Neurotransmitter Gamma-aminobutyric Acid Research Articles

Metabolomic Analysis Reveals the Linkage between Sleep-Enhancing Effects and Metabolite Biomarkers and Pathways of Different Casein Hydrolysates in Chronic Unpredictable Mild Stressed Mice.

Casein hydrolysates have been proven to exert varying sleep-enhancing and anxiolytic effects due to their distinct release of potential peptides. However, their underlying sleep-enhancing mechanisms at the metabolic level remain unclear. This study aims to investigate the potential sleep-enhancing mechanism of casein hydrolysates through an integrated approach of untargeted and targeted metabolomics in CUMS-induced anxiety mice for the first time. The results showed seven potential biomarkers were identified and screened using orthogonal partial least-squares discriminant analysis, random forest model, and pathway analysis, including ornithine, l-proline, l-prolinamide, inhibitory neurotransmitters gamma-aminobutyric acid, 5-HIAA, fumaric acid, and 4-oxoglutaramate. Moreover, casein hydrolysates exerted sleep-enhancing effects through multiple metabolic pathways, mainly including the GABAergic system, tryptophan metabolism, and cAMP response signaling pathway, which was validated by targeted metabolomics and vital protein expressions. It was interesting that casein hydrolysates with diverse representative peptide compositions exhibited varying activity, which could be attributed to distinct alterations in metabolites via different pathways.

Evaluation of neurotransmitters (Gamma-aminobutyric acid and serotonin) and apoptosis factor (Caspase-7) as biomarkers for the diagnosis of autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disability characterized by impaired communication and social skills along with restricted interests and repetitive behaviors. Biomarkers such as γ-aminobutyric acid (GABA), serotonin (5-Hydroxytryptamine, 5-HT) and caspase-7, showing potential for early diagnosis and management of ASD. To evaluate the effectiveness of GABA, serotonin and caspase-7 as novel biomarkers to predict autism at an early stage. A case- control study which started from November 2023 to June 2024, that involved 77 children’s patients, newly diagnosed with autism. The control group was comprised of 61 age- and sex-matched apparently healthy children, they had no history of autism and any other chronic diseases. Serum samples were analyzed for GABA, serotonin and caspase-7 by using enzyme linked immune-sorbent assay (ELISA) technique. The statistical package for social sciences (SPSS- 26) was used for data analyses. The study revealed significantly elevated GAMA and caspase-7 levels; while, no significant differences of serotonin level between the autistic children’s patients and the control group. This study provides a groundbreaking revelation of the biochemical markers (GAMA and caspase-7) and autism spectrum disorder, the myriad metabolic and neurochemical dysfunctions of which form a complex tapestry of ASD.

Eucalyptus essential oil exerted a sedative-hypnotic effect by influencing brain neurotransmitters and gut microbes via the gut microbiota-brain axis.

Sleep disorders are becoming more and more common, leading to many health problems. However, most of current available medications to treat sleep disorders are addictive and even impair cognitive abilities. Therefore, it is important to find a natural and safe alternative to treat sleep disorders. In this study, twenty-four 8-week-old male ICR mice (25 ± 2g) were equally divided into three groups: the control group (gavage of 0.9% saline), the eucalyptus essential oil (EEO) group (10mg/kg B.W.), and the diazepam group (1mg/kg B.W.). Firstly, open field test and sleep induction test were used to determine the sedative-hypnotic effect of EEO. Secondly, the effect of EEO on neurotransmitters in the mice brain was determined. Finally, based on the gut microbiota-brain axis (GMBA), the effect of EEO on the intestinal flora of mice was explored. It was found that EEO significantly reduce the activity and prolong the sleep duration of mice, exhibiting a good sedative-hypnotic effect. In the brain, EEO could increase the levels of sleep-promoting neurotransmitters, such as glutamine, Gamma-aminobutyric acid (GABA), glycine, tryptophan, N-acetylserotonin, and 5-hydroxyindoleacetic acid (5-HIAA). In the intestine, EEO was found to increase the diversity of gut microbes, the abundance of short chain fatty acid (SCFA) producing flora, and the abundance of functional flora synthesizing GABA and glycine neurotransmitters. These studies suggested that EEO exerted a sedative-hypnotic effect by acting on gut microbes and neurotransmitters in the brain. EEO has the potential to become a natural and safe alternative to traditional hypnotic sedative drugs.

