Lesopitron (dihydrochloride)

Lesopitron dihydrochloride is a full and selective 5-HT_1A receptor agonist with IC₅₀ of 125 nM in rat hippocampal membranes. IC50 & Target: IC50:125 nM (5-HT_1A receptor, in rat hippocampal membranes)^[1] In Vitro: In vitro binding and autoradiographic studies with [³H]8-OH-DPAT and [³H]Lesopitron as radioligands confirm that Lesopitron binds to 5-HT_1A receptors in the rat brain with a relatively high affinity (pK_i=7.35). As expected of a full agonist at postsynaptic 5-HT_1A receptors, Lesopitron (IC₅₀=125 nM) inhibits forskolin-stimulated adenylate cyclase activity in rat hippocampal membranes to the same extent as 5-HT. Lesopitron inhibits the firing of serotoninergic neurons both in vitro (in brainstem slices, IC₅₀=120 nM)^[1]. In Vivo: Lesopitron inhibits the firing of serotoninergic neurons both in vivo (in chloral hydrate-anaesthetized rats, ID₅₀=35 μg/kg i.v.)^[1]. Lesopitron administered at a dose which induces anxiolytic behaviour in rats (30 μg/kg, i.p.) markedly reduces 5-HT levels (to 45% of the basal value) in cortical perfusates^[2].