1 Department of Anatomy, Shandong University School of Medicine, Jinan 250012, China.
2 Department of Nephrology, Shandong University Qilu Hospital, Jinan, China

Abstract 

Protein kinase C regulates neurite outgrowth in spinal cord neurons 

Ping YANG1,2, Zhen-Qiang LI1, Lin SONG1, Yu-Qin YIN3 

1Department of Anatomy, Third Military Medical University, Chongqing 400038, China 
2Department of Neurobiology, Third Military Medical University, Chongqing 400038, China 
3Laboratory for Neuroscience, Department of Neurosurgery, Children's Hospital, Harvard Medical School, Boston 02115 

Objective 
To determine the effects of insulin-like growth factor-1 (IGF-1) on the expression of preprotachykinin (PPT) mRNA encoding substance P (SP) and calcitonin gene-related peptide (CGRP) mRNA in cultured dorsal root ganglion (DRG) neurons with excitotoxicity induced by glutamate (Glu) 
Methods 
DRGs were dissected from embryonic day 15 Wistar rats. DRG neurons were dissociated and cultured for 48 h and then exposed to Glu (0.2 mmol/L) or Glu (0.2 mmol/L) plus IGF-1 (5 nmol/L, 10 nmol/L and 20 nmol/L) for 12 h. The DRG neurons in control group were exposed to only growth media throughout the experiment. After that, the living DRG neurons were observed under inverted phase contrast microscope and microphotographs were taken. The expression levels of PPT and CGRP mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). 
Results 
IGF-1 could inhibit Glu-induced shortening of neurite. Besides, IGF-1 could significantly increase the levels of PPT mRNA and CGRP mRNA in primary cultured DRG neurons with Glu-induced excitotoxicity, in a dose-dependent manner. 
Conclusion 
IGF-1 may exert neuroprotective effects on DRG neurons against Glu-induced excitotoxicity, probably through regulating the expression levels of PPT and CGRP mRNAs.

Keywords

insulin-like growth factor-1, glutamate, substance P, calcitonin gene-related peptide, dorsal root ganglion

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