Golexanolone is a novel small molecule GABA-A receptor-modulating steroid antagonist under development for the treatment of cognitive and vigilance disorders caused by allosteric over-activation of GABA-A receptors by neurosteroids. It restored spatial learning and motor coordination in animal models of hepatic encephalopathy (HE) and mitigated the effects of intravenous allopregnanolone in healthy adults in a dose-dependent fashion. Herein, we report data on the safety, pharmacokinetics (PK) and efficacy of golexanolone in adult patients with cirrhosis. Following single/multiple ascending dose studies, adults with Child-Pugh A/B cirrhosis and abnormal continuous reaction time (CRT) on screening were randomized to 3 weeks' dosing with golexanolone (10, 40 or 80 mg BID) or placebo. CRT, psychometric hepatic encephalopathy score (PHES), animal naming test (ANT), Epworth sleepiness scale (ESS) and electroencephalogram (mean dominant frequency [MDF]; delta+theta/alpha+beta ratio [DT/AB]) were obtained at baseline, 10, and 21 days. Golexanolone exhibited satisfactory safety and PK. Baseline characteristics were similar between the 12 and 33 patients randomized to placebo or golexanolone, respectively. By prespecified analyses, golexanolone was associated with directionally favourable changes vs. placebo in ESS (p = 0.047), MDF (p = 0.142) and DT/AB (p = 0.021). All patients also showed directionally favourable changes in CRT, PHES and ANT, but with no statistical difference between golexanolone and placebo. Post hoc analyses taking into account the variability and improvement in CRT, PHES and ANT observed between screening and baseline suggested an efficacy signal by cognitive measures as well. Golexanolone was well tolerated and associated with improvement in cognitive performance. These results implicate GABA-A receptor-modulating neurosteroids in the pathogenesis of HE and support the therapeutic potential of golexanolone. Many patients with cirrhosis experience subtle but disabling cognitive problems, including sleepiness and poor attention span, that impair their ability to be gainfully employed or carry out activities of daily living. This pilot study tested the hypothesis that these problems with cognition, for which there is no approved treatment, might be improved by an experimental drug, golexanolone, designed to normalize the function of receptors which inhibit brain function. The results of this study suggest that golexanolone is well tolerated and may improve cognition, as reflected by measures of sleepiness, attention span and brain wave activity, paving the way for future larger studies of this promising experimental drug. EudraCT 2016-003651-30.

GABAA receptor modulating steroid antagonists (GAMSA) selectively inhibit neurosteroid-mediated enhancement of GABA-evoked currents at the GABAA receptor. 3α-hydroxy-neurosteroids, notably allopregnanolone and tetrahydrodeoxycorticosterone (THDOC), potentiate GABAA receptor-mediated currents. On the contrary, various 3β-hydroxy-steroids antagonize this positive neurosteroid-mediated modulation. Importantly, GAMSAs are specific antagonists of the positive neurosteroid-modulation of the receptor and do not inhibit GABA-evoked currents. Allopregnanolone and THDOC have both negative and positive actions. Allopregnanolone can impair encoding/consolidation and retrieval of memories. Chronic administration of a physiological allopregnanolone concentration reduces cognition in mice models of Alzheimer's disease. In humans an allopregnanolone challenge impairs episodic memory and in hepatic encephalopathy cognitive deficits are accompanied by increased brain ammonia and allopregnanolone. Hippocampal slices react in vitro to ammonia by allopregnanolone synthesis in CA1 neurons, which blocks long-term potentiation (LTP). Thus, allopregnanolone may impair learning and memory by interfering with hippocampal LTP. Contrary, pharmacological treatment with allopregnanolone can promote neurogenesis and positively influence learning and memory of trace eye-blink conditioning in mice. In rat the GAMSA UC1011 inhibits an allopregnanolone-induced learning impairment and the GAMSA GR3027 restores learning and motor coordination in rats with hepatic encephalopathy. In addition, the GAMSA isoallopregnanolone antagonizes allopregnanolone-induced anesthesia in rats, and in humans it antagonizes allopregnanolone-induced sedation and reductions in saccadic eye velocity. 17PA is also an effective GAMSA in vivo, as it antagonizes allopregnanolone-induced anesthesia and spinal analgesia in rats. In vitro the allopregnanolone/THDOC-increased GABA-mediated GABAA receptor activity is antagonized by isoallopregnanolone, UC1011, GR3027 and 17PA, while the effect of GABA itself is not affected.

