投射于腰骶髓后连合核的传递伤害性刺激的初级传入纤维的来源探索—c-fos表达方法

本课题组的既往研究曾发现 ,膀胱的初级传入投射纤维中有一部分传递伤害性刺激 ,投射于腰骶髓的后连合核。本研究的目的是通过比较盆腔内脏和后肢躯体性结构的伤害性刺激诱导 FOS阳性反应在大鼠后连合核的表达状况 ,藉以确定投射于后连合核的传递痛信号的初级传入的来源。本实验分别向盆腔内脏的膀胱和直肠以及坐骨神经支配的小腿外侧皮肤及腓肠肌等四个不同部位注入 2 %福尔马林溶液 ,用免疫组织化学方法观察了腰骶段脊髓内 FOS的表达状况 ;并向此四部位注射生理盐水作为对照。结果证明 ,将 2 %福尔马林溶液注入膀胱或直肠内腔后可主要诱导 L6,S1 ,S2 节段后连合核出现大量 FOS阳性细胞核( 2 5～ 95个 /片 ) ;向小腿外侧皮肤或腓肠肌注射福尔马林溶液 ,则主要在背角浅层出现浓密的 FOS阳性细胞核而在后连合核仅发现极少量的 FOS阳性细胞核 ( <5个 /片 ) ;在不给予福尔马林刺激的对照组 ,后连合核内也出现极少量散在的 FOS阳性细胞核 ( <3个 /片 )即后连合核内出现极少量的传递躯体伤害性刺激的传入成分与不给予福尔马林刺激的对照组结果无明显差别 ,这种极少量的神经元在神经机能的传递上不应有何作用。因而 ,本研究结果提示 ,盆腔内脏来源的痛信号初级传入成分是后连合核内唯一的有机能意义的痛传入成

INVESTIGATION OF THE ORIGIN OF THE PRIMARY AFFERENT TRANSFERRING NOXIOUS STIMULI AND PROJECTING TO THE DORSAL COMMISSURAL NUCLEUS OF THE LUMBOSACRAL SPINAL CORD IN THE RAT-c-fos EXPRESSION METHOD

Our present purpose is to observe FOS protein expression induced by visceral and somatic noxious stimuli in the dorsal commissural nucleus (DCN) of the lumbosacral spinal cord of the rat. Visceral stimuli were performed by infusion of formalin into the urinary bladder or rectum and somatic stimuli were done by lateral shank subcutaneous injection and gastrocnemius injection of formalin. FOS expression was visualized by an immunohistochemical reactive method. In control rats, a few neurons with weak FOS-like immunoreactivity were scattered in the DCN (less than 3 cells/section). After infusion of fomalin into the bladder or rectum, however, the number of FOS-positive neurons in the DCN was greatly increased (about 25～95 cells/section). Although lateral shank subcutaneous injection and gastrocnemius injection of fomalin resulted in many FOS-positive neurons in the dorsal horn, only a small number of them were observed in the DCN (less than 5 cells/section). The present results suggest that the DCN in the lumbosacral spinal cord may be an sole area receiving noxious information from the pelvic organs, but it may not be involved in receiving somatic noxious information from the hindlimb. Our results indicate that DCN is an appropriate region to investigate the mechanism of analgesia. (Figure 2 on plate 26)