DENSITIES OF I-2-IMIDAZOLINE RECEPTORS, ALPHA(2)-ADRENOCEPTORS AND MONOAMINE-OXIDASE-B IN BRAINS OF SUICIDE VICTIMS

In the frontal cortex of suicide victims, the density of I-2-imidazoli ne receptors labeled by [H-3]idazoxan was lower (40%) than that in hea lthy subjects. In the same brains, the immunoreactivity of a 29/30 kDa imidazoline receptor protein was also found to be significantly decre ased (19%) and it showed a positive correlation with the density of I- 2-imidazoline receptors. Also in the same brains, the density of alpha (2)-adrenoceptor antagonist binding sites labeled by [H-3]RX821002 (2- methoxy idazoxan) was found to be unchanged. The density of brain I-2- imidazoline receptors, correlated with aging in control subjects but n ot in suicides. The density of brain MAO-B sites labeled by [H-3]Ro 19 -6327 (lazabemide) in suicides was no different to that in age-matched controls. As expected, the density of brain MAO-B sites in suicides s howed a positive correlation with age, but it did not correlate with t he density of I-2-imidazoline receptors in the same brains. The data i ndicate that the I-2-imidazoline receptors labeled by [H-3]idazoxan in the brain of suicides is related to a 29/30 kDa imidazoline receptor protein identified by immunoblot analysis. The data also indicate that the brain I-2-imidazoline receptor cannot be identified with the MAO- B isoenzyme. The decreased density of I-2-imidazoline receptors in the brain of suicide victims might play a role in the pathogenesis of maj or depression. Copyright (C) 1996 Elsevier Science Ltd.