Schepelmann K, Messlinger K, Schaible H G, Schmidt R F
Physiologisches Institut, Universität Würzburg, F.R.G.
Neuroscience. 1992 Sep;50(1):237-47. doi: 10.1016/0306-4522(92)90395-i.
The effects of prostaglandin I2 on the discharge properties of fine articular afferents (group III and group IV fibers) in the cat were examined by extracellular recordings from single units dissected from the medial articular nerve of the knee joint. Prostaglandin I2 was applied intra-arterially close to the joint in doses of 0.3-30 micrograms per 0.3 ml bolus injection, and its effects on the spontaneous activity as well as on discharges evoked by mechanical and chemical stimulation (bradykinin) were monitored. Prostaglandin E2 was also applied and the effects of prostaglandins I2 and E2 on particular units were compared. An excitatory effect of prostaglandin I2 was observed in 49% of 37 group III and in 37% of 27 group IV units. A sensitization to passive movements of the joint occurred in 71% of 31 group III and 48% of 21 group IV units. Sixty-seven per cent of 32 units (groups III and IV) were both excited and sensitized by prostaglandin I2 to movements of 27% were sensitized but not excited. In 64% of 11 group III and 63% of eight group IV units studied the responses to bradykinin were enhanced by prostaglandin I2. Prostaglandin E2 had qualitatively similar effects as prostaglandin I2 but excited and sensitized a lower proportion of articular afferents. Forty-one per cent of the units were sensitive to both prostaglandins but 26% of the fibers were only sensitive to prostaglandin I2. None of the units was exclusively sensitive to prostaglandin E2. In general, the excitatory and sensitizing effects of prostaglandin E2 had a longer duration than those exerted by prostaglandin I2. We conclude that prostaglandin I2 increases the sensitivity to mechanical stimuli as well as to chemical stimulation by bradykinin in the majority of articular group III and group IV fibers. Moreover, in a large proportion of articular afferents, prostaglandin I2 had an excitatory effect. Thus, prostaglandin I2 may be an inflammatory mediator which is important for inflammation-evoked activity in slowly conducting afferents and it may participate in the development of arthritic hyperalgesia and pain.
通过对从猫膝关节内侧关节神经分离出的单个单位进行细胞外记录，研究了前列腺素I2对猫细关节传入神经（III组和IV组纤维）放电特性的影响。以每0.3ml推注注射0.3 - 30微克的剂量，将前列腺素I2动脉内注射到靠近关节处，并监测其对自发活动以及对机械和化学刺激（缓激肽）诱发放电的影响。还应用了前列腺素E2，并比较了前列腺素I2和E2对特定单位的影响。在37个III组单位中的49%和27个IV组单位中的37%观察到前列腺素I2的兴奋作用。在31个III组单位中的71%和21个IV组单位中的48%出现了对关节被动运动的敏化。32个单位（III组和IV组）中的67%被前列腺素I2兴奋并敏化，27%仅被敏化但未被兴奋。在研究的11个III组单位中的64%和8个IV组单位中的63%中，前列腺素I2增强了对缓激肽的反应。前列腺素E2具有与前列腺素I2定性相似的作用，但兴奋和敏化关节传入神经的比例较低。41%的单位对两种前列腺素均敏感，但26%的纤维仅对前列腺素I2敏感。没有单位仅对前列腺素E2敏感。一般来说，前列腺素E2的兴奋和敏化作用持续时间比前列腺素I2更长。我们得出结论，前列腺素I2增加了大多数关节III组和IV组纤维对机械刺激以及对缓激肽化学刺激的敏感性。此外，在很大一部分关节传入神经中，前列腺素I2具有兴奋作用。因此，前列腺素I2可能是一种炎症介质，对慢传导传入神经中炎症诱发的活动很重要，并且可能参与关节炎性痛觉过敏和疼痛 的发展。