Inhibitory gamma-aminobutyric acidergic neurons in the anterior cingulate cortex participate in the comorbidity of pain and emotion.

Pain is often comorbid with emotional disorders such as anxiety and depression. Hyperexcitability of the anterior cingulate cortex has been implicated in pain and pain-related negative emotions that arise from impairments in inhibitory gamma-aminobutyric acid neurotransmission. This review primarily aims to outline the main circuitry (including the input and output connectivity) of the anterior cingulate cortex and classification and functions of different gamma-aminobutyric acidergic neurons; it also describes the neurotransmitters/neuromodulators affecting these neurons, their intercommunication with other neurons, and their importance in mental comorbidities associated with chronic pain disorders. Improving understanding on their role in pain-related mental comorbidities may facilitate the development of more effective treatments for these conditions. However, the mechanisms that regulate gamma-aminobutyric acidergic systems remain elusive. It is also unclear as to whether the mechanisms are presynaptic or postsynaptic. Further exploration of the complexities of this system may reveal new pathways for research and drug development.

Rapid Analytical Method for Quantification of Gamma-Hydroxybutyrate (GHB) in Hair by UPLC-MS/MS.

Gamma-hydroxybutyrate (GHB), an endogenous compound related to the neurotransmitter gamma-aminobutyric acid (GABA), is used as a therapeutic and recreational drug and as a "weapon" in drug-facilitated crimes. The very short window of detection of GHB in conventional matrices (blood and urine) makes necessary the use of alternative matrices like hair. Hair has a long window of detection and the possibility to perform segmental analysis, which makes it very useful for proving GHB intake. In the present work, a method for quantification of GHB in hair was developed and validated. Hair (10 mg) was washed twice with dichloromethane and then incubated at room temperature with Milli-Q water in an ultrasound bath for 30 min. Analysis was performed by UPLC-MS/MS using a CORTECS UPLC HILIC (1.6 μm), 2.1 × 100-mm column, and a gradient with acetonitrile and ammonium acetate (10 mM) at pH 6.0, with a total run-time of 10 min. For detection, a triple quadrupole mass spectrometer in ESI negative mode was used. The method was validated, following the criteria established in the "AAFS Standard Practices for Method Validation in Forensic Toxicology" guideline, obtaining satisfactory results for linearity (0.5-50 ng/mg), accuracy (95.0%-103.2%), imprecision (< 10.2%), limit of detection (0.1 ng/mg) and quantification (0.5 ng/mg), exogenous selectivity (no interferences), matrix effect (less than -44.2%), extraction efficiency (> 86.4%), process efficiency (> 46.1%), and autosampler stability (< 4.3%). The method was used for the analysis of 26 authentic hair samples, 25 from non-drug users, obtaining values between < LOQ and 6.25 ng/mg of endogenous GHB and 1 from a former GHB chronic user to prove abstinence.

Dynamic changes in seizure state and anxiety-like behaviors during pentylenetetrazole kindling in rats

