Melanomacrophage Centers in Nile Tilapia (Oreochromis niloticus L.) as Biomarker for Carbamate Exposure

Melanomacrophage centers are aggregates of pigment-containing cells found in the animal’s hematopoietic tissues. Changes in its characteristics have been used to assess the influence of pesticide exposure, and as tools for potential monitoring for fish and environmental health. This study aimed to evaluate the pesticide-induced hepatic and splenic melanomacrophage center responses in Nile tilapia (Oreochromis niloticus L.) following exposure to fenobucarb in varying lengths of exposure. Five test groups were exposed to constant dose of fenobucarb at 0.08 mg L-1at different periods (0, 7, 14, 21, and 28 days). Fenobucarb only induced significant changes in the splenic melanomacrophage centers. Splenic melanomacrophage centers significantly increased in number in response to the increasing lengths of exposure. Increasing trend of size and cover was also observed, however, significant difference was only detected at 28 days exposure period. Significant difference in hemosiderin and lipofuscin pigments was also detected at 28 days exposure which suggests tissue destruction after prolonged exposure. This study confirms the potential of melanomacrophage centers as a sensitive biomarker for fenobucarb exposure indicated by the changes in its characteristics, particularly in the spleen.