Mechanisms Underlying The Effect Of Gut Microbiota On Regulating Central Post-stroke Pain

Objective: Central Post-Stroke Pain(CPSP)is a type of chronic pain in which blood or ischemic stroke is associated with persistent,intermittent,or paroxysmal pain.The pathogenesis of CPSP is relatively complex and has not yet been fully elucidated.The destruction of blood brain barrier(BBB)??after stroke has created the conditions for immune cells to enter the Central nervous system(CNS).The immune cells are rapidly activated and enter the CNS through the damaged BBB and migrate to the site of injury.Although these immune cells are indispensable for the removal of tissue debris and tissue repair,immune cells release a large number of cytotoxic molecules during the activation process,increasing the risk of CPSP.The excitability of neuronal cells is mainly influenced by the channel state of gamma-aminobutyric acid(GABA)signaling pathway.GABA and stromal cell-derived factor-1(SDF-1)and their receptors are co-localized in many cell types including neurons.This chemokine system can GABA signaling pathway interactions.At the presynaptic level,stimulation of CXCR4 by SDF-1 can release a large amount of neuronal GABA by activating CD4+ Treg cells,thereby activating the GABA-A inhibitory signaling pathway and inducing hyperpolarization of neurons to decrease the excitability of neurons.Intestinal flora plays an important role in the inflammatory process induced by diseases of the central nervous system.After stroke,the inherent mucosal barrier of the intestine is destroyed,allowing the colonies originally colonized in the intestine to break through the physical barrier into the bloodstream,which in turn induces the body’s peripheral immune response.Intestinal flora can also regulate the expression of SDF-1/CXCR4 and provide differentiation signals for the host immune system.Actively studying the effects of commonly used clinical treatment options on the intestinal microflora homeostasis,and targeted optimization of the intestinal microbiota,may improve the impact of intestinal flora on the host and regulate the body’s immune system.CPSP treatment plays a role.Methods: It is proposed that 45 SPF 9-week-old male Sprague-Dawley rats were randomly divided into three groups: surgery(TIS)group,antibiotics group and controls group.Vertebral infarction models in Sprague-Dawley rats were established using endothelin-1 local injection(positioning(front): anterior-posterior(AP)-3.00 mm;internal-external(ML)-3.00 mm;dorsoventral(DV)-6.00 mm).One week before the model was established,a 35-day von Frey pain was started,a reference was made every four days,and a pain threshold was recorded.Rats were sacrificed 36 to 37 days after the establishment of the thalamic infarction model,and brain,intestinal tissue,and cecal contents were taken.After obtaining experimental animal specimens,we applied ELISA to quantitatively detect the expression of GABA in brain and intestine tissues;we used PCR and immunofluorescence double staining technique to locate and quantify SDF-1/CXCR4 in brain and intestine tissues;Western Blot and Immunofluorescence double staining technique was used to locate and quantitatively detect the expression of CD4+CD25+Foxp3+Treg cells in brain and intestinal tissues.Results: The expression of SDF-1 and CD4+CD25+Foxp3+Treg in intestinal tissue was increased in the TIS group after thalamic infarction compared with the Controls group.The expression of SDF-1 and CD4+CD25+Foxp3+Treg in the Antibiotics group was the weakest.However,the expression of SDF-1 and CD4+CD25+Foxp3+Treg around the thalamic infarction was not significantly different between the TIS group and the Antibiotics group and the Controls group.The GABA level in the control group was higher around the thalamic infarction,and the GABA levels in the TIS group and the Antibiotics group were significantly lower than those in the Control group(P<0.05).Controls group SDF-1 m RNA has a certain expression in the thalamus,gastrointestinal tissue,but the expression is weak.SDF-1 m RNA was increased in the TIS group compared with the Controls group,and SDF-1 m RNA in the Antibiotics group was lower than in the Controls group.Compared with the Control group,there were significant differences between the TIS group and the Antibiotics group(P<0.05),and the SDF-1 m RNA expression in the thalamus was not significantly different between the three groups.Conclusion: Infarction of the thalamus can lead to changes in the composition of the intestinal microflora,and regulate the occurrence of CPSP by affecting the immune response and regulating the expression of the inhibitory neurotransmitter GABA.The use of antibiotics(meropenem + vancomycin)to kill the intestinal flora will have an effect on the CPSP.