IntroductionExcessive anxiety is a mental disorder, and its treatment involves the use of benzodiazepines, a class of drugs that enhance the effects of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABAA receptor. Anxiety disorders are frequent comorbidities in patients with epilepsy, and it has been speculated that anxiety disorders and epileptic seizures share common neurobiological mechanisms. However, conflicting results regarding anxiolytic and anxiogenic effects have been reported in animal models of epilepsy induced by pentylenetetrazole (PTZ) injections, and the causes of this discrepancy are unknown. We hypothesized that anxiety-like behaviors would change dynamically according to the changes in epilepsy susceptibility that occur during the PTZ kindling process. Therefore, we attempted to change anxiety-like behaviors bidirectionally depending on the number of PTZ injections. MethodsAdult male rats were injected with PTZ 20 times every other day, and stages of seizure onset were classified according to the Racine staging system. Anxiety-like behaviors were measured after 10 and 20 injections. The control group was injected with an equal volume of saline solution. Anxiety-like behaviors were investigated using the open-field, light/dark transition, elevated plus maze, and social interaction tests. ResultsBimodal changes in seizure stage were observed in response to PTZ kindling. The increase in the seizure stage was transiently suppressed after 10 injections, and this decrease in epileptic sensitivity disappeared after 20 injections. However, none of the rats reached a fully kindled state after 20 PTZ injections. After 10 PTZ injections, anxiety-like behaviors decreased compared with those of the control group in the open field, light/dark transition, and elevated plus-maze tests. The anxiolytic effects correlated with the seizure stage in individual rats. After 20 PTZ injections, anxiety-like behaviors returned to control levels. ConclusionPTZ kindling induced bimodal changes in the seizure stage. Anxiety-like behaviors decreased with transient decrease in epileptic sensitivity and returned to control levels with the disappearance of these states. These findings suggest a common neurobiological mechanism underlying anxiety disorders and epileptic seizures. In addition, the discrepancy in the previous studies, in which anxiety levels increase or decrease in PTZ-kindled animals, may be due to examination at different phases of the kindling process.

Comparison of Different Doses of Pregabalin to Prevent Succinylcholine-Initiated Fasciculations and Myalgia in Patients Under General Anesthesia: A Randomised Controlled Study.

Background Succinylcholine (SCh) is the most commonly used muscle relaxant during endotracheal intubation, and it is known to cause fasciculations and postoperative myalgia. Pregabalin is structurally similar to the neurotransmitter gamma-aminobutyric acid (GABA), which is known to reduce SCh-induced fasciculations and myalgia. Materials and methods This study was conducted on patients who underwent surgery under general anesthesia. A total of 201 patients of both genders were assigned to one of the following groups:Group PL (pregabalin low dose) received cap pregabalin 75 mg, Group PH (pregabalin high dose) received cap pregabalin 150 mg, and Group P (placebo) received saccharine pill 10 mg, administered two hours prior to surgery. Results Both the incidence and severity of fasciculations and myalgia were reduced in patients who received pregabalin compared to the placebo group (PH>PL>P). It was observed that as the severity of fasciculations increased, myalgia also increased. The time of the first analgesic dose was longer in the pregabalin group (PH>PL>P). The attenuation of pressor response and hemodynamic stability was greater in the pregabalin group (Group PH>PL>P). Sedation levels were insignificant among groups. The incidence of adverse effects was also insignificant. Conclusion Preoperative prophylactic administration of pregabalin orally in Group PL and PH reduced the incidence and severity of fasciculations and myalgia. Group PH was found to be more effective than PL. Pressor response attenuation was found to be more effective in Group PH.

A Systematic Review on Sedative and Hypnotics

Abstract: Sedative and hypnotic drugs are central nervous system depressants primarily used to induce calmness, reduce anxiety, and promote sleep. These medications include benzodiazepines, barbiturates, and various non-benzodiazepine sleep aids, each varying in their mechanism of action, efficacy, and safety profiles. Benzodiazepines, such as diazepam and alprazolam, enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA-A receptor, resulting in sedative, anxiolytic, muscle relaxant, and anticonvulsant effects. They are commonly prescribed for anxiety disorders, insomnia, seizures, and muscle spasms. However, their use is associated with risks of tolerance, dependence, and withdrawal symptoms. Barbiturates, such as phenobarbital, were once widely used for their sedative and hypnotic properties but have largely been replaced by benzodiazepines and other safer alternatives due to their higher risk of overdose and dependence. Barbiturates enhance GABAergic transmission but also directly activate GABA receptors, leading to more profound central nervous system depression. Non-benzodiazepine sleep aids, including drugs like zolpidem, eszopiclone, and zaleplon, act on the benzodiazepine receptor site but have a different chemical structure. These drugs are often preferred for short-term treatment of insomnia due to their relatively lower risk of dependence and adverse effects compared to benzodiazepines.

