Light-dark differences in [3H]-paroxetine binding to rabbit platelet membranes

Summary [³H]-Paroxetine binding to rabbit blood platelet membranes from samples obtained under light and dark conditions was examined. Animals were kept on a 14 h light (L) — 10 h dark (D) schedule and blood samples were collected at L + 7 and D + 5 h. Significant differences were found for B_max values of [³H]-paroxetine binding, with low B_max values during the light period and high B_max values during the dark period. The K_d values were not significantly different. These results confirm previous observations on light-dark differences of [³H]-imipramine binding in rabbit blood platelets suggesting the existence of a circadian rhythm for the 5-HT transporter complex.Send offprint requests to S. Z. Langer at the above address