小鼠脊髓背角神经元向臂旁核及丘脑中线/板内核群的分支投射

Collateral projections from the spinal dorsal horn to the parabrachial nucleus and midline/intralaminar thalamic nuclei in mice

目的:观察脊髓背角P物质受体(substance P receptor,SPR)阳性神经元向臂旁核及中线/板内核群的分支投射并为其参与痒觉信息传递提供证据。方法:利用小动物脑立体定位仪向10只8周龄C57BL/6小鼠的臂旁核及丘脑中线/板内核群内分别注射四甲基罗达明(tetramethylrhodamine-dextran,TMR)及荧光金(fluoro-gold,FG),观察小鼠脊髓背角的TMR/FG双标神经元。结合免疫荧光组织化学染色方法观察双标神经元表达SPR和在急性痒模型下表达Fos的情况。结果:脊髓背角I层、脊髓外侧核(lateral spinal nucleus,LSN)及脊髓背角IV～V层均可观察到TMR/FG双标神经元,且部分双标神经元分别表达SPR及Fos蛋白。结论:脊髓背角存在同时向臂旁核及丘脑中线/板内核群发出分支投射的神经元,部分双标神经元表达SPR并参与痒觉信息的传递。

Objective: To observe whether spinal dorsal horn( SDH) substance P receptor( SPR)-immunoreactive(-ir) neurons send collateral projections to the parabrachial nucleus( PBN) and midline/intralaminar thalamic nuclei( MINT) and whether these neurons are activated by itch stimulation. Methods: Ten C57BL/6 mice were stereotactically injected with tetramethylrhodamine-dextran( TMR) into the left PBN and fluoro-gold( FG) into the MINT. Sections of the SDH were used for detecting TMR/FG double-labled neurons and for detecting SPR/TMR/FG or Fos/TMR/FG immunofluorescence histochemical triple stained neurons. Results: TMR/FG double-labeled neurons were observed mainly in the right lamina I,lateral spinal nucleus( LSN) and laminae IV ~ V of the SDH. Some of these collateral projection neurons showed SPR-ir staining. Under the acute itch condition,some of TMR/FG double-labeled neurons were activated and expressed Fos protein. Conclusion: SPR-expressing neurons in SDH send collateral projections to both the PBN and MINT,which might be involved in itch signal transmission.