Abstract: Objective: To observe the changes in neurotrophic factors and their receptors in the lumbar spinal cord of age-increasing rats (1, 3, 6, 12, 18 and 24 months), and to investigate their correlation with age increasing. Methods: The expression of neurotrophic factors and their high receptors in the lumbar spinal cord of rats were measured by immunohistochemistry and western blot. Nissl staining was used for detecting the number of survival neurons. Results: The expression of nerve growth factor (NGF) and its receptor TrkA, brain derived neurotrophic factor (BDNF) and its receptor TrkB, and gliocyte derived neurotrophic factor (GDNF) in lumbar spinal cord of rats showed changes in relation to the age increasing. Their expression was lower at the age of 1 month, reached the peak in 6-month-old rats, and decreased significantly at the age of 24 months, in which the decline of GDNF was more obvious. The number of survival neurons in lumbar spinal cord kept at a high level from 1 to 6-month-old rats, then decreased gradually, and reached the lowest level at the age of 24 months. Conclusion: The expression of neurotrophic factors and their receptors shows changes with age increasing, decreases in aged rats especially, which may be one of the mechanisms involved in spinal cord aging.

Key words: spinal cord, aging, neurotrophic factors, rat