Traumatic brain injury (TBI) frequently results in long-term cognitive and functional deficits, yet routine diagnostic tools often fail to capture the diffuse network dysfunction and underlying neurochemical changes that contribute to poor recovery. Resting-state EEG is sensitive to injury-related abnormalities in neural oscillations, while [11C]flumazenil PET quantifies gamma-aminobutyric acid (GABAA) receptor availability-a key determinant of inhibitory tone and cortical synchronization-but these modalities are rarely integrated. Linking EEG spectral features to molecular measures of GABAA function may provide translational biomarkers that bridge non-invasive neurophysiological findings with underlying neurochemical status. The primary aim of this study was to determine whether resting-state EEG spectral features, particularly in the high-frequency beta and gamma bands, track longitudinal changes in GABAA receptor availability measured with [11C]flumazenil PET in individuals recovering from TBI. A secondary aim was to characterize the persistence of low-frequency abnormalities (increased delta, reduced alpha) over the first year of recovery and explore their potential relevance as non-invasive markers of network dysfunction. We analysed EEG data from 68 subjects with TBI and 75 non-brain-injured controls; longitudinal follow-up EEG data were available for 37 TBI participants and 20 non-brain-injured controls. We found that the TBI subjects exhibited significantly higher delta power and lower alpha power; this remained at the chronic visit. Among the longitudinally studied subjects, a subset of seven TBI participants and six non-brain-injured controls were studied with [11C]flumazenil PET data. We found strong positive correlations between longitudinal changes in [11C]flumazenil PET measured GABAA receptor availability and concurrent changes in EEG high beta (r 2 = 0.79, P < 0.01) as well as low and high gamma power (r 2 = 0.71, P < 0.05; r 2 = 0.77, P < 0.01) in TBI subjects for the 'eyes-open' condition. These exploratory findings provide preliminary evidence that GABAA receptor availability, measured via [11C] flumazenil PET, is associated with high-frequency EEG power in TBI. This PET-EEG coupling may reflect underlying changes in excitatory-inhibitory network balance consistent with restoration of fronto-striatal arousal and neuronal membrane 'tone' under the mesocircuit model, although the small sample size of the cohort with multimodal measurements warrants cautious interpretation and further replication. Nonetheless, the observations in this cohort are consistent with a key role of increasing inhibitory activity across fronto-striatal neurons and networks in recovery from TBI.

Remimazolam, an ultra-short-acting benzodiazepine metabolized by carboxylesterase-1 (CES1), permits specific antagonism by flumazenil, enabling active reversal unavailable with propofol-based sedation. However, the safety profile of this reversal strategy-including re-sedation risk, seizure concerns, and special population considerations-remains incompletely characterized.

This study evaluated the anxiolytic and memory-protective effects of withanolide D in adult zebrafish (Danio rerio). The compound was administered at doses of 4, 20, and 40 mg/kg and showed no signs of toxicity after 96 h of observation at any of the doses tested. In the open field test, withanolide D reduced locomotor activity, indicating a sedative-like effect. Nevertheless, in the light/dark test, doses of 20 and 40 mg/kg produced an anxiolytic-like response, suggesting that anxiolytic and motor effects may partially overlap depending on dose. The anxiolytic effect observed at the minimum effective dose (20 mg/kg) was reversed by flumazenil (FMZ), supporting the involvement of a benzodiazepine-sensitive GABAA modulatory domain. Furthermore, withanolide D, at a dose of 4 mg/kg, prevented ethanol-induced memory impairment in the inhibitory avoidance task, suggesting a protective effect on memory consolidation. Molecular docking analyses revealed favorable interactions of withanolide D at the extracellular α1γ2 interface of the GABAA receptor, supporting a putative allosteric interaction in a functionally related modulatory region rather than definitive occupation of the classical diazepam site. Consistently, normal mode analysis (NMA) showed that withanolide D increases receptor mobility compared to diazepam, with RMSF values reaching up to 0.98 Å, indicating enhanced structural flexibility and dynamic modulation of the protein. Thus, these findings suggest that withanolide D has therapeutic potential for the treatment of anxiety, in addition to providing protective effects on memory.

