Diminished synaptosomal dopamine (DA) release and DA autoreceptor supersensitivity in schizophrenia

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Abstract
Post-mortem brain regions of schizophrenics were investigated in comparison to matched controls regarding synaptosomal K+-stimulated [3H]DA release and its modulation by DA autoreceptors. Brain specimens were cryopreserved in liquid nitrogen until release experiments; synaptosomes from brain pieces preincubated with dimethylsulfoxide have unchanged ability for [3H]DA release and its autoreceptor-mediated inhibition after cryo-preservation. Release data were individually corrected for post-mortem delay back to the zero-time state based on [3H]DA release alterations after in situ preservation of rat heads. In schizophrenia, the K+-stimulated [3H]DA release from superfused synaptosomes of the nucleus (n.) accumbens and n. caudatus was diminished significantly. Furthermore, functional supersensitivity of the modulatory DA autoreceptors could be demonstrated in these regions. The alterations demonstrated seem not to be due primarily to medication since in neuroleptic-free patients similar changes were shown.