Abstract:  ObjectiveTo observe the effect of Taohong Siwu Decoction on postherpetic neuralgia (PHN) rats and to
explore the role of EphrinBs/EphBs pathway in it. Methods A total of 60 SD rats were divided into blank group, model
group (PHN model was established by chronic infection of varicella-zoster virus), positive group (27 mg·kg-1·d-1 of
pregabalin was given by intragastric administration after modeling), treatment group (5 g·kg-1·d-1 of Taohong Siwu Decoction
was given by intragastric administration after modeling), treatment + EphB2-Fc group (after intrathecal injection of 5 μg
EphB2-Fc on the 3rd day of modeling, 5 g·kg-1·d-1 of Taohong Siwu Decoction was given by intragastric administration) and
treatment + EphrinB2-Fc group (after intrathecal injection of 5 μg EphrinB2-Fc on the 3rd day of modeling, 5 g·kg-1·d-1 of
Taohong Siwu Decoction was given by intragastric administration) using random number table. The mechanical pain
threshold of rats was measured by behavioral method at the 1st, 7th and 14th days after administration. The levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the spinal cord of rats were measured by enzyme-linked
immunosorbent assay (ELISA). Terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used
to detect apoptosis of spinal cord neurons. Fluorescence was used to detect the cysteinyl aspartate specific proteinase 3
(Caspase-3) activity in spinal cord. Western blot assay was used to detect the expressions of EphrinB2 and EphB2 in
EphrinBs/EphBs pathway. Results Compared with the blank group, the mechanical pain threshold was significantly lower
in model group, while the levels of IL-1β, TNF- α, apoptosis index of spinal nerve cells, Caspase-3 activity and the
expression levels of EphrinB2 and EphB2 proteins were significantly higher (P＜0.05). Compared with the model group, the
mechanical pain threshold of the rats treated with Taohong Siwu Decoction was significantly higher on the 7th day and 14th
day after administration (P＜0.05). However, the levels of IL-1β, TNF-α in the spinal cord, apoptosis index of spinal nerve
cells, Caspase-3 activity and the expression levels of EphrinB2 and EphB2 proteins were significantly decreased (P＜0.05).
The expression of EphB2 protein in the spinal cord of rats treated with EphBs blocker EphB2-Fc was significantly lower than
that of the treatment group (P＜0.05). After treatment with EphBs agonist EphrinB2-Fc, the expression level of EphrinB2
protein in the spinal cord of rats was significantly lower than that of the treatment group, while the expression level of EphB2
protein was significantly higher than that of the treatment group (P＜0.05). ConclusionTaohong Siwu Decoction may
reduce the release of inflammatory factors and the apoptosis of spinal nerve cells by inhibiting EphrinBs/EphBs pathway, and
play an analgesic role in PHN rats.

Key words: neuralgia, postherpetic, inflammation, apoptosis, receptors, Eph family, Ephrins, Taohong Siwu Decoction, EphrinBs/EphBs pathway