[Effects of Yiqi Huayu Decoction on brain-derived neurotrophic factor expression in rats with lumbar nerve root injury].

Objective: To observe the effects of Yiqi Huayu Decoction, a compound traditional Chinese herbal medicine, on brain-derived neurotrophic factor (BDNF) expression in lumbar nerve root and soleus of rats after lumbar nerve root compression injury.

Methods: A total of 120 male SD rats were randomly allocated into sham-operated group, untreated group, methycobal injection group and Yiqi Huayu Decoction group. Surgery were performed on rats of untreated group, methycobal injection group and Yiqi Huayu Decoction group by placing a micro-silica gel on right L(4) dorsal root ganglia, while rats in sham-operated group received skin and paravertebral muscle incision only. Rats in the methycobal injection group and the Yiqi Huayu Decoction group were given intramuscular injection of methycobal and intragastric administration of Yiqi Huayu Decoction respectively. Rats in the sham-operated group and the untreated group received intragastric administration of normal saline of equal volume as Yiqi Huayu Decoction. The compressed nerve roots and right soleus were harvested after 10-, 30- and 60-day treatment. Microstructure of the compressed nerve roots were revealed under a transmission electron microscope. BDNF protein expression in the compressed nerve roots and mRNA expression in right solues were detected with enzyme-linked immunosorbent assay (ELISA) and real-time quantitative reverse transcription-polymerase chain reaction respectively.

Results: The protein expression level of BDNF in compressed nerve root in the untreated group was slightly changed with no significance as compared with sham-operated group. BDNF protein expression in the Yiqi Huayu Decoction group was gradually increased and reached the peak level after 60-day treatment with significant difference as compared with the untreated group (P<.01). The expression of BDNF mRNA in soleus was significantly up-regulated 10 days after nerve root injury (P<0.01), and was slowly decreased to the normal level at day 60 (P>0.05). Compared with the untreated group, BDNF mRNA expression in soleus muscle in the Yiqi Huayu Decoction group was significantly down-regulated after 10-day treatment (P<0.01), while was increased after 60-day treatment (P<0.01).

Conclusion: Yiqi Huayu Decoction can inhibit the increase of BDNF expression at the early phase after nerve injury, which may have something to do with alleviation of neuropathic pain, and increase BDNF expression at the late phase to promote nerve regeneration.