EFFECTS OF DYNORPHIN-A(1-13) ON CARBON MONOXIDE-INDUCED DELAYED AMNESIA IN MICE

The effects of dynorphin A (1-13) on carbon monoxide (CO)-induced amne sia in mice were investigated. Memory deficiency was apparent during Y -maze testing 5 days after CO exposure (delayed amnesia). Percent alte rnation in the GO-exposed group was significantly lower than that in t he control group. Administration of dynorphin A (1-13) (1.5 nmol, i.c. v.) 15 min before the Y-maze test session reversed the impairment of s pontaneous alternation performance in the GO-exposed group. To determi ne whether this effect was mediated via kappa opioid receptors, we att empted to block the effect of dynorphin A using the kappa opioid recep tor antagonist nor-binaltorphimine. Nor-binaltorphimine (5.44 nmol, i. c.v.) blocked the effect of dynorphin A. (1-13) on delayed amnesia. Dy norphin A (1-13) did not affect the impairment of alternation induced by the blockade of NMDA-receptors by dizocilpine (MK-801), but signifi cantly prevented the impairment induced by mecamylamine. These results suggest that dynorphin A (1-13) modulates the kappa receptor-mediated opioid neuronal system, and reverses the impairment of spontaneous al ternation performance induced by CO exposure. Copyright (C) 1997 Elsev ier Science Inc.