Studies on serotonergic markers in the human hippocampus: changes in subjects with bipolar disorder

Background: Various studies suggest the hippocampus and serotonergic systems are important in the pathology of bipolar disorder (BD). We therefore measured hippocampal serotonergic markers in post-mortem tissue from BD and control subjects. Methods: The density and affinity of [3H]citalopram binding to the serotonin transporter (SERT), as well as the density of the 5HT2A, 5HT1A, 5HT1D and 5HT1F receptors were measured. Results: The density of SERT and 5HT receptors was no different in BD. There was a significant decrease in the affinity of [3H]citalopram binding to SERT in the stratum lacunosum-moleculare (Slac) in BD (Kd mean±S.E.M.=4.3±0.8 vs. 1.9±0.3 nM). Limitations: This study was completed using relatively small cohorts. Conclusions: There are no generalised changes in hippocampal serotonergic markers in the hippocampus from subjects with BD. There is a decreased affinity of radioligand binding to Slac SERT in subjects with BD.