Effects of genistein on the modulation of stress and immune response in fish
Abstract
Experiments were conducted to investigate the effects of genistein as a nutraceutical in modulating stress and the immune response in fish, maintained in aquaculture conditions. Two widely aquacultured fish species, tilapia ( Oreochromis niloticus) and steelhead salmon (Oncorhynchus mykiss), representing warm water and cool water environments, respectively, were selected for these experiments. Fish were obtained from certified hatcheries and were acclimated in their respective environments, warm water (24±2°C; 76±4°F) and cool water (17±2°C; 62±4°F), for two weeks prior to the beginning of the experiments. Within each environment, fish were divided into two groups and maintained in two different conditions- controlled and stressed (by crowding; density > 40 g/l). Within each condition, fish were further divided into two treatments and fed either regular commercial feed or genistein supplemented commercial feed (@400 mg/kg) for 8 weeks. Fish were sampled at weeks 0, 2, 4, 6, and 8 and were assessed for physiological (length, weight, condition factor, blood glucose, packed cell volume, plasma protein, spleen somatic index, and heat shock proteins) and immunological parameters (spleen cell proliferation and macrophage respiratory burst activity). In general, fish held in control groups had relatively better growth, physiological state and immune response than stressed fish. Within the controlled or stressed conditions, fish that received genistein supplemented feed did not show any statistically significant improvement (P>0.05) in any of the physiological or immunological parameters. However, some parameters (spleen somatic index and spleen cell proliferation) in the warm water fish (tilapia) did show a pattern of higher activity in the supplemented group. It is possible that fish, being poikilothermic, were not able to digest and/or absorb genistein due to their slow metabolic rate. Also genistein may only act on pathways that are specific for cancer and virus infection rather than general physiological system and immune response. Further research is necessary before making any definite conclusions, on the benefit of genistein in aquaculture.
Degree
M.S.
Advisors
Mustafa, Purdue University.
Subject Area
Physiology|Aquatic sciences|Immunology
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