Imidazoline receptor proteins are decreased in the hippocampus of individuals with major depression

Background: A downregulation of I-2-imidazoline binding sires has been repo rted in frontal cortices of depressed suicide victims, according so I-2-rad ioligand binding and confirmed by Western blotting. We now report Western b lots of imidazoline receptor proteins in hippocampi of subjects with and wi thout depression at the time of death. Methods: Postmortem diagnoses were obtained from 17 cases of Axis I major d epressive disorder and 17 cases without Axis I psychopathology. No psychotr opic compounds were found in body fluids. Hippocampi were removed sectioned , and assessed histologically. Throughout the analysis, each major depressi ve disorder sample was paired with a sample from a psychiatrically healthy subject based an equivalent life spans and postmortem delays. The antiserum was identical to that used in previous studies that reported a downregulat ion of cortical 29/30-kd imidazoline receptor-binding proteins in depressio n. Results: A triad of imidazoline receptor-binding protein bands (40-50 kd) w as detected in the human hippocampus. Subjects with major depressive disord er had significantly less intensity in each imidazoline receptor-binding pr oteins band compared with central subjects (p =.01 for overall bands). Conclusions: The present results can be aligned with previous reports of do wnregulation of I-2-radioligand binding sites in both cortices and platelet s of depressed patients. (C) 2000 Society of Biological Psychiatry.