α2-Adrenoceptors in the brain of suicide victims: increased receptor density associated with major depression

Abstract

To examine directly in the brain the status of the α 2-adrenoceptor in major depression, the specific binding of the agonists [ 3H]clonidine and [ 3H]UK 14304 was quantitated in various brain regions of suicide victims with a retrospective diagnosis of depression or other psychiatric disorders. In depressed suicides, the binding capacity of [ 3H]clonidine was found to be increased in the hypothalamus (B max 35%–55% greater), and to a lesser extent in the frontal cortex, as compared with that in matched controls, schizophrenic suicides, or suicides with various diagnosis. The binding capacity of [ 3H]UK 14304 also was found increased in the frontal cortex (B max 30% greater), and to a lesser extent in the hypothalamus, of depressed suicides. In other brain regions such as the amygdala, hippocampus, and cerebellum there also was a tendency for an increased receptor density associated with suicide. Moreover, in the frontal cortex of suicides, the potency of norepinephrine in displacing the binding of the antagonist [ 3H] idazoxan also was found increased (K i decreased eight-fold). The results indicate that the density and affinity of α 2A-adrenoceptors in the high-affinity state are increase the brain of depressed suicides.