Ginger (Zingiber Officinale Roscoe) ameliorates ethanol-induced cognitive impairment by modulating NMDA and GABA-A receptors in rat hippocampus.

Brain damage caused by ethanol abuse may lead to permanent damage, including severe dementia. The aim of this study was to investigate the effects of ginger powder on ethanol-induced cognitive disorders by examining oxidative damage and inflammation status, and the gene expression of N-methyl-D-aspartate (NMDA) and γ-Aminobutyric acid (GABA)-A receptors in the hippocampus of male rats. 24 adult male Sprague-Dawley rats were allocated randomly to four groups as follows control, ethanol (4g/kg/day, by gavage), ginger (1g/kg/day, by gavage), and ginger-ethanol. At the end of the study, memory and learning were evaluated by the shuttle box test. Moreover, to explore mechanisms involved in ethanol-induced cognitive impairment and the protective effect of ginger, the expression of Nuclear factor kappa B (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), NMDA receptor, and GABA-A receptor was measured along with inflammatory and oxidative biomarkers in the hippocampus tissue. The results showed that ethanol could induce cognitive impairment in the ethanol group, while pretreatment with ginger could reverse it. The gene expression of the NF-κB/ Tumor necrosis factor (TNF)-α/Interleukin (IL)-1ß pathway and NMDA and GABA-A receptors significantly increased in the ethanol group compared to the control group. While pretreatment with ginger could significantly improve ethanol-induced cognitive impairment through these pathways in the ginger-ethanol group compared to the ethanol group (P < 0.05). It can be concluded that ginger powder could ameliorate ethanol-induced cognitive impairment by modulating the expression of NMDA and GABA-A receptors and inhibiting oxidative damage and the NF-κB/TNF-α/IL-1ß pathway in the rat hippocampus.

4-Phenylbutyrate promoted wild-type γ-aminobutyric acid type A receptor trafficking, reduced endoplasmic reticulum stress, and mitigated seizures in Gabrg2+/Q390X mice associated with Dravet syndrome.

OBJECTIVE: γ-Aminobutyric acid type A (GABAA ) receptor subunit gene mutations are major causes of various epilepsy syndromes, including severe kinds such as Dravet syndrome. Although the GABAA receptor is a major target for antiseizure medications, treating GABAA receptor mutations with receptor channel modulators is ineffective. Here, we determined the effect of a novel treatment with 4-phenylbutyrate (PBA) in Gabrg2+/Q390X knockin mice associated with Dravet syndrome. METHODS: We used biochemistry in conjunction with differential tagging of the wild-type and the mutant alleles, live brain slice surface biotinylation, microsome isolation, patch-clamp whole-cell recordings, and video-monitoring synchronized electroencephalographic (EEG) recordings in Gabrg2+/Q390X mice to determine the effect of PBA in vitro with recombinant GABAA receptors and in vivo with knockin mice. RESULTS: We found that PBA reduced the mutant γ2(Q390X) subunit protein aggregates, enhanced the wild-type GABAA receptor subunits' trafficking, and increased the membrane expression of the wild-type receptors. PBA increased the current amplitude of GABA-evoked current in human embryonic kidney 293T cells and the neurons bearing the γ2(Q390X) subunit protein. PBA also proved to reduce endoplasmic reticulum (ER) stress caused by the mutant γ2(Q390X) subunit protein, as well as mitigating seizures and EEG abnormalities in the Gabrg2+/Q390X mice. SIGNIFICANCE: This research has unveiled a promising and innovative approach for treating epilepsy linked to GABAA receptor mutations through an unconventional antiseizure mechanism. Rather than directly modulating the affected mutant channel, PBA facilitates the folding and transportation of wild-type receptor subunits to the cell membrane and synapse. Combining these findings with our previous study, which demonstrated PBA's efficacy in restoring GABA transporter 1 (encoded by SLC6A1) function, we propose that PBA holds significant potential for a wide range of genetic epilepsies. Its ability to target shared molecular pathways involving mutant protein ER retention and impaired protein membrane trafficking suggests broad application in treating such conditions.

Epiberberine induced p53/p21-dependent G2/M cell cycle arrest and cell apoptosis in gastric cancer cells by activating γ-aminobutyric acid receptor- ß3.

