Pharmacological screening of a new valproic acid derivative using the pharmacoencephalography method in rats

Introduction. The naïve Bayes classifier combined with principal component analysis allows to distinguish the effects of antipsychotic agents effectively as well as evaluate their dose-dependency based on their impact on electroencephalogram parameters in rats. Further development of this method requires its validation as an instrument for the screening of new understudied molecules. Valproic acid derivatives appear to be a promising neuropharmacological group as they exhibit not only antiepileptic activity but also mood-stabilizing, antimigraine, neuroprotective and analgesic effects.Aim. This work was carried out to perform the pharmacological screening of a valproic acid aminoester (AVA) that exhibits antidote properties in case of poisoning with anticholinesterase agents.Materials and methods. The experiments were conducted in white outbred rats with chronically implanted electrocorticographic electrodes. AVA was administered at doses of 0,5, 5 and 30 mg/kg. The training set, used as a reference to determine the pharmacological effects of each dose of the investigated substance, included matrixes of effects of 7 drugs: the antiepileptic agent sodium valproate, the D2-dopamine receptor blocker haloperidol, the M-cholinergic receptor blocker tropicamide, the H1-histamine receptor blocker chloropyramine, the acetylcholinesterase inhibitor galantamine, the sedative dexmedetomidine, and the anxiolytic phenazepam.Results and discussion. AVA at the dose of 0,5 mg/kg showed effects similar to those of sodium valproate, while a tenfold dose increase led to the predominance of an atropine-like effect. When administered at the dose of 30 mg/kg, the compound exhibited dexmedetomidine-like action. The central M-anticholinergic effect of AVA was confirmed by an arecoline test in mice, in which the substance at a dose of 88 mg/kg completely abolished the onset of tremor. Dexmedetomidine-like action was cancelled by the administration of atipamezole in equimolar quantities, which may indicate the potential сapability of AVA to activate α2-adrenergic receptors at a high dose. The results of molecular docking suggest that this effect is related specifically to the original aminoester molecule and not to its presumable active metabolites.Сonclusion. The obtained results confirm the effectiveness of the naïve Bayes classifier as an instrument for the prediction of the pharmacological activity of compounds based on their impact on electroencephalogram parameters in rats. Identification of new pharmacological effects of understudied compounds may widen the potential range of their clinical application as well as reveal probable adverse effects.