The response of melanin, lipofuscin and hemosiderin pigments in melanomacrophage centers to nonylphenol exposure in goldfish (Carassius auratus )

This study aimed to evaluate the histological effect of nonylphenol on the activity of goldfish (Carassius auratus) immune system by measuring the accumulation of melanomacrophage pigments in the kidney and spleen of goldfish. Therefore, immature goldfish were exposed to 10-6 and 10-7M nonylphenol (NP) for 25 days. Tissue processing was carried out followed by Hematoxylin-eosin (H&E), Perls Prussian blue (PPB) and periodic acid Schiff (PAS) staining to identify melanin, hemosiderin and lipofuscin, respectively. Then, image processing was performed using ImageJ software (ver. 1.53 e) to quantify the pigment content of melanomacrophage centers (MMCs). The exposure to NP led to decrease of MMC formation containing hemosiderin pigment in the spleen, and did not affect the formation of MMCs containing this pigment in the kidney. MMC formation containing lipofuscin pigment decreased and increased in the spleen and kidney, respectively, after exposure to NP (P<0.05). The exposure to NP led to the increase of MMC formation in both organs in a dose-dependent manner. Generally, melanin increased in a dose-dependent manner and seems to be a better indicator of exposure to NP.