Lecozotan HCl (SRA-333) is a potent and selective 5-HT antagonist that significantly enhances KCl-stimulated glutamate and acetylcholine release from the hippocampal dentate gyrus and has cognitive enhancing properties. Chronic administration of Lecozotan HCl did not induce 5-HT(1A) receptor tolerance or desensitization in a behavioral model demonstrating 5-HT(1A) receptor function.

Lecozotan HCl (0.3 mg/kg; s.c.) antagonized the decrease in hippocampal extracellular 5-HT induced by 8-hydroxy-2-dipropylaminotetralin (8-OH-DPAT) and had no effects alone at doses 10-fold higher. Lecozotan HCl significantly potentiated the potassium chloride-stimulated release of glutamate and acetylcholine in the dentate gyrus of the hippocampus. Chronic administration of Lecozotan HCl did not induce 5-HT(1A) receptor tolerance or desensitization in a behavioral model indicative of 5-HT(1A) receptor function.[1]
In drug discrimination studies, Lecozotan HCl (0.01-1 mg/kg i.m.) did not substitute for 8-OH-DPAT and produced a dose-related blockade of the 5-HT(1A) agonist discriminative stimulus cue. In aged rhesus monkeys, Lecozotan HCl produced a significant improvement in task performance efficiency at an optimal dose (1 mg/kg p.o.). Learning deficits induced by the glutamatergic antagonist MK-801 [(-)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate] (assessed by perceptually complex and visual spatial discrimination) and by specific cholinergic lesions of the hippocampus (assessed by visual spatial discrimination) were reversed by Lecozotan HCl (2 mg/kg i.m.) in marmosets.[1]