ABSTRACT
ObjectiveTo investigate the mechanism of Yiqi Huoxue Tongluo prescription （YHTP） in the treatment of diabetic neuropathic pain （DNP）. MethodNinety SPF-grade SD male rats were randomized into blank， model， low- （2.25 g·kg-1）， medium- （4.5 g·kg-1）， and high-dose （9 g·kg-1） YHTP， and mecobalamin （0.175 mg·kg-1） groups. Except those in the blank group， the rats in the remaining 5 groups were fed with a high-fat and high-glucose diet and subjected to intraperitoneal injection of low-dose （35 mg·kg-1） streptozotocin （STZ） to establish the model of DNP. The sciatic nerve conduction velocity in DNP rats was measured by the neurophysiological method， and the levels of interleukin-6 （IL-6）， IL-1β， and tumor necrosis factor-α （TNF-α） were measured by enzyme-linked immunosorbent assay （ELISA）. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was employed to measure the mRNA levels of glial fibrillary acidic protein （GFAP） and extracellular signal-regulated kinase （ERK） in the spinal cord. Western blot was employed to measure the protein levels of GFAP and phosphorylated ERK （p-ERK）， and immunofluorescence staining to measure the fluorescence intensity of GFAP and p-ERK in the spinal cord. In the cell experiments， 100 mmol·L-1 high glucose was used to induce the activation of astrocytes （CTX-TNA2） for the modeling of nerve cell injury. The cells were randomized into the normal， model， drug-containing serum （10% YQHT）， inhibitor ［10 mol·L-1 corynoxeine （COR）］， drug-containing serum + inhibitor （10% YHTP + 10 mol·L-1 COR） groups. The levels of pro-inflammatory factors （TNF-α and IL-1β） and the anti-inflammatory factor IL-10 in CTX-TNA2 cells were determined by ELISA， and the protein levels of GFAP and p-ERK in CTX-TNA2 cells by Western blot. ResultThe animal experiments showed that compared with the blank group， the model group presented reduced mechanical withdrawal threshold （MWT）， thermal work limit （TWL）， and nerve conduction velocity， elevated levels of fasting blood glucose， IL-1β， TNF-α， and IL-6， and up-regulated protein levels of GFAP and p-ERK， and mRNA levels of ERK1， ERK2， GFAP （P<0.01）. Compared with model group， YHTP increased the MWT， TWL， and sciatic nerve conduction velocity （P<0.01）， lowered the levels of IL-1β， TNF-α， and IL-6 （P<0.01）， and down-regulated the protein levels of GFAP and p-ERK， and mRNA levels of ERK1， ERK2， GFAP in the spinal cord （P<0.05， P<0.01）. The cell experiments showed that compared with the blank group， the model group had decreased survival rate， elevated levels of pro-inflammatory factors， and up-regulated protein levels of ERK and GFAP （P<0.01）. Compared with the model group， the YHTP-containing serum lowered the levels of IL-1β and TNF-α （P<0.05， P<0.01）， elevated the level of IL-10 （P<0.01）， and down-regulated the protein levels of ERK and GFAP （P<0.01）. ConclusionYHTP may inhibit the activation of astrocytes by inhibiting the ERK signaling pathway to reduce inflammation and thus relieve DNP.