Paper Information

Title: 

MUSCIMOL STATE-DEPENDENT MEMORY: INVOLVEMENT OF DORSAL HIPPOCAMPAL Μ-OPIOID RECEPTORS

Type: POSTER
Author(s): JAFARI SABET M.*,JANAT DASTJERDI I.
 
 *DEPARTMENT OF PHARMACOLOGY, SCHOOL OF MEDICINE, QAZVIN UNIVERSITY OF MEDICAL SCIENCES, QAZVIN, IRAN
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

In the present study, the effects of subcutaneous (s.c.) injections of morphine, a μ-opioid receptor agonist and intra-dorsal hippocampal (intra-CA1) injections of naloxone, a μ-opioid receptor antagonist on muscimol state-dependent memory were examined in mice. Each mouse was anaesthetized and its head was oriented in a stereotaxic instrument. Two stainless-steel cannulae were placed (bilaterally) above the CA1 regions of the dorsal hippocampus. A singletrial step-down passive avoidance task was used for the assessment of memory retention in adult male NMRI mice. Pre-training intra-CA1 administration of a GABAA receptor agonist, muscimol (0.025, 0.05, 0.1 and 0.2μg/mouse) dose dependently induced impairment of memory retention. Pre-test injection of muscimol (0.05, 0.1 and 0.2 μg/mouse, intra-CA1) induced state-dependent retrieval of the memory acquired under pre-training muscimol (0.1 μg/mouse, intra-CA1) influence. Pre-test injection of morphine (0.5 and 1mg/kg, s.c.) 30min before the administration of muscimol (0.1μg/mouse, intra-CA1) dose dependently inhibited muscimol state-dependent memory. Pre-test intra-CA1 injection of naloxone (0.1 and 0.2μg/mouse, intra-CA1) improved pre-training muscimol (0.1μg/mouse)-induced retrieval impairment. Moreover, pre-test administration of naloxone (0.1 and 0.2μg/mouse, intra-CA1) with an ineffective dose of muscimol (0.025μg /mouse) significantly restored the retrieval and induced muscimol state-dependent memory. These findings implicate the involvement of a dorsal hippocampal μ-opioid receptor mechanism in muscimol state-dependent memory.

 
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