Long-term exposure to ionic liquid [C8mim]Br induces the potential risk of anxiety and memory deterioration through disturbing neurotransmitter systems

1-octyl-3-methylimidazolium bromide ([C8mim]Br), one of the ionic liquids (ILs), has been used in various fields as an alternative green solvent of conventional organic solvents. Increased application and stabilization of imidazole ring structure lead to its release into the aquatic environment and long-term retention. Structure-activity relationship consideration suggested that ILs may be acetylcholinesterase inhibitors; however, neurotoxicity in vivo, especially the underlying mechanisms is rarely studied. In this study, the zebrafish were exposed to 2.5–10 mg/L [C8mim]Br for 28 days to comprehensively evaluate the neurotoxicity of ILs on adult zebrafish from the behavioral profiles and neurotransmitter systems for the first time. The results indicate that zebrafish exhibit suppressed spatial working memory and anxious behaviors. To assess the potential neurotoxic mechanisms underlying the behavioral responses of zebrafish, we measured the levels of neurotransmitters and precursors, key enzyme activities, and expression levels of relevant genes. Nissl staining showed significant neural cell death in zebrafish after 28-day [C8mim]Br exposure, with corresponding decreases in the levels of neurotransmitters (acetylcholine, glutamate, 5-hydroxytryptophan, gamma-aminobutyric acid, dopamine, and norepinephrine). Furthermore, these results were associated with mRNA expression levels of the disrupted neurotransmitter key genes (th, tph2, mao, slc6a3, ache, gad67). Overall, our study determined that [C8mim]Br caused potential mental disorders like anxiety and memory deterioration in zebrafish by impairing neurotransmitter systems, providing recommendations for the industrial production and application of [C8mim]Br.

Examination of acute spin exercise on GABA levels in aging and stroke: The EASE study protocol.

Changes in regional levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) may indicate the potential for favorable responses to the treatment of stroke affecting the upper extremity. By selectively altering GABA levels during training, we may induce long-term potentiation and adjust excitatory/inhibitory balance (E/I balance). However, the impact of this alteration may be limited by neural damage or aging. Aerobic exercise has been shown to increase GABA levels in the sensorimotor cortex and improve motor learning by widening the dynamic range of E/I balance. The cross-sectional project, Effects of Acute Exercise on Functional Magnetic Resonance Spectroscopy Measures of GABA in Aging and Chronic Stroke (EASE), is designed to assess the functional relevance of changes in GABA concentration within the sensorimotor cortex before and after an acute aerobic exercise session. EASE will enroll 30 participants comprised of healthy younger adults (18-35 years; n = 10), older adults (60+ years; n = 10), and persons with chronic stroke (n = 10) affecting distal upper extremity function. We will use resting magnetic resonance spectroscopy to measure all participants' GABA levels at rest before and after aerobic exercise. In addition, we will employ functional magnetic resonance spectroscopy using motor skill acquisition and recall tasks in healthy adults. We hypothesize that acute aerobic exercise will increase resting sensorimotor GABA concentration and that higher GABA resting levels will predict better motor learning performance on measures taken both inside and outside the magnet. We also hypothesize that a higher dynamic range of GABA during task-based spectroscopy in healthy adults will predict better motor skill acquisition and recall. The EASE project will evaluate the effect of acute exercise on GABA levels as a biomarker of upper extremity motor skill learning with two populations (aging adults and those with chronic stroke). We predict that acute exercise, higher sensorimotor GABA levels, and broader dynamic range will be related to better motor skill acquisition.

