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The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development.

De Marco RJ, Groneberg AH, Yeh CM, Treviño M, Ryu S - Front Behav Neurosci (2014)

Bottom Line: Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish.We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established.The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging.

View Article: PubMed Central - PubMed

Affiliation: Developmental Genetics of the Nervous System, Max Planck Institute for Medical Research Heidelberg, Germany.

ABSTRACT
The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging.

No MeSH data available.


Related in: MedlinePlus

Locomotion, oxygen consumption and visual responses remain unaltered after stressor stress. (A) Locomotor activity of larvae pre-incubated with E2, NaCl50mM and NaCl100mM swimming individually in darkness at 28°C (±0.1°C). (B) Average locomotion (over 600 s) plotted against whole body cortisol for larvae pre-treated with E2, NaCl50mM and NaCl100mM. (C) Net oxygen consumption rates (OCRs) of groups of (eight) larvae pre-treated with E2, NaCl50mM or NaCl100mM. (A,C: sample size in parentheses). (D) Swim velocity of single dark-adapted larvae pre-treated with E2, NaCl50mM or NaCl100mM before, during and after a 10 s square pulse of white light (0.1 mW*cm−2). (E) Exemplary trace from an optomotor test depicting a larva’s heading (relative to the long axis of a rectangular swimming chamber) as a function of time; during the test, single larvae are presented with gray dots (of variable contrast, diameter, velocity and number) ventrally displayed against a white background via a computer screen beneath the chamber (see Methods). No preferred heading can be detected when the dots remain stationary (OFF); by contrast, larvae swim in the direction of the moving dots when they move along the long axis of the chamber (ON), thereby showing a preferred heading. Following acclimation and baseline recording, dot movements begin automatically when the larva is at one of chamber’s sides (either left or right); dots move towards the chamber’s opposite side and the time elapsed until the larva reaches the end of the chamber (latency) is taken as indicative of response strength. (F) Latency (s) from an optomotor test as a function of dot contrast for larvae pre-treated with E2, NaCl50mM or NaCl100mM.
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Figure 3: Locomotion, oxygen consumption and visual responses remain unaltered after stressor stress. (A) Locomotor activity of larvae pre-incubated with E2, NaCl50mM and NaCl100mM swimming individually in darkness at 28°C (±0.1°C). (B) Average locomotion (over 600 s) plotted against whole body cortisol for larvae pre-treated with E2, NaCl50mM and NaCl100mM. (C) Net oxygen consumption rates (OCRs) of groups of (eight) larvae pre-treated with E2, NaCl50mM or NaCl100mM. (A,C: sample size in parentheses). (D) Swim velocity of single dark-adapted larvae pre-treated with E2, NaCl50mM or NaCl100mM before, during and after