5-HT1A receptor binding in euthymic bipolar patients using positron emission tomography with [carbonyl-11C]WAY-100635

Background: This study was undertaken to examine whether brain 5-HT1A receptor binding is reduced in euthymic bipolar patients. Methods: Eight medicated euthymic bipolar patients and 8 healthy volunteers underwent positron emission tomography scanning using the selective 5-HT1A receptor radioligand [carbonyl-C-11]WAY-100635. Results: No significant difference in global postsynaptic parametric binding potential (BPND) was found between euthymic bipolar patients (mean +/- SD, 4.24 +/- 0.76) and healthy volunteers (mean +/- SD, 4.34 +/- 0.86). Ninety five percent Confidence Intervals for the difference in group mean global postsynaptic BPND were -0.77 to 0.97. Analysis of regional BPND did not reveal regional differences between patients and healthy controls. Limitations: The number of subjects studied was limited and all subjects were on medication. Conclusions: In contrast to previous findings of reduced 5-HT1A receptor binding in untreated unipolar and bipolar depressed patients [Sargent, PA., Kjaer, K.H., Bench, C.J., Rabiner, E.A., Messa, C., Meyer, J., Gunn, R.N., Grasby, P.M., Cowen, P.J., 2000. Brain serotonin1A receptor binding measured by positron emission tomography with [C-11]WAY-100635: effects of depression and antidepressant treatment. Arch. Gen. Psychiatry 57, 174-180]; [Drevets, W.C., Frank, E., Price, J.C., Kupfer, DJ., Holt, D., Greer, P.J., Huang, Y., Gautier, C., Mathis, C., 1999. PET imaging of serotonin1A receptor binding in depression. Biol. Psychiatry 46, 1375-1387] and in recovered unipolar depressed patients [Bhagwagar, Z., Rabiner, E.A., Sargent, P.A., Grasby, P.M., Cowen, P.J., 2004. Persistent reduction in brain serotonin1A receptor binding in recovered depressed men measured by positron emission tomography with [C-11]WAY-100635. Mol. Psychiatry 9, 386-92], this study found no difference in 5-HT1A receptor BPND between medicated euthymic bipolar patients and healthy controls. Normal 5-HT1A receptor BPND in these patients may be a result of drug treatment or could indicate that reduced 5-HT1A receptor binding is specific to the depressed state in bipolar patients. (C) 2009 Elsevier B.V. All rights reserved.