. However, the impact of platelet count on outcome in patients with established HCC is not well studied.

C-reactive protein is an independent predictor for hepatocellular carcinoma recurrence after liver transplantation.

Background: Serum C-reactive protein (CRP) is a prognostic factor for overall survival (OS) and recurrence of hepatocellular carcinoma (HCC) in patients treated with resection or non-surgical treatment. Here, we investigated the association of elevated CRP (≥1 vs. <1 mg/dL) with (i) recurrence of HCC and (ii) OS after liver transplantation (LT).

Programmed cell death protein-1 (PD-1)-targeted immunotherapy in advanced hepatocellular carcinoma: efficacy and safety data from an international multicentre real-world cohort.

Background: Programmed cell death protein-1-targeted immunotherapy has shown promising results in phase II studies of hepatocellular carcinoma.

Aim: To evaluate safety and efficacy of nivolumab and pembrolizumab in an international, multicentre, real-world cohort of patients with advanced hepatocellular carcinoma.

Methods: Sixty-five patients treated with nivolumab (n = 34) or pembrolizumab (n = 31) between July 10, 2015 and December 31, 2018 (data cut-off) across six centres in Austria and Germany were retrospectively analysed.

Trigeminal neuropathic pain development and maintenance in rats are suppressed by a positive modulator of α6 GABA receptors.

γ-Aminobutyric acid type A (GABA ) receptors containing the α6 subunit are located in trigeminal ganglia, and their reduction by small interfering RNA increases inflammatory temporomandibular and myofascial pain in rats. We thus hypothesized that enhancing their activity may help in neuropathic syndromes originating from the trigeminal system. Here, we performed a detailed electrophysiological and pharmacokinetic analysis of two recently developed deuterated structurally similar pyrazoloquinolinone compounds.

International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.

GABA receptors are the major inhibitory transmitter receptors in the brain. They are ligand-gated chloride channels and the site of action of benzodiazepines, barbiturates, neuroactive steroids, anesthetics, and convulsants. GABA receptors are composed of five subunits that can belong to different subunit classes.

Long-term remission in advanced stage hepatocellular carcinoma? A chance for cure?

Liver resection, transplantation, and local ablation are potential curative treatment options but can only be offered to patients with early stage hepatocellular carcinoma (HCC). Patients with macrovascular tumor invasion and extrahepatic metastases are candidates for palliative systemic therapies. Achieving radiological complete response can be associated with long-term remission and excellent outcome.

The α6 subunit-containing GABA receptor: A novel drug target for inhibition of trigeminal activation.

Novel treatments against migraine are an urgent medical requirement. The α6 subunit-containing GABA receptors (α6GABARs) are expressed in trigeminal ganglia (TG), the hub of the trigeminal vascular system (TGVS) that is involved in the pathogenesis of migraine. Here we reveal an unprecedented role of α6GABARs in ameliorating TGVS activation using several pharmacological approaches in an animal model mimicking pathological changes in migraine.

Transforming Growth Factor-β and Axl Induce CXCL5 and Neutrophil Recruitment in Hepatocellular Carcinoma.

Transforming growth factor (TGF)-β suppresses early hepatocellular carcinoma (HCC) development but triggers pro-oncogenic abilities at later stages. Recent data suggest that the receptor tyrosine kinase Axl causes a TGF-β switch toward dedifferentiation and invasion of HCC cells. Here, we analyzed two human cellular HCC models with opposing phenotypes in response to TGF-β.