Traumatic brain injury is a major cause of long-term cognitive impairment, yet the mechanisms underlying recovery remain poorly understood. Neuroimaging methods such as diffusion magnetic resonance imaging (MRI), functional MRI (fMRI), and positron emission tomography (PET) provide insight into micro- and macro-scale changes post-traumatic brain injury (TBI), but the relationships between regional cellular and functional alterations remain unclear. In this exploratory study, we conducted a longitudinal, multimodal neuroimaging analysis quantifying TBI-related pathologies in four biomarkers, namely flumazenil PET derived binding potential, diffusion MRI (dMRI)-derived structural connectivity, and resting-state fMRI-derived functional connectivity and fractional amplitude of low-frequency fluctuations in individuals with complicated mild-to-severe brain injury at the subacute (4-6 months post-injury) and chronic (1-year post-injury) stages. The TBI sample consisted of 41 fMRI, 40 dMRI, and nine PET subjects, with 16 fMRI and dMRI and seven PET longitudinal measurements. The control sample consisted of 14 dMRI and fMRI and 19 PET subjects scanned at a single time point for comparison with TBI subjects at both time points. Most of the PET and MRI subjects are overlapping in both TBI and control groups. Brain injury related regional pathologies, and their changes over time in TBI subjects, were correlated across the four biomarkers. Our results reveal complex, dynamic changes over time. We found that flumazenil-PET binding potential was significantly reduced in frontal and thalamic regions in brain-injured subjects, consistent with neural loss and dysfunction, with partial recovery over time. Functional hyperconnectivity was observed in brain injured subjects initially but declined while remaining elevated compared to non-injured controls, whereas cortical structural hypoconnectivity persisted. Importantly, we observed that brain injury-related alterations across MRI modalities became more strongly correlated with flumazenil-PET at the chronic stage. Regions with chronic reductions in flumazenil-PET binding also showed weaker structural node strength and lower amplitude of low-frequency fluctuations, a relationship that was not found at the subacute stage. This observation could suggest a progressive convergence of structural and functional disruptions with neuronal dysfunction and loss over time. Additionally, regions with declining structural node strength also exhibited decreases in functional node strength, while these same regions showed increased amplitude of low-frequency fluctuations over time. This pattern suggests that heightened intrinsic regional activity may serve as a compensatory mechanism in regions increasingly disconnected due to progressive axonal degradation. Altogether, these findings advance our understanding of how multimodal neuroimaging captures the evolving interplay between neuronal integrity, structural connectivity, and functional dynamics after brain injury. Given the exploratory nature of this study, stemming from the modest sample size, future work in larger cohorts will be essential to validate and refine these preliminary associations as well as the inclusion of multiple measures of healthy controls. Clarifying these interrelationships could inform prognostic models and enhance knowledge of degenerative, compensatory, and recovery mechanisms in traumatic brain injury.

Emerging sedative agents are increasingly being explored to improve the safety and effectiveness of procedural sedation in pediatric emergency care. Traditional agents such as propofol and ketamine remain widely used because of their rapid onset and clinical effectiveness; however, they may be associated with adverse effects, including hypotension, respiratory depression, and emergence reactions, which require careful monitoring during pediatric procedural sedation. In this context, newer pharmacologic approaches have been investigated to optimize safety and procedural control. Remimazolam, a benzodiazepine metabolized by tissue esterases, demonstrates rapid clearance, minimal drug accumulation, and stable hemodynamic profiles. Clinical studies suggest comparable efficacy to propofol in procedural sedation, with potential advantages including reduced respiratory depression and a lower incidence of emergence delirium. Its reversibility with flumazenil may further enhance safety in selected clinical scenarios. Dexmedetomidine, a selective α2-adrenergic receptor agonist, provides sedation that resembles natural sleep and offers intrinsic analgesic properties with minimal respiratory depression. Although its onset of action may be slower than that of agents such as propofol, dexmedetomidine is associated with favorable respiratory stability and may be particularly useful in pediatric patients requiring cooperative or prolonged sedation. Intranasal administration represents a noninvasive alternative in situations where intravenous access has not yet been established, although its pharmacokinetic profile may result in delayed onset. These agents have been applied in a variety of pediatric procedures, including painful interventions, imaging studies, and short diagnostic procedures. Their use may be particularly valuable in children with developmental disorders or complex comorbidities, where stable hemodynamic and respiratory profiles are essential. Contemporary safety frameworks emphasize structured risk assessment, airway preparedness, weight-based dosing strategies, and continuous monitoring techniques such as capnography and pulse oximetry. Current evidence from randomized and observational studies suggests that emerging sedative strategies may provide effective procedural sedation while maintaining favorable safety profiles when appropriately integrated into multimodal sedation approaches. Nevertheless, important knowledge gaps remain, including limited pediatric data for certain agents, the need for standardized protocols, and the evaluation of long-term outcomes in younger patient populations.