BACKGROUND AND PURPOSE: Epiberberine (EPI) is one of the most important bioalkaloid found in the rhizome of Coptis chinensis, which has been observed to exhibit pharmaceutical effects against gastric cancer (GC). Nevertheless, the potential mechanism of EPI against GC cells still remains unclear. This study aimed to identify the core receptor on GC cells through which EPI inhibited the growth of GC cells and to explore the underlying inhibitory mechanisms. METHODS: To identify hub receptor targets that respond to EPI treatment, RNA sequencing (RNA-Seq) data from a tumor-bearing mouse model were analyzed using bioinformatics method and molecular docking. The binding interaction between EPI and GABRB3 was validated through western blotting based-cellular thermal shift assay (WB-CETSA). To further verify the binding region between EPI and GABRB3 through circular dichroism (CD) chromatography, fragments of the extracellular and transmembrane domains of the GABRB3 protein were expressed and purified in vitro. Stable cell lines with the overexpression or knockdown of GABRB3 were established using the recombinant lentivirus system. MTT ((3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)) assay, colony formation assay, invasion and migration experiments, and flow cytometry were conducted to validate the inhibitory effect of EPI on the GC cells via GABRB3. Additionally, western blotting was utilized to explore the potential inhibitory mechanisms. RESULTS: Through the combination of multiple bioinformatics methods and molecular docking, we found that the γ-aminobutyric acid type A receptor subunit -ß3 (GABRB3) might be the critical receptor target in response to EPI treatment. The results of WB-CETSA analysis indicated that EPI significantly promoted the thermostability of the GABRB3 protein. Importantly, EPI could directly bind to GABRB3 and alter the secondary structure of GABRB3 fragments similar to the natural agonist, γ-aminobutyric acid (GABA). The EPI-induced suppression of the malignant phenotype of GC cells was dependent on the presence of GABRB3. GABRB3 expression was positively correlated with TP53 in patients with GC. The binding of EPI to GABRB3 stimulated p53 accumulation in GC cells. This activated the p21/CDK1/cyclinB1 pathway, resulting in G2/M cell cycle arrest, and induced the Bcl-2/BAX/Caspase axis-dependent cell apoptosis. CONCLUSION: This study revealed the target receptor for EPI in GC cells and provided new insights into its anticancer mechanisms.

Emergence of consciousness from anesthesia through ubiquitin degradation of KCC2 in the ventral posteromedial nucleus of the thalamus.

The emergence of consciousness from anesthesia, once assumed to be a passive process, is now considered as an active and controllable process. In the present study, we show in mice that, when the brain is forced into a minimum responsive state by diverse anesthetics, a rapid downregulation of K+/Cl- cotransporter 2 (KCC2) in the ventral posteromedial nucleus (VPM) serves as a common mechanism by which the brain regains consciousness. Ubiquitin-proteasomal degradation is responsible for KCC2 downregulation, which is driven by ubiquitin ligase Fbxl4. Phosphorylation of KCC2 at Thr1007 promotes interaction between KCC2 and Fbxl4. KCC2 downregulation leads to γ-aminobutyric acid type A receptor-mediated disinhibition, enabling accelerated recovery of VPM neuron excitability and emergence of consciousness from anesthetic inhibition. This pathway to recovery is an active process and occurs independent of anesthetic choice. The present study demonstrates that ubiquitin degradation of KCC2 in the VPM is an important intermediate step en route to emergence of consciousness from anesthesia.

Innate Immune Cell-Related Pathology in the Thalamus Signals a Risk for Disability Progression in Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Our aim was to investigate whether 18-kDa translocator protein (TSPO) radioligand binding in gray matter (GM) predicts later disability progression in multiple sclerosis (MS). METHODS: In this prospective imaging study, innate immune cells were investigated in the MS patient brain using PET imaging. The distribution volume ratio (DVR) of the TSPO-binding radioligand [11C]PK11195 was determined in 5 GM regions: thalamus, caudate, putamen, pallidum, and cortical GM. Volumetric brain MRI parameters were obtained for comparison. The Expanded Disability Status Scale (EDSS) score was assessed at baseline and after follow-up of 3.0 ± 0.3 (mean ± SD) years. Disability progression was defined as an EDSS score increase of 1.0 point or 0.5 point if the baseline EDSS score was ≥6.0. A forward-type stepwise logistic regression model was constructed to compare multiple imaging and clinical variables in their ability to predict later disability progression. RESULTS: The cohort consisted of 66 patients with MS and 18 healthy controls. Patients with later disability progression (n = 17) had more advanced atrophy in the thalamus, caudate, and putamen at baseline compared with patients with no subsequent worsening. TSPO binding was significantly higher in the thalamus among the patients with later worsening. The thalamic DVR was the only measured imaging variable that remained a significant predictor of disability progression in the regression model. The final model predicted disability progression with 52.9% sensitivity and 93.9% specificity with an area under the curve value of 0.82 (receiver operating characteristic curve). DISCUSSION: Increased TSPO radioligand binding in the thalamus has potential in predicting short-term disability progression in MS and seems to be more sensitive for this than GM atrophy measures.

