The effects of antidepressant treatments and lithium upon 5-HT1A receptor function.

1) The functional effects of the 5-HT1A receptor selective ligand, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) can be divided into effects mediated by presynaptic (somato-dendritic) autoreceptors and postsynaptic receptors. Hypothermic responses in the mice and rat reflect presynaptic effects. Stereotypic motor responses in the rat reflect postsynaptic function. 2) These functional models of 5-HT1A receptor activity have been used to examine the effects of different antidepressant treatments and lithium during acute (24h) and chronic (14 day) administration. 3) Presynaptic 5-HT1A-mediated hypothermia is attenuated by chronic treatment with amitriptyline, desipramine, zimeldine, high dose mianserin, tranylcypromine, lithium and repeated electroconvulsive shock (ECS). Thus, all these treatments may increase tolerance to increased release of 5-HT. 4) Postsynaptic 5-HT1A-mediated motor effects are attenuated by desipramine, zimeldine and ECS but enhanced by lithium. 5) The 5-HT1A receptor appears to be an important locus for the actions of antidepressant treatments and lithium.