title: Nerve growth factor improves functional recovery by inhibiting endoplasmic reticulum stress-induced neuronal apoptosis in rats with spinal cord injury.
abstract: BACKGROUND
  Endoplasmic reticulum (ER) stress-induced apoptosis plays a major role in various diseases, including spinal cord injury (SCI). Nerve growth factor (NGF) show neuroprotective effect and improve the recovery of SCI, but the relations of ER stress-induced apoptosis and the NGF therapeutic effect in SCI still unclear.
  
  
  METHODS
  Young adult female Sprague-Dawley rats's vertebral column was exposed and a laminectomy was done at T9 vertebrae and moderate contusion injuries were performed using a vascular clip. NGF stock solution was diluted with 0.9% NaCl and administered intravenously at a dose of 20 μg/kg/day after SCI and then once per day until they were executed. Subsequently, the rats were executed at 1d, 3 d, 7d and 14d. The locomotor activities of SCI model rats were tested by the 21-point Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test and footprint analysis. In addition, Western blot analysis was performed to identify the expression of ER-stress related proteins including CHOP, GRP78 and caspase-12 both in vivo and in vitro. The level of cell apoptosis was determined by TUNEL in vivo and Flow cytometry in vitro. Relative downstream signals Akt/GSK-3β and ERK1/2were also analyzed with or without inhibitors in vitro.
  
  
  RESULTS
  Our results demonstrated that ER stress-induced apoptosis was involved in the injury of SCI model rats. NGF administration improved the motor function recovery and increased the neurons survival in the spinal cord lesions of the model rats. NGF decreases neuron apoptosis which measured by TUNEL and inhibits the activation of caspase-3 cascade. The ER stress-induced apoptosis response proteins CHOP, GRP78 and caspase-12 are inhibited by NGF treatment. Meanwhile, NGF administration also increased expression of growth-associated protein 43 (GAP43). The administration of NGF activated downstream signals Akt/GSK-3β and ERK1/2 in ER stress cell model in vitro.
  
  
  CONCLUSIONS
  The neuroprotective role of NGF in the recovery of SCI is related to the inhibition of ER stress-induced cell death via the activation of downstream signals, also suggested a new trend of NGF translational drug development in the central neural system injuries which involved in the regulation of chronic ER stress.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhang
authors.forename: Fenzan
authors.initials: F
authors.lastname: Wu
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Kong
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Huijun
authors.initials: H
authors.lastname: Chen
authors.forename: Liancheng
authors.initials: L
authors.lastname: Deng
authors.forename: Yi
authors.initials: Y
authors.lastname: Cheng
authors.forename: Libing
authors.initials: L
authors.lastname: Ye
authors.forename: Sipin
authors.initials: S
authors.lastname: Zhu
authors.forename: Xie
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhouguang
authors.initials: Z
authors.lastname: Wang
authors.forename: Hongxue
authors.initials: H
authors.lastname: Shi
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Fu
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Li
authors.forename: Huazi
authors.initials: H
authors.lastname: Xu
authors.affiliation: Key Laboratory of Biotechnology and Pharmaceutical Engineering, Molecular Pharmacology Research Center, School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China. linliwzmc@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.forename: Jian
authors.initials: J
authors.lastname: Xiao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001522:Behavior, Animal; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000473:pathology; D005260:Female; D020932:Nerve Growth Factor / Q000494:pharmacology*; D016716:PC12 Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000473:pathology*; D013312:Stress, Physiological
chemical_list: D020932:Nerve Growth Factor