Protective Effect and Mechanism of Polysaccharides from Cordyceps cicadae on Acute Liver Injury Induced by D-GlaN in Mice

[Objectives]To observe the protective effect of Cordyceps cicadae polysaccharides on acute liver injury induced by D-galactosamine( D-GlaN) in mice,and to explore its mechanism. [Methods] Seventy-five male Kunming mice were randomly and evenly divided into 5 groups according to the digital table method: normal group( CK)( injected intraperitoneally with saline solution),model group( injected intraperitoneally with D-GlaN),low-dose C. cicadae polysaccharides group( administered with 0. 5 g/kg of C. cicadae polysaccharides solution by gavage),middle-dose C. cicadae polysaccharides group( administered with 1. 0 g/kg of C. cicadae polysaccharides solution by gavage) and high-dose C. cicadae polysaccharides group( administered with 2. 0 g/kg of C. cicadae polysaccharides solution by gavage). After 12 d of administration,the liver histopathological score,liver homogenate indexes( superoxide dismutase,SOD; malondialdehyde,MDA; glutathione peroxidase,GSH-Px; nitric oxide,NO) and serum markers( aspartate transaminase,AST; alanine transaminase,ALT; alkaline phosphatase,ALP; cholinesterase,CHE) of mice in each group were detected. The expression levels of nuclear factor-κB( NF-κB) and tumor necrosis factor-α( TNF-α) in liver tissues were detected by immunohistochemistry. [Results]The liver histopathological score and the MDA,NO,AST,ALT,ALP,NF-κB and TNF-α levels were significantly higher( P < 0. 05) and the SOD,GSH-Px and CHE levels were significantly lower( P <0. 05) in the model group compared with the normal group. Compared with those in the model group,the liver tissue histopathological scores in the low-,middle-and high-dose C. cicadae polysaccharides groups were all significantly reduced( P < 0. 05). With the increase of treatment dose,the liver tissue histopathological scores showed a significant decrease( P < 0. 05). Compared with the model group,the levels of MDA,NO,AST,ALT,ALP,NF-κB and TNF-α were significantly lower( P < 0. 05),and the levels of SOD,GSH-Px and CHE were significantly higher( P < 0. 05) in the low-,middle-and high-dose C. cicadae polysaccharides groups. With the increase of treatment dose,the levels of MDA,NO,AST,ALT,ALP,NF-κB and TNF-α declined significantly( P < 0. 05),while the levels of SOD,GSH-Px and CHE rose significantly( P < 0. 05). [Conclusions] C. cicadae polysaccharides have a significant protective effect on D-GlaN-induced acute liver injury in mice in a dose-dependent manner,and the mechanism may be related to the inhibition of NF-κB inflammatory signaling pathway.

Upregulation of Chemokine CXCL12 in the Dorsal Root Ganglia and Spinal Cord Contributes to the Development and Maintenance of Neuropathic Pain Following Spared Nerve Injury in Rats

Emerging evidence indicates that CXCL12/ CXCR4 signaling is involved in chronic pain. However, few studies have systemically assessed its role in direct nerve injury-induced neuropathic pain and the underlying mech- anism. Here, we determined that spared nerve injury （SNI） increased the expression of CXCL12 and its cognate receptor CXCR4 in lumbar 5 dorsal root ganglia （DRG） neurons and satellite glial cells. SNI also induced long- lasting upregulation of CXCL12 and CXCR4 in the ipsi- lateral L4-5 spinal cord dorsal horn, characterized by CXCL12 expression in neurons and microglia, and CXCR4 expression in neurons and astrocytes. Moreover, SNI- induced a sustained increase in TNF-α expression in the DRG and spinal cord. Intraperitoneal injection （i.p.） of the TNF-α synthesis inhibitor thalidomide reduced the SNI-in- duced mechanical hypersensitivity and inhibited the expression of CXCL12 in the DRG and spinal cord. Intrathecal injection （i.t.） of the CXCR4 antagonist AMD3100, both 30 rain before and 7 days after SNI, reduced the behavioral signs of allodynia. Rats given an i.t. or i.p. bolus of AMD3100 on day 8 of SNI exhibited attenuated abnormal pain behaviors. The neuropathic pain established following SNI was also impaired by i.t. admin- istration of a CXCL12-neutralizing antibody. Moreover, repetitive i.t. AMD3100 administration prevented the acti- vation of ERK in the spinal cord. The mechanical hyper- sensitivity induced in nai＇ve rats by i.t. CXCL12 was alleviated by pretreatment with the MEK inhibitor PD98059. Collectively, our results revealed that TNF-α might mediate the upregulation of CXCL12 in the DRG and spinal cord following SNI, and that CXCL 12/CXCR4 sig- naling via ERK activation contributes to the development and maintenance of neuropathic pain.

Toll-like receptor 4-mediated nuclear factor-κB activation in spinal cord contributes to chronic morphine-induced analgesic tolerance and hyperalgesia in rats

Nuclear factor kappa B（NF-κB） in the spinal cord is involved in pro-infl ammatory cytokine-mediated pain facilitation. However, the role of NF-κB activation in chronic morphine-induced analgesic tolerance and the underlying mechanisms remain unclear. In the present study, we found that the level of phosphorylated NF-κB p65（p-p65） was increased in the dorsal horn of the lumbar 4–6 segments after intrathecal administration of morphine for 7 consecutive days, and the p-p65 was co-localized with neurons and astrocytes. The expression of TNF-α and IL-1β was also increased in the same area. In addition, pretreatment with pyrrolidinedithiocarbamate（PDTC） or SN50, inhibitors of NF-κB, prevented the development of morphine analgesic tolerance and alleviated morphine withdrawal-induced allodynia and hyperalgesia. The increase in TNF-α and IL-1β expression induced by chronic morphine exposure was also partially blocked by PDTC pretreatment. In another experiment, rats receiving PDTC or SN50 beginning on day 7 of morphine injection showed partial recovery of the anti-nociceptive effects of morphine and attenuation of the withdrawal-induced abnormal pain. Meanwhile, intrathecal pretreatment with lipopolysaccharide from Rhodobacter sphae-roides, an antagonist of toll-like receptor 4（TLR4）, blocked the activation of NF-κB, and prevented the development of morphine tolerance and withdrawal-induced abnormal pain. These data indicated that TLR4-mediated NF-κB activation in the spinal cord is involved in the development and maintenance of morphine analgesic tolerance and withdrawalinduced pain hypersensitivity.