A Multifaceted GABA A

In the present study, we have elucidated the functional characteristics and mechanism of action of methaqualone (2-methyl-3-o-tolyl-4(3H)-quinazolinone, Quaalude), an infamous sedative-hypnotic and recreational drug from the 1960s– 1970s. Methaqualone was demonstrated to be a positive allosteric modulator at human a1,2,3,5b2,3g2S GABAA receptors (GABAARs) expressed in Xenopus oocytes, whereas it dis-played highly diverse functionalities at the a4,6b1,2,3d GABAAR subtypes, ranging from inactivity (a4b1d), through negative (a6b1d) or positive allosteric modulation (a4b2d, a6b2,3d), to superagonism (a4b3d). Methaqualone did not interact with the benzodiazepine, barbiturate, or neurosteroid binding sites in the GABAAR. Instead, the compound is proposed to act through the transmembrane b(1)/a(–) subunit interface of th

Amiodarone biokinetics, the formation of its major metabolite and neurotoxicity after acute and repeated exposure of brain cell cultures

The difficulty in mimicking nervous system complexity and cell-cell interactions as well as the lack of kinetics information has limited the use of in vitro neurotoxicity data. Here, we assessed the biokinetic profile as well as the neurotoxicity of Amiodarone after acute and repeated exposure in two advanced rodent brain cell culture models, consisting of both neurons and glial cells organized in 2 or 3 dimensions to mimic the brain histiotypic structure and function. A strategy was applied to evidence the abiotic processes possibly affecting Amiodarone in vitro bioavailability, showing its ability to adsorb to the plastic devices. At clinically relevant Amiodarone concentrations, known to induce neurotoxicity in some patients during therapeutic treatment, a complete uptake was observed in both models in 24h, after single exposure. After repeated treatments, bioaccumulation was observed, especially in the 3D cell model, together with a greater alteration of neurotoxicity markers. After 14 days, Amiodarone major oxidative metabolite (mono-Ndesethylamiodarone) was detected at limited levels, indicating the presence of active drug metabolism enzymes (i.e. cytochrome P450) in both models. The assessment of biokinetics provides useful information on the relevance of in vitro toxicity data and should be considered in the design of an Integrated Testing Strategy aimed to identify specific neurotoxic alerts, and to improve the neurotoxicity assay predictivity for human acute and repeated exposure