Presentation Title

Biochemical and Genetic Consequences of Sleep Deprivation in Zebrafish (Danio rerio)

Location

Nessmith-Lane Atrium

Session Format

Poster Presentation

Research Area Topic:

Natural & Physical Sciences - Biology

Abstract

Sleep deprivation has been linked with various abnormal behaviours and negative effects on health in humans. Continual (chronic) elevated stress levels have been linked with serious health implications. The objective of the current study is to examine the potential stress effects of sleep deprivation in a vertebrate organism. Specifically, the behavioural, biochemical and genetic response of sleep deprivation, as a result of prolonged light exposure, will be studied in zebrafish (Danio rerio). In fish, corticosteroid production occurs via the same pathway as terrestrial vertebrates. The increased production of blood corticosteroids in response to stress is one of the most evolutionary conserved organismal responses to stress. Sleep-like states in D. rerio have been defined as continuous intervals of immobility for ‰ä´ 6 seconds. Behavioural analysis of D. rerio (n=18) using an integrative tracking software (Ethovision XT, Noldus) has demonstrated that D. rerio held under a normal photoperiod (12 hr light/12 hr dark) spend ~70% of their time in a sleep like state during dark hours and continuous exposure to light for 24 hours results in increased activity and almost complete loss of time spent in a sleep-like state (n=18). Additionally, acute sleep deprivation resulted in a 40% increase in whole body cortisol (2.182 versus 1.566 ng/g for control D. rerio; n=9), demonstrating that lack of sleep does induce a stress response at the physiological level in D. rerio. A chronic sleep deprivation trial (4 weeks: 24 hr light/0 hr dark) is currently being conducted to assess the long term effects of sleep deprivation. Preliminary behavioural and morphological observations from this chronic trial suggest that fish are unable to adapt to continual light exposure (fish continue to show increased activity levels and complete lack of sleep-likestate) and that long term sleep deprivation has negative health effects on the organism (sleep deprived fish exhibit colour pattern loss, increased redness in the gills and reduced growth). Subsequently, it is hypothesized that whole body cortisol concentrations in fish experiencing chronic sleep deprivation will be significantly elevated compared to fish only experiencing an acute sleep deprivation. To further investigate the effects of acute and chronic sleep deprivation, mRNA expression levels will be analyzed in D. rerio to investigate the mechanisms that control the release and synthesis of glucocorticoids by the hypothalamic-pituitary axis during stress (StAR, p450scc, 11ë_-hyd) and the mechanisms controlling the circadian rhythm (cry1a, Bmal1a, and clock1a). Understanding the effects of sleep deprivation at a biochemical and physiological level will not only provide insight to the importance of obtaining adequate sleep to one’s overall health and wellbeing, but also help aid in targeting the key mechanisms underpinning the health implications.

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This work is licensed under a Creative Commons Attribution 4.0 License.

Presentation Type and Release Option

Event

Start Date

4-16-2016 10:45 AM

End Date

4-16-2016 12:00 PM

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Apr 16th, 10:45 AM Apr 16th, 12:00 PM

Biochemical and Genetic Consequences of Sleep Deprivation in Zebrafish (Danio rerio)

Nessmith-Lane Atrium

Sleep deprivation has been linked with various abnormal behaviours and negative effects on health in humans. Continual (chronic) elevated stress levels have been linked with serious health implications. The objective of the current study is to examine the potential stress effects of sleep deprivation in a vertebrate organism. Specifically, the behavioural, biochemical and genetic response of sleep deprivation, as a result of prolonged light exposure, will be studied in zebrafish (Danio rerio). In fish, corticosteroid production occurs via the same pathway as terrestrial vertebrates. The increased production of blood corticosteroids in response to stress is one of the most evolutionary conserved organismal responses to stress. Sleep-like states in D. rerio have been defined as continuous intervals of immobility for ‰ä´ 6 seconds. Behavioural analysis of D. rerio (n=18) using an integrative tracking software (Ethovision XT, Noldus) has demonstrated that D. rerio held under a normal photoperiod (12 hr light/12 hr dark) spend ~70% of their time in a sleep like state during dark hours and continuous exposure to light for 24 hours results in increased activity and almost complete loss of time spent in a sleep-like state (n=18). Additionally, acute sleep deprivation resulted in a 40% increase in whole body cortisol (2.182 versus 1.566 ng/g for control D. rerio; n=9), demonstrating that lack of sleep does induce a stress response at the physiological level in D. rerio. A chronic sleep deprivation trial (4 weeks: 24 hr light/0 hr dark) is currently being conducted to assess the long term effects of sleep deprivation. Preliminary behavioural and morphological observations from this chronic trial suggest that fish are unable to adapt to continual light exposure (fish continue to show increased activity levels and complete lack of sleep-likestate) and that long term sleep deprivation has negative health effects on the organism (sleep deprived fish exhibit colour pattern loss, increased redness in the gills and reduced growth). Subsequently, it is hypothesized that whole body cortisol concentrations in fish experiencing chronic sleep deprivation will be significantly elevated compared to fish only experiencing an acute sleep deprivation. To further investigate the effects of acute and chronic sleep deprivation, mRNA expression levels will be analyzed in D. rerio to investigate the mechanisms that control the release and synthesis of glucocorticoids by the hypothalamic-pituitary axis during stress (StAR, p450scc, 11ë_-hyd) and the mechanisms controlling the circadian rhythm (cry1a, Bmal1a, and clock1a). Understanding the effects of sleep deprivation at a biochemical and physiological level will not only provide insight to the importance of obtaining adequate sleep to one’s overall health and wellbeing, but also help aid in targeting the key mechanisms underpinning the health implications.