Mechanisms Of GABAergic System Mediating Electroacupuncture To Relieve Airway Inflammation In Asthmatic Mice

BackgroundAsthma is a heterogeneous disease of respiratory system,characterized by chronic airway inflammation,often accompanied by symptoms such as airway hyperresponsiveness and airflow limitation.Improper treatment can lead to serious consequences.Both clinical and laboratory studies have shown that electroacupuncture(EA)can effectively relieve asthma,but the underlying therapeutic mechanism is not fully understood.Studies have demonstrated increase in the levels of inhibitory transmitter γ-aminobutyric acid(GABA)and expressions of GABA A receptor(y-aminobutyric acid type A receptor,GABAAR)after EA treatment.The previous study of our group found that GABAAR agonists can regulate the inflammatory pathway toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B(TLR4/MyD88/NF-κB)to reduces airway inflammation in asthmatic mice.Therefore,we speculated that EA can activate the GABAergic system,thereby inhibiting the TLR4/MyD88/NF-κB signaling pathway and relieving airway inflammation in asthmatic mice.MethodsThe female BALB/c mice with a body weight of 20～25g were selected for the establishment of asthma model.Ovalbumin(OVA)was used for sensitization and challenge on mice.The mice were sensitized by 50ug OVA solution(intraperitoneal injection)on the 1st and 8th day,respectively,and 200ug OVA solution nasal instillation on the 21st,23rd,25th,and 28th day for challenge.Between the 8th and 21st days,EA treatment was employed on Feishu(BL13)and Tiantu(CV22)acupoints for about 30 minutes every other day.On the 29th day,the mice were subjected to pulmonary function test.Bronchoalveolar lavage fluid(BALF)was collected for inflammatory cells classification,counts,and cytokine detection(IL-4,IL-5,IL-13).The left lung was used for tissue staining,the right lung was collected for protein detection.In experiment 1,Western blot and immunostaining techniques were used to detect the GABA content,as well as the expressions of GABAAR and TLR4/MyD88/NF-κB signaling pathway in the lung tissue of mice in each group.The mice were randomly divided into 4 groups with 5 mice in each group:normal control group(Control),normal mice treated with EA group(EA),asthma group(OVA)and asthmatic mice treated with EA group(OVA+EA).In experiment 2,GAB AAR antagonist was used to further clarify the role of GAB AAR in the treatment of asthma by EA and the effects of GABAAR on TLR4/MyD88/NF-κB signaling pathway.The mice were randomly divided into 4 groups with 5 mice in each group:normal control group(Control),asthma group(OVA),asthmatic mice treated with EA group(OVA+EA)and asthmatic mice treated with EA plus GABAAR antagonist group(OVA+EA+antagonist).The lung function of the mice in each group was detected,the infiltration of inflammatory cells and the mucus secretion of goblet cells in the mice were observed by pathological tissue staining,the inflammatory cells in BALF were classified and counted by Swiss-Giemsa staining,and the inflammatory factors in BALF were detected by ELISA.The expressions of TLR4/MyD88/NF-κB signaling pathway were detected by Western blot and immunohistochemistry staining.ResultsIn experiment 1,compared with the Control group,the levels of GABA and the expressions of GABAAR in lung tissue of mice in the OVA group were significantly increased(P<0.01).There were no differences between Control and EA group(P>0.05).The levels of GABA and the expressions of GABAAR in the OVA+EA group was significantly increased compared with the OVA group(P<0.05).Compared with the Control group,the expressions of TLR4,MyD88,and NF-κB were significantly increased in the OVA group(P<0.01).Compared with the OVA group,TLR4,MyD88,and NF-κB were inhibited in the OVA+EA group(P<0.05).In experiment 2,compared with the OVA+EA group,the airway resistance of the mice was increased(P<0.05),the inflammatory cells infiltration was increased(P<0.01),the mucus secretion of goblet cells was increased(P<0.01),the counts of inflammatory cells in BALF were increased(P<0.05),and the levels of inflammatory factors were increased(P<0.05)in lung tissue of mice in the OVA+EA+antagonist group.Compared with the OVA+EA group,the expressions of TLR4,MyD88,and NF-κB were increased in the OVA+EA+antagonist group(P<0.01).ConclusionsEA can increase the levels of GABA and the expressions of GABAAR in the lung tissue of asthmatic mice.The activation of GABAergic system inhibits the TLR4/MyD8 8/NF-κB signaling pathway,thereby reducing airway inflammation in asthmatic mice.BackgroundHypotension is a common complication caused by spinal anesthesia(SA),which may have adverse impacts on the condition of the parturient and fetus.Liquid infusion was found to be relatively effective for reducing the incidence of hypotension.However,the question of whether colloid preload can optimize hemodynamic variables in the cesarean section remains controversial.This study aims to determine the effects of colloid preload on the incidence of hypotension induced by SA in elective cesarean section.MethodsRelated keywords were searched on PubMed,EMBASE,and Cochrane Library from inception dates to May 2020.Randomized controlled trials on the effects of colloid preload on hypotension during cesarean section were included.Studies included were evaluated for eligibility and quality.The primary outcome was the intra-operative incidence of hypotension and severe hypotension.The secondary outcomes included the lowest intra-operative systolic blood pressure,the maximal intra-operative heart rate,the intra-operative needs of ephedrine and phenylephrine,the incidence of maternal nausea and/or vomiting,and neonatal outcomes(umbilical artery pH and Apgar scores).Apart from the above,Review Manager 5.3 was used for the data analysis.ResultsAltogether nine randomized controlled trials were included in the meta-analysis.There were no significant differences in the incidence of intra-operative hypotension,severe hypotension,or neonatal outcomes between the colloid preload group and controlgroup,except for the umbilical artery pH.ConclusionThis meta-analysis suggests that colloid preload does not significantly reduce the incidence of hypotension associated with SA in elective cesarean section.