Biological activities of gaba-producing probiotics from fermented panchagavya

Abstract Panchagavya, a venerable elixir from the Ayurvedic tradition, merits scholarly inspection. It denotes the sacred offerings of cow’s milk, urine, dung, ghee and curd, holding medicinal import within Ayurveda’s ancient practices. This study aims to illuminate differences between probiotic variants V2 and V7, through findings on their pharmacological applications and biochemical concentrations. It is proposed that fermented panchagavya’s psychobiotic strains may exhibit favorable reactions worth examining. Chiefly, the organic synthesis of neurotransmitters by beneficial bacteria is of interest. The regulatory neurotransmitter gamma-aminobutyric acid (GABA) could potentially be generated by a panchagavya-derived probiotic. Through serial dilution culture of bacteria obtained from fermented panchagavya, their growth and GABA formation, as evaluated by thin-layer chromatography and ultraviolet-visible spectrometric analysis, are observed. Strain V2 demonstrates promising pharmacological properties including antioxidant, anti-inflammatory, anti-diabetic and anti-obesity effects, as well as inhibition of albumin denaturation and heat-induced hemolysis. It presents a higher concentration of such activities than V7. Biochemical tests further indicate V2’s larger percentage of GABA synthesis, supporting prospective therapeutic applications. After sequencing selected strains to explore psychobiotic functioning, their isolation holds medical import as GABA-producing beneficial bacteria from fermented panchagavya.

Behavioral comorbidities treatment by fecal microbiota transplantation in canine epilepsy: a pilot study of a novel therapeutic approach.

Anxiety and cognitive dysfunction are frequent, difficult to treat and burdensome comorbidities in human and canine epilepsy. Fecal microbiota transplantation (FMT) has been shown to modulate behavior in rodent models by altering the gastrointestinal microbiota (GIM). This study aims to investigate the beneficial effects of FMT on behavioral comorbidities in a canine translational model of epilepsy. Nine dogs with drug-resistant epilepsy (DRE) and behavioral comorbidities were recruited. The fecal donor had epilepsy with unremarkable behavior, which exhibited a complete response to phenobarbital, resulting in it being seizure-free long term. FMTs were performed three times, two weeks apart, and the dogs had follow-up visits at three and six months after FMTs. Comprehensive behavioral analysis, including formerly validated questionnaires and behavioral tests for attention deficit hyperactivity disorder (ADHD)- and fear- and anxiety-like behavior, as well as cognitive dysfunction, were conducted, followed by objective computational analysis. Blood samples were taken for the analysis of antiseizure drug (ASD) concentrations, hematology, and biochemistry. Urine neurotransmitter concentrations were measured. Fecal samples were subjected to analysis using shallow DNA shotgun sequencing, real-time polymerase chain reaction (qPCR)-based Dysbiosis Index (DI) assessment, and short-chain fatty acid (SCFA) quantification. Following FMT, the patients showed improvement in ADHD-like behavior, fear- and anxiety-like behavior, and quality of life. The excitatory neurotransmitters aspartate and glutamate were decreased, while the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and GABA/glutamate ratio were increased compared to baseline. Only minor taxonomic changes were observed, with a decrease in Firmicutes and a Blautia_A species, while a Ruminococcus species increased. Functional gene analysis, SCFA concentration, blood parameters, and ASD concentrations remained unchanged. Behavioral comorbidities in canine IE could be alleviated by FMT. This study highlights FMT's potential as a novel approach to improving behavioral comorbidities and enhancing the quality of life in canine patients with epilepsy.

Isoflurane-induced neuroinflammation and NKCC1/KCC2 dysregulation result in long-term cognitive disorder in neonatal mice

