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Autoradiographic Demonstration of Increased α2-Adrenoceptor Agonist Binding Sites in the Hippocampus and Frontal Cortex of Depressed Suicide Victims


  • Dedicated to Daniel X. Freedman, in memoriam.

Address correspondence and reprint requests to Dr. J. A. García-Sevilla at Lab. Neurofarmacologia, Dept. Biologia Fonamental i Ciències de la Salut, Universitat de les Illes Balears, Cra. Valldemossa Km 7.5, E-07071 Palma de Mallorca (Balears), Spain.


Abstract: To examine directly in the brain the status of α2-adrenoceptors in major depression, the specific binding of the agonist [3H]UK 14304 was measured by quantitative receptor autoradiography in the hippocampus and frontal cortex of suicide victims (n = 17) with a retrospective diagnosis of depression (n = 7) or other psychiatric disorders (n = 10) as well as of matched control subjects (n = 9). In suicide victims, a significant increase in the number of α2-adrenoceptors was found in the CA1 field (40%) and dentate gyrus (20%) of the hippocampus and in the external layers I (33%) and II (31%) of the frontal cortex, compared with that in matched controls. In depressed suicide victims, the increase in α2-adrenoceptors in the CA1 field (57%) was significantly greater (24%, p < 0.05) than that observed in the group of suicide victims with other diagnoses (26%). In the same depressed suicide victims, the increase in cortical α2-adrenoceptors was restricted to layer I (34%) and it was equivalent to that found in layer I (33%) of suicide victims with other diagnoses. The results indicate that suicide is associated with increases in the high-affinity state of brain α2-adrenoceptors and that there is a pronounced localized increase of this inhibitory receptor in the hippocampus of depressed suicide victims.