SUMMARYIn the search for paradigms of postulated abnormalities in indolamine function in the brain in affective disorders, 5-HT uptake and release was estimated in platelets from patients suffering from severe depressive illness. Neither of these measures was altered by the illness and the most likely explanation for the negative findings was that in this setting platelets are not a suitable model.On the evidence available at the present time, it seems probable that there are abnormalities in amine metabolism in affective illness. Definition of these abnormalities is hampered by the inaccessibility of the brain and, in particular, that part of it likely to be involved in the functional disorder. The problem would be simplified if the inquiry could be narrowed down on the one hand to changes in transport or binding of amines, and on the other to alterations in their synthesis or degradation. Pletscher (1968) has suggested that the platelet is a suitable model for some of the processes occurring in amine-utilizing neurones in the central nervous system. In the present study we have extended this concept to see if the behaviour of platelets in vitro would shed any light on the nature of the abnormalities in amine metabolism in affective disordersthat is, would reveal the presence and nature of pathological processes rather than just act as a model for normal biochemical/physiological functions. Previous studies have shown that there are peripheral abnormalities in indolamine metabolism in severe depressive illness (Coppen, Shaw, Malleson, Eccleston, and Gundy, 1965).The main criticism levelled at peripheral studies in psychiatric illness is that there are no a priori reasons for equating central events with those occurring elsewhere in the body. The contrary view could be argued, however, that parallel mechanisms might well respond similarly to, for instance, an abnormal hormonal milieu, and it is on such grounds that peripheral studies are justified. All were patients suffering from severe depressive illness and were diagnosed on the basis of experiencing a proportion of such symptoms as depression of mood, diurnal variation of mood, early morning waking, loss of energy, interest, concentration, appetite and libido, delusions of guilt and unworthiness, etc. None had taken lithium, none had received phenothiazines or other tranquillizingdrugs fora minimum of four weeks and none had had antidepressant therapy for at least two weeks. They were studied in the first few days after admission and again one week after full recovery induced by a course of electroconvulsive therapy.Control subjects were normal volunteers from hospital and laboratory staffs.
UPTAKE AND RELEASE OF 5-HYDROXYTRYPTAMINE (5-HT) BY PLATELETSThe methods used were modified from those of Stacey (1961). Venous blood was taken between 09.15 and 09.45 hours after overnight fasting, was mixed with onetenth its volume of a solution containing disodium edetate (IOg/l.), sodium chloride (7g/l.), and glucose (1 g/l.), and was spun at 1,000 g for five minutes...
