Changes in metabotropic glutamate receptor 4 expression and the effects of L-2-amino-4-phosphonobutyrate in a rodent model of diffuse brain injury.
OBJECTIVE
To examine the changes in the expression of mGluR4 after diffuse brain injury (DBI) and to determine the role of its specific agonist L-2-amino-4-phosphonobutyrate (L-AP4) in vivo.


METHODS
A total of 161 male SD rats were randomized into the following groups. Group A included normal control, sham-operated control and DBI group. DBI was produced according to Marmarou's diffuse head injury model. mRNA expression of mGluR4 was detected by hybridization in situ. Group B included DBI alone, DBI treated with normal saline and DBI treated with L-AP4. All DBI rats were trained in a series of performance tests, following which they were subjected to DBI. At 1 and 12 hours, animals were injected intraventricularly with L-AP4 (100 mmol/L, 10 microl) or normal saline. Motor and cognitive performances were tested at 1, 3, 7, 14 days after injury and the damaged neurons were also detected.


RESULTS
There was no significant difference between normal control group and sham-operated group in the expression of mGluR4 (P>0.05). The animals exposed to DBI showed significantly increased expression of mRNA of mGluR4 compared with the sham-operated animals 1 h after injury (P<0.05). At 6 hours, the evolution of neuronal expression of mGluR4 in the trauma alone group was relatively static. Compared with saline-treated control animals, rats treated with L-AP4 showed an effective result of decreased number of damaged neurons and better motor and cognitive performances.


CONCLUSIONS
Increased expression of mGluR4 is important in the pathophysiological process of DBI and its specific agonist L-AP4 can provide remarkable neuroprotection against DBI not only at the histopathological level but also in the motor and cognitive performance.
Bai
Hong-min
HM
Department of Neurosurgery, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China. baihmfmmu@hotmail.com
Wang
Wei-min
WM
Li
Tian-dong
TD
Fei
Zhou
Z
D000613:Aminobutyrates / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001930:Brain Injuries / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects* / Q000378:metabolism*
D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D018094:Receptors, Metabotropic Glutamate; C012729:2-amino-4-phosphonobutyric acid; C108823:metabotropic glutamate receptor 4