Articles: gaba-modulators-pharmacology.
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Benzodiazepines (BZDs) produce various pharmacological actions by binding to and allosterically regulating GABAA receptors. Several in vitro studies have demonstrated diazepam, the prototypic BZD, produces a high-dose action that cannot be countered with the classical BZD-binding site antagonist flumazenil. Here, we investigate the existence and behavioral relevance of non-classical BZD binding sites in zebrafish larvae. ⋯ These results provide direct in vivo evidence for non-classical BZD-binding sites, which may be located at the second transmembrane domain of GABAA receptors and contribute to BZD-induced anesthesia.
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Journal of neurotrauma · Aug 2019
Diazepam Inhibits Post-Traumatic Neurogenesis and Blocks Aberrant Dendritic Development.
Traumatic brain injury (TBI) triggers a robust increase in neurogenesis within the dentate gyrus of the hippocampus, but these new neurons undergo aberrant maturation and dendritic outgrowth. Because gamma-aminobutyric acid (GABA)A receptors (GABAARs) modulate dendritic outgrowth during constitutive neurogenesis and GABAAR-modulating sedatives are often administered to human patients after TBI, we investigated whether the benzodiazepine, diazepam (DZP), alters post-injury hippocampal neurogenesis. ⋯ DZP did not reduce cortical injury, reactive gliosis, or cell proliferation early after injury, but decreased c-Fos activation in the dentate gyrus at both early and late time-points after TBI, suggesting an association between neuronal activity and post-injury neurogenesis. Because DZP blocks post-injury neurogenesis, further studies are warranted to assess whether benzodiazepines alter cognitive recovery or the development of complications after TBI.
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Review
GABA allosteric modulators: An overview of recent developments in non-benzodiazepine modulators.
γ-Aminobutyric acid (GABA) is the major inhibitory transmitter controlling synaptic transmission and neuronal excitability. It is present in a high percentage of neurons in the central nervous system (CNS) and also present in the peripheral nervous system, and acts to maintain a balance between excitation and inhibition. GABA acts via three subclasses of receptors termed GABAA, GABAB, and GABAC. ⋯ The development of ligands for these binding sites has also led to an improved understanding of the different physiological functions and pathological processes and offers the opportunity for the development of novel therapeutics. This review focuses on the medicinal chemistry aspects including drug design, structure-activity relationships (SAR), and mechanism of actions of GABA modulators, including non-benzodiazepine ligands at the benzodiazepine binding site and modulators acting at sites other than the high-affinity benzodiazepine binding site. Recent advances in this area their future applications and potential therapeutic effects are also highlighted.
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In juvenile and young adult mice monocular deprivation (MD) shifts the ocular dominance (OD) of binocular neurons in the primary visual cortex (V1) away from the deprived eye. However, OD plasticity is completely absent in mice older than 110 days, but can be reactivated by treatments which decrease GABA levels in V1. Typically, these OD shifts can be prevented by increasing GABAergic transmission with diazepam. ⋯ On the contrary, this treatment led to a depression of V1 input through the previously closed contralateral eye, the characteristic signature of OD plasticity in juvenile mice during the critical period. Interestingly, the same result was obtained after AD. Taken together, these results suggest that cross-modally restored OD plasticity does not only depend on reduction of GABA levels in V1, but also requires other, so far unknown mechanisms.
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Functional neurologic outcome for children with refractory and super-refractory status epilepticus has not been well defined. ⋯ Mortality in this population was high. The majority of children experienced some degree of disability at discharge. Despite prolonged pentobarbital infusion, there were cases of survival with good neurologic outcome.