Effect of 2-ethyl-6-methylpyridinol-3-yl-thiooctanoate and its Non-Esterified Components on the Behavior of Rats in an Elevated Plus Maze

The effect of thioctic acid (TA), 2-ethyl-6-methyl-3-hydroxypyridine hydrochloride (emoxypine), and their ester derivative (2-ethyl-6-methylpyridinol-3-yl-thiooctanoate, thioxypine) on the behavior of rats in an elevated plus maze (EPM) was studied. Intraperitoneal administration (three times) of TA, emoxypine, and their equimolar mixture in single doses of 36.25, 72.5, and 145 μmol/kg enhanced individual manifestations of anxious behavior in the EPM but did not cause full-blown anxiogenic effects. Similar pro-anxiogenic effects were observed when TA was administered in a dose of 36.25 μmol/kg and emoxypine in doses of 72.5 and 145 μmol/kg. The equimolar mixture of the non-esterified components of thioxypine had a pro-anxiogenic effect in doses of 36.25 and 72.5 μmol/kg. Combination of TA and 2-ethyl-6-methyl-3-hydroxypyridine into the ester potentiated their pro-anxiogenic activity, which manifested as an extensive anxiogenic effect of thioxypine when administered three times in a dose of 145 μmol/kg.