Facilitation of memory retrieval by pretest morphine mediated by μ but not δ and κ opioid receptors

Abstract

Mice were trained to avoid electric shock (0.6 mA) in a step-through type passive avoidance learning task, retention being measured 24 h after the training trial. Morphine 10 mg/kg administered 30 min before the test trial (pretest) facilitated memory retrieval, and the effect was completely antagonized by 1 mg/kg naloxone, a selective μ-opioid receptor antagonist. On the other hand, pretest administration of 0.01–10 mg/kg DTLET, a selective δ-opioid receptor agonist, did not produce the same effect as morphine. Nor-binaltorphimine, a κ-opioid receptor antagonist, did not antagonize the effect of pretest morphine, at doses of 1 and 2 mg/kg. These results suggest that the facilitation of memory retrieval by pretest morphine is mediated through μ- but not δ- or κ-opioid receptors.

DOI: 10.1007/BF02244099

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Cite this paper

@article{Shiigi2005FacilitationOM, title={Facilitation of memory retrieval by pretest morphine mediated by μ but not δ and κ opioid receptors}, author={Yasuyuki Shiigi and Masakatsu Takahashi and Hiroshi Kaneto}, journal={Psychopharmacology}, year={2005}, volume={102}, pages={329-332} }