Protective Effects Of Ketanserin On Lung In Septic Rats

Objective To study the protective effect of peripheral serotonin antagonist(5-HT2A)ketanserin on lung injury in septic rats,and to explore its mechanism.Methods 1.72 SD male rats were randomly divided into sham operation group(sham group),sepsis group(clp group),ketanserin 1 mg/kg group(k1 group)and ketanserin 4 mg/kg group(k2 group),18 rats in each group were randomly divided into three subgroups of 6h,12 h and 24 h,with 6 in each subgroup.The sham group was treated with cecal exploration.The clp group,k1 group and k2 group were all established with cecal ligation and perforation(CLP)to establish a sepsis model.After successful modeling,the sham group and the clp group were intraperitoneally injected with 2.5 mL/kg normal saline,the k1 group was intraperitoneally injected with ketanserin 1 mg/kg,and the k2 group was injected intraperitoneally with ketanserin 4 mg/kg.Specimens were collected from each subgroup at 6h,12 h and 24 h after modeling.2.Serum levels of serotonin,TLR4,NF-КB,TNF-α,IL-6,IL-10,MIP-2 and SP-D were measured by ELISA.The left lung tissue wet-dry weight ratio,lung coefficient,lung water content and the protein content in the alveolar lavage fluid were measured.NF-КB p65 protein expression in lung tissue was measured by Western blot analysis.Pathological changes of lung tissue were observed under the optical microscope.Results 1.The levels of serum 5-HT was no significant difference in sham group at any time points.The serum 5-HT of rats in clp group was significantly higher than that of sham group at each time point(P <0.05),especially at 24 h.The serum 5-HT decreased at different time points in the k1 and k2 groups compared with the clp group,which was the most significant at 24h(P <0.05).The serum 5-HT levels in the k2 group was higher than that of k1 the group and decreased significantly at 24 h(P < 0.05).2.There was no significant difference with serum inflammatory factors(TLR4,NF-КB,TNF-α,IL-6)in sham group at each time point.The serum inflammatory factors(TLR4,NF-КB,TNF-α,IL-6)in the clp group were significantly higher than those in the sham group at each time point(P <0.05),expecially at 24 h.The serum inflammatory factors(TLR4,NF-КB,TNF-α,IL-6)in the k2 group decreased at each time points compared with the clp group,decreasing obviously at 12 h.The serum inflammatory factors in the k2 group decreased at the corresponding time points of the k1 group,changing significantly at 12 h.3.The levels of serum IL-10 was no significant difference in sham group at each time point.The serum IL-10 levels in clp group was significantly higher than that in sham group at the corresponding time points(P <0.05),expceially at 24 h.The serum IL-10 levels at each time point in k1 group was significantly higher than that in clp group(P <0.05),and being the most significant at 12 h.The serum IL-10 levels increased significantly at 6h and 12 h compared with k2 group(P<0.05),and increased signifficatly at 12 h,but decreased at 24h(P <0.05).4.The levels of serum SP-D and MIP-2 were no significant difference in the sham group at each time point.The serum SP-D and MIP-2 in the clp group were significanlly higher than those of the sham group at each time point(P <0.05),expecially at 24 h.The levels of serum SP-D and MIP-2 in the k1 and k2 groups were significantly lower than those in the clp group(P <0.05),expecially at 12 h.The serum SP-D and MIP-2 levels in the k2 group at different time points were lower than that in the k1 group(P <0.05),and expecially at 12 h.5.The lung wet/dry weight,lung coefficient,lung water content and protein content of alveolar lavage fluid were no significant difference in sham group at each time point,which were significantly increased in clp group,comparing with those of the sham group at each time point(P <0.05),expecially at 24 h.The lung wet/dry weight,lung coefficient,lung water content and protein content of alveolar lavage fluid of k1 group were decreased comparing with those of clp group at each time point;and the lung wet/dry weight,lung coefficient,lung water content and alveolar lavage fluid protein content of k2 group were decreased comparing with those of k1 group at each time point in k2.6.Western blot analysis showed that there was no significant difference in the expression of NF-КB p65 protein in sham group at each time piont.The expression of NF-КB p65 protein in clp group was significantly higher than that in sham group at each time point(P <0.05).The expression of NF-КB p65 protein in k1 group and k2 group were significantly lower than that in clp group at each time point(P <0.05).The expression of NF-КB p65 protein in k2 group was significantly lower than that in k1 group at each time point(P <0.05).7.Pathological changes of lung tissue: the pathological damage of sham group was the mildest,and the pathological damage of clp group was the heaviest.The pathological damage of k1 group was alleviated compared with clp group,which was significantly worse than that of sham group.The pathological damage of k2 group at each time point compared with clp group and K1 group,it was significantly relieved,which was worse than sham group.Conclusion Platelet activation in early sepsis releases a large amount of 5-HT,activating inflammatory factors,and causing lung damage.Ketanserin protects the lungs by blocking peripheral 5-HT signaling,inhibiting the release of inflammatory factors,and alleviating pulmonary edema.The mechanism may be that ketanserin inhibits the inflammatory signaling pathway(TLR4-NF-КB-TNF-α-IL-6)to regulate the levels of inflammatory factors,thereby exerting a protective effect on the lungs,and with the higher concentration of ketanserin,the more obvious its protective effect.