Serotonin uptake and imipramine binding in blood platelets and brain of Fawn-hooded and Sprague Dawley rats

Abstract

The kinetic parameters of serotonin (5-HT) uptake and imipramine binding of the synaptosomes and blood platelets of male Fawn-hooded rats, which have a 5-HT storage abnormality, and normal Sprague-Dawley rats were compared. The V max for 5-HT uptake of synaptosomes from Fawn-hooded rats was significantly greater than that of Sprague-Dawley rats whereas that of the platelets did not differ. The K m values of both the synaptosomes and platelets of the two rat strains were not significantly different. The B max values for 3H-imipramine binding on both platelets and brain of Fawn-hooded rats were significantly lower than those of the Sprague-Dawley rats. The K d of imipramine binding to platelet membranes from Fawn-hooded rats was significantly less than that of the Sprague-Dawley rats but the K d of the synaptosomes was not significantly different. These results indicate that 5-HT uptake and imipramine binding sites may be independently regulated and that platelets do not always manifest abnormalities present in brain 5-HT neurons and vice versa.