Sumatriptan down-regulates calcitonin gene-related peptide expression via extracellular signalregulated 1/2 and c-Jun N-terminal kinase signaling transduction pathways in rat trigeminal ganglion after organ culture / 中华神经科杂志

ABSTRACT

Objective To explore the effects of sumatriptan on the modulation of calcitonin generelated peptide(CGRP) expression and its involving intracellular signaling transduction mechanisms in rat trigeminal ganglion(TG) after organ culture.Methods Using organ culture in vitro model,54 isolated TGs of SD rats were randomly divided into fresh group ( n =6 ),control group ( n =6 ) and experimental group (n =42,6 TGs for each subgroup).Experimental group included seven subgroups,which were respectively pretreated with four different concentrations of sumatriptan,specific inhibitors of extracellular signalregulated kinases 1/2 (ERK1/2) pathway (U0126 and PD98059 ),and the inhibitor of c-Jun N-terminal kinase (JNK) (SP600125).After co-cultured with above intervention agents for 24 h,CGRP-immunoreactivity (CGRP-ir) positive neurons and CGRP-mRNA expression levels were quantified by immunohistoehemistry stain and real-time polymerase chain reaction,respectively.Phosphorylated ERK1/2 (pERK1/2) and JNK (pJNK) proteins levels were determined by Western-blotting method.Results The CGRP-ir ( + ) neurons expression levels were significantly increased after 24 h organ culture.However,0.10 and 0.50 mg/ml concentrations of sumatriptan remarkably decreased the CGRP-ir ( + ) neurons expression levels.The positive cell percentage,positive optic area,integrated optical density,mean optical density and CGRP-mRNA expression level in TG were significantly reduced than control groups (tPCP =8.652,26.382; tarea =6.220,13.917; tIA =5.606,15.904; tM14 =2.661,21.748; tmRNA =8.032,15.675.P ＜ 0.05 ).The CGRP-mRNA expressions were significantly down-regulated after co-incubation with concentration of 0.50 mg/ml sumatriptan for 24 h in TG of SD rat ( P ＜0.05 ).The levels of pERK1/2 and pJNK protein kinase detected by Western-blotting were significantly reduced by 0.50 mg/ml concentration of sumatriptan,the degrees of which were closed to the ERK1/2 and JNK pathway specific blockers.Conclusion It suggests that the optimal concentration of sumatriptan significantly down-regulates CGRP over-expression via intracellular ERK1/2 and JNK signaling transduction pathways in TG after organ culture.