Magnesium sulphate suppresses over-expression of nerve growth factor （NGF） mRNA in cortex of mice in formalin pain

doi:10.3969/j.issn.2095-3402.2001.02.003

Abstract：Objective　To investigate the changes of NGF mRNA levels and explore the effects of MgSO4 on the expression of NGF mRNA in cortex of mice in formalin test.　Methods　 Female Balb/c mice received formalin solution injection in the plantar surface of one hindpaw after 10m following MgSO4 or NS administration. Thereafter, NGF mRNA level analyses in cortex by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR)were made at 3, 6, 12 and 24 h after formalin injection（n=4，per time point）. In a separate group of mice (n=4) without any treatment were sacrificed to examine normal NGF mRNA levels. 　Results　①The NGF mRNA expression in cortex in the mice with NS administration increased significantly at 6, 12 and 24h in comparison with that in normal control（5、2.5 and 2 fold，respectively）after formalin injection.　②The increases of NGF mRNA have been shortened significantly at 6、12 and 24 h in the group of MgSO4 compared to that in the NS (P<0.01、0.05 and 0.05，respectively) following formalin injection.　Conclusion　①There is an overexpression of NGF mRNA in the cortex of female mice after formalin injection. ②MgSO4 can restrain largely the over expression of NGF mRNA in cortex of mice with formalin injection. ③We suggest that the main action of MgSO4 on nervous system, analgesia included, involve with its inhibition from the expression of NGF mRNA in central nervous system.