EFFECT OF AGING AND SEX ON THE [H-3]-PAROXETINE BINDING TO HUMAN PLATELETS

Since there exist conflicting results with regard to the possible effe ct of aging on platelet [H-3]-imipramine binding, taken as a periphera l marker of the serotonin (5-HT) transporter, we reinvestigated this m atter by comparing the binding of the more selective ligand [H-3]-paro xetine in 20 aged and 23 young subjects. The results showed that neith er the maximum binding capacity nor the dissociation constant (K-d) we re significantly different in the two groups. When the subjects were c ompared according to sex, the young females revealed a statistically s ignificant lower K-d than the males, while the contrary was true for t he aged females. The K-d was significantly and negatively correlated t o age in males. In addition, a significant age x gender interaction wa s also observed. Therefore, the sex of a subject would seem to provoke significant age-related changes in the K-d of [H-3]-paroxetine bindin g to platelet membranes. This might indicate modifications in the 5-HT transporter that could form the basis of a sex-related difference in vulnerability to disorders, such as depression, where a dysfunction at this level is hypothesized. (C) 1998 Elsevier Science B.V.