Decades of research were instrumental in identifying the brain function controlling speech production. However, our understanding of the regulation of neuronal excitability via neurotransmission during speaking remains scant as the role of the inhibitory GABAergic system in controlling speech production is unknown. Using PET with [[11]C]flumazenil radioligand combined with PET with [[11]C]raclopride and functional MRI in healthy humans, we investigated the GABAergic neurotransmission and its relationship with dopaminergic function and brain activity during speaking and at the resting state. We demonstrate significant associations between neural activity and GABAA receptor binding during speaking, with positive associations found in the inferior and superior parietal cortices, inferior frontal gyrus, supplementary motor area, superior temporal gyrus, putamen, and negative associations identified in the left inferior and middle frontal gyri. Neural activity was related to the interaction between the GABAergic neurotransmission and nigrostriatal dopamine release in the left associative caudate nucleus and sensorimotor putamen. Conversely, significant correlations between GABAergic neurotransmission and resting-state activity were limited to the primary visual cortex and the cerebellar lobule VI. These data provide the first direct evidence of the specific interactions of GABAergic and dopaminergic transmission with neural activity controlling the production of speech in healthy humans. Our findings suggest that GABAergic modulation of brain activity is exerted at different stages of speech control, from auditory perception to motor production, whereas dopaminergic function is important for maintaining the balance between excitation and inhibition within the speech motor circuitry.

Menthol, a natural monoterpene extracted from Mentha species, has gained attention as an alternative sedative and anesthetic in aquaculture. However, its physiological safety range and potential sublethal toxicity remain insufficiently defined. This study investigated the cardiac and behavioral effects of menthol sedation in Oreochromis niloticus, aiming to identify a therapeutic window and elucidate its underlying mechanisms of action. Juvenile fish were exposed to graded concentrations of menthol (100-250 mg/L) to evaluate induction and recovery times, cardiac rhythm stability, and electrocardiographic parameters, including heart rate, QRS amplitude, and PQ and QT intervals. Additional assays with the GABAA receptor antagonist flumazenil (1 mg kg[-][1], i.p.) were performed to determine neurophysiological mediation. Menthol induced a concentration-dependent decrease in heart rate and prolongation of ventricular conduction intervals, characterizing sinus bradycardia without arrhythmia. Concentrations between 100 and 200 mg/L provided effective sedation and rapid recovery while maintaining hemodynamic stability, defining a safe therapeutic window. Above 200 mg/L, pronounced bradycardia and delayed recovery were observed, indicating sublethal cardiac depression. Flumazenil significantly prolonged anesthesia induction, confirming GABAA-mediated mechanisms in menthol sedation. These findings establish the physiological safety limits for menthol use in Nile tilapia and highlight its ecotoxicological significance, as excessive or environmental exposure may impair cardiac homeostasis in aquatic organisms. The results contribute to defining safe anesthetic practices and to understanding the toxicodynamic implications of natural sedatives in aquatic ecosystems.

Syzygium cumini L. Skeels, commonly known as jamelão, is a fruit with high nutraceutical value and reported medicinal properties, including neuropharmacological potential. This study evaluated the anxiolytic effects and safety profile of S. cumini fruit ethanolic/methanolic extract (EMEScF) in adult zebrafish (Danio rerio), aZF, a well-established animal model for behavioral neuroscience due to its genetic and physiological similarities to mammals. No signs of toxicity or mortality at extract concentrations up to 1.0 mg/mL over 96 h in acute toxicity assays. Behavioral assessments using the Open Field Test and Light & Dark Test demonstrated that the extract induced anxiolytic-like effects without sedation, contrasting with diazepam's sedative profile. Further pharmacological analyses using serotonergic antagonists cyproheptadine, pizotifen, and granisetron attenuated the anxiolytic effects, implicating 5-HT1B, 5-HT2A/2C, and 5-HT3A/3B receptors in the extract's mechanism of action. Additionally, flumazenil prevented anxiolytic-like effects, suggesting involvement of the GABAA receptor. Molecular docking studies supported these findings, showing strong binding affinities of major anthocyanins, such as delphinidin, malvidin, and petunidin to serotonergic and GABAergic receptor models, with petunidin displaying the highest stability and affinity. In an alcohol withdrawal-induced anxiety-like model, EMEScF effectively reduced anxiety-like behaviors, comparable to diazepam. These results indicate that EMEScF exerts anxiolytic-like effects mediated by serotonergic and GABAergic systems, without motor impairment or toxicity, positioning it as a promising natural alternative for anxiety treatment.

Although widely prescribed globally, benzodiazepines (BZDs) are commonly misused and involved in a high rate of drug-related deaths worldwide. Novel chemically similar compounds, designer BZDs (DBZDs), have emerged on the recreational market with little information available on their pharmacodynamic effects. An in vitro α1β2γ2 GABAA assay was used to determine the activity and explore structure-activity relationships of 42 DBZDs plus 11 prescription BZDs. Their interaction with the BZD α[+]/γ2[-] interface was explored using the BZD antagonist flumazenil. Most of the D/BZDs were positive allosteric modulators, but 4'-chlorodiazepam and 4'-fluorodiazepam were negative allosteric modulators, although the activity was not antagonized by flumazenil. All metabolites tested were active. This data informs the interpretation of intoxications, harm reduction measures, and drugs legislation for DBZDs; demonstrates the importance of testing new drugs as they emerge on the recreational market; and offers insights into how BZD chemical modifications alter GABAA pharmacodynamics.