Recombinant adenovirus vectors and transfection agents comprising cationic lipids are widely used as gene delivery vehicles for functional expression in cultured cells. Consequently, these tools are utilized to investigate the effects of functional over-expression of proteins on insulin mediated events. However, we have previously reported that cationic lipid reagents cause a state of insulin unresponsiveness in cell cultures. In addition, we have found that cultured cells often do not respond to insulin stimulation following adenovirus treatment. Infection with adenovirus compromises vital functions of the host cell leading to the activation of protein kinases central to insulin signalling, such as protein kinase B/Akt. Therefore, we investigated the effect of adenovirus infection on insulin unresponsiveness by means of Akt activation in cultured cells. Moreover, we investigated the use of baculovirus as a heterologous viral gene delivery vehicle to circumvent these phenomena. Since the finding that baculovirus can efficiently transduce mammalian cells, the applications of this viral system in gene delivery has greatly expanded and one advantage is the virtual absence of cytotoxicity in mammalian cells. We show that infection of human neuroblastoma SHSY-5Y and liver C3A cells with recombinant adenovirus results in the activation of Akt in a dose dependent manner. In addition, this activation makes treated cells unresponsive to insulin stimulation as determined by an apparent lack of differential phosphorylation of Akt on serine-473. Our data further indicate that the use of recombinant baculovirus does not increase the phosphorylation of Akt in SHSY-5Y and C3A cells. Moreover, following infection with baculovirus, SHSY-5Y and C3A cells respond to insulin by means of phosphorylation of Akt on serine-473 in the same manner as uninfected cells. Widely-used adenovirus vectors for gene delivery cause a state of insulin unresponsiveness in human SHSY-5Y and C3A cells in culture due to the activation of central protein kinases of the insulin signalling pathway. This phenomenon can be avoided when studying insulin signalling by using recombinant baculovirus as a heterologous viral expression system. In addition, our data may contribute to an understanding of the molecular mechanisms underlying baculovirus infection of human cells.

Objectives In Vitro: To study the effects of GR3027 (golexanolone) on neurosteroid-induced GABA-mediated current responses under physiological GABAergic conditions with recombinant human α5β3γ2L and α1β2γ2L GABA_A receptors expressed in human embryonic kidney cells, using the response patch clamp technique combined with the Dynaflow™ application system. With α5β3γ2L receptors, 0.01–3 μM GR3027, in a concentration-dependent manner, reduced the current response induced by 200 nM THDOC + 0.3 µM GABA, as well as the THDOC-induced direct gated effect. GR3027 (1 μM) alone had no effect on the GABA-mediated current response or current in the absence of GABA. With α1β2γ2L receptors, GR3027 alone had no effect on the GABA-mediated current response or did not affect the receptor by itself. Meanwhile, 1–3 µM GR3027 reduced the current response induced by 200 nM THDOC + 30 µM GABA and 3 µM GR3027 that induced by 200 nM THDOC when GABA was not present. Objectives In Vivo: GR3027 reduces allopregnanolone (AP)-induced decreased learning and anesthesia in male Wistar rats. Rats treated i.v. with AP (2.2 mg/kg) or vehicle were given GR3027 in ratios of 1:0.5 to 1:5 dissolved in 10% 2-hydroxypropyl-beta-cyclodextrin. A dose ratio of AP:GR3027 of at least 1:2.5 antagonized the AP-induced decreased learning in the Morris Water Mase (MWM) and 1:7.5 antagonized the loss of righting reflex (LoR). GR3027 treatment did not change other functions in the rat compared to the vehicle group. Conclusions: GR3027 functions in vitro as an inhibitor of GABA_A receptors holding α5β3γ2L and α1β2γ2L, in vivo, in the rat, as a dose-dependent inhibitor toward AP’s negative effects on LoR and learning in the MWM.

