Effect of ammonia-N on histology and expression of immunoglobulin M and component C3 in the spleen and head kidney of Pelteobagrus vachellii

Ammonia-N is toxic to many aquatic animals and serves as a key stress factor in aquatic environments. The effects of ammonia-N stress on the immune response of darkbarbel catfish Pelteobagrus vachellii were investigated in this study. Changes in overall histology, and in the expression of complement C3 and immunoglobulin M (IgM) in spleen and head kidney, and lysozyme and C3 in serum, were measured in 1 and 5 mg/L ammonia-N. Hyperemia, melano-macrophage assembly and loose splenosis were evident in spleen tissue. Both lysozyme and component C3 were significantly reduced in serum (P 0.05). IgM expression also increased significantly at 6–12 h in spleen and 6–24 h in head kidney after the 1 mg/L treatment (P