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Frontiers in Pharmacology 2021The interest in AMPA receptors as a target for epilepsy treatment increased substantially after the approval of perampanel, a negative AMPA receptor allosteric...
The interest in AMPA receptors as a target for epilepsy treatment increased substantially after the approval of perampanel, a negative AMPA receptor allosteric antagonist, for the treatment of partial-onset seizures and generalized tonic-clonic seizures. Here we performed a screening for activity against native calcium-permeable AMPA receptors (CP-AMPARs) and calcium-impermeable AMPA receptors (CI-AMPARs) among different anticonvulsants using the whole-cell patch-clamp method on isolated Wistar rat brain neurons. Lamotrigine, topiramate, levetiracetam, felbamate, carbamazepine, tiagabin, vigabatrin, zonisamide, and gabapentin in 100-µM concentration were practically inactive against both major subtypes of AMPARs, while phenytoin reversibly inhibited them with IC50 of 30 ± 4 μM and 250 ± 60 µM for CI-AMPARs and CP-AMPARs, respectively. The action of phenytoin on CI-AMPARs was attenuated in experiments with high agonist concentrations, in the presence of cyclothiazide and at pH 9.0. Features of phenytoin action matched those of the CI-AMPARs pore blocker pentobarbital, being different from classical competitive inhibitors, negative allosteric inhibitors, and CP-AMPARs selective channel blockers. Close 3D similarity between phenytoin and pentobarbital also suggests a common binding site in the pore and mechanism of inhibition. The main target for phenytoin in the brain, which is believed to underlie its anticonvulsant properties, are voltage-gated sodium channels. Here we have shown for the first time that phenytoin inhibits CI-AMPARs with similar potency. Thus, AMPAR inhibition by phenytoin may contribute to its anticonvulsant properties as well as its side effects.
PubMed: 34950035
DOI: 10.3389/fphar.2021.775040 -
Scientific Reports Jan 2020Rodents are widely used for animal research in Egypt. Pentobarbital is the most common anesthetic agent; however overdoses may affect the experimental outcomes and limit...
Rodents are widely used for animal research in Egypt. Pentobarbital is the most common anesthetic agent; however overdoses may affect the experimental outcomes and limit the use of tissues. To investigate the effects of sodium pentobarbital overdoses during exsanguination, three groups (6 rats/group) of male and female rats were injected i.p. with 50, 100 and 150 mg/kg of sodium pentobarbital, then carotid exsanguination was performed immediately after loss of consciousness. Hypoxia-inducible factor 1-alpha (Hif1a) and tumor necrosis factor-alpha (Tnfa) mRNA expressions in liver and kidney organs were evaluated. As well as, serum aminotransferase activities (AST&ALT), glucose, urea, creatinine, malondialdehyde (MDA), reduced glutathione (GSH) and catalase (CAT) levels were determined. The histological alterations in liver, kidney and spleen were studied. It was found that Hif1a and Tnfa were significantly overexpressed in the studied organs and serum AST, glucose, creatinine and urea levels were significantly increased after sodium pentobarbital overdoses (100 and 150 mg/kg) compared to 50 mg/kg dose. Similarly, significant increase in MDA and GSH levels of liver, kidney and spleen were noticed. Results showed gender difference where Hif1a and Tnfa levels were significantly overexpressed at high dose of sodium pentobarbital of liver and kidney organs in female more than male rats. Since euthanasia protocol may influence the physiological variables and affect genes' expression, it is recommended to avoid sodium pentobarbital overdose during euthanasia as it may interfere with the biochemical, molecular and histological measurements.
Topics: Adjuvants, Anesthesia; Animals; Biomarkers; Exsanguination; Female; Glutathione; Kidney; Liver; Liver Function Tests; Male; Malondialdehyde; Oxidative Stress; Pentobarbital; Rats; Rats, Wistar
PubMed: 31942001
DOI: 10.1038/s41598-019-57252-7 -
Anesthesiology Nov 2017Previous studies showed that synaptic transmission is affected by general anesthetics, but an anesthetic dose response in freely moving animals has not been done. The...
BACKGROUND
Previous studies showed that synaptic transmission is affected by general anesthetics, but an anesthetic dose response in freely moving animals has not been done. The hippocampus provides a neural network for the evaluation of isoflurane and pentobarbital on multisynaptic transmission that is relevant to memory function.
METHODS
Male Long-Evans rats were implanted with multichannel and single electrodes in the hippocampus. Spontaneous local field potentials and evoked field potentials were recorded in freely behaving rats before (baseline) and after various doses of isoflurane (0.25 to 1.5%) and sodium pentobarbital (10 mg/kg intraperitoneal).
RESULTS
Monosynaptic population excitatory postsynaptic potentials at the basal and apical dendrites of CA1 were significantly decreased at greater than or equal to 0.25% (n = 4) and greater than or equal to 1.0% (n = 6) isoflurane, respectively. The perforant path evoked multisynaptic response at CA1 was decreased by ~50% at greater than or equal to 0.25% isoflurane (n = 5). A decreased population excitatory postsynaptic potential was accompanied by increased paired-pulse facilitation. Population spike amplitude in relation to apical dendritic population excitatory postsynaptic potential was not significantly altered by isoflurane. Spontaneous hippocampal local field potential at 0.8 to 300 Hz was dose-dependently suppressed by isoflurane (n = 6), with local field potential power in the 50- to 150-Hz band showing the highest decrease with isoflurane dose, commensurate with the decrease in trisynaptic CA1 response. Low-dose pentobarbital (n = 7) administration decreased the perforant path evoked trisynaptic CA1 response and hippocampal local field potentials at 78 to 125 Hz.
CONCLUSIONS
Hippocampal networks are sensitive to low doses of isoflurane and pentobarbital, possibly through both glutamatergic and γ-aminobutyric acid-mediated transmission. Network disruption could help explain the impairment of hippocampal-dependent cognitive functions with low-dose anesthetic.
Topics: Anesthetics, General; Animals; Electrodes, Implanted; Excitatory Postsynaptic Potentials; Hippocampus; Isoflurane; Male; Nerve Net; Pentobarbital; Rats; Rats, Long-Evans; Synapses
PubMed: 28902674
DOI: 10.1097/ALN.0000000000001861 -
Transplantation Proceedings Oct 2016Because the choice of anesthetic affects the rodent orthotopic liver transplantation (OLT) model, we compared the effects of isoflurane, ketamine, chloral hydrate, and... (Comparative Study)
Comparative Study
PURPOSE
Because the choice of anesthetic affects the rodent orthotopic liver transplantation (OLT) model, we compared the effects of isoflurane, ketamine, chloral hydrate, and pentobarbital on the OLT model.
BASIC PROCEDURES
OLT was performed using the two-cuff technique. Two hundred male rats were randomly divided into five groups: control, isoflurane, ketamine, chloral hydrate, and pentobarbital groups. Rectal temperatures, respiratory rates, arterial blood values (pH, PaCO, PaO, and SatO), liver function tests and histopathology, recovery times, and anhepatic stage mortality rates were assessed.
MAIN FINDINGS
Compared with controls, respiratory rates decreased by 20% in the isoflurane group, and decreased by 40%-50% in the ketamine, chloral hydrate, and pentobarbital groups. The PaO, SatO, and pH levels in the ketamine, chloral hydrate, and pentobarbital groups were significantly lower than those in the isoflurane and control groups (P < .05). Only the pentobarbital group displayed significant liver histopathologic changes along with significantly higher levels of serum alanine aminotransferase and total bilirubin, but a significantly lower level of serum albumin, compared with the control group (P < .05). The isoflurane group had a 0% anhepatic stage mortality rate compared with rates of 30%-40% in the other anesthetic groups.
