title: Microinjection of dynorphin into the hippocampus impairs spatial learning in rats.
abstract: The effect of hippocampal dynorphin administration on learning and memory was examined in spatial and nonspatial tasks. Bilateral infusion of dynorphin A(1-8) (DYN; 10 or 20 micrograms in one microliters) into the dorsal hippocampus resulted in a dose-related impairment of spatial working memory in a radial maze win-stay task. Subsequent experiments found that acquisition of a reference memory task in the water maze was impaired by DYN injections (20 micrograms/microliters) in the dorsal hippocampus, but not in the ventral hippocampus, and that this impairment could be blocked by naloxone. In a nonspatial task, posttraining DYN injections in the dorsal hippocampus had no effect on retention of step-through passive avoidance. These results suggest that dynorphin specifically interferes with spatial learning and memory, and that this effect is mediated by opioid receptors in the dorsal hippocampus.
authors.affiliation: Curriculum in Toxicology, North Carolina State University, Raleigh.
authors.forename: K L
authors.initials: KL
authors.lastname: McDaniel
authors.forename: W R
authors.initials: WR
authors.lastname: Mundy
authors.forename: H A
authors.initials: HA
authors.lastname: Tilson
mesh_terms: D000818:Animals; D004347:Drug Interactions; D004399:Dynorphins / Q000008:administration & dosage* / Q000494:pharmacology; D004924:Escape Reaction / Q000187:drug effects*; D006624:Hippocampus / Q000187:drug effects*; D007858:Learning / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D008845:Microinjections; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D009270:Naloxone; D004399:Dynorphins