Evaluating changes in GABAergic and glutamatergic pathways in early life following prenatal stress and postnatal neurosteroid supplementation.

BACKGROUND: A correct balance of activity of the GABA and glutamate systems is vital for optimal neurodevelopment and general CNS function, and the dysregulation of this balance has been implicated in a number of neurological conditions. Maternal exposure to stressors is known to have long lasting, deleterious impacts on neurobehaviour, and similarly, results in dysregulation of inhibitory and excitatory pathways in the offspring. The current study aimed to examine effects on these pathways in a guinea pig model of prenatal stress and to elucidate whether increased neuroprotective support by postnatal neurosteroid supplementation would ameliorate adverse outcomes. METHODS: Prenatal stress was achieved by exposing pregnant guinea pigs dams to a strobe light for 2hrs/day on gestational age (GA) 50, 55, 60 and 65. Dams were allowed to spontaneously deliver (~GA70) and pups were orally administered either allopregnanolone analogue, ganaxolone (5 mg/kg/day in 45% cyclodextrin), the translocator protein (TSPO) agonist, emapunil (XBD173; 0.3 mg/kg/day in 1% tragacanth gum) or vehicle on postnatal days (PND) 1-7. Hippocampal samples were collected at PND30 to measure relative mRNA expression of components involved in the inhibitory GABAergic pathway and exctitatory glutamatergic pathway by real-time PCR. GABAergic interneurons were quantified by assessing immunohistochemical protein expression of markers parvalbumin, calbindin and calretinin. RESULTS: mRNA expression of GABAergic pathway components at one week of age indicated immature expression profiles of the GABAA receptors as well as decreased GABA synthesis and transport suggesting reduced extrasynaptically-mediated tonic inhibition. Expression profiles of the pathways examined evolved between one week and one month of age but an imbalance in inhibitory/excitatory components persisted. The allopregnanolone analogue ganaxolone offered some protection against excitotoxicity in female hippocampus, however neurosteroid supplementation with ganaxolone or emapunil were unable to fully correct the GABAergic/glutamatergic imbalance observed following prenatal stress. CONCLUSION: Prenatal stress leads to programmed lasting effects on the major inhibitory and excitatory pathways in the guinea pig brain that continue evolving between the equivalent of early and late childhood. Neurosteroid therapies particularly improved outcomes in females. Further studies are required to identify additional therapeutic targets that are able to fully restore imbalances in the excitatory and inhibitory systems, which may act to prevent development of childhood behavioural disorders.

Imaging of neuroinflammation due to repetitive head injury in currently active kickboxers.

PURPOSE: Chronic traumatic encephalopathy refers to a neurodegenerative disease resulting from repetitive head injury of participants in contact sports. Similar to other neurodegenerative diseases, neuroinflammation is thought to play a role in the onset and progression of the disease. Limited knowledge is available regarding the neuroinflammatory consequences of repetitive head injury in currently active contact sports athletes. PET imaging of the 18-kDa translocator protein (TSPO) allows quantification of microglial activation in vivo, a marker of neuroinflammation. METHODS: Eleven rank A kickboxers and 11 age-matched controls underwent TSPO PET using [11C]-PK11195, anatomical MRI, diffusion tensor imaging, and neuropsychological testing. Relevant imaging parameters were derived and correlated with the outcomes of the neuropsychological testing. RESULTS: On a group level, no statistically significant differences were detected in non-displaceable binding potential (BPND) using PET. Individually, 3 kickboxers showed increased BPNDs in widespread regions of the brain without a correlation with other modalities. Increased FA was observed in the superior corona radiata bilaterally. DTI parameters in other regions did not differ between groups. CONCLUSION: Despite negative results on a group level, individual results suggest that neuroinflammation may be present as a consequence of repetitive head injury in active kickboxers. Future studies using a longitudinal design may determine whether the observed TSPO upregulation is related to the future development of neuropsychiatric symptoms.

The imidazodiazepine, KRM-II-81: An example of a newly emerging generation of GABAkines for neurological and psychiatric disorders.

