Early expression of injury-induced neuropeptide Y in primary sensory neurons and the cuneate nucleus in diabetic rats with median nerve transection.
In this study we examined the temporal changes in neuropeptide Y (NPY) expression in dorsal root ganglion (DRG) neurons and cuneate nucleus (CN) in streptozotocin (STZ)-induced diabetic rats with or without median nerve transection (MNT). Numerous NPY-like immunoreactive (NPY-LI) neurons and fibers were detected in the DRG and CN of the diabetic MNT (DMNT) rats respectively, but not in those with diabetes-alone. Following MNT, the time-course of NPY expression pattern in the diabetic DRG and CN was similar and both peaked at 2 weeks, which was earlier than those in the non-diabetic MNT rats. Consequently, the expression of neurotrophin-3 (NT-3) immunoreactivity in DRG neurons was coincidentally decreased and reached the nadir at 2 weeks in the diabetic MNT rats, which was also earlier than that in the non-diabetic MNT rats. Following electrical stimulation of the injured nerves, the number of NPY-LI fibers became attenuated and the induced c-Fos-LI cells concurrently appeared in the ipsilateral CN. In the diabetic CN, the number of c-Fos-LI cells also peaked at 2 weeks after MNT, which was consistent with the temporal pattern of changes in NPY expression. The results suggest that in diabetes, MNT induced NPY expression via the reduction of NT-3, and electrical stimulation of the injured median nerve evoked the release of NPY and accordingly more c-Fos-LI cells were identified in the CN. Furthermore, this study demonstrated early NPY and c-Fos expression in the diabetic rats after MNT, suggesting that the development of neuropathic signs may be advanced in hyperglycemic rats.
Lin
Chi-Te
CT
Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taiwan.
Tsai
Yi-Ju
YJ
Chen
Seu-Hwa
SH
Wang
Hsin-Ying
HY
Lin
Lung-Huang
LH
Lue
June-Horng
JH
D000704:Analysis of Variance; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004558:Electric Stimulation; D005727:Ganglia, Spinal / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008475:Median Nerve / Q000293:injuries* / Q000378:metabolism; D008526:Medulla Oblongata / Q000378:metabolism*; D018613:Microscopy, Confocal; D009478:Neuropeptide Y / Q000378:metabolism*; D020933:Neurotrophin 3 / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000378:metabolism*; D013997:Time Factors
D009478:Neuropeptide Y; D020933:Neurotrophin 3; D016760:Proto-Oncogene Proteins c-fos