Analysis of nociceptive system in pathologic conditions

多模态受体是外周疼痛受体之一，参与急性和慢性炎症性疼痛。它的兴奋性可以被炎症相关物质、组织温度的变化等所改变。在急性或慢性炎症过程中，炎症介质如BK、PGs、5-HT被认为在炎症区域释放。到目前为止，由于自由神经末梢的体积小，还不可能记录它们的受体活动。目前，我们很有可能利用背根神经节细胞（DRG细胞）的细胞内记录和膜片钳技术来阐明介质对伤害感受器膜或细胞内动力学的作用机制，因为我们已经证明DRG细胞的膜特性和对辣椒素（CAP）的敏感性与受体膜非常相似。在本项目中，我们利用神经生理学技术阐明了BK （10muM）对培养的完整大鼠DRG细胞的影响。结果如下：(1)培养细胞24h内。不论有无NGF， BK均不影响cap敏感细胞的膜电位、膜输入电阻和膜电流。(2) cap敏感细胞培养超过48小时。被BK动作电位去极化。在有NGF的细胞中，BK的去极化作用明显大于无NGF的细胞。下一步，我们将观察pg和5-HT对培养DRG细胞的影响，并将其与急性或慢性病理状态下大鼠的结果进行比较。

The polymodal receptor, one of the peripheral pain receptors, is involved in acute and chronic inflammatory pain. Its excitability is able to be modified by inflammation-related substances, changes in tissue temperature, etc. Under acute or chronic inflammatory processes, inflammatory mediators such as BK,PGs, 5-HT are suggested to be released in inflammatory region. So far, it has been impossible to record receptor activities from free nerve endings because of their small size. At present we have a good possibility to clarify the mechanisms of action of mediators on nociceptor membrane or intracellular dynamics using intracellular recording and patch clamp techniques from dorsal root ganglion cells (DRG cells), since we have demonstrated that the membrane characteristics and sensitivity to capsaicin (CAP) of DRG cells are closely resemble those of receptor membrane.In this project we clarified the effect of BK (10muM) on cultured DRG cells from intact rat, using of neurophysiological techniques. The results are followed :(1) In cultured cell within 24 hr.with and without NGF,the BK did not affect membrane potential, membrane input resistance and membrane current of CAP-sensitive cells.(2) Cultured CAP-sensitive cells more than 48 hr.were depolarized by the BK with action potentials. In the cultured cells with NGF the depolarization by the BK were much bigger than one of cultured cells without NGF.For next steps, we will observe PGs and 5-HT effects on cultured DRG cells and they will be compared with results obtained from rats under acute or chronic pathological conditions.