PRINCIPAL CONCLUSIONS
Isoflurane should be the preferred anesthetic for rodent OLT surgery due to its minimal respiratory and hepatic physiological effects as well as its low anhepatic phase mortality rate. Secondary to isoflurane, ketamine and chloral hydrate may be administered as donor anesthetics. Pentobarbital use should be avoided entirely in rodent OLT surgery due to its significant hepatotoxic effects.
Topics: Anesthetics; Animals; Chloral Hydrate; Isoflurane; Ketamine; Liver; Liver Transplantation; Male; Models, Animal; Monitoring, Physiologic; Pentobarbital; Random Allocation; Rats, Sprague-Dawley; Respiration
PubMed: 27788823
DOI: 10.1016/j.transproceed.2016.06.057 -
Pharmaceutics Feb 2023Pentobarbital is a drug of choice to limit motion in children during paediatric procedural sedations (PPSs). However, despite the rectal route being preferred for...
Pentobarbital is a drug of choice to limit motion in children during paediatric procedural sedations (PPSs). However, despite the rectal route being preferred for infants and children, no pentobarbital suppositories are marketed, and therefore they must be prepared by compounding pharmacies. In this study, two suppository formulations of 30, 40, 50, and 60 mg of pentobarbital sodium were developed using hard-fat Witepsol W25 either alone (formulation F1) or with oleic acid (formulation F2). The two formulations were subjected to the following tests described in the European Pharmacopoeia: uniformity of dosage units, softening time, resistance to rupture, and disintegration time. The stability of both formulations was also investigated for 41 weeks of storage at 5 ± 3 °C using a stability-indicating liquid chromatography method to quantify pentobarbital sodium and research breakdown product (BP). Although both formulae were compliant to uniformity of dosage, the results were in favour of a faster disintegration of F2 compared to F1 (-63%). On the other hand, F1 was found to be stable after 41 weeks of storage unlike F2 for which several new peaks were detected during the chromatographic analysis, suggesting a shorter stability of only 28 weeks. Both formulae still need to be clinically investigated to confirm their safety and efficiency for PPS.
PubMed: 36986615
DOI: 10.3390/pharmaceutics15030755 -
Epileptic Disorders : International... Dec 2021Treatment of super-refractory status epilepticus (SRSE) is associated with various complications of anaesthetic coma therapy. This study aimed to describe the factors... (Observational Study)
Observational Study
Treatment of super-refractory status epilepticus (SRSE) is associated with various complications of anaesthetic coma therapy. This study aimed to describe the factors affecting the prognosis, especially in-hospital mortality, of patients receiving pentobarbital coma therapy for the treatment of SRSE. This was a retrospective cohort study conducted in a single tertiary referral centre with patients who received pentobarbital coma therapy for the treatment of SRSE from 2006 to 2018. Exploratory analyses were performed for clinical, laboratory, electrographic, and radiological factors for the entire cohort and were compared between the mortality and survivor groups. In total, 19 patients were enrolled, and five (26.3%) patients died in the hospital. The maximal pentobarbital infusion dose was higher in the mortality group than in the survivor group (4.4±1.0 mg/kg/h vs. 2.9±1.4 mg/kg/h, respectively; p=0.025). The high-dose pentobarbital infusion group (>3.75 mg/kg/h) underwent longer mechanical ventilation (24 [20-36.75] vs. 41 [28-70], p=0.025) and blood culture results were more frequently positive, suggestive of septicaemia (8.3% vs. 57.1%, p=0.038). The group of SRSE patients treated with pentobarbital coma therapy who died in the hospital received a higher pentobarbital infusion dose compared to survivors; a complication of high-dose pentobarbital infusion was septicaemia. Considering the high rate of septicaemia observed, systematic treatment strategies focusing on infectious complications should be established and implemented. The association between maximal pentobarbital infusion dose and in-hospital mortality needs to be further validated.
