title: Knockdown of spinal cord postsynaptic density protein-95 prevents the development of morphine tolerance in rats.
abstract: The activation of spinal cord N-methyl-D-aspartate (NMDA) receptors and subsequent intracellular cascades play a pivotal role in the development of opioid tolerance. Postsynaptic density protein-95 (PSD-95), a molecular scaffolding protein, assembles a specific set of signaling proteins around NMDA receptors at neuronal synapses. The current study investigated the possible involvement of PSD-95 in the development of opioid tolerance. Opioid tolerance was induced by intrathecal injection of morphine sulfate (20 microg/10 microl) twice a day for 4 consecutive days. Co-administration of morphine twice daily and PSD-95 antisense oligodeoxynucleotide (50 microg/10 microl) once daily for 4 days not only markedly reduced the PSD-95 expression and its binding to NMDA receptors in spinal cord but also significantly prevented the development of morphine tolerance. In contrast, co-administration of morphine twice daily and PSD-95 missense oligodeoxynucleotide (50 microg/10 microl) once daily for 4 days did not produce these effects. The PSD-95 antisense oligodeoxynucleotide at the doses we used did not affect baseline response to noxious thermal stimulation or locomotor function. The present study indicates that the deficiency of spinal cord PSD-95 attenuates the development of opioid tolerance. These results suggest that PSD-95 might be involved in the central mechanisms of opioid tolerance and provide a possible new target for prevention of development of opioid tolerance.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, 355 Ross, 720 Rutland Avenue, Baltimore, MD 21205, USA.
authors.forename: W-J
authors.initials: WJ
authors.lastname: Liaw
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.forename: F
authors.initials: F
authors.lastname: Tao
authors.forename: M
authors.initials: M
authors.lastname: Yaster
authors.forename: R A
authors.initials: RA
authors.lastname: Johns
authors.forename: Y-X
authors.initials: YX
authors.lastname: Tao
mesh_terms: D000818:Animals; D000076122:Disks Large Homolog 4 Protein; D004361:Drug Tolerance / Q000502:physiology*; D007278:Injections, Spinal; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins; D009020:Morphine / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; C033652:postsynaptic density proteins; D009020:Morphine