ABSTRACT
Objective To analyse the analgesic effect and possible mechanism of panax notoginseng saponin (PNS) on mouse models of chronic inflammatory pain caused by complete Freund’s adjuvant (CFA). Methods A total of 48 male C57BL/ 6J mice were divided randomly into four groups: normal saline control group (Ctrl), CFA group (CFA), CFA + PNS group (CFA+PNS), CFA + dexamethasone (DEX) group (CFA+DEX). Von Frey filaments were used to detect mechanical pain in mice. Immunohistochemistry was used to detect the number and morphological changes of glial fibrillary acidic protein (GFAP) positive astrocytes. Western blotting was used to detect the expressions of GFAP, nucleotide-binding and oligomerization domain(NOD)-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), Caspase-1, interleukin (IL)-1β, and IL-18 in mice’s spinal cord segments in each group. Results Compared with the Ctrl group, mice in the CFA group showed a significant decrease in mechanical pain thresholds at day 1, day 3, day 5, day 7, and day 14. Additionally, there was a significant decrease in NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the spinal cord of the mice. PNS intervention could relieve mechanical pain and down-regulate the expressions of NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the spinal cord of mice, with no significant difference compared with the CFA+DEX group. CFA group mice had significantly more GFAP positive cells in their posterior horns than Ctrl group mice, as measured by immunohistochemistry; PNS intervention decreased the number of GFAP positive cells in the posterior horn of the spinal cord in model mice;DEX had no effect on the number of GFAP positive cells in the dorsal horn of spinal cord. According to Western blotting results, GFAP expression in the spinal cord of the CFA group was significantly more than that of the Ctrl group; PNS intervention significantly reduced GFAP expression in the spinal cord of CFA group mice;DEX had no effect on the expression of GFAP in the posterior horn of spinal cord. Conclusion PNS has a good alleviating effect on inflammatory pain, and its mechanism may be related to inhibition of astrocyte activation and NLRP3 inflammasome activation.
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Objective To investigate the effect of environmental enrichment (EE) on lipopolysaccharide (LPS) induced cognitive dysfunction in mice. Methods A total of thirty six 3 weeks old Kunming mice experienced 8 weeks of EE or standard environment (SE) feeding. After 8 weeks, they were divided into three groups: standard environment+ normal saline (SE+NS) group, standard environment+lipopolysaccharide (SE+LPS) group, environmental enrichment+ lipopolysaccharide (EE+LPS) group. The open field test was used to measure the locomotive of mice, and the cognitive function was determined by novelty object recognition test. The expression of microglial marker ionized calcium binding adaptor molecule-1 (IBA-1) in hippocampus was determined by immunohistochemical staining. The expression of microglial activation marker CD68 and NOD-like receptor protein 3 (NLRP3) inflammasome related protein in the hippocampus was detected by Western blotting. Results In the open field test, there was no difference in the activity among the three groups. Compared with the SE + NS group, SE + LPS group showed decreased discrimination ratio in novelty object recognition task, with remarkably up-regulated expression of CD68 in the hippocampus (P< 0. 01) . In addition, SE+LPS group exhibited significantly enhanced expression of NLRP3, apoptosis associated speck-like protein (ASC), Caspase-1 and interleukin-1β(IL-1β) in the hippocampus compared with SE + NS group (P < 0. 05) . Compared with the SE + LPS group, EE+LPS group showed enhanced discrimination ratio in the object recognition task, with down-regulated expression of CD68, NLRP3, ASC, Caspase-1, IL-1β and IL-18 in the hippocampus (P < 0. 01) . Conclusion Environmental enrichment can alleviate LPS induced cognitive dysfunction, which might be attributed to the inhibiting of microglia and NLRP3 activation in the hippocampus.
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Objective To detect the dynamic expression of insulin-like growth factor 2 (IGF2) in lateral geniculate body (LGB) during the critical period of visual development. Methods Three groups of Kunming mice of different ages were selected for testing, which were 3 weeks old, 5 weeks old and 7 weeks old, twelve in each group. The forepaw-reaching reflex test was used to detect whether the visual function of the mice was normal in each group. Immunohistochemical technique was used to detect the expression of IGF2 protein and its receptor in the lateral geniculate body of normal mice at week 3, 5 and 7 postnatal, and to analyze the expression of the protein of IGF2 and its receptor in each part of the lateral geniculate body. Results The expression of IGF2 protein in the dorsal lateral geniculate nucleus decreased significantly at week 5 postnatal and increased significantly at week 7 postnatal, and increased gradually over time at week 5 and week 7 postnatal in the ventral geniculate nucleus. The expression of IGF2 receptor protein in the dorsal lateral geniculate nucleus and ventral nucleus increased significantly at week 5 postnatal, and at week 7 postnatal, the expression of IGF2 receptor decreased to week 3 level in lateral geniculate body of mice. Conclusion The expression of IGF2 and its receptor in lateral geniculate body of mice during critical period of visual development changed dynamically, and the expression patterns of IGF2 and its receptor in different parts of LGB were not completely consistent. The expression of IGF2 and its receptors may be related to the plasticity of visual development in mice.
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Objective To investigate the expression of BRD 4 in the spinal cord and its relationship with acute in-flammation pain induced by formaldehyde in mice.Methods Thirty-six mice were randomly divided into three groups:control group,formaldehyde group and indomethacin+formaldehyde group;25 μL 1%formaldehyde was injected into the right plantar to establish the acute inflammationpain model,while the indomethacin(20 mg/kg) was injected intraperitoneally 1 hour before formaldehyde injection.Then,all the mice were video recored for 1h to observe the spontaneous pain.Then,cell localization of BRD4 in the spinal cord of normal mice was determined by immunofluorescence assasy.The expression of BRD4 in spinal cord was detected by immunohistochemistry and Western blot.Results Immunofluorescence showed that BRD 4 was mainly co-locolized with the neuronal marker NeuN in the spinal cord of normal mice.Formaldehyde injection could induce two-phase spontaneous pain, while indomethacin intervention could only decrease the second phase pain(P<0.05).Furthermore,formaldehyde injec-tion led to significantly enhanced expression of BRD 4 in bilateral spinal cord,which was remarkbly inhibited by in-domethacin(P<0.05).Conclusions Up-regulation of BRD4 in spinal dorsal horn may be involved in the acute in-flammatory pain.