BackgroundThe inhalational anesthetic isoflurane is commonly utilized in clinical practice, particularly in the field of pediatric anesthesia. Research has demonstrated its capacity to induce neuroinflammation and long-term behavioral disorders; however, the underlying mechanism remains unclear [1]. The cation-chloride cotransporters Na+–K+–2Cl−–1 (NKCC1) and K+–2Cl−–2 (KCC2) play a pivotal role in regulating neuronal responses to gamma-aminobutyric acid (GABA) [2]. Imbalances in NKCC1/KCC2 can disrupt GABA neurotransmission, potentially leading to neural circuit hyperexcitability and reduced inhibition following neonatal exposure to anesthesia [3]. Therefore, this study postulates that anesthetics have the potential to dysregulate NKCC1 and/or KCC2 during brain development.MethodsWe administered 1.5% isoflurane anesthesia to neonatal rats for a duration of 4 h at postnatal day 7 (PND7). Anxiety levels were assessed using the open field test at PND28, while cognitive function was evaluated using the Morris water maze test between PND31 and PND34. Protein levels of NKCC1, KCC2, BDNF, and phosphorylated ERK (P-ERK) in the hippocampus were measured through Western blotting analysis. Pro-inflammatory cytokines IL-1β, IL-6, and TNF-α were quantified using ELISA.ResultsWe observed a decrease in locomotion trajectories within the central region and a significantly shorter total distance in the ISO group compared to CON pups, indicating that isoflurane induces anxiety-like behavior. In the Morris water maze (MWM) test, rats exposed to isoflurane exhibited prolonged escape latency onto the platform. Additionally, isoflurane administration resulted in reduced time spent crossing in the MWM experiment at PND34, suggesting long-term impairment of memory function. Furthermore, we found that isoflurane triggered activation of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α; downregulated KCC2/BDNF/P-ERK expression; and increased the NKCC1/KCC2 ratio in the hippocampus of PND7 rats. Bumetadine (NKCC1 specific inhibitors) reversed cognitive damage and effective disorder induced by isoflurane in neonatal rats by inhibiting TNF-α activation, normalizing IL-6 and IL-1β levels, restoring KCC2 expression levels as well as BDNF and ERK signaling pathways. Based on these findings, it can be speculated that BDNF, P-ERK, IL-1β, IL-6 and TNF - α may act downstream of the NKCC1/KCC2 pathway.ConclusionsOur findings provide evidence that isoflurane administration in neonatal rats leads to persistent cognitive deficits through dysregulation of the Cation-Chloride Cotransporters NKCC1 and KCC2, BDNF, p-ERK proteins, as well as neuroinflammatory processes.

Oxygen consumption rate of flatworms under the influence of wake- and sleep-promoting neurotransmitters.

Flatworms are among the best studied animal models for regeneration; however, they also represent an emerging opportunity to investigate other biological processes as well. For instance, flatworms are nocturnal and sleep during the day, a state that is regulated by sleep/wake history and the action of the sleep-promoting neurotransmitter gamma-aminobutyric acid (or GABA). Sleep is widespread across the animal kingdom, where it serves many nonexclusive functions. Notably, sleep saves energy by reducing metabolic rate and by not doing something more energetically taxing. Whether the conservation of energy is apparent in sleeping flatworms is unclear. We measured the oxygen consumption rate (OCR) of flatworms dosed with either (1) GABA (n = 29) which makes flatworms inactive or (2) dopamine (n = 20) which stimulates flatworms to move, or (3) day and night neurotransmitter-free controls (n = 28 and 27, respectively). While OCRdid not differ between the day and night, flatworms treated with GABA used less oxygen than those treated with dopamine, and less than the day-time control. Thus, GABA affected flatworm physiology, ostensibly by enforcing energy-conserving sleep. Evidence that dopamine increased metabolism was less strong. This work broadens our understanding of flatworm physiology and expands the phylogenetic applicability of energy conservation as a function of sleep.

HISTOSTRUCTURAL ALTERATIONS IN THE CEREBRAL ARCHITECTURE ASSOCIATED WITH THE PROGRESSION OF ALCOHOL INTOXICATION: AN EXPERIMENTAL ANALYSIS

The aim of this study is to evaluate the histological changes in the cerebellum of rat brains following chronic alcohol intoxication. Materials and Methods. We employed a classical approach for modeling chronic alcohol intoxication by administering 40% ethanol to rats (n=55) in a dosage of 2 ml per 100 g of body weight daily for three months. The cerebellar structure was then analyzed. Results. This study investigates the impact of chronic alcohol intoxication on the histological structures of the cerebellar cortex. The cerebellum, like the nervous system overall, possesses a significant cellular and functional reserve. However, teratogenic factors, including ethanol, notably influence the activity of cerebellar neurons, increasing it. Ethanol exposure during early pregnancy can lead to prenatal growth retardation, stillbirth, cleft palate, hydrocephaly, and reductions in fetal body size. There is evidence suggesting a correlation between blood ethanol levels and a reduction in the number of Purkinje cells. Chronic alcohol consumption results in cerebellar ataxia, alterations in upper limb movements, decreased reaction speeds, reduced attention concentration, impaired coordination accuracy, and disturbances in postural stability and balance. Conclusion. The cerebellum, especially during development, is particularly vulnerable to the toxic effects of alcohol. Recent research suggests that changes in the neurotransmission of gamma-aminobutyric acid (GABA)-dependent receptors may contribute to cerebellar dysfunction induced by ethanol. Ethanol exposure increases the release of GABA not only in Purkinje cells but also in the interneurons of the molecular layer and granule cells.

