Stress responses are activated by the hypothalamic-pituitary-adrenal axis (HPA axis), culminating in the release of glucocorticoids. During prolonged periods of secretion of glucocorticoids or inappropriate behavioral responses to a stressor, pathologic conditions may occur. Increased glucocorticoid concentration is linked to generalized anxiety, and there are knowledge gaps regarding its regulation. It is known that the HPA axis is under GABAergic control, but the contribution of the individual subunits of the GABA receptor is largely unknown. In this study, we investigated the relationship between the α5 subunit and corticosterone levels in a new mouse model deficient for Gabra5, which is known to be linked to anxiety disorders in humans and phenologs observed in mice. We observed decreased rearing behavior, suggesting lower anxiety in the Gabra5-/- animals; however, such a phenotype was absent in the open field and elevated plus maze tests. In addition to decreased rearing behavior, we also found decreased levels of fecal corticosterone metabolites in Gabra5-/- mice indicating a lowered stress response. Moreover, based on the electrophysiological recordings where we observed a hyperpolarized state of hippocampal neurons, we hypothesize that the constitutive ablation of the Gabra5 gene leads to functional compensation with other channels or GABA receptor subunits in this model.

• MeSH
• Glucocorticoids * MeSH
• Corticosterone * MeSH
• Humans MeSH
• Mice MeSH
• Receptors, GABA-A genetics   metabolism   MeSH
• Receptors, GABA metabolism   MeSH
• Pituitary-Adrenal System metabolism   MeSH
• Hypothalamo-Hypophyseal System metabolism   MeSH
• Anxiety MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

BACKGROUND: Postictal potentiation presented immediately after cortical seizures in immature rats might be due to imbalance between excitation and inhibition. The aim of the present study was to determine whether augmentation of inhibition mediated by GABAA receptors could also suppress the postictal potentiation. METHODS: Twelve-day old rats with implanted electrodes were used in our study. Five drugs were tested: the agonist muscimol, the positive modulator midazolam and three neurosteroids affecting GABAA receptors-allopregnanolone, pregnanolone sulphate and pregnanolone glutamate. RESULTS: None of the five drugs was able to suppress potentiation appearing immediately after cortical epileptic afterdischarges, but all of them exhibited delayed anticonvulsant action 10 (in the case of midazolam and muscimol) or 20 min (all three steroids) after cortical seizures. CONCLUSION: Our results support a role of GABA in augmentation of cortical after discharges after longer intervals, whereas immediate postictal potentiation is not affected by GABAergic drugs. Due to similar effect with GABAergic drugs, the main mechanism of action of the three steroids tested is potentiation of GABAergic inhibition.

• MeSH
• Anticonvulsants pharmacology   MeSH
• Time Factors MeSH
• Electrodes, Implanted MeSH
• Rats MeSH
• Midazolam pharmacology   MeSH
• Disease Models, Animal MeSH
• Muscimol pharmacology   MeSH
• Neurosteroids pharmacology   MeSH
• Rats, Wistar MeSH
• Receptors, GABA-A drug effects   metabolism   MeSH
• Seizures drug therapy   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH

Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7-11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. In the hippocampus, the α4 subunit was downregulated after the 2-month interval. Changes in receptor binding were highly dependent on the receptor type, the interval after treatment cessation, and the brain structure. GABAA receptor binding was increased in almost all of the brain structures after the 48-h interval. BZD-binding was decreased in many brain structures involved in the neuronal networks associated with emotional behavior, anxiety, and cognitive functions after the 2-month interval. Binding of the GABAB receptors changed depending on the interval and brain structure. Overall, the described changes may affect both synaptic development and functioning and may potentially cause behavioral impairment.

