Reverse-gavage feeding as a novel administration to investigate the immunomodulatory effects of plant-based medicines on the immunity of giant freshwater prawn, Macrobrachium rosenbergii: A case study of Scutellaria radix water extract

The application of herbal medicine is one of the ancientest worldwide approaches to treating diseases. This study aimed to examine the effect of Scutellaria radix on the immune responses of Macrobrachium rosenbergii by reverse-gavage feeding and their resistance against Lactococcus garvieae . In brief, M. rosenbergii was administered with S. radix water extract at 1, 5, and 10 µg/µl using reverse-gavage feeding (RGF). Total hemocyte count (THC), phenoloxidase (PO) activity, respiratory bursts (RBs) activity, transglutaminase (TG) activity, and lysozyme activity of hemocytes were evaluated to discover the immunological responses of prawn post-RGF. The results showed that the concentration of S. radix extract at 5 µg µl –1 increased the immune responses of M. rosenbergii compared with the control group. In the case of the gene, expressions were observed from the hepatopancreas and midgut, in which proxinectin showed no significant difference, LGBP and proPO were expressed by all concentrations in a time-dependent manner. The present findings suggest that S. radix water extract at 5 µg µl –1 may enhance the immune responses and gene expressions in M. rosenbergii using RGF.