BINDING OF 5-HT(1A) RECEPTOR AND 5-HT TRANSPORTER LIGANDS IN RAT CORTEX AND HIPPOCAMPUS FOLLOWING CHOLINERGIC AND SEROTONERGIC LESIONS

The cellular localisation of 5-HT1A receptor and 5-HT transporter binding sites in the rat cortex and hippocampus has been examined. Lesions of either basal forebrain neurones or serotonergic neurones did not affect [H-3]8-OH-DPAT binding, suggesting that 5-HT1A binding sites are not localised on cholinergic or serotonergic nerve terminals. The binding of the 5-HT transporter ligand, [H-3]citalopram was unaffected by the cholinergic lesion whereas binding was reduced in both the hippocampus and cortex following serotonergic lesions. A reduction in binding site density rather than an alteration in affinity was responsible for this effect. While these data suggest that [H-3]citalopram binding sites are located on serotonergic nerve terminals, the abolition of hippocampal binding sites contrasted with a 50% loss in cortical tissue.