Abnormal platelet 5-hydroxytryptamine uptake and imipramine binding in postnatal dysphoria.

Platelet 14C-5-hydroxytryptamine (14C-5-HT) uptake, 3H-imipramine binding and monoamine oxidase (MAO) activity were measured in women 5 days postpartum and compared with depression scores (Edinburgh Postnatal Depression Scale) at that time and 6 weeks later. Mean Km of 14C-5-HT uptake was significantly reduced in the group showing dysphoria at 5 days (p less than 0.01). Mean Kd of 3H-imipramine binding was significantly increased in the group who later went on to become depressed at 6 weeks postpartum (p less than 0.03). Vmax for 14C-5-HT uptake, Bmax for 3H-imipramine binding and MAO activity did not differ between depressed and non-depressed patients on either occasion. Although the observed changes manifested in a system known to be disturbed in other forms of depression, they were in affinity rather than Bmax or Vmax. Even though probably not of direct physiological significance, such results, if confirmed, together with other pointers in the literature, suggest biochemical abnormalities specific to the puerperal period.