title: Antisense oligonucleotide knockdown of mGlu₅ receptor attenuates the antinociceptive tolerance and up-regulated expression of spinal protein kinase C associated with chronic morphine treatment.
abstract: Spinal metabotropic glutamate receptor 5 (mGlu₅ receptor) is known to influence the development of intrathecal morphine antinociceptive tolerance. However, the signaling mechanisms remain unknown. We carried out intrathecal administration of an antisense oligodeoxynucleotide (ODN), which results in reduced expression of spinal mGlu₅ receptor, to determine its effects on morphine tolerance and spinal protein kinase C (PKC) expression. Rats were treated intrathecally with saline, morphine, mGlu5 receptor antisense ODN or mGlu5 receptor mismatched ODN. Behavioral tests were used to test the thermal and mechanical pain thresholds. Eight days later, rats were sacrificed and spinal cords were harvested to assess the expression of spinal PKC (α, γ and ε) by Western blotting and real-time polymerase chain reaction (PCR). Compared to control, intrathecal mGlu₅ receptor antisense ODN resulted in a ~53.9% reduction of spinal mGlu₅ receptor after 8days treatment. The mGlu5 receptor antisense ODN prevented the development of morphine tolerance. Expression of spinal PKC (α, γ and ε) was up-regulated at the mRNA and protein levels during the development of tolerance. Meanwhile, antisense ODN but not mismatched ODN reduced the spinal dorsal horn levels of PKC (α, γ and ε) which had been up-regulated after morphine exposure. We conclude that mGlu₅ receptor participates in the development of morphine tolerance. Expression of spinal PKC (α, γ and ε) at the mRNA and protein levels increased during morphine tolerance. Antisense ODN of mGlu₅ receptor prevented the tolerance and inhibited the altered expression of spinal PKC (α, γ and ε) during the development of tolerance.
authors.affiliation: Department of Anesthesiology, Shanghai Sixth People's Hospital, Shanghai Jiaotong University, Shanghai 200233, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Moxi
authors.initials: M
authors.lastname: Chen
authors.forename: Quanhong
authors.initials: Q
authors.lastname: Zhou
authors.forename: Ying
authors.initials: Y
authors.lastname: Xue
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Vida J
authors.initials: VJ
authors.lastname: Bil De Arce
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004361:Drug Tolerance; D055785:Gene Knockdown Techniques; D007278:Injections, Spinal; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008159:Lumbar Vertebrae; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D020319:Oligodeoxyribonucleotides, Antisense / Q000008:administration & dosage / Q000494:pharmacology*; D017288:Pain Threshold / Q000187:drug effects; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors*; D013116:Spinal Cord / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000701:Analgesics, Opioid; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D009020:Morphine; D011493:Protein Kinase C