Platelet and lymphocyte free intracellular calcium in affective disorders.
Many studies have demonstrated pharmacologic similarities between platelet and brain 5-HT2 binding sites. Therefore it may be possible to use platelets as a model for the central serotonergic neuron. Accordingly, a previous report (Kusumi et al. 1991b) about elevated [Ca2+]i after serotonin stimulation in platelets of depressed patients was interpreted as further evidence for enhanced serotonergic sensitivity in depression. However, a very recent study showed an enhanced thrombin-induced platelet Ca2+ response, rather suggesting abnormalities of intracellular Ca2+ regulation in affective disorders. In the present study we have determined 5-HT2- and thrombin-induced Ca2+ responses in platelets and additionally phytohemagglutin (PHA)-induced Ca2+ increase in lymphocytes of medicated depressed patients (8 mono- and 2 bipolar, HRSD > 17) and of ten sex- and age-matched controls. The results showed no significant difference in basal calcium levels between the two groups and no significant difference in the Ca2+ response to thrombin although the response was higher in the patients. The Ca2+ increase after serotonin stimulation in depressed patients was significantly (P < 0.05) higher than in healthy controls. By contrast, the Ca2+ response to PHA in lymphocytes was significantly decreased in the patients. Our data confirm elevated Ca2+ responses after 5-HT2 receptor activation even in mediated depressed patients. However, Ca2+ responses in lymphocytes were decreased. Together with the observations of an enhanced Ca2+ response in platelets after thrombin stimulation, we speculate that the findings rather suggest alterations of [Ca2+]i regulation in depression than specific changes of serotonergic sensitivity.
Eckert
A
A
Department of Psychopharmacology, Central Institute of Mental Health, Mannheim, Germany.
Gann
H
H
Riemann
D
D
Aldenhoff
J
J
Müller
W E
WE
D000328:Adult; D000368:Aged; D000928:Antidepressive Agents / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D002478:Cells, Cultured; D003866:Depressive Disorder / Q000188:drug therapy / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000502:physiology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D012701:Serotonin / Q000502:physiology*
D000928:Antidepressive Agents; D011985:Receptors, Serotonin; D012701:Serotonin; D002118:Calcium