Dietary Tryptophan Induces Opposite Health-Related Responses in the Senegalese Sole (Solea senegalensis) Reared at Low or High Stocking Densities With Implications in Disease Resistance

In conclusion, while dietary tryptophan supplementation might have harmful effects in control fish, it might prove to be a promising strategy to overcome chronic stress-induced disease susceptibility in farmed Senegalese sole. Introduction Every physiological response (e.g., metabolism, mineral balance, reproduction, growth, and immune function) is at least partly regulated by neuroendocrine mechanisms, which, in teleosts, are orchestrated by the hypothalamus-pituitary-interrenal (HPI) axis. Neuroendocrine signals are released upon stimulation of HPI axis and responses are highly different within each context. In fish, the stress response, triggered by both internal and external signals, consists of the production and secretion of different molecules, such as the corticotropin-releasing hormone (Crh) and Crh-binding protein (Crhbp) in the hypothalamus, adrenocorticotropic hormone (ACTH) in the pituitary, and cortisol in the head-kidney interrenal tissue (Bonga, 1997; Flik et al., 2006). The latter has been generally recognized as the most important stress indicator in fish (Tort, 2011) and, amongst other intermediates, ACTH is the ultimate cortisol secretion-inducer. ACTH is a polypeptide hormone encoded in the medium region of the proopiomelanocortin gene (pomc) which post-translational processing yields not only ACTH, but γ, α and β-melanocyte-stimulating hormone (MSH) and β-endorphin (Takahashi et al., 2013; Navarro et al., 2016). In mos...
Source: Frontiers in Physiology - Category: Physiology Source Type: research