• MeSH
• Benzodiazepines pharmacology   MeSH
• gamma-Aminobutyric Acid metabolism   MeSH
• Hippocampus drug effects   metabolism   MeSH
• Clonazepam pharmacology   MeSH
• Rats MeSH
• Real-Time Polymerase Chain Reaction MeSH
• Brain drug effects   metabolism   MeSH
• Animals, Newborn MeSH
• Rats, Inbred WF MeSH
• Receptors, GABA-A metabolism   MeSH
• Receptors, GABA-B metabolism   MeSH
• Protein Binding MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Seven steroid epoxides were prepared from 5α-pregn-2-en-20-one and 5α-pregn-3-en-20-one and their side-chain derivatives. All compounds were tested in vitro for binding to γ-aminobutyric acid (GABAA) receptor, some of them also in vivo for anticonvulsant action. 2α,3α-Epoxy-5α-pregnan-20-one inhibited the TBPS binding to the GABAA receptor and showed a moderate anticonvulsant action in immature rats. In contrast, its 3α,4α-isomer was inactive. More polar epoxide derivatives, modified at the side chain were less active or inactive. Noteworthy, diol 20, the product of trans-diaxial opening of the 2α,3α-epoxide 4, was not able to inhibit the TBPS binding, showing that the activity of the epoxide is due to the compound itself and not to its hydrolytic product. The 3α-hydroxyl group is known to be essential for the GABAA receptor binding. Despite the shortness of in vivo effects which are probably due to metabolic inactivation of the products prepared, our results show that the 2α,3α-epoxy ring is another structural pattern with ability to bind the GABAAR.

• MeSH
• Anticonvulsants chemistry   pharmacology   MeSH
• Epoxy Compounds chemical synthesis   chemistry   MeSH
• Hydroxylation MeSH
• Neurotransmitter Agents chemical synthesis   chemistry   MeSH
• Rats, Wistar MeSH
• Receptors, GABA-A metabolism   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Tuberous sclerosis complex (TSC) is a rare multi-system genetic disease characterized by several neurological disorders, the most common of which is the refractory epilepsy caused by highly epileptogenic cortical lesions. Previous studies suggest an alteration of GABAergic and glutamatergic transmission in TSC brain indicating an unbalance of excitation/inhibition that can explain, at least in part, the high incidence of epilepsy in these patients. Here we investigate whether TSC cortical tissues could retain GABAA and AMPA receptors at early stages of human brain development thus contributing to the generation and recurrence of seizures. Given the limited availability of pediatric human brain specimens, we used the microtransplantation method of injecting Xenopus oocytes with membranes from TSC cortical tubers and control brain tissues. Moreover, qPCR was performed to investigate the expression of GABAA and AMPA receptor subunits (GABAA α1-5, β3, γ2, δ; GluA1, GluA2) and cation chloride co-transporters NKCC1 and KCC2. The evaluation of nine human cortical brain samples, from 15 gestation weeks to 15years old, showed a progressive shift towards more hyperpolarized GABAA reversal potential (EGABA). This shift was associated with a differential expression of the chloride cotransporters NKCC1 and KCC2. Furthermore, the GluA1/GluA2 mRNA ratio of expression paralleled the development process. On the contrary, in oocytes micro-transplanted with epileptic TSC tuber tissue from seven patients, neither the GABAA reversal potential nor the GluA1/GluA2 expression showed similar developmental changes. Our data indicate for the first time, that in the same cohort of TSC patients, the pattern of both GABAAR and GluA1/GluA2 functions retains features that are typical of an immature brain. These observations support the potential contribution of altered receptor function to the epileptic disorder of TSC and may suggest novel therapeutic approaches. Furthermore, our findings strengthen the novel hypothesis that other developmental brain diseases can share the same hallmarks of immaturity leading to intractable seizures.

• MeSH
• Child MeSH
• Epilepsy etiology   MeSH
• Cohort Studies MeSH
• Humans MeSH
• Brain growth & development   metabolism   pathology   MeSH
• Brain Diseases pathology   MeSH
• Oocytes MeSH
• Receptors, GABA-A metabolism   MeSH
• Symporters metabolism   MeSH
• Tuberous Sclerosis genetics   pathology   physiopathology   MeSH
• Xenopus MeSH
• Seizures physiopathology   MeSH
• Animals MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Excessive stimulation of NMDA receptors with glutamate or other potent agonists such as NMDA leads to excitotoxicity and neural injury. In this study, we aimed to provide insight into an animal model of brain excitotoxic damage; single unilateral infusion of NMDA at mild dose into the hippocampal formation. NMDA infusion induced chronic, focal neurodegeneration in the proximity of the injection site. The lesion was accompanied by severe and progressive neuroinflammation and affected preferentially principal neurons while sparing GABAergic interneurons. Furthermore, the unilateral lesion did not cause significant impairment of spatial learning abilities. Finally, GluN1 and GluN2B subunits of NMDA receptor were significantly upregulated up to 3 days after the NMDA infusion, while GABAA α5 subunit was downregulated at 30 days after the lesion. Taken together, a single infusion of NMDA into the hippocampal formation represents an animal model of excitotoxicity-induced chronic neurodegeneration of principal neurons accompanied by severe neuroinflammation and subunit specific changes in NMDA and GABAA receptors.