Topics: Coma; Hospital Mortality; Humans; Pentobarbital; Retrospective Studies; Sepsis; Status Epilepticus
PubMed: 34642129
DOI: 10.1684/epd.2021.1333 -
Annals of Palliative Medicine Apr 2021L-theanine (L-THE), a natural amino acid found in green tea, has been shown to improve anxiety and sleep. Neumentix proprietary spearmint extract (PSE), which is...
BACKGROUND
L-theanine (L-THE), a natural amino acid found in green tea, has been shown to improve anxiety and sleep. Neumentix proprietary spearmint extract (PSE), which is commonly found in beverage flavoring a pharmaceutical, also has a wide range of health benefits, including cognitive performance improvement.
METHODS
Four experiments tested the effects of L-THE and PSE on sleep: a direct sleeping test, pentobarbital-induced sleeping test, sub-hypnotic pentobarbital-induced sleeping test, and sodium barbital-induced sleeping test. Presence of neurotransmitters in brain tissue was detected by liquid chromatography mass spectroscopy (HP LC-MS) during these studies.
RESULTS
Pentobarbital-induced sleeping and sodium barbital-induced sleeping tests examined the potential effect of L-THE/PSE mixture on synergistic sleep, while neurotransmitter levels in the brain were determined by the high performance liquid chromatography/mass spectroscopy (HPLC/MS) method. L-THE and L-THE/PSE mixture showed increased sleep duration and shortened sleep latency when co-administrated with pentobarbital or sodium barbital. The mixture also increased sleeping rate when co-administrated with the pentobarbital at sub-hypnotic dose. Additionally, the L-THE, PSE and L-THE/PSE mixture significantly increased the concentrations of acetylcholine (Ach), γ-aminobutyric acid (GABA), and decreased the concentration of serotonin (5-HT) in the brain.
CONCLUSIONS
These data demonstrated that L-THE/PSE mixture regulates sleep disorders via the GABA receptor and neurotransmitter systems.
Topics: Animals; Brain; Glutamates; Mice; Neurotransmitter Agents; Sleep; gamma-Aminobutyric Acid
PubMed: 33966405
DOI: 10.21037/apm-21-663 -
Veterinary Research Communications Dec 2023A bearded vulture (Gypaetus barbatus) found dead in northern Spain presented external lesions consistent with electrocution as the cause of death. During forensic...
A bearded vulture (Gypaetus barbatus) found dead in northern Spain presented external lesions consistent with electrocution as the cause of death. During forensic examination, macroscopic lesions suggested potential comorbidity, so samples were collected for molecular and toxicological analyses. Gastric content and liver were analysed for toxic substances, and pentobarbital (a common pharmaceutical used for euthanasia in domestic animals) was detected at a concentration of 37.3 and 0.05 µg/g, respectively. Other toxicological, viral and endoparasite analyses (avian malaria, avian influenza and flaviviruses) were negative. Thus, although the cause of death was electrocution, pentobarbital intoxication likely impaired the equilibrium and reflexes of the individual, possibly causing the bird to contact energized wires that it would not have otherwise. These results underline the importance of comprehensive analysis of forensic cases of wildlife deaths and reveal barbiturate poisoning as an additional threat for the conservation of the bearded vulture in Europe.
Topics: Animals; Falconiformes; Pentobarbital; Birds; Spain; Poisons
PubMed: 37145336
DOI: 10.1007/s11259-023-10093-2 -
Anesthesia and Analgesia Sep 2014Anesthetics enhance γ-aminobutyric acid (GABA)-mediated inhibition in the central nervous system. Different agents have been shown to act on tonic versus synaptic GABA...
BACKGROUND
Anesthetics enhance γ-aminobutyric acid (GABA)-mediated inhibition in the central nervous system. Different agents have been shown to act on tonic versus synaptic GABA receptors to different degrees, but it remains unknown whether different forms of synaptic inhibition are also differentially engaged. With this in mind, we tested the hypothesis that different types of GABA-mediated synapses exhibit different anesthetic sensitivities. The present study compared effects produced by isoflurane, halothane, pentobarbital, thiopental, and propofol on paired-pulse GABAA receptor-mediated synaptic inhibition. Effects on glutamate-mediated facilitation were also studied.
