• Neuropharmacology · Oct 2003

    Comparative Study

    Effects of direct periaqueductal grey administration of a cannabinoid receptor agonist on nociceptive and aversive responses in rats.

    • D P Finn, M D Jhaveri, S R G Beckett, C H Roe, D A Kendall, C A Marsden, and V Chapman.
    • Institute of Neuroscience, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK. david.finn@nottingham.ac.uk
    • Neuropharmacology. 2003 Oct 1; 45 (5): 594-604.

    AbstractThe analgesic potential of cannabinoids may be hampered by their ability to produce aversive emotion when administered systemically. We investigated the hypothesis that the midbrain periaqueductal grey (PAG) is a common substrate mediating the anti-nociceptive and potential aversive effects of cannabinoids. The rat formalin test was used to model nociceptive behaviour. Intra-PAG microinjection of the excitatory amino acid D,L-homocysteic acid (DLH) was used to induce an aversive, panic-like reaction characteristic of the defensive "fight or flight" response. Administration of the cannabinoid receptor agonist HU210 (5 microg/rat) into the dorsal PAG significantly reduced the second phase of formalin-evoked nociceptive behaviour, an effect which was blocked by co-administration of the CB(1) receptor antagonist SR141716A (50 microg/rat). This anti-nociceptive effect was accompanied by an HU210-induced attenuation of the formalin-evoked increase in Fos protein expression in the caudal lateral PAG. Intra-dorsal PAG administration of HU210 (0.1, 1 or 5 microg/rat) significantly reduced the aversive DLH-induced explosive locomotor response. The anti-nociceptive effect of HU210 is likely to result from activation of the descending inhibitory pain pathway. Mechanisms mediating the anti-aversive effects of cannabinoids in the PAG remain to be elucidated. These data implicate a role for the PAG in both cannabinoid-mediated anti-nociceptive and anti-aversive responses.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        

    hide…

What will the 'Medical Journal of You' look like?

Start your free 21 day trial now.

We guarantee your privacy. Your email address will not be shared.