Document Detail

Cannabinoid CB1 receptors of the rat central amygdala mediate anxiety-like behavior: interaction with the opioid system.
MedLine Citation:
PMID:  18797248     Owner:  NLM     Status:  MEDLINE    
Cannabinoids, which are the active compounds of marijuana, produce some pharmacological effects similar to the opioids. In addition, there are functional interactions between the cannabinoid and opioid systems. In this study, we investigated the effects of intraperitoneal (i.p.) injection of opioid drugs on responses induced by intracentral amygdala (intra-CeA) microinjection of cannabinoid CB1 receptor agents in rats, using the elevated plus maze test of anxiety. I.p. injection of morphine (6 and 9 mg/kg) 30 min before testing, increased the percentage open arm time (%OAT) and the percentage open arm entries (%OAE), but not locomotor activity, showing an anxiolytic-like response. I.p. administration of the opioid receptor antagonist, naloxone (1 mg/kg) 15 min before testing, significantly reduced %OAT, but not %OAE and locomotor activity. The drug, however, tended to decrease locomotor activity. Intra-CeA administration of arachidonylcyclopropylamide (ACPA, an agonist shown to selectively activate CB1 receptors; 1.25 and 5 ng/rat) increased %OAT and %OAE but not locomotor activity, indicating an anxiolytic-like response. Coadministration of morphine (6 mg/kg, i.p.) plus ACPA (0.125 ng/rat, intra-CeA) increased the anxiolytic-like response. Administration of naloxone reversed the effects of intra-CeA injection of ACPA. Intra-CeA administration of the cannabinoid CB1 receptor antagonist, AM251 (2.5, 25, and 100 ng/rat) did not alter %OAT and %OAE, but the higher doses of the drug (25 and 100 ng/rat) reduced locomotor activity. Coadministration of morphine (6 mg/kg) or naloxone (0.1 mg/kg) with AM251 showed an anxiolytic-like response. In conclusion, the results may indicate an anxiolytic-like effect for cannabinoid CB1 receptors of the CeA and the existence of an interaction between the cannabinoid and the opioid systems in the modulation of anxiety.
Mohammad-Reza Zarrindast; Shadi Sarahroodi; Ardeshir Arzi; Mohammad Javad Khodayar; Saba Taheri-Shalmani; Ameneh Rezayof
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Behavioural pharmacology     Volume:  19     ISSN:  0955-8810     ISO Abbreviation:  Behav Pharmacol     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-19     Completed Date:  2009-01-23     Revised Date:  2009-07-07    
Medline Journal Info:
Nlm Unique ID:  9013016     Medline TA:  Behav Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  716-23     Citation Subset:  IM    
Department of Pharmacology, School of Medicine and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran.
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MeSH Terms
Amygdala / drug effects,  physiopathology*
Anxiety / physiopathology*
Arachidonic Acids / pharmacology
Arousal / drug effects,  physiology*
Fear / drug effects,  physiology
Maze Learning / drug effects,  physiology
Morphine / pharmacology
Motor Activity / drug effects,  physiology
Naloxone / pharmacology
Narcotic Antagonists / pharmacology
Rats, Wistar
Receptor, Cannabinoid, CB1 / drug effects,  physiology*
Receptors, Opioid / drug effects,  physiology*
Reg. No./Substance:
0/Arachidonic Acids; 0/Narcotic Antagonists; 0/Receptor, Cannabinoid, CB1; 0/Receptors, Opioid; 0/arachidonylcyclopropylamide; 465-65-6/Naloxone; 57-27-2/Morphine

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