이 연구는 흰쥐의 허리신경뿌리 찢김손상 후 허리척수에서 osteopontin (OPN)의 발현을 in situ hybridization 조직화학법, 면역세포화학법 및 western blot 분석법으로 조사하였다. 정상 동물에서 OPN을 발현하는 세포는 앞쪽뿔에 위치한 운동신경원과 사이신경원이었다. 찢김 손상 후 1일부터, OPN 발현세포 수는 앞뿔과 중간부위에서 증가하였고, 3일에는 비교적 강한 OPN이 손상 받은 쪽의 회색질 전 부위에 걸쳐 증가하였다. 7일에는 OPN 발현 양상이 3일의 것과 유사하였으나, 앞뿔과 중간부위에서 OPN 발현 세포수는 최고치를 나타내었다. 이들 발현세포는 신경세포였다. 찢김 손상후 14일에는 뒤뿔에 위치한 OPN 발현 세포는 거의 소실하였고, 발현 양상이 1일의 것과 유사하였다. 28일에는 OPN 발현 세포가 정상에서 보다 더 감소하였다. 이 결과로 찢김 손상 후 허리 척수에서 증가 발현된 OPN은 신경원의 손상과정에 중요한 역할을 할 것으로 생각된다.
This study investigated the expression of osteopontin (OPN) in rat lumbar spinal cords after lumbar nerve root avulsion, using in situ hybridization histochemistry, immunocytochemistry and western blot analysis. Cells expressing OPN were motoneurons and interneurons in the ventral horn, but no signals were observed in neurons in the dorsal horn of the normal lumbar spinal cord. From day 1 after avulsion injury, OPN mRNA-labeled neurons increased in the ventral horn and the intermediate zone. By day 3, relatively strong OPN mRNA signals were found throughout the gray matter of the injured side of the spinal cord with OPN mRNA-labeled cells scattered in the superficial dorsal horn. By day 7, the labeling patterns for OPN mRNA were similar to those on day 3, but the numbers of OPN mRNA-labeled cells in the ventral horn and the intermediate zone peaked. At this point, these labeled cells were also more densely packed and the intensity of signals was stronger. Interestingly, these labeled cells were neurons, but not glial cells such as astrocytes or microglia. This OPN mRNA-labeled cell profile in the dorsal horn had nearly disappeared by day 14 after avulsion injury, and the labeling pattern became similar to that on day 1. By day 28, after avulsion injury, the numbers of OPN mRNA-labeled cells decreased further below control values. These results suggest that increased expression of OPN in the rat lumbar spinal cord after avulsion injury might play an important role in the pathogenesis of damaged neurons.
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