Effect And Mechanism Of Panax Notoginseng Sapoins In Acute Inflammatory Visceral Pain In Kunming Mice

[Objective] To investigate the analgesic effect of Panax Notoginseng Saponins(PNS) on the acute inflammatory visceral induced by acetic acid in mice and its relationship with the activation of astrocytes in the spinal cord. [Methods] Male Kunming mice were used in the present study. The animals were divided into different groups as follows:(1)Acute visceral pain group induced by intraperitoneal injection of 0.25 ml 1% acetic acid(Acetic Acid, AA), normal saline group were injected with the same volume normal saline(Normal saline, NS) and blank control group;(2)PNS pre-treatment group:1 hour before injecting with 1% acetic acid(i.p), mice were intraperitoneally injected with 50mg/kg PNS(50mg/kg Pre-PNS+AA), or 100mg/kg PNS(100mg/kg Pre-PNS+AA), or 200mg/kg PNS(200mg/kg Pre-PNS+AA) or the same volume of normal saline(Pre-NS+AA);( 3) PNS treatment group:animals were intraperitoneally injected with 1% acetic acid and 200mg/kg PNS(C-PNS) or normal saline(C-NS) at the same time. Immediately after intraperitoneal injection of acetic acid or normal saline, the visceral pain behaviour(abdominal contraction) was observed for 1 hour.After the visceral pain behaviour test, the animals were sacrificed for the determination of GFAP and glutamine synthetase(GS) in the spinal cord by immunohistochemistry and Western Blot.1 hour after intraperitoneal injection of 200mg/kg PNS(PNS group) or normal saline(NS group), the locomotive activity of animals were assessed by the open field test. [Results] 1. Compared with the NS group, acetic acid leads to significantly increased number of writhing response.2. PNS pre-treatment dose dependently alleviate the visceral pain induced by acetic acid. Compared with the Pre-NS-AA group, the number of writhing response in the 100mg/kg Pre-PNS+AA and 200mg/kg Pre-PNS+AA were remarkably reduced(P<0.001);3. There was no significant difference in the he number of writhing response between C-NS and C-PNS(P> 0.05).4. No difference in the locomotive activity, the number of crossing and time spent on the central grid were found between the NS group and the 200mg/kg PNS in the open field test(P> 0.05).5. The results of immunohistochemistry and Western-blot showed that there was significantly increased expression of GFAP and GS in the spinal cord of Pre-NS+AA group and 200mg/kg Pre-PNS+AA group than the control group(P <0.001); When compared with the Pre-NS+AA group, the expression of GFAP and GS in the spinal cord of 200mg/kg Pre-PNS+AA group were significantly decreased(P <0.01). [Conclusion] PNS pre-treatment can alleviate acute inflammatory visceral pain induced by acetic acid in mice, which might be associated with the de-activation of astrocyte in the spinal cord.