Fucoxanthin alters the apelin-13/APJ pathway in certain organs of γ-irradiated mice.

Apelin-13 and APJ are implicated in different key physiological processes. This work aims at exploring the radioprotective effect of fucoxanthin (FX) on γ-radiation (RAD)-induced changes in the apelin-13/APJ pathway, which causes damage in the liver, kidney, lung and spleen of mice. Mice were administered FX (10 mg kg-1 day-1, i.p) and exposed to γ-radiation (2.5 Gy week-1) for four consecutive weeks. The treatment of irradiated mice by FX resulted in a significant amendment in protein expression of the apelin-13/APJ/NF-κB signalling pathway concurrently with reduced hypoxia (hypoxia-inducible factor-1α), suppressed oxidative stress marker (malondialdehyde), enhanced antioxidant defence mechanisms (reduced glutathione and glutathione peroxidase), a modulated inflammatory response [interleukin-6 (IL-6), monocyte chemoattractant protein-1, IL-10 and α-7-nicotinic acetylcholine receptor) and ameliorated angiogenic regulators [matrix metalloproteinase (MMP-2), MMP-9 and tissue inhibitor of metalloproteinase-1), as well as the tissue damage indicator (lactate dehydrogenase) in organ tissues. In addition, there were significant improvement in serum inflammatory markers tumour necrosis factor-α, IL-10, IL-1β and C-reactive protein compared with irradiated mice. The histopathological investigation of the FX + RAD organ tissues support the biochemical findings where the improvements in the tissues' architecture were obvious when compared with those of RAD. FX was thus shown to have a noticeable radioprotective action mediated through its regulatory effect on the apelin-13/APJ/NF-κB signalling pathway attributed to its antioxidant and anti-inflammatory activity that was reflected in different physiological processes. It could be recommended to use FX in cases of radiation exposure to protect normal tissues.