• MeSH
• Maze Learning drug effects   physiology   MeSH
• Nerve Degeneration diagnostic imaging   metabolism   pathology   MeSH
• Functional Laterality MeSH
• Hippocampus diagnostic imaging   drug effects   metabolism   pathology   MeSH
• Disease Models, Animal MeSH
• N-Methylaspartate administration & dosage   toxicity   MeSH
• Neurodegenerative Diseases diagnostic imaging   metabolism   pathology   MeSH
• Neuroimmunomodulation physiology   MeSH
• Neurons drug effects   metabolism   pathology   MeSH
• Rats, Long-Evans MeSH
• Receptors, GABA-A metabolism   MeSH
• Receptors, N-Methyl-D-Aspartate metabolism   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Postictal refractoriness may be taken as an expression of lasting activity of inhibitory systems arresting seizures. We tested drugs interfering with GABAergic inhibitory system in pairs of cortical epileptic afterdischarges induced with 1-min interval in rats. Under control conditions the second stimulation failed to elicit an afterdischarge. This postictal refractoriness was not affected by antagonists of GABAA receptors acting at three binding sites (bicuculline, picrotoxin, benzodiazepine inverse agonist Ro 19-4603) as well as by a less specific antagonist pentetrazol. In contrast, antagonist of GABAB receptors CGP35348 partially blocked the refractoriness. Cooperation of different inhibitory systems is probably necessary to abolish postictal refractoriness in neocortex. This article is part of the Special Issue entitled 'GABAergic Signaling in Health and Disease'.

• MeSH
• Azepines pharmacology   MeSH
• Bicuculline pharmacology   MeSH
• Electric Stimulation MeSH
• Epilepsy drug therapy   physiopathology   MeSH
• Electrodes, Implanted MeSH
• Cerebral Cortex drug effects   physiopathology   MeSH
• Organophosphorus Compounds pharmacology   MeSH
• Pentylenetetrazole pharmacology   MeSH
• Picrotoxin pharmacology   MeSH
• Rats, Wistar MeSH
• GABA-A Receptor Antagonists pharmacology   MeSH
• Receptors, GABA-A metabolism   MeSH
• GABA-B Receptor Antagonists pharmacology   MeSH
• Receptors, GABA-B metabolism   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH

ETHNOPHARMACOLOGICAL RELEVANCE: Persian shallot (Allium stipitatum) is a bulbous plant native to Turkey, Iran and Central Asia. It is frequently used in folk medicine for the treatment of a variety of disorders, including inflammation and stress. Antiinflammatory and neurological activities of pyrithione and four related sulfur-containing pyridine N-oxides which are prominent constituents of Allium stipitatum were tested. METHODS: The antiinflammatory activity was tested by the ability of the compounds to inhibit cyclooxygenase (COX-1 and COX-2), whereas the neurological activities were evaluated by assessing the compounds ability to inhibit monoamine oxidase-A (MAO-A) and acetylcholinesterase (AChE). The compounds׳ affinity for the serotonin transport protein (SERT) and the GABAA-benzodiazepine receptor were also investigated. RESULTS: 2-[(Methylthio)methyldithio]pyridine N-oxide showed very high antiinflammatory effects which are comparable with those of common pharmaceuticals (IC₅₀ of 7.8 and 15.4 µM for COX-1 and COX-2, respectively). On the other hand, neurological activities of the compounds were rather modest. Some compounds moderately inhibited AChE (IC₅₀ of 104-1041 µM) and MAO-A (IC₅₀ of 98-241 µM) and exhibited an affinity for the SERT and GABAA-benzodiazepine receptor. CONCLUSIONS: Our findings may help to rationalize the wide use of Persian shallot for the treatment of inflammatory disorders.

