Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/30079
Appears in Collections:Aquaculture Journal Articles
Peer Review Status: Refereed
Title: Environmental Cycles, Melatonin, and Circadian Control of Stress Response in Fish
Author(s): Sánchez-Vázquez, Francisco Javier
López-Olmeda, Jose Fernando
Vera, Luisa Maria
Migaud, Herve
López-Patiño, Marcos Antonio
Míguez, Jesús M.
Keywords: daily rhythm
light
temperature
HPI axis
wavelength
thermocycles
fish welfare
Issue Date: 11-Jun-2019
Date Deposited: 11-Sep-2019
Citation: Sánchez-Vázquez FJ, López-Olmeda JF, Vera LM, Migaud H, López-Patiño MA & Míguez JM (2019) Environmental Cycles, Melatonin, and Circadian Control of Stress Response in Fish. Frontiers in Endocrinology, 10, Art. No.: 279. https://doi.org/10.3389/fendo.2019.00279
Abstract: Fish have evolved a biological clock to cope with environmental cycles, so they display circadian rhythms in most physiological functions including stress response. Photoperiodic information is transduced by the pineal organ into a rhythmic secretion of melatonin, which is released into the blood circulation with high concentrations at night and low during the day. The melatonin rhythmic profile is under the control of circadian clocks in most fish (except salmonids), and it is considered as an important output of the circadian system, thus modulating most daily behavioral and physiological rhythms. Lighting conditions (intensity and spectrum) change in the underwater environment and affect fish embryo and larvae development: constant light/darkness or red lights can lead to increased malformations and mortality, whereas blue light usually results in best hatching rates and growth performance in marine fish. Many factors display daily rhythms along the hypothalamus-pituitary-interrenal (HPI) axis that controls stress response in fish, including corticotropin-releasing hormone (Crh) and its binding protein (Crhbp), proopiomelanocortin A and B (Pomca and Pomcb), and plasma cortisol, glucose, and lactate. Many of these circadian rhythms are under the control of endogenous molecular clocks, which consist of self-sustained transcriptional-translational feedback loops involving the cyclic expression of circadian clock genes (clock, bmal, per, and cry) which persists under constant light or darkness. Exposing fish to a stressor can result in altered rhythms of most stress indicators, such as cortisol, glucose, and lactate among others, as well as daily rhythms of most behavioral and physiological functions. In addition, crh and pomca expression profiles can be affected by other factors such as light spectrum, which strongly influence the expression profile of growth-related (igf1a, igf2a) genes. Additionally, the daily cycle of water temperature (warmer at day and cooler at night) is another factor that has to be considered. The response to any acute stressor is not only species dependent, but also depends on the time of the day when the stress occurs: nocturnal species show higher responses when stressed during day time, whereas diurnal fish respond stronger at night. Melatonin administration in fish has sedative effects with a reduction in locomotor activity and cortisol levels, as well as reduced liver glycogen and dopaminergic and serotonergic activities within the hypothalamus. In this paper, we are reviewing the role of environmental cycles and biological clocks on the entrainment of daily rhythms in the HPI axis and stress responses in fish.
DOI Link: 10.3389/fendo.2019.00279
Rights: © 2019 Sánchez-Vázquez, López-Olmeda, Vera, Migaud, López-Patiño and Míguez. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY - https://creativecommons.org/licenses/by/4.0/). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Licence URL(s): http://creativecommons.org/licenses/by/4.0/

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