Analysis of anti-nociceptive mechanism induced by gamma knife irradiation for intractable pain

伽玛刀垂体放射外科(GKPR)用于治疗癌症疼痛，取得了显著的效果。然而，GKPR的镇痛机制尚不清楚。我们建立了一种大鼠GKPR方法。由于在大剂量GKPR后观察到垂体萎缩，我们证实GK照射在大鼠垂体上是正确的。接下来，我们确定了120GyGK照射对脑垂体的影响，该照射的能量与实际治疗相似。而正常大鼠经GK照射后，未观察到与伤害性反应有关的行为学改变。免疫印迹和组织化学分析显示，GK处理组大鼠垂体Iba-1阳性细胞(巨噬细胞/小胶质细胞)明显增多。进一步的研究，如在慢性炎症性疼痛模型中对垂体进行GK照射，可能会阐明GK诱导的抗伤害性作用的机制。

Gamma knife pituitary radiosurgery (GKPR) is used to manage cancer pain and has provided marked effects. However, the analgesic mechanism of GKPR remains unclear. We established a GKPR method for rats. Since pituitary atrophy was observed after high-dose GKPR, we confirmed that the GK irradiation had been correctly performed on the rat pituitary. Next, we determined the effects of 120Gy GK irradiation, a dose similar in energy to actual treatment, on the pituitary. However, no behavioral changes related to nociceptive responses were observed after GK irradiation of pituitary in the normal rat. Immunoblotting and histochemical analysis showed that Iba-1 positive cells (macrophage/microglia) were significantly increased at the GK treated pituitary. Further studies, such as GK irradiation of the pituitary in a chronic inflammatory pain model, may clarify the mechanisms underlying the anti-nociceptive effects induced by GK.