• MeSH
• Acetylcholinesterase metabolism   MeSH
• Cholinesterase Inhibitors pharmacology   MeSH
• Cyclooxygenase 1 metabolism   MeSH
• Cyclooxygenase 2 metabolism   MeSH
• Cyclooxygenase Inhibitors pharmacology   MeSH
• Monoamine Oxidase Inhibitors pharmacology   MeSH
• Horseradish Peroxidase MeSH
• Rats MeSH
• Monoamine Oxidase metabolism   MeSH
• Brain drug effects   metabolism   MeSH
• RNA-Binding Proteins metabolism   MeSH
• Pyridines pharmacology   MeSH
• Receptors, GABA-A metabolism   MeSH
• Shallots * MeSH
• Thiones pharmacology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

(25R)-3β-Hydroxy-5α-spirostan-12-one (hecogenin) and 11α-hydroxypregn-4-ene-3,20-dione (11α-hydroxyprogesterone) were used as starting materials for the synthesis of a series of 11- and 12-substituted derivatives of 5ξ-pregnanolone (3α-hydroxy-5α-pregnan-20-one and 3α-hydroxy-5β-pregnan-20-one), the principal neurosteroid acting via γ-aminobutyric acid (GABA). These analogues were designed to study the structural requirements of the corresponding GABAA receptor. Their biological activity was measured by in vitro test with [(3)H]flunitrazepam as radioligand in which allopregnanolone and its active analogues stimulated the binding to the GABAA receptor. Analysis of the SAR data suggests dependence of the flunitrazepam binding activity on the hydrophobic-hydrophilic balance of the groups at the C-ring edge rather than on specific interactions between them and the receptor.

• MeSH
• Protein Conformation MeSH
• Quantitative Structure-Activity Relationship * MeSH
• Models, Molecular MeSH
• Mice MeSH
• Neurons metabolism   MeSH
• Pregnanolone analogs & derivatives   chemical synthesis   metabolism   MeSH
• Receptors, GABA-A chemistry   metabolism   MeSH
• Chemistry Techniques, Synthetic MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Repeated administration of partial agonist of benzodiazepine receptors Ro 19-8022 (a derivative of quinolizine class) does not elicit withdrawal in adult rats. Our older data demonstrated that single injection of Ro 19-2088 to immature rats induces increased sensitivity to convulsant action of pentylenetetrazol as a withdrawal phenomenon. To know if repeated administration of the partial agonist has the same effect we injected rats at postnatal days 7 to 11 with an anticonvulsant dose of Ro 19-2088 (0.5 mg/kg i.p.) and tested them 24 h, 48 h and 4 days after the last injection. Repeated administration of Ro 19-8022 resulted also in an increased sensitivity to convulsant action of pentylenetetrazol in immature rats (higher incidence and severity of seizures). This effect was significant 24 h after the last injection but only outlined 48 h after administration. No signs of hypersensitivity were seen at 4-day interval. There is a difference between immature and adult brain in an appearance of withdrawal symptom after administration of the partial agonist of benzodiazepine receptors Ro 19-2088.

• MeSH
• Substance Withdrawal Syndrome etiology   metabolism   physiopathology   MeSH
• Anticonvulsants administration & dosage   toxicity   MeSH
• Time Factors MeSH
• Quinolizines administration & dosage   toxicity   MeSH
• Rats MeSH
• Disease Models, Animal MeSH
• Brain metabolism   physiopathology   drug effects   MeSH
• Drug Partial Agonism MeSH
• Pentylenetetrazole MeSH
• Rats, Wistar MeSH
• Pyrrolidines administration & dosage   toxicity   MeSH
• Receptors, GABA-A metabolism   drug effects   MeSH
• Drug Administration Schedule MeSH
• Carrier Proteins metabolism   drug effects   MeSH
• Age Factors MeSH
• Seizures chemically induced   metabolism   physiopathology   prevention & control   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH