Dai Yi, Iwata Koichi, Kondo Eiji, Morimoto Toshifumi, Noguchi Koichi
Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan Department of Oral physiology, Osaka University, Faculty of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
Pain. 2001 Feb 15;90(3):287-296. doi: 10.1016/S0304-3959(00)00411-5.
In order to clarify the central mechanisms of thermal hyperalgesia produced by peripheral nerve injury, Fos protein-like immunoreactive (Fos-LI) cells in spinal dorsal horn neurons were studied in rats with chronic constriction nerve injury (CCI) following graded thermal stimulation of the hind paw. The graded thermal stimuli (cold: 5, 10 and 15 degrees C, heat: 42, 46 and 54 degrees C) were applied to the plantar surface of the operated hind paw 14 days after CCI or sham operation, and the number of Fos-LI cells in the spinal dorsal horn was quantified. Many Fos-LI cells were expressed in the superficial laminae of the spinal dorsal horn both in sham-operated and CCI rats following thermal stimulation. Fos-LI cells were mainly restricted to the medial half of the superficial laminae of the spinal dorsal horn, and were sparsely distributed in the deeper laminae. The number of Fos-LI cells in the superficial laminae (laminae I--II) of the dorsal horn was significantly higher in CCI rats after stimulation at 10 and 46 degrees C, but not at the other stimulating temperatures (5, 15, 42, and 54 degrees C) as compared to that in sham-operated rats. In laminae III-IV, the number of Fos-LI cells was significantly higher at all stimulus temperatures in CCI rats when compared to the sham-operated rats. No distribution difference of Fos-LI cells was observed between CCI and sham-operated rats in laminae V--VI. Thus, in the spinal dorsal horn of the CCI rats, there was a selective increase in thermal stimulus-induced Fos-LI cells in the superficial dorsal horn after stimulating at near noxious threshold intensities and a non-selective increase in Fos-LI cells in laminae III--IV after both noxious and innocuous thermal stimuli. The increase of Fos-LI cells in the superficial laminae may be related to hypersensitivity to noxious stimuli while the increase of Fos-LI cells in laminae III--IV may be related to an increased sensitivity to both noxious and innocuous stimuli that leads to increased reflex activity following nerve injury.
为阐明外周神经损伤所致热痛觉过敏的中枢机制，在对后爪进行分级热刺激后，研究了慢性压迫性神经损伤（CCI）大鼠脊髓背角神经元中Fos蛋白样免疫反应性（Fos-LI）细胞。在CCI或假手术14天后，将分级热刺激（冷：5、10和15℃，热：42、46和54℃）施加于手术侧后爪的足底表面，并对脊髓背角中Fos-LI细胞的数量进行定量。热刺激后，假手术大鼠和CCI大鼠的脊髓背角浅层均有许多Fos-LI细胞表达。Fos-LI细胞主要局限于脊髓背角浅层的内侧半部分，在深层分布稀疏。与假手术大鼠相比，CCI大鼠在10℃和46℃刺激后，背角浅层（I-II层）的Fos-LI细胞数量显著增加，但在其他刺激温度（5、15、42和54℃）下则无显著差异。在III-IV层，与假手术大鼠相比，CCI大鼠在所有刺激温度下Fos-LI细胞的数量均显著增加。在V-VI层，未观察到CCI大鼠和假手术大鼠之间Fos-LI细胞的分布差异。因此，在CCI大鼠的脊髓背角中，接近有害阈值强度刺激后，浅层背角热刺激诱导的Fos-LI细胞有选择性增加，有害和无害热刺激后，III-IV层的Fos-LI细胞均有非选择性增加。浅层Fos-LI细胞的增加可能与对有害刺激的超敏反应有关，而III-IV层Fos-LI细胞的增加可能与对有害和无害刺激的敏感性增加有关，从而导致神经损伤后反射活动增强。
