The Potentiating Effect of Serotonin and Epinephrine on Collagen-induced Whole Blood Aggregation and Secretion

Effects of long-term lithium treatment on monoaminergic functions in major depression

Platelet [14C]serotonin uptake, the density of serotonin transporters and 5HT(2) receptors, and 5HT(2) and alpha(2) receptor function in platelets were investigated in 29 outpatients (15 women and 14 men) diagnosed as having a major affective disorder (21 bipolar and 8 unipolar). The data were compared with data for 26 healthy volunteers matched for age, sex and season. No differences were found in the mean values for the uptake velocity (V(max)) and the affinity (K(m)) of the transport carrier for serotonin between patients and controls. However, female patients had lower V(max) compared to male patients and female control subjects. A positive correlation between plasma lithium and V(max) and a tendency toward a negative correlation between plasma lithium and K(m) was observed. Furthermore, there were no differences in platelet B(max) and K(d) for [3H]paroxetine binding and K(d) for [3H]LSD binding between patients and controls. However, there was an increased number of platelet 5-HT(2) receptors and a difference in serotonin-mediated potentiation of platelet ATP secretion between patients compared to controls, especially in women. The findings in the present study suggest that lithium has a net ameliorating impact on serotonin uptake which may render it resistant to change. They also postulate that the effect of lithium may be attained by a dual influence on postsynaptic serotonergic structures, as it increases both the density and the sensitivity of 5-HT(2) receptors.

Effects of aprotinin during cardiopulmonary bypass in patients treated with acetylsalicylic acid

Of 35 acetylsalicylic acid (ASA)-treated patients undergoing coronary artery bypass surgery, 10 received a high dose of aprotinin (mean 5.2 x 10(6) KIU) during cardiopulmonary bypass (CPB); in 15 cases low-dose aprotinin (2 x 10(6) KIU) was added to the CPB priming solution, and 10 patients made up a control group without aprotinin. Median total blood loss was 52% less in aprotinin-treated patients, irrespective of dose, than in the controls. Fibrin-D dimer levels remained low in patients treated with high-dose aprotinin, but increased significantly in the control group. Platelet adhesion and platelet adenosine triphosphate secretion were reduced after CPB in all patients. Whole-blood aggregation after bypass was enhanced in aprotinin-treated patients. Aprotinin inhibited fibrinolysis and seemingly preserved platelet function despite ASA treatment. In view of the possible risks and relatively high cost of aprotinin, use of a high dose seems unnecessary, since a low dose was equally effective in reducing blood loss in ASA-treated patients.

Serotonergic 'vulnerability' in affective disorder: a study of the tryptophan depletion test and relationships between peripheral and central serotonin indexes in citalopram-responders

A double-blind study of the tryptophan depletion (TD) challenge was performed on a sample consisting of 20 patients with a major depressive disorder in clinical remission after citalopram treatment. TD was induced by the intake of 43 g of an amino acid mixture containing the five large neutral amino acids. The control group received the same mixture, to which 2.3 g tryptophan had been added. Five of the 12 challenged patients showed a worsening of depressive symptoms during the day of the test. In contrast, there was no mood alteration in the eight control patients. Baseline cortisol levels were significantly higher in responders to TD compared to those in non-responders and controls. Platelet serotonin-receptor function and plasma prolactin levels were correlated. There was a significant positive correlation in the baseline data between rated mood state and plasma cortisol and a significant inverse correlation between related mood state and plasma tryptophan concentration. Thus low mood appeared to be associated with low serotonin precursor availability as well as with high cortisol levels.