Details

Autor(en) / Beteiligte

• Cai, You-Qing
• Chen, Shao-Rui
• Han, Hee-Dong
• Sood, Anil K
• Lopez-Berestein, Gabriel
• Pan, Hui-Lin

Titel

Role of M₂, M₃, and M₄ muscarinic receptor subtypes in the spinal cholinergic control of nociception revealed using siRNA in rats

Ist Teil von

• Journal of neurochemistry, 2009-11, Vol.111 (4), p.1000-1010

Ort / Verlag

Oxford, UK: Oxford, UK : Blackwell Publishing Ltd

Erscheinungsjahr

2009

Link zum Volltext

Quelle

Wiley-Blackwell subscription journals

Beschreibungen/Notizen

• Muscarinic acetylcholine receptors (mAChRs) are involved in the control of nociception in the spinal cord. The M₂, M₃, and M₄ mAChR subtypes are present in the spinal dorsal horn. However, the role of the individual subtypes in the anti-nociceptive effect produced by mAChR agonists is uncertain. Here, we determined the contribution of M₂, M₃, and M₄ subtypes to spinal muscarinic analgesia by using small-interference RNA (siRNA) targeting specific mAChR subtypes in rats. The neuronal uptake and distribution of a chitosan-siRNA conjugated fluorescent dye in the spinal cord and dorsal root ganglion were confirmed after intrathecal injection. The control and gene-specific siRNA-chitosan complexes were injected intrathecally for three consecutive days. Quantitative reverse-transcription polymerase chain reaction analysis showed that treatment with siRNA targeting M₂, M₃, or M₄ subtype produced a large reduction in the corresponding mRNA levels in the dorsal root ganglion and dorsal spinal cord. Also, the protein levels of the mAChR subtypes in the spinal cord were significantly down-regulated by siRNA treatment, as determined by the immunoprecipitation and receptor-binding assay. Treatment with the M₂-siRNA caused a large reduction in the inhibitory effect of muscarine on the nociceptive withdrawal threshold. Furthermore, M₄ knockdown at the spinal level significantly reduced the anti-nociceptive effect of muscarine. However, the anti-nociceptive effect of muscarine was not significantly changed by the M₃-specific siRNA. Our study suggests that chitosan nanoparticles can be used for efficient delivery of siRNA into the neuronal tissues in vivo. Our findings also provide important functional evidence that M₂ and M₄, but not M₃, contribute to nociceptive regulation by mAChRs at the spinal level.