甘草粗提物对鲫的抗应激及免疫保护功效研究

采用腹腔注射和混饲投喂两种方式研究中药甘草(Glycyrrhiza uralensis Fiseh)粗提物对鲫(Carassius auratus)的抗应激和免疫保护功效。将一部分粗提物按0.5%和2%的质量分数制成药饵投喂实验鲫,分别在第14 d、28 d、35 d、42 d、56 d采集血样;将另一部分粗提物用无菌生理盐水按0.5%和2%的浓度配成针剂腹腔注射鲫,分别在第3 d、7 d、14 d、21 d、28 d采集血样。结果显示:投喂实验中药物组和对照组血清皮质醇水平均呈先升后降趋势,除第14 d外,药物组皮质醇水平都低于同期对照组。在最后一次采样中(56 d),对照组、低剂量组和高剂量组的皮质醇水平分别为147.85 ng/mL、79.41 ng/mL和66.47 ng/mL。腹注实验中对照组皮质醇水平一直呈上升趋势,最后一次采样(28 d)高达274.23 ng/mL,显著高于药物组(P<0.01)。投喂甘草提取物56 d后,用Aeromonas hydrophila对鲫进行人工感染,低剂量组和高剂量组一周后的死亡率分别为45.0%和55.0%,显著低于对照组的70.0%(P<0.05)。腹注甘草提取物后第28 d,鲫受A.hydrophila菌人工感染,对照组、低剂量组和高剂量组的死亡率分别为60.0%、55.0%和35.0%,高剂量组显著低于对照组(P<0.05)。实验表明,投喂和腹注甘草粗提物后,可明显提高鲫的抗应激能力,并能增强鱼体对A.hydrophila的抵抗力。

Effect of Liquorice Extracts on the Resistance of Carassius auratus to Stress and Pathogen Infection

By using oral administration and intraperitoneal injection of liquorice extracts to Cararssius auratus,the effect of liquorice extracts on the resistance to stress and aquatic pathogen infection were evaluated in this paper.The medicated diets for oral administration to C.auretus was prepared with liquorice at concentration of 0%,5% and 2%.Blood samples from the fish were collected at day 14,28,35,42 and 56 respectively.Liquorice for intraperitoneal injection to C.auratus was prepared with sterilized saline at concentration of 0%,5% and 2%.Blood samples from the fish were collected at day 3,7,14,21,and 28,respectively.The results showed that the cortisol levels in the oral adminstrated group increased at the beginning and then decreased in both tested and control group,but on day 14,the cortisol level in the tested group was lower than that in control group.In the last blood sample(day 56)the cortisol level in control group(0%),low-dose group(2%)and high-dose group(5%)were 147.85 ng/mL,79.41 ng/mL and 66.47 ng/mL,respectively.In the intraperitoneal injection trial,the cortisol level in control group rose all along and reached 274.23 ng/mL on day 28,which was higher than that in tested group(P<0.01).After fed with liquorice extract for 56 days,crucian were infected artificially with Aeromonas hydrophila.One week later,the mortality of low-dose group and high-dose group was 45.0% and 55.0%,respectively,which was lower than that of control group(70.0%,P<0.05).On day 28 in the trial intraperitoneally injected with liquorice extracts fish were challenged with A.hydrophila.One week later,the mortality of control group,low-dose group and high-dose group was 60.0%,55.0% and 35.0%,respectively,and the mortality of high-dose group was lower than that of control group(P<0.05).The present study indicated that both intraperitoneal infection and oral administration of liquorice extracts to Casassius auratus could enhance the resistance of the fish to stress and A.hydrophila infection.