Journal of Affective Disorders 52 (1999) 225–233 Brief report 3 3 Altered [ H]imipramine and 5-HT2 but not [ H]paroxetine binding sites in platelets from depressed patients a, a ,c b b b a * P. Rosel , B. Arranz , J. Vallejo , P. Alvarez , J.M. Menchon , T. Palencia , a M.A. Navarro a Hormone Unit ( Department of Biochemistry), Feixa llarga s / n, Hospitalet de Llobregat, Barcelona, Spain b Department of Psychiatry. Hospital Princeps d’ Espanya, Barcelona, Spain c Benito Menni, CASM, Barcelona, Spain Received 18 June 1997; received in revised form 3 February 1998; accepted 5 February 1998 Abstract Background: Serotonergic system alterations were studied in 51 depressed patients classified according to DSM-III-R 3 criteria for major depression with melancholia compared to 31 healthy controls. Method: [ H]Imipramine and 3 [ H]paroxetine binding sites and the 5HT2 receptor were simultaneously determined in blood platelet membranes. Results: A 3 significantly lower maximum binding in [ H]imipramine binding was observed in depressed patients compared to controls (1134674 vs. 17126106 fmol / mg protein, P , 0.0001) without changes in the equilibrium dissociation constant 3 (1.1060.05 vs. 1.2560.09 nM). [ H]Paroxetine binding did not differ between the two groups ( B , 1441655 vs. 1280681 max fmol / mg protein; K , 0.06060.002 vs. 0.06260.002 nM). The K value of 5HT2 binding was lower in depressed patients d d than controls (0.9560.04 vs. 1.1560.09 nM, P , 0.039) without changes in maximum binding (140611 vs. 127614 3 fmol / mg protein). Conclusions: Taken together, these results suggest that [ H]imipramine and 5HT2 receptors may be good biological markers for serotonergic dysfunction in depressive disorders.  1999 Elsevier Science B.V. All rights reserved. 3 3 3 Keywords: [ H]Imipramine; [ H]Paroxetine; [ H]Ketanserin; 5HT2; Endogenous depression 1. Introduction and Nemeroff, 1994). The strongest evidence of this serotonergic dysfunction is lower central 5HT turn- Alterations in the serotonergic system have been over, indicated by reduced cerebrospinal fluid con- widely reported in the etiology of affective disorders centration of 5-HIAA (the major metabolite of and in suicidal behavior (Asberg et al., 1976; Mur- serotonin) particularly in depressed patients who phy et al., 1978; Risch and Nemeroff, 1992; Owens make violent suicide attempts (Asberg et al., 1976, 1984). * Corresponding author. The 5-HT reuptake sites have been extensively 0165-0327 / 99 / $ – see front matter  1999 Elsevier Science B.V. All rights reserved. PII: S0165-0327(98)00030-5