GABAkines, or positive allosteric modulators of γ-aminobutyric acid-A (GABAA) receptors, are used for the treatment of anxiety, epilepsy, sleep, and other disorders. The search for improved GABAkines, with reduced safety liabilities (e.g., dependence) or side-effect profiles (e.g., sedation) constituted multiple discovery and development campaigns that involved a multitude of strategies over the past century. Due to the general lack of success in the development of new GABAkines, there had been a decades-long draught in bringing new GABAkines to market. Recently, however, there has been a resurgence of efforts to bring GABAkines to patients, the FDA approval of the neuroactive steroid brexanolone for post-partum depression in 2019 being the first. Other neuroactive steroids are in various stages of clinical development (ganaxolone, zuranolone, LYT-300, Sage-324, PRAX 114, and ETX-155). These GABAkines and non-steroid compounds (GRX-917, a TSPO binding site ligand), darigabat (CVL-865), an α2/3/5-preferring GABAkine, SAN711, an α3-preferring GABAkine, and the α2/3-preferring GABAkine, KRM-II-81, bring new therapeutic promise to this highly utilized medicinal target in neurology and psychiatry. Herein, we also discuss possible conditions that have enabled the transition to a new age of GABAkines. We highlight the pharmacology of KRM-II-81 that has the most preclinical data reported. KRM-II-81 is the lead compound in a new series of orally bioavailable imidazodiazepines entering IND-enabling safety studies. KRM-II-81 has a preclinical profile predicting efficacy against pharmacoresistant epilepsies, traumatic brain injury, and neuropathic pain. KRM-II-81 also produces anxiolytic- and antidepressant-like effects in rodent models. Other key features of the pharmacology of this compound are its low sedation rate, lack of tolerance development, and the ability to prevent the development of seizure sensitization.

Gamma-Aminobutyric Acid (GABA) Promotes Growth in Zebrafish Larvae by Inducing IGF-1 Expression via GABAA and GABAB Receptors.

Insulin-like growth factor-1 (IGF-1) primarily increases the release of gamma-aminobutyric acid (GABA) in neurons; moreover, it is responsible for the promotion of longitudinal growth in children and adolescents. Therefore, in this study, we investigated whether exogenous GABA supplementation activates IGF-mediated growth performance. Zebrafish larvae treated with GABA at three days post fertilization (dpf) showed a significant increase in the total body length from 6 to 12 dpf through upregulation of growth-stimulating genes, including IGF-1, growth hormone-1 (GH-1), growth hormone receptor-1 (GHR-1), and cholecystokinin A (CCKA). In particular, at 9 dpf, GABA increased total body length from 3.60 ± 0.02 to 3.79 ± 0.03, 3.89 ± 0.02, and 3.92 ± 0.04 mm at concentrations of 6.25, 12.5, and 25 mM, and the effect of GABA at 25 mM was comparable to 4 mM ß-glycerophosphate (GP)-treated larvae (3.98 ± 0.02 mm). Additionally, the highest concentration of GABA (50 mM) -induced death in 50% zebrafish larvae at 12 dpf. GABA also enhanced IGF-1 expression and secretion in preosteoblast MC3T3-E1 cells, concomitant with high levels of the IGF-1 receptor gene (IGF-1R). In zebrafish larvae, the GABA-induced growth rate was remarkably decreased in the presence of an IGF-1R inhibitor, picropodophyllin (PPP), which indicates that GABA-induced IGF-1 enhances growth rate via IGF-1R. Furthermore, we investigated the effect of GABA receptors on growth performance along with IGF-1 activation. Inhibitors of GABAA and GABAB receptors, namely bicuculline and CGP 46381, respectively, considerably inhibited GABA-induced growth rate in zebrafish larvae accompanied by a marked decrease in the expression of growth-stimulating genes, including IGF-1, GH-1, GHR-1, and CCKA, but not with an inhibitor of GABAC receptor, TPMPA. Additionally, IGF-1 and IGF-1R expression was impaired in bicuculline and CGP 46381-treated MC3T3-E1 cells, but not in the cells treated with TPMPA. Furthermore, treatment with bicuculline and CGP 46381 significantly downregulated GABA-induced IGF-1 release in MC3T3-E1 cells. These data indicate that GABA stimulates IGF-1 release via GABAA and GABAB receptors and leads to growth promotion performance via IGF-1R.

Targets and underlying mechanisms related to the sedative and hypnotic activities of saponins from Rhodiola rosea L. (crassulaceae).

