Spatial and temporal expression patterns of apoptosis-related genes in rat spinal cord during normal aging

Kim, Jong Min; Chung, Yoon Hee; Shin, Chung Min; Park, Kyeong Han; Cho, Sa Sun; Baik, Sang Ho; Cha, Choong Ik

Abstract

The pattern of distribution in rat spinal cord and changing pattern during normal aging of c-Fos, Bcl-2, Bax, and p53 expression were investigated by immunohistochemical staining. Male Sprague-Dawley rats at the age of one week, five months, and two years were studied. C-Fos immunoreactivity was observed diffusely in gray matters in neonatal rats, preferentially located in deep dorsal horn and around central canal. Compared with those of neonatal rats, immunoreactive cells decreased prominently in adult rats. In aged rats, these cells were not seen in any segments. In a transverse section, spatial expression of Bcl-2 and Bax proteins showed a diffuse distribution pattern with immunore-activity more prominent in the anterior horn. Continuing expression of these proteins was shown in each age group. In adult rats, Bcl-2 immunoreactivity was decreased drastically compared to that of neonatal rats. The immunoreactivity was higher in aged than in adult rats, but the number of immunoreactive cells was not different between aged and neonatal rats. The number of Bax-immunoreactive cells was greater in adult than in neonatal rats; in aged rats, it was similar with that of adult rats. The spinal cords of neonatal rats were not p53-immunoreactive, though p53-positive cells were detected in all segments of adult spinal cord. P53-positive cells were stained along the cellular margin, with a pale central portion. The pattern of p53 immunoreactivity in adult and aged rats was similar; the number of p53-positive cells, however, was higher in aged rats than in adult. In conclusion, we demonstrated that the expression patterns of c-Fos, Bcl-2, Bax, and p53 proteins in rat spinal cord change during normal aging for the first time.