Trending Study On Apoptosis And The Relevant Neurotrophic Factors Of Neuron After Peripheral Nerve Ischemia In Rat

Objective: To observe the apoptosis and the showing character of NGF, GDNF in the lumbar segment and the dorsal root ganglion (DRG) neurons. To investigate the relationship between neuron apoptosis and neurotrophic factors (NTFs), and provide theoretical basis for the study of peripheral neuropathy in basic medical science and clinic medical science.Methods: 30 adult Wistar rats were randomly divided into six groups, with five rats each. Experimental side common iliac artery was ligated to lead to peripheral nerve ischemia .The rats were sacrificed on the 3rd 5th 7th 14th 21st and 28th day after operation respectively and perfused with 4% paraformaldegyde. The forth to sixth lumbar spinal cord segment and the forth to sixth lumbar DRG were harvested and post-fixed in 4% paraformaldehyde, embodied in paraffin and sectioned as usual. Light microscope, TUNEL and immunohetochanity technologies were applied in this study.Results: The expression of NGF, GDNF and neuron apoptosis after peripheral nerve ischemia varified ondifferent day.1. NGF The positive productions were brown granules and distributed in plasma of small and medium neurons. The positive rate of experimental side did not change on the early stage and became obviously lower than that of control side on the 5th day and peaked on the 7th day. After that the rate decreased gradually as time going on.2. GDNF The positive productions distributed in plasma. The positive GDNF immunoreactivity was presented in small neurons and large neurons. Some Schwann cells and axon area of fibers were also stained. The positive rate of experimental side became obviously higher than that of control side and reached the peak on the 3rd day and decreased as time going on, it reached normal criteria after 14 days.3. Apoptosis The positive productions were located in nuclear of neuron. The typical feature was marginated and condensed chromatin, the expression of apoptosis in DRG of experimental side began to increase after 3 days and reached the peak on the 7th day and gradually recovered after that, reached normal criteria after 4 weeks. The expression in spinal cord of experimental side began to increase on the 5th day, reached the peak on the 14th day .The positive rate decreased as time going on, but the expression of apoptosis was still obviously higher than that of control side after 4 weeks.Conclusion: In the progress of peripheral nerve ischemia, when the expression of NGF and GDNF by L4-L6 Lumbar spinal cord motoneurons and DRG neurons decreased as time going on, the positive rate of apoptosis increasing. There is negative correlation between the apoptosis and NTFs. GDNF increased in the early stage and played a role in protecting neuron against injuries. The percent of lost neurons in DRG is higher than that in spinal cord. Ischemia injury has powerful effect on DRG than on spinal cord. There is remarkable correlation between the activity of NTFs and apoptosis. Both NGF and GDNF have protective effects on injuries by ischemia. The main reason of neuron apoptosis was the result of NTFs reduced after nerve ischemia.