The Immunomodulatory Effect of Intraperitoneal Injection of Licorice Extract on Giant Salamander

The effect of licorice extract on non-specific immune function of giant salamanders was studied by intraperitoneal injection. The results showed that the lysozyme activity in the drug group increased, and the lysozyme activity increased with the increase of dose. From the 7th day onwards, each sampling of the drug group showed significant differences compared to the control group (P<0.05). The phagocytic activity of macrophages in the drug group showed some fluctuations, but there was no significant difference compared to the control group. The white blood cell volume value of the high-dose group gradually increased in the first three samplings, and showed a significant difference compared to the control group at 14 days (P<0.05). It decreased slightly in the last two samplings, but was still higher than the control group at the same time. The spleen organ coefficient of the low-dose group was (0.7 ± 0.01) % at 28 days, higher than that of the control group (0.4 ± 0.05) %, and the high-dose group was (0.7 ± 0.07) % at 14 days, higher than that of the control group (0.4 ± 0.02) %. Both differences were significant (P<0.05). After the last sampling (28 days), artificial infection with <i>Aeromonas hydrophila</i> bacteria resulted in a mortality rate of 80% in the control group, 50% in the low-dose group, and 30% in the high-dose group, all lower than the control group. The drug group also had higher immune protection rates than the control group. The results indicate that intraperitoneal injection of licorice extract can improve the immune function and disease resistance of giant salamanders to a certain extent.