Protective effect of hydroferrate fluid, MRN-100, against lethality and hematopoietic tissue damage in γ-radiated Nile tilapia, Oreochromis niloticus

Abstract

Hydroferrate fluid, MRN-100, an iron-based compound derived from bivalent and trivalent ferrates, is a potent antioxidant compound. Therefore, we examined the protective effect of MRN-100 against γ-radiation-induced lethality and damage to hematopoietic tissues in fish. A total of 216 Nile tilapia fish (Oreochromis niloticus) were randomly divided into four groups. Group 1 served as a control that was administered no radiation and no MRN-100 treatment. Group 2 was exposed only to γ-radiation (15 Gy). Groups 3 and 4 were pre-treated with MRN-100 at doses of either 1 ml/l or 3 ml/l in water for 1 week, and subsequently exposed to radiation while continuing to receive MRN-100 for 27 days. The survival rate was measured, and biochemical and histopathological analyses of hematopoietic tissues were performed for the different treatment groups at 1 and 4 weeks post-radiation. Exposure to radiation reduced the survival rate to 27.7%, while treatment with MRN-100 maintained the survival rate at 87.2%. In addition, fish exposed to γ-radiation for 1 week showed a significant decrease in the total number of white blood cells (WBCs) and red blood cells (RBCs) series. However, treatment with MRN-100 protected the total WBC count and the RBCs series when compared with irradiated fish. Furthermore, significant histological lesions were observed in the hepatopancreas, spleen and gills of irradiated fish. However, treatment with MRN-100 protected the histopathology of various organs. We conclude that MRN-100 is a radioprotective agent in fish and may be useful as an adjuvant treatment to counteract the adverse side effects associated with radiation exposure.

Keywords: Oreochromis niloticus; hydroferrate fluid; radiation; survival.

Fig. 1.

Effect of MRN-100 on survival percentage in Oreochromis niloticus after γ-radiation. Fish were divided into four equal groups (G1–G4), each consisting of 47 fish. The dead fish among the groups were recorded daily for 27 days after exposure to radiation.

Fig. 2.

Effect of MRN-100 on the WBC count of Oreochromis niloticus after γ-radiation. WBCs were isolated from the caudal vein and counted at 1 and 4 weeks post-radiation. Data represents the mean ± SD of 5–7 fish in each group compared with the control, untreated group. **P < 0.01.

Fig. 3.

Effects of MRN-100 on in the RBC series of Oreochromis niloticus after γ-radiation and MRN-100 treatment. The RBC series include: RBC counts, HGB, HCT, MCV, MCH and MCHC. These parameters were examined at 1 and 4 weeks post-radiation. Data represent the mean ± SD of 5–7 fish in each group compared with the control, untreated group. *P < 0.01, **P < 0.05.

Fig. 4.

Effect of MRN-100 on the platelet count (PLT) of Oreochromis niloticus after γ-radiation and MRN-100 treatment. Platelet counts were performed at 1 and 4 weeks post-radiation. Data represent the mean ± SD of 5–7 fish in each group compared with the control, untreated group.

Fig. 5.

Effect of MRN-100 on the SGPT level of Oreochromis niloticus after γ-radiation. SGPT levels were examined at 1 and 4 weeks post-radiation. Data represent the mean ± SD of 5–7 fish in each group. G2 was statistically significant compared with the control, untreated group. **P < 0.001.

Fig. 6.

Histological section of Oreochromis niloticus hepatopancreas at 1 week post-radiation. (A) Control hepatopancreas with normal histology, where the liver (L) is anatomically joined with the pancreatic tissue (P). Notice the presence of zymogen granules (arrows). (B) Irradiated hepatopancreas shows increased pancreatic necrosis and an increased number of severely degenerative hepatocytes in the liver portion. (C) MRN-100-treated and irradiated hepatopancreas. Notice the normality of the pancreatic and liver tissues and the presence of zymogen granules (arrows). (×40 magnification with H&E stain).

Fig. 7.

Histological section of Oreochromis niloticus spleens at 1 week post-radiation. (A) Control spleen with normal histology with the presence of melanin pigments (white arrowheads). (B) Irradiated spleen. Notice the absence of melanin pigments, the hyperplasia in the melanomacrophage cells (yellow circles highlight), and the increased amount of vacuolation (yellow arrows). (C) MRN-100 treated and irradiated spleen. Notice the presence of dark melanin cells (white arrowheads). (×40 magnification with H&E stain).

Fig. 8.

Longitudinal sections of Oreochromis niloticus gills at 1 week post-radiation. (A) Control gill filaments and lamellae. The width of the epithelial tissue is indicated by a bracket. (B) Irradiated gill filaments. Notice an increase in thickness of the supporting cartilaginous rods. The hyperplasia of the epithelial tissue is indicated by the bracket. The secondary lamellae became shorter (arrowheads) or disappeared completely from the surface of the gill filaments, as seen in the gill filament on the bottom. Notice also the lamellar fusion forming lumps (arrows). (C) MRN-100 treated and irradiated gill filaments appear normal, with absence of the hyperplasia in the epithelial tissue. (×40 magnification with H&E stain).