三七总皂苷对大黄鱼抗变形假单胞菌感染能力的影响

Effects of Panax notoginseng saponins on resistance of large yellow croaker(Larimichthys crocea)against Pseudomonas plecoglossicida

为研究三七总皂苷(Panax notoginseng saponins,PNS)对大黄鱼(Larimichthys crocea)抗变形假单胞菌(Pseudomonas plecoglossicida)感染能力的影响,首先通过体外试验测定PNS对变形假单胞菌的抑制效果,然后将PNS溶液腹腔注射体质量为20~30 g的大黄鱼,3 d后用浓度为1.02×10^(9)CFU/L的变形假单胞菌浸泡感染2 h,并测定感染前后全脾和后肾组织中的相对含菌量及TNF-α等免疫相关因子的表达水平。结果表明:质量浓度为50、25 mg/mL的PNS体外抑菌效果显著(P<0.05);PNS注射给药的大黄鱼(PNS组)在变形假单胞菌感染后8 d时的存活率较生理盐水注射组(对照组)高18.46%(P>0.05);变形假单胞菌感染后第4、8天,PNS组大黄鱼脾、后肾组织中的相对含菌量略低于对照组(P>0.05);PNS组脾组织TNF-α蛋白表达水平在感染变形假单胞菌前后均显著低于对照组(P<0.05),但其mRNA转录水平在感染后显著高于对照组(P<0.05)。研究表明,PNS在体外对变形假单胞菌具有抑制效果,注射PNS能在一定程度上增强大黄鱼抗变形假单胞菌感染的能力,降低感染后脾和后肾组织中的菌量,调控TNF-α等炎症因子的表达,提高感染后的存活率。

To probe into effects of Panax notoginseng saponins(PNS)on the resistance of large yellow croaker(Larimichthys crocea)against Pseudomonas plecoglossicida,the inhibitory effect of PNS on P.plecoglossicida was detected in vitro,and mortality,relative pathogen load and expression level of immune related factors such as TNF-αwere determined in the spleen and hind kidney of large yellow croaker weighing from 20 g to 30 g intraperitoneously injected with PNS solution before and after infection with P.plecoglossicida.On the third day post injection,the fish was infected with P.plecoglossicida at a concentration of 1.02×10^(9)CFU/L by immersion.The results showed that PNS at a concentration of 50.00 mg/mL and 25.00 mg/mL had significant antibacterial effect in vitro(P<0.05);the survival rate of fish injected with PNS(PNS group)was 18.46%higher than that of fish injected with sterile saline solution(control group)8 days after infection with P.plecoglossicida(P>0.05);As for the PNS group,the protein expression level of TNF-αin the spleen tissue was consistently lower than that in the control group(P<0.05),while the mRNA level was higher than that in the control group after infection(P<0.05).The finding indicated that PNS could inhibit P.plecoglossicida in vitro,injection of PNS could enhance the resistance of large yellow croaker against P.plecoglossicida,reduce bacterial load in spleen and hind kidney,regulate the expression of TNF-α,and improve the survival rate after infection.