Phenibutan-an Illegal Food Supplement With Psychotropic Effects and Health Risks.

Phenibut (β-phenyl-γ-aminobutyric acid) is an analog of the neurotransmitter gamma-aminobutyric acid (GABA). Like abapentin and pregabalin, it inhibits α2-δ-subunits of voltagedependent presynaptic calcium channels. The potential harm resulting from the use of these gabapentinoids is currently a matter of debate. This review is based on pertinent publications retrieved by a selective literature search and on cases reported to the Giftinformationszentrum-Nord (GIZ-Nord), a poison information center at the University of Göttingen, Germany. Phenibut is a prescription drug in Russia but its production, possession, use, trafficking, or administration is illegal in Germany. The phenibut toxicity syndrome resembles that of gabapentinoids and GABA mimetics: benzodiazepine-like with - drawal symptoms including epileptic seizures, delirium and paradoxical activation have been described, as have cases of abuse and dependence. A few cases of use in the setting of multidrug abuse, and of phenibut-related death, have been described to date in the USA. The GIZ-Nord received 17 inquiries about phenibut, 55 about gabapentin, and 126 about pregabalin over the period 2008-2022. Over the same period, the GIZ-Nord was informed of 1207 cases involving Z substances and 4324 involving benzodiazepines. In the majority of the registered intoxications, including those with phenibut, the symptoms were mild. Overdoses of phenibut (2-100 g) were reported in 15 of the 17 cases; 8 of the persons who had taken an overdose were somnolent. In such cases, observation in intensive care was recommended. Respiratory depression or coma was not encountered in any case, not even in the patient who had taken 100 g of phenibut. Phenibut causes symptoms resembling those of gabapentinoid and benzodiazepine use. There have been reports of phenibut use in combination with other psychotropic drugs; in particular, its use together with opiates could increase the risk of coma and respiratory depression. No deaths due to phenibut intoxication have been published in Germany or elsewhere in Western Europe, although such cases may have been overlooked, as this drug is still largely unknown to Western medicine.

Delirium Tremens: A Review of Clinical Studies.

Delirium tremens (DT) is a severe condition resulting from alcohol withdrawal. This review highlights the challenges in diagnosing and managing DT and emphasizes the importance of early recognition and intervention to prevent complications and ensure optimal patient outcomes. The discussion of the pathophysiology of DT, focusing on the neurochemical imbalances involving the neurotransmitters gamma-aminobutyric acid and glutamate, explains how chronic alcohol dependence leads to these imbalances and contributes to the hyperexcitability seen in DT. The management of DT involves ensuring patient safety and alleviating symptoms, primarily through pharmacological approaches, such as benzodiazepines. Closely monitoring vital signs and electrolyte imbalances is necessary due to autonomic dysregulation associated with DT. The mention of the potential complexity of DT when coexisting with other conditions emphasizes the need for additional research to advance comprehension, identify predictive factors, and enhance its management.

The Role of GABA and Insulin Regulated Aminopeptidase on Insulin Resistance and GLUT4 in Prediabetes and Type 2 Diabetes Mellitus

