Animal experiment:

Solutions of?KA,?ABT-239 and?SVP are prepared in pyrogen-free normal saline for injection except for TDZD-8, which is dissolved in 10% DMSO and are administered?intraperitoneally in a volume not exceeding 10?mL/kg. The animals are divided into ten groups. The first group (CTRL) receive vehicle (0.9% sodium chloride) only whereas animals in the second group (VEH) are given vehicle followed by KA at a dose of 10mg/kg, i.p. (pH 7.2±1), this being the dose that induces low-grade?seizures?(stage 0-4) in all the animals without any mortality in a range finding study. The KA dose employs to evoke SE in mice in various studies mostly varied from as low as 6-20mg/kg to as high as 25-45mg/kg. Animals in the next two groups are administered ABT-239 in increasing doses of 1 (AL) and 3mg/kg (AH) 30?min before KA challenge. These doses ranging from 0.1 to 3mg/kg of ABT-239 display disease modifying attributes in a mice model of?Alzheimer?s disease as well as improved cognitive functions. The fifth and sixth group receive graduated doses of 150 (SL) and 300mg/kg (SH) of SVP 30?min prior to KA injection. The seventh and eight group receive combinations of subeffective dose (maximum possible dose at which there is no protection) of SVP at 150mg/kg with ABT-239 at 1 (SLAL) and 3mg/kg (SLAH) respectively followed 30?min later by KA. The remaining two groups receive low dose combination at 1 and 5mg/kg (ALTL) and a high dose combination at 3 and 10mg/kg (AHTH) of ABT-239 and TDZD-8, respectively before KA exposure. The doses of TDZD-8 chosen are based on previous studies where doses ranging from 1 to 10mg/kg reduced inflammation and tissue injury as well as improve psychiatric conditions.

ABT-239 is a novel, highly efficacious, non-imidazole class of H3R antagonist and a transient receptor potential vanilloid type 1 (TRPV1) antagonist.

Perfusion of the TMN with ABT-239 (10 μM) increases histamine release from the TMN, NBM, and cortex, but not from the striatum or NAcc. TMN perfusion with ABT-239 activates c-Fos selectively in the NBM and cortex[4].

ABT-239 (3 mg/kg, i.p.) significantly delays onset of seizure, reduces behavioral seizures elicited by KA, and reduces in the incidence of head bobbing and forelimb clonus in mice. ABT-239 (1 mg/kg, i.p.) in conbination with sub-therapeutic dose of SVP (150 mg/kg, i.p.), significantly decreases the number of immobility, head bobbing and forelimb clonus, where as a higher dose combination of ABT-239 (3 mg/kg, i.p.) causes enhanced reduction in all the stages. ABT-239 (3 mg/kg, i.p.) and TDZD-8 (10 mg/kg, i.p.) have more powerful reduction in the number of pyknotic neurons in mice hippocampi. The high dose combination of ABT-239 and TDZD-8 produces the most pronounced increase in Bcl-2 expression as well as decrease in the level of Bax[1]. ABT-239 (3 mg/kg, i.p.) administration transforms a short-term learning event into a long-term remembered experience in WT but not in histamine-depleted mice[2]. Concomitant administration of either ABT-239 (1 and 3 mg/kg, i.p.) and nicotine (0.035 mg/kg, i.p.), or ABT-239 (0.1 mg/kg, i.p.) and nicotine (0.0175 mg/kg, i.p.) further increases nicotine-induced improvement in both memory acquisition and consolidation[3].

[1]. Bhowmik M, et al. Histamine H3 receptor antagonism by ABT-239 attenuates kainic acid induced excitotoxicity in mice. Brain Res. 2014 Sep 18;1581:129-40. [2]. Provensi G, et al. Donepezil, an acetylcholine esterase inhibitor, and ABT-239, a histamine H3 receptor antagonist/inverse agonist, require the integrity of brain histamine system to exert biochemical and procognitive effects in the mouse. Neuropharmacolo [3]. Kruk M, e tal. Effects of the histamine H2 receptor antagonist ABT-239 on cognition and nicotine-induced memory enhancement in mice. Pharmacol Rep. 2012;64(6):1316-25. [4]. Munari L, et al. Selective brain region activation by histamine H2 receptor antagonist/inverse agonist ABT-239 enhances acetylcholine and histamine release and increases c-Fos expression. Neuropharmacology. 2013 Jul;70:131-40.