Rhodiola rosea L. (Crassulaceae) are popularly used as a natural supplement for the treatment of insomnia and anxiety. Here, saponin extracts from R. rosea were investigated for their roles on relieving sleeplessness. The levels of neurotransmitters, hormones, and inflammation cytokines in plasma, and the expression of 5-hydroxytryptamine (5-HT), γ-aminobutyric acid (GABA), prostaglandin D2 (PGD2), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) in the hypothalamus and hippocampus were detected using ELISA, RT-PCR, and western blotting. First, the butanol fraction extracted from R. rosea was collected as the total saponins (HJT-I), then a saponin-rich fraction (HJT-II) was obtained after the further purification of HJT-I. The saponin contents of HJT-I and HJT-II were 28.92% and 65.69%, respectively. Second, behavioral tests were performed and showed that both HJT-I and HJT-II could effectively reduce the duration of immobility in the tail suspension test, and shorten sleep latency and prolong the sleep duration time in the sodium barbital-induced sleeping test, with HJT-II better than HJT-I. Third, ELLISA results showed that the concentrations of GABA, 5-HT, norepinephrine (NA), PGD2, and IL-1ß in plasma were significantly increased after HJT-I and HJT-II administration, while IL-6 was decreased. HJT-I and HJT-II also exhibited differential modulation of the receptors of 5-HT, GABA, PGD2, and IL-1ß expression. In hypothalamus, HJT-II was more powerful than HJT-I in regulation of the GABAARα2, GABAARα3, and glutamic acid decarboxylase (GAD) 65/67 expression, as well as 5-HT2A and IL-1ß. As for DPR and PGD2, HJT-II was more effective in the hippocampus. The efficacy of HJT-I was better than HJT-II at stimulating GABAARα2, GAD 65/67, 5-HT1A, and IL-1ß expression in the hippocampus. In conclusion, the potential sedative and hypnotic effects of HJT-I and HJT-II may possibly be related to the serotonergic, GABAAergic, and immune systems, while the underlying mechanism of HJT-I and HJT-II differed from each other.

Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.

There are many nonopioid central nervous system depressant substances that share a gamma-aminobutyric acid (GABA) receptor-related mechanism of action. These sedatives-hypnotics can be indicated to treat anxiety, seizures, depression, and insomnia but are also used as substances of abuse and used to facilitate sexual assault. Barbiturates, methaqualone, and glutethimide were among the first type A GABA receptor-mediated sedative-hypnotics. Their clinical use was limited for most indications by serious adverse events and strong abuse potential but continue to be used illicitly around the world. The benzodiazepines supplanted barbiturates for most indications because they were less likely to cause severe adverse events in monotherapy. Flunitrazepam is a newer benzodiazepine that is preferentially used recreationally and to facilitate sexual assault. Flunitrazepam has greater potency and higher affinity for the type A GABA receptor than most benzodiazepines. Gamma-hydroxybutyric acid is sought illicitly for its hypnotic, euphoric and anabolic effects as well as to facilitate sexual assault. When any of these GABAergic drugs are used in high doses or with other sedative hypnotic agents, respiratory depression, coma, and death have occurred. Chronic use of these GABAergic drugs can lead to significant withdrawal syndromes. Phenibut and selank are poorly studied Russian drugs with GABAergic mechanisms that are inexplicably sold to US consumers as dietary supplements. Poison control center calls regarding phenibut have increased substantially over the past 5 years. Desired euphoriant effects account for the recreational and illicit use of many GABA-modulating agents. However, illicit use can lead to significant toxicities related to abuse, dependence, and subsequent withdrawal syndromes. Significant evaluation of developing agents with GABA properties should be conducted to determine abuse potential before public access ensues.

Impact of Dysfunctional Feed-Forward Inhibition on Glutamate Decarboxylase Isoforms and γ-Aminobutyric Acid Transporters.

Absence seizures are associated with generalised synchronous 2.5-4 Hz spike-wave discharges causing brief and sudden alteration of awareness during childhood, which is known as childhood absence epilepsy (CAE). CAE is also associated with impaired learning, psychosocial challenges, and physical danger. Absence seizures arise from disturbances within the cortico-thalamocortical (CTC) network, including dysfunctional feed-forward inhibition (FFI); however, the precise mechanisms remain unclear. In epileptic stargazers, a genetic mouse model of CAE with chronic seizures, levels of γ-aminobutyric acid (GABA), and expression of GABA receptors are altered within the CTC network, implicating altered GABAergic transmission in absence seizures. However, the expression of GABA synthesising enzymes (GAD65 and GAD67) and GABA transporters (GAT-1 and 3) have not yet been characterised within absence seizure models. We found a specific upregulation of GAD65 in the somatosensory cortex but not the thalamus of epileptic stargazer mice. No differences were detected in GAD67 and GAT-3 levels in the thalamus or somatosensory cortex. Then, we assessed if GAD65 upregulation also occurred in Gi-DREADD mice exhibiting acute absence seizures, but we found no change in the expression profiles of GAD65/67 or GAT-3. Thus, the upregulation of GAD65 in stargazers may be a compensatory mechanism in response to long-term dysfunctional FFI and chronic absence seizures.

GABA-producing Lactobacillus plantarum inhibits metastatic properties and induces apoptosis of 5-FU-resistant colorectal cancer cells via GABAB receptor signaling.