METHODS
Synaptic responses were measured in rat hippocampal brain slices. Orthodromic paired-pulse stimulation was used to assess anesthetic effects on either glutamate-mediated excitatory inputs or GABA-mediated inhibitory inputs to CA1 neurons. Antidromic stimulation was used to assess anesthetic effects on CA1 background excitability. Agents were studied at equieffective concentrations for population spike depression to compare their relative degree of effect on synaptic inhibition.
RESULTS
Differing degrees of anesthetic effect on paired-pulse facilitation at excitatory glutamate synapses were evident, and blocking GABA inhibition revealed a previously unseen presynaptic action for pentobarbital. Although all 5 anesthetics depressed synaptically evoked excitation of CA1 neurons, the involvement of enhanced GABA-mediated inhibition differed considerably among agents. Single-pulse inhibition was enhanced by propofol, thiopental, and pentobarbital, but only marginally by halothane and isoflurane. In contrast, isoflurane enhanced paired-pulse inhibition strongly, as did thiopental, but propofol, pentobarbital, and halothane were less effective.
CONCLUSIONS
These observations support the idea that different GABA synapses use receptors with differing subunit compositions and that anesthetics exhibit differing degrees of selectivity for these receptors. The differing anesthetic sensitivities seen in the present study, at glutamate and GABA synapses, help explain the unique behavioral/clinical profiles produced by different classes of anesthetics and indicate that there are selective targets for new agent development.
Topics: Anesthesiology; Anesthetics; Animals; Barbiturates; Bicuculline; CA1 Region, Hippocampal; Data Interpretation, Statistical; Dendrites; Dose-Response Relationship, Drug; Evoked Potentials; GABA Antagonists; In Vitro Techniques; Kinetics; Male; Neural Inhibition; Patch-Clamp Techniques; Pharmaceutical Solutions; Picrotoxin; Rats; Rats, Sprague-Dawley; Receptors, GABA-A; Synapses
PubMed: 24977633
DOI: 10.1213/ANE.0000000000000321 -
Neuropsychopharmacology : Official... Jan 2023Neurosteroids that positively modulate GABA receptors are among a growing list of rapidly acting antidepressants, including ketamine and psychedelics. To develop...
Neurosteroids that positively modulate GABA receptors are among a growing list of rapidly acting antidepressants, including ketamine and psychedelics. To develop increasingly specific treatments with fewer side effects, we explored the possibility of EEG signatures in mice, which could serve as a cross-species screening tool. There are few studies of the impact of non-sedative doses of rapid antidepressants on EEG in either rodents or humans. Here we hypothesize that EEG features may separate a rapid antidepressant neurosteroid, allopregnanolone, from other GABA positive modulators, pentobarbital and diazepam. Further, we compared the actions GABA modulators with those of ketamine, an NMDA antagonist and prototype rapid antidepressant. We examined EEG spectra during active exploration at two cortical locations and examined cross-regional and cross-frequency interactions. We found that at comparable doses, the effects of allopregnanolone, despite purported selectivity for certain GABAR subtypes, was indistinguishable from pentobarbital during active waking exploration. The actions of diazepam had recognizable common features with allopregnanolone and pentobarbital but was also distinct, consistent with subunit selectivity of benzodiazepines. Finally, ketamine exhibited no distinguishing overlap with allopregnanolone in the parameters examined. Our results suggest that rapid antidepressants with different molecular substrates may remain separated at the level of large-scale ensemble activity, but the studies leave open the possibility of commonalities in more discrete circuits and/or in the context of a dysfunctional brain.
Topics: Humans; Mice; Animals; Pregnanolone; Ketamine; Pentobarbital; Receptors, GABA-A; Diazepam; Neurosteroids; Antidepressive Agents; gamma-Aminobutyric Acid; Electroencephalography
PubMed: 36168047
DOI: 10.1038/s41386-022-01450-x