Effects of nonylphenol on hematological parameters and immune responses in immature rainbow trout (Oncorhynchus mykiss)

ABSTRACT This study investigated the effects of nonylphenol (NP) on hematological and immunological parameters in both male and female rainbow trout (Oncorhynchus mykiss). Fish were randomly distributed into six groups and administered with NP (10, 50 and 100 μg g-1 week-1 BW) and a single dose of 17-β estradiol (E2; 2 μg g-1 week-1 BW, positive control). The solvent controls received ethanol and coconut oil as a vehicle, while the controls were not injected. Red blood cells (RBCs) count, hematocrit (Hct), hemoglobin (Hb), white blood cells (WBCs), and lymphocytes demonstrated a NP dose-dependent decrease, whereas mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), monocytes, and neutrophils showed an increasing trend in both male and female fish 21 days post-treatment. Also, RBCs, Hb, MCHC, WBCs, and lymphocytes were significantly reduced (p<0.05) in E2 treated fish. Lysozyme, complement components (C3 and C4) and immunoglobulin M (IgM) were increased in fish sera subjected to 10 and 50 μg g-1 NP, while these decreased in groups administered with 100 μg g-1 NP and 2 μg g-1 E2. Except for C4 level at 10 μg g-1 NP, no significant differences were observed in hematological and immunological parameters of male and female in each treatment. Overall, a frequent exposure to NP could lead to adverse effects on fish immune-physiological functions which may cause serious ecological threats of fish natural population sustainability.