Golexanolone improves motor and non-motor symptoms in the 6-OHDA rat model of Parkinson's disease (PD) and reduces neuroinflammation in the striatum, without inducing dyskinesias. To understand the underlying mechanisms, we hypothesized that activated microglia in substantia nigra (SN) have increased glutaminase and glutamate production; glutamate uptake by astrocytes induces GABA release and enhanced GABA_A receptors activation contributes to loss of tyrosine hydroxylase (TH) and dopamine. The study aims were to assess if: 1) the mechanisms proposed occur and are reversed by golexanolone; 2) improvement by golexanolone is maintained with pathological progression; 3) an earlier treatment start provides more beneficial effects. Daily golexanolone treatment from one week after model induction by unilateral injection of 6-OHDA in male rats was performed. Motor function, fatigue and short-term memory were assessed after four and eight weeks. At three and nine weeks, TH, glutamate and dopamine, as well as glutaminase in microglia and GABA in astrocytes were analyzed. 6-OHDA rats show microglia activation in SN, with increased glutaminase and glutamate. Increased glutamate is associated with reduced GABA into astrocytes and increased extracellular GABA, which enhances GABA_A receptors activation in neurons, contributing to loss of TH and dopamine, and altering TrkB signaling. Golexanolone reduces activation of microglia at early and long time after 6-OHDA injection, reduces activation of the glutaminase-glutamate-GABA-TH-dopamine pathway at three weeks after surgery and preserves TrkB membrane expression associated with dopamine receptors, despite the loss of dopamine, at a longer time. Both mechanisms contribute to sustained improvement of fatigue and motor and cognitive functions. Early treatment affords more beneficial effects than late treatment on PD symptoms. Golexanolone affords sustained improvement of PD symptoms in the rat model by reducing neuroinflammation, increasing dopaminergic signaling and therefore could be considered for clinical evaluation in patients with PD.

Background and Objectives: Neuroinflammation plays a significant role in liver and neurological disorders via its disruption of neurotransmission, which alters cerebral function, resulting in cognitive and motor impairment, fatigue, anxiety, and depression. A key interaction exists between GABAergic neurotransmission and neuroinflammation, whereby excessive GABA_A receptor activation exacerbates cognitive and behavioural impairment. Golexanolone, a novel GABA_A-receptor-modulating steroid antagonist (GAMSA), primarily attenuates GABAergic potentiation via GABA_A-positive steroid allosteric receptor modulators such as allopregnanolone. This review aims to summarize new evidence showing that golexanolone improves peripheral inflammation, neuroinflammation, and neurological alterations in animal models of different neurological pathologies. We provide an overview of the first clinical trial using this novel compound. Results: In rat models of hyperammonemia and minimal hepatic encephalopathy (MHE), peripheral inflammation induces microglia and astrocyte activation and neuroinflammation, altering GABAergic neurotransmission and resulting in cognitive and motor impairment. Golexanolone’s unique dual action reduces peripheral inflammation and glial activation, thus normalizing neurotransmission and cognitive and motor function. Furthermore, a phase II study in cirrhotic patients with MHE shows that golexanolone is well tolerated and improves cognition. Similarly, in a model of primary biliary cholangitis (PBC) involving bile-duct ligation, peripheral inflammation, neuroinflammation, and altered neurotransmission—associated with fatigue, impaired memory, and locomotor gait and motor incoordination—were reversed by the dual action of golexanolone. In the Parkinson’s disease (PD) rat model induced by neurotoxin 6-OHDA, rats exhibited fatigue, anhedonia, impaired memory, and locomotor gait and motor incoordination, which were associated with microglia and astrocyte activation in the substantia nigra and striatum, in addition to tyrosine hydroxylase (TH) loss. Golexanolone reduces microglia and astrocyte activation, partially reduces TH loss, and improves fatigue, anhedonia, memory, locomotor gait, and motor incoordination. Golexanolone also normalizes elevated levels of α-synuclein. Conclusions: These findings suggest that golexanolone has beneficial therapeutic effects for treating fatigue, depression, motor, and cognitive impairment across diverse neuroinflammatory conditions, including synucleinopathies.