[Effect of phenylalanine on the Nogo-66 receptor expression in the cortical neurons of rats].
OBJECTIVE
This study examined the effect of high concentration of phenylalanine (Phe) on Nogo-66 receptor (NgR) expression in the cortical neurons of rats in vitro in order to investigate whether NgR is involved in the etiology of Phe-induced brain damage.


METHODS
Neurons from the cerebral cortex of embryonic rats were cultured for 3 days and then were treated with 0.9 mM Phe. After 12, 24 and 48 hrs of Phe treatment, mRNA and protein expression of NgR was detected by real-time PCR and Western blot respectively. Growth cones and growth axons of neurons were detected by immunofluorescence and immunohistochemistry respectively after 12 and 24 hrs of Phe treatment.


RESULTS
The length of growth axons of neurons was significantly shorter after 12 and 24 hrs of Phe treatment compared with the control group without Phe treatment (P<0.05). Growth cones collapse occurred in 12.5+/-9.7% and 24.1+/-4.5% of neurons respectively after 12 and 24 hrs of Phe treatment but only in 3.5+/-1.5% in the control group (P<0.01). The protein level of NgR after 12, 24 and 48 hrs of Phe treatment was up-regulated, with 9.0, 9.4 and 12.6 times as the control. mRNA level of NgR in the Phe treatment group did not differ from control.


CONCLUSIONS
High concentration of Phe can induce an increased NgR protein expression in cortical neurons, and the increased NgR expression may contribute to the growth cones collapse and the inhibitory activities of axon regeneration after injury.
Huang
Cheng-Jiao
CJ
Department of Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
Gu
Xue-Fan
XF
Zhang
Yong-Jun
YJ
Ye
Jun
J
Li
Duan
D
Huang
Li-Su
LS
D000818:Animals; D015153:Blotting, Western; D002540:Cerebral Cortex / Q000737:chemistry / Q000187:drug effects*; D058851:GPI-Linked Proteins; D007150:Immunohistochemistry; D009185:Myelin Proteins / Q000032:analysis* / Q000235:genetics; D000070816:Nogo Receptor 1; D010649:Phenylalanine / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000235:genetics
D058851:GPI-Linked Proteins; D009185:Myelin Proteins; D000070816:Nogo Receptor 1; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C486581:Rtn4r protein, rat; D010649:Phenylalanine