PLATELET [H-3] PAROXETINE BINDING, 5-HT-STIMULATED CA2-HT CONTENT IN WINTER SEASONAL AFFECTIVE-DISORDER( RESPONSE, AND 5)

The present study was designed to evaluate cellular serotonergic funct ions in winter seasonal affective disorder (SAD) using serotonin (5-HT )-stimulated Ca2+ response as an integrated measure of 5-HT2 receptor function in platelets, [H-3]paroxetine binding to characterize the pla telet 5-HT transporter and 5-HT content as an index of the platelet st orage capacity for this neurotransmitter amine. Purified density-depen dent subpopulations of platelets in untreated and light-treated SAD pa tients and matched controls were investigated in order to control for possible variations in platelet turnover We found no differences betwe en SAD patients and controls on any of the measures, nor between light therapy conditions in SAD patients, although We found a higher B-max of [H-3]paroxetine binding and 5-HT content in heavy platelets compare d to light platelets. Although the validity of platelet serotonergic m easures as a model for brain serotonergic systems still remains to be elucidated, we found no evidence of platelet serotonergic abnormalitie s in our sample of SAD patients.