Effects of phencyclidine on levels of dynorphin 1-17 and dynorphin 1-8 immunoreactivities in various brain regions

Dynorphin (Dyn) is an endogenous ligand of kappa opioid receptor. Our previous work has shown that Dyn was involved in the pathophysiological process of schizophrenia. In this study, the levels of Dyn 1-17 and Dyn 1-8 immunoreactivities (ir) in rat brain regions were investigated after acute and chronic administrations of phencyclidine (PCP), a psychotomimetic drug which causes typical schizophrenia-like symptoms. The results are as follows: (1) In acute administration group, the levels of Dyn 1-17 and 1-8 (ir) in hypothalamus and hippocampus, the levels of Dyn 1-8 in striatum and Dyn 1-17 in frontal cortex were increased markedly, but no significant changes of Dyn 1-17 (ir) in striatum and Dyn 1-8 (ir) in frontal cortex were observed. (2) In chronic administration group, the levels of Dyn 1-17 and 1-8 in frontal cortex were increased and those of Dyn 1-8 in hippocampus were decreased markedly but no significant changes were seen in hypothalamus and striatum. The results suggest that Dyn and endogenous PCP-like substance may be involved in the regulation of mental activity and there are interactions between kappa and PCP/delta opioid receptors in brain.