Lesopitron dihydrochloride is a full and selective 5-HT 1A receptor agonist with IC 50 of 125 nM in rat hippocampal membranes. In Vitro In vitro binding and autoradiographic studies with [ 3 H]8-OH-DPAT and [ 3 H]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 (IC 50 =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, IC 50 =120 nM). MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Lesopitron inhibits the firing of serotoninergic neurons both in vivo (in chloral hydrate-anaesthetized rats, ID 50 =35 μg/kg i.v.) . 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. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal administration Rats Male Wistar rats weighing 270-300 g, are used. Lesopitron is administered either through the dialysis probe (dissolved in artificial CSF) or i.p. (dissolved in 0.9% saline, 2 mL/kg body weight). aladdin has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:5-HT 1A Receptor 125 nM (IC 50 , in rat hippocampal membranes)