Abstract:

Objective To investigate the efficacy of the Tibetan medicine Elsholtzia eriostachya and albendazole, either alone or in combination, in treatment of secondary Echinococcus multiulocularis metacestode in rats, and to explore a new approach for treatment of the metacestode infection with Tibetan medicine combined with western medicine. Methods The SD male rats were laparotomized to expose the liver for injection with 0.2 ml of protoscoleces suspension (containing 2 × 10³ protoscoleces) to establish the rat model of secondary E. multiulocularis metacestode infection. The 40 model rats were divided into the albendazole treatment group [50 mg/(kg·d)], Elsholtzia eriostachya treatment group [50 mg/(kg·d)], albendazole [25 mg/(kg·d)]+Elsholtzia eriostachya [25 mg/(kg·d)] group, and the infection control group. Another 10 healthy SD rats were used as the healthy control group. Rats in the 3 treatment groups received two courses of treatment by gavage with once daily for consecutive 4 weeks, at an interval of 5 days between courses. Rats in the infection control group and healthy control group were given an equal volume of normal saline. After two courses of treatment, the rats body were weighed, the liver lesion diameter was measured, and the spleen index was calculated. The liver and spleen tissues in each group were obtained and sectioned for HE staining. Histopathological changes were observed under optical microscope and the ultrastructure of liver lesions was further observed under a transmission electron microscope. Results The diameters of rat liver lesions in the albendazole group, Elsholtzia eriostachya group and the combination group were (0.72 ± 0.06) cm, (0.79 ± 0.10) cm, and (0.62 ± 0.05) cm, respectively, all of which were smaller than the (1.10 ± 0.11) cm of the control group (P < 0.01). The diameter of the lesion in the combination group was significantly smaller than that of the albendazole group and the Elsholtzia eriostachya group (P < 0.01). The spleen index of the combined medication group was 5.28 ± 0.59, which was significantly higher than that of the albendazole group (3.35 ± 0.43) and the Elsholtzia eriostachya group (3.56 ± 0.40) (P < 0.01). Furthermore, the HE staining revealed obvious proliferation of white marrow in rat spleen tissues in the infection group and the three treatment groups, with the presence of a large number of heteromorphic megakaryocytes. The liver lesions in three treatment groups all showed collapse of the cyst wall and significant reduction of protoscoleces. Obvious lymphocyte infiltration was seen in the Elsholtzia eriostachya group, and necrosis and hyaline degeneration were obvious in the combined treatment group. Ultrastructural observations of liver tissues showed that treatment with Elsholtzia eriostachya and albendazole alone or in combination lead to the destruction of the mitochondrial structure of the germinal membrane cells of the metacestode. In the combination treatment group, the metacestode showed loose wall structure, and the microvilli of the germinal cortex became thicker, shorter or even disappeared,. eosinophils and macrophages increased significantly in the Elsholtzia eriostachya group. Conclusion The treatment with combination of Elsholtzia eriostachya and albendazole presented a good therapeutic effect on secondary E. multiulocularis metacestode infection in rats.

Key words: Echinococcus multilocularis protoscoleces infection, Tibetan medicine, Elsholtzia eriostachya