Low-weight anorexia nervosa is related with a reduced 5-HT1A receptor bound in platelet membranes

Bellido I, Gomez A, Lopez-Arquillos C1, Tinaone F2, Beato L3, and Sanchez de la Cuesta F. D. Pharmacology and Clinical Therapeutic. Medicine School.1 D. Psychiatry,1 D. Endocrinology, Carlos Haya Hospital, Malaga.3 D. Eating disorders, Ciudad Real Hospital, Ciudad Real. Spain. ibellido@uma.es

Patients with anorexia nervosa (AN) and low-weight have demonstrated a reduction in brain serotonin (5-HT) turnover leading to hypotheses about dysfunction in the 5-HT receptors. Pharmacotherapy of anorexia nervosa has also traditionally focused on the use of antidepressants and there is some evidence that the use of SSRIs may help in preventing relapse in weight restored patients. Experimental administration of 8OH-DPAT stimulates eating behaviour (Currie et al., 2004). And an increased binding of the 5-HT1A receptors in some regions of the central nervous system has been reported in women who had recovered from bulimia-type AN as well as from the anxiety-related restricting-type of AN by positron emission tomography (Bailer et al., 2005). Thus this is not a rutinary technique; it is necessary to found a sensitive peripheral marker which may facilitate the identification of true pathophysiologic abnormalities in eating-disordered and provide a basis for the design of therapeutic interventions or monitoring of response to treatment. The 5-HT1A receptors have been directly described in lymphocytes (Farjardo et al., 2003) and in-directly described in platelet (Martini et al., 2004). Enhanced platelet 5-HT2A receptor binding has been reported in AN patients but there are no data about 5-HT1A receptors. In the present study, we determined the presence of 5-HT1A receptors by the binding of 8OH-DPAT in platelet membranes of peripheral blood from controls and AN patients trying to found a peripheral marker of AN stage. We studied the platelet membrane 5-HT1A receptors of low-weight Anorexia Nervosa patients vs. control. Low-weight females with clinical diagnoses of AN (CIE-10 rating scale) were compared with healthy female. Epidemiological, pharmacological, analytical and other pathological antecedents data and eating-related psychopathology (depressive, obsessive-compulsive, anxious and aggressiveness symptoms) were measured by appropriate rating scales. The platelet membrane 5-HT1A receptors were marked by the 5-HT1A receptor agonist 3H-8OH-DPAT using biochemical binding techniques (Ieni et al., 1988). Eleven low-weight females (19.8±1 years old) with AN and 11 age-matched healthy female were studied. The AN patients showed a mean of 27.3±7 months of duration of illness with 15.7±3.6 visits to the endocrine service and a last free-symptoms periods of 4.8±4 months. They showed: stature: 159±2 cm, initial weight 53.8±2 kg, minimal weight 38.2±1 kg, actual weight 41.5±1 kg, corporal fat 5.02±0.6 kg and a % of corporal fat 12.1±1 (measure by impedanciometry). Patients with AN had a significantly reduced number of 5-HT1A binding sites (Bmax 0.54±0.2 fmol/mg of protein) in platelet membranes compared with healthy volunteers (Bmax 3.25±0.3 fmol/mg of protein)(ANOVA test, p<0.05). Reduced platelet membrane 5-HT1A receptor binding coexists with low-weight AN status.

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