Background: Different proposed mechanisms for insulin resistance have been put forth to understand the relationship and changes in insulin resistance. Looking at the levels of insulin, the neurotransmitter gamma-aminobutyric acid, glucose transport type 4, and the newly discovered enzyme insulin regulated aminopeptidase may provide an integrated perspective on insulin resistance. Objectives: To study the role of serum gamma-aminobutyric acid and insulin regulated aminopeptidase enzyme levels in pathogenesis of insulin resistance and translocation of glucose transport type 4 in patients with type2 diabetes mellitus and pre-diabetes ones. Subjects and methods: Ninety individuals were divided into three age- and BMI matched groups (diabetics, prediabetics, healthy) were assessed for glycated hemoglobin (turbidometry method), fasting serum glucose (colorimetric method), serum insulin (electrochemiluminescence immunoassay method), homeostatic model assessment for insulin resistance, serum gamma-aminobutyric acid, glucose transporter type 4, and insulin regulated aminopeptidase measured by the sandwich ELISA method. The cut-off value was adopted according to the World Health Organization, individuals with their fasting serum glucose lower than 110 mg/ml, and glycated hemoglobin level not more than 5.7 % are considered healthy individuals. Result: The mean (±SD) values of serum insulin regulated aminopeptidase, gamma-aminobutyric acid and glucose transport type 4 showed significantly lower levels with greater increases in insulin resistance, represented by the significant decrease in diabetics group who have high insulin resistance compared with pre-diabetics and healthy individuals’ groups (p &lt; 0.05). They also significantly decrease in individuals with the pre-diabetic stage compared to healthy individuals without insulin resistance (p &lt; 0.05). Significant negative correlations were found between HOMA-IR values and each of GABA, IRAP, and GLUT4. Conclusion: Decreasing gamma-aminobutyric acid may promote insulin resistance and prediabetes/diabetes onset. Decreased insulin regulated aminopeptidase levels suggest a role alongside glucose transport type 4 in glucose uptake, allowing screening for prediabetes risk.

Clustered de novo start-loss variants in GLUL result in a developmental and epileptic encephalopathy via stabilization of glutamine synthetase

Glutamine synthetase (GS), encoded by GLUL, catalyzes the conversion of glutamate to glutamine. GS is pivotal for the generation of the neurotransmitters glutamate and gamma-aminobutyric acid and is the primary mechanism of ammonia detoxification in the brain. GS levels are regulated post-translationally by an N-terminal degron that enables the ubiquitin-mediated degradation of GS in a glutamine-induced manner. GS deficiency in humans is known to lead to neurological defects and death in infancy, yet how dysregulation of the degron-mediated control of GS levels might affect neurodevelopment is unknown. We ascertained nine individuals with severe developmental delay, seizures, and white matter abnormalities but normal plasma and cerebrospinal fluid biochemistry with de novo variants in GLUL. Seven out of nine were start-loss variants and two out of nine disrupted 5' UTR splicing resulting in splice exclusion of the initiation codon. Using transfection-based expression systems and mass spectrometry, these variants were shown to lead to translation initiation of GS from methionine 18, downstream of the N-terminal degron motif, resulting in a protein that is stable and enzymatically competent but insensitive to negative feedback by glutamine. Analysis of human single-cell transcriptomes demonstrated that GLUL is widely expressed in neuro- and glial-progenitor cells and mature astrocytes but not in post-mitotic neurons. One individual with a start-loss GLUL variant demonstrated periventricular nodular heterotopia, a neuronal migration disorder, yet overexpression of stabilized GS in mice using in utero electroporation demonstrated no migratory deficits. These findings underline the importance of tight regulation of glutamine metabolism during neurodevelopment in humans.

New drugs for small animals in 2023

In 2023, 2 novel pharmaceutical agents for small animals were released on the German market: the structural but non-functional analog of the inhibitory neurotransmitter gamma-aminobutyric acid pregabalin with an anxiolytic active component and the dopamine agonist ropinirole in form of eye drops to induce vomiting. Two established active veterinary pharmaceutical ingredients became available for additional species: The phosphorus compound butafosfan was additionally approved for horses, dogs and cats and the mineral sodium chloride as an isotonic sodium chloride solution was also approved for rabbits and guinea pigs. In addition, for small animals, there were new releases of an agent (dexamethasone) in a novel pharmaceutical formulation, one drug with a new route of administration (hydrocortisone aceponate), one drug with a new content of the active ingredient (firocoxib) as well as one veterinary drug with a new combination of active ingredients in a novel pharmaceutical formulation (gentamicin+mometasone+posaconazole). Furthermore, one combination of active ingredients (diprophylline+heptaminol) is available on the market for small animals again.