5-Fluorouracil (5-FU) is an essential drug in systemic chemotherapy treatments for colorectal cancer (CRC). Despite the development of several treatment strategies over the past decades, the patient benefits of 5-FU-based therapies have been compromised by the development of chemoresistance. Differences in treatment responses among CRC patients may be due to genetic and epigenetic factors unique to individuals. Therefore, important factors for realizing personalized medicine are to accurately understand the causes and mechanisms of drug resistance to 5-FU-based therapies and to identify and validate prognostic biomarkers. Gut microbes that interact directly with the host contribute to human health and cancer control. Lactobacillus plantarum, in particular, has the potential to be a therapeutic agent by producing bioactive compounds that may benefit the host. Here, we investigated the gamma-aminobutyric acid (GABA) and GABAB receptor (GABABR)-dependent signaling pathway as a treatment option for 5-FU-resistant HT-29 cells. GABA-producing L. plantarum activates anti-proliferative, anti-migration, and anti-invasion effects against 5-FU-resistant HT-29 cells. The inhibitory effects of GABA-producing L. plantarum are mediated via GABABR. Activated GABABR induces apoptosis through the inhibition of cAMP-dependent signaling pathways and cellular inhibitor of apoptosis protein 2 (cIAP2) expression. Thus, the GABAergic system has potential in 5-FU-resistant HT-29 cells as a predictive biomarker. In addition, GABA-producing L. plantarum is promising as an adjuvant treatment for 5-FU-resistant CRC, and its intervention in neurobiological signaling imply new possibilities for chemoprevention and the treatment of colon cancer-related diseases.

Involvement of opioidergic and GABAergic systems in the anti-nociceptive activity of the methanolic extract of Cuscuta Epithymum Murr. in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Cuscuta epithymum Murr. (CE) is a parasitic plant used as a traditional medicine to treat various diseases such as muscle and joint pains and headache different parts of the world, Europe in the north, Asia in the east. AIM OF THE STUDY: In this study, we aimed to investigate the anti-nociceptive effect of the methanolic extract of the aerial parts of CE and its probable mechanism(s) in mice. MATERIALS AND METHODS: The anti-nociceptive activity of different doses of CE methanolic extract (2.5, 5, 10, 25, 50 and 100 mg/kg, i.p.) was assessed using tail flick, formalin and writhing tests. Morphine (5 mg/kg, s.c.) was used as positive control drug. The possible mechanisms were evaluated by using naloxone (4 mg/kg, i.p.), ondansetron (4 mg/kg, i.p.), picrotoxin (0.6 mg/kg, i.p.) and MK-801 (0.03 mg/kg, i.p.). RESULTS: GC-MS analysis indicated that one of the main components of CE extract was terpenoid compounds. The CE extract (25-100 mg/kg), like morphine, reduced tail flick latency and nociceptive response in both phases of the formalin test. We also observed that the extract significantly decreased the number of abdominal contractions dose-dependently from 5 to 100 mg/kg. The results of tail flick and the first phase of formalin test proved that unlike ondansetron and MK-801, naloxone and picotroxin were able to reverse the anti-nociceptive effect of CE extract. CONCLUSION: Our observations showed the anti-nociceptive potential of the CE extract, which may be mediated by opioidergic and GABAergic systems.

Paeoniflorin elicits the anti-proliferative effects on glioma cell via targeting translocator protein 18 KDa.

As a natural compound isolated from Paeoniae radix, Paeoniflorin (PF) has been shown the antitumor effects in various types of human cancers including glioma, which is one of the serious tumors in central nervous system. Translocator protein 18 KDa (TSPO) has been shown to be relevant to the glioma aetiology. However, the regulation of PF in TSPO and neurosteriods biosynthesis on glioma is still unclear. In the present study, the glioma cell (U87 and U251) were cultured and used to quantify the bindings of PF on TSPO. Results indicated that there was not significant different between IC50 of PF and TSPO ligand PK11195. Moreover, PF exerted the anti-proliferative effects in glioma cell with a dose dependent inhibition from 12.5 to 100 µM in vitro. Consistent with the effects of PK11195, lowered levels on progesterone, allopregnanolone, as well as TSPO mRNA were induced by PF (25 and 50 µM). Furthermore, a xenograft mouse model with U87 cell-derived was significant inhibited by PF treatment, as well as the PK11195 administration. These results demonstrate that PF exerts its antitumor effects associated with the TSPO and neurosteroids biosynthesis in glioma cells could be a promising therapeutic agent for glioma therapy.

GABA-enriched teas as neuro-nutraceuticals.

Teas enriched in GABA are consumed for their beneficial effects on blood pressure, stress and anxiety. These effects may involve actions of GABA on the central and peripheral nervous systems. The anaerobic procedures for the production of GABA-enriched teas increase GABA levels by 10-20 times. They also significantly alter the levels of other constituents that may interact with the actions of GABA. These include epigallocatechin gallate, caffeine and theanine. The possible interactions of these active constituents make the understanding of the effects of GABA-enriched teas complex. More data is needed to establish where and how GABA is acting following consumption of GABA-enriched teas. While there is considerable evidence that such GABA is acting on GABA receptors in the periphery, there is rather less evidence that is acting directly in the brain. Certainly, there is more to the action of GABA-enriched teas than GABA itself.

Antidepressant effects of 3-(3,4-methylenedioxy-5-trifluoromethyl phenyl)-2E-propenoic acid isobutyl amide involve TSPO-mediated mitophagy signalling pathway.

Piper laetispicum C. DC is one of the Chinese herbal medicines used for alleviating depressive disorders. G11-5 [3-(3, 4-methylenedioxy-5-trifluoromethyl phenyl)-2E-propenoic acid isobutyl amide] is synthesized based on the chemical structure of an active integrant of Piper laetispicum C. DC. The present study assessed the antidepressant effect of G11-5 and investigated the underlying mechanism with learned helplessness (LH) and social defeat stress (SDS) mice model of depression. In the LH model, mice were exposed to 60 inescapable electric shocks once a day for three consecutive days followed by 2-week drug administration and helpless behaviour assessment. In the SDS model, mice were subjected to repeated social defeat by an aggressive CD-1 mouse once a day for consecutive 10 days. Following oral administration for 2 weeks, the mice were subjected to a series of behavioural tests including social interaction test. G11-5 significantly decreased the number of escape failures induced by LH paradigm, meanwhile increased the social interaction ratio and shortened the immobility time in forced swimming test for the SDS-exposed mice, suggesting remarkable antidepressant effect. Moreover, G11-5 ameliorated the changes in mitophagy-related proteins induced by two stress exposures and restored retrograde axonal transport and neurotransmitter release. Our findings suggested that G11-5 exhibited an obvious antidepressant through TSPO-mediated mitophagy pathway.

Gypenosides mediate cholesterol efflux and suppress oxidized LDL induced inflammation in retinal pigment epithelium cells.

Age-related macular degeneration (AMD) is a predominant cause of visual deficit in aged population. Abnormal accumulation of cholesterol, including oxidized low-density lipoprotein (oxLDL), underneath the retinal pigment epithelium (RPE) cells contributes to the development of AMD. Gypenosides (Gyp) are glycosides extracted from Gynostemma pentaphyllum and have demonstrated protective effects against inflammation and oxidative stress. To determine the therapeutic potential of Gyp for AMD, we investigated its effect on cholesterol trafficking and metabolism and assessed the protective function of Gyp against oxLDL-induced damage in RPE cells. Cholesterol efflux to high-density lipoprotein (HDL) and human serum was significantly increased in RPE cells treated with Gyp when compared to untreated control cells. Expression of cholesterol metabolism (CYP27A1, CYP46A1) and trafficking (TSPO, ABCA1 and ABCG1) genes was also markedly increased in Gyp-treated RPE cells. OxLDL-treated RPE cells had significantly increased cholesterol accumulation and lipid droplet formation. There were marked increases in reactive oxygen species (ROS) generation and proinflammatory cytokines via NF-κB activation in RPE cells treated with oxLDL, while incubation with Gyp rectified these changes. These findings provide pharmacological evidence that Gyp has the potential to treat patients with early onset AMD by promoting cellular cholesterol removal from RPE cells and inhibiting inflammation and oxidative stress.

Tanycytic TSPO inhibition induces lipophagy to regulate lipid metabolism and improve energy balance.

