[3H]GR113808 binding to serotonin 5-HT4 receptors in the postmortem neocortex of Alzheimer disease: a clinicopathological study

Abnormalities in neural transmission of serotonin (5-HT) may play a role in both cognitive and neuropsychiatric features of Alzheimer disease (AD). We measured 5-HT4 receptors in the postmortem frontal and temporal cortex of 34 AD subjects and 15 controls by radioligand binding with [3H]GR113808. Receptor binding data was then correlated with prospectively assessed cognitive (Mini-Mental State Examination, MMSE) and behavioral (Present Behavioural Examination, PBE) data. [3H]GR113808 binding affinity (KD) and density (Bmax) in AD were unchanged compared to controls in both cortical regions, and did not correlate with MMSE or PBE data. The binding parameters were also not related to disease duration, senile plaque and neurofibrillary tangle counts, and neuroleptic medication. We conclude that unlike other 5-HT receptors, 5-HT 4 receptor binding affinity and density do not seem to be affected in the frontal and temporal cortex in AD and may not have a direct role in the clinical features of the disease.