Hypothalamic glial cells named tanycytes, which line the 3rd ventricle (3V), are components of the hypothalamic network that regulates a diverse array of metabolic functions for energy homeostasis. Herein, we report that TSPO (translocator protein), an outer mitochondrial protein, is highly enriched in tanycytes and regulates homeostatic responses to nutrient excess as a potential target for an effective intervention in obesity. Administration of a TSPO ligand, PK11195, into the 3V, and tanycyte-specific deletion of Tspo reduced food intake and elevated energy expenditure, leading to negative energy balance in a high-fat diet challenge. Ablation of tanycytic Tspo elicited AMPK-dependent lipophagy, breaking down lipid droplets into free fatty acids, thereby elevating ATP in a lipid stimulus. Our findings suggest that tanycytic TSPO affects systemic energy balance through macroautophagy/autophagy-regulated lipid metabolism, and highlight the physiological significance of TSPO in hypothalamic lipid sensing and bioenergetics in response to overnutrition. ABBREVIATIONS: 3V: 3rd ventricle; ACAC: acetyl-Coenzyme A carboxylase; AGRP: agouti related neuropeptide; AIF1/IBA1: allograft inflammatory factor 1; AMPK: AMP-activated protein kinase; ARC: arcuate nucleus; Atg: autophagy related; Bafilo: bafilomycin A1; CAMKK2: calcium/calmodulin-dependent protein kinase kinase 2, beta; CCCP: carbonyl cyanide m-chlorophenylhydrazone; CNS: central nervous system; COX4I1: cytochrome c oxidase subunit 4I1; FFA: free fatty acid; GFAP: glial fibrillary acidic protein; HFD: high-fat diet; ICV: intracerebroventricular; LAMP2: lysosomal-associated membrane protein 2; LD: lipid droplet; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MBH: mediobasal hypothalamus; ME: median eminence; MEF: mouse embryonic fibroblast; NCD: normal chow diet; NEFM/NFM: neurofilament medium; NPY: neuropeptide Y; OL: oleic acid; POMC: pro-opiomelanocortin-alpha; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; Rax: retina and anterior neural fold homeobox; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; RER: respiratory exchange ratio; siRNA: small interfering RNA; SQSTM1: sequestosome 1; TG: triglyceride; TSPO: translocator protein; ULK1: unc-51 like kinase 1; VCO2: carbon dioxide production; VMH: ventromedial hypothalamus; VO2: oxygen consumption.

[GABAergic approach of postpartum depression: A translational review of literature]. / Approche GABAergique de la dépression du post-partum : une revue critique translationnelle.

INTRODUCTION: Prevalence of postpartum depression (PPD) ranges from 10 to 15 % of parturients. The impact of the PPD is major on the maternal bond and the health of both mother and child. Its physiopathological mechanisms appear to differ from other types of depression. Today, pharmacotherapy is based on nonspecific treatment, and recent therapeutic advances in this field require a comprehensive approach of the implication of the GABAergic system in the development of PPD. Neurosteroid levels during pregnancy and after parturition and the GABA-A-r modulation are thought to be involved in PPD. OBJECTIVE: To evaluate if the GABAergic approach is relevant in postpartum depression management. METHODS: We conducted a systematic review of literature based on the MEDLINE database with the following Medical Subject Headings (MeSH): "postpartum depression", "GABA", "ganaxolone", "brexanolone", "allopregnanolone", prior to September 2019. We selected articles in English: preclinical and clinical studies, literature review, observational and therapeutic studies. RESULTS: Preclinical models (mouse and rat) show changes in GABAergic inhibition in the peripartum period and correlation between allopregnanolone and GABA-A-r plasticity. This plasticity in the peripartum period maintains levels of inhibition adapted despite increased neurosteroid levels. KO models for the GABA-A-r δ subunit develop depression and anxiety symptoms in the postpartum period, and a change in the expression of the gene coding for the GABA-R alpha-4 subunit was found. Artificial inhibition of progesterone metabolism during post-partum increased depression symptoms. GABAergic fluctuation seems to be interrelated with other systems such as those of oxytocins. A synthetic neurosteroid (SGE-516) was tested on mouse models of PPD, KO for δ-GABA-A-r or KCC2, and showed decreased depressive symptoms and better mothering. Clinical studies confirm neurosteroid fluctuation and changes in the GABAergic system during the peripartum period. Allopregnanolone is the neurosteroid the most studied in PPD, and it is elevated in the brain during the pregnancy. Studies disagree on the presence of significant differences in allopregnanolone plasma levels during pregnancy or postpartum between women with PPD or not. Women with a history of PPD have greater susceptibility to neurosteroid withdrawal. Imagery and genetical data also show a link between allopregnanolone and PPD. The GABA-A-r may not recover in time following a reduced number during pregnancy, and this mismatch between neurosteroid levels and their receptor may trigger PPD. Several randomized controlled trials investigated brexanolone administrated IV, a synthetic formulation of allopregnanolone, and demonstrated a rapid and well tolerated reduction in depressive symptoms. In March 2019 brexanolone obtained FDA approval in PPD indication under the name Zulresso. However, there are differences in the time of beginning of PPD, which could constitute different subgroups of this disease, and which physiopathology could respond to different mechanisms. Prenatal depression does not respond to a GABAergic approach, but women without any risk factor or previous mood disorder developing PPD in the weeks following childbirth could be particularly responsive to this kind of treatment. CONCLUSION: Disability to modulate GABA-A-r expression during pregnancy and restore its previous state after parturition appears to trigger PPD. The GABAergic system is a promising pharmacotherapy target. From preclinical to clinical studies for about twenty years the GABAergic system has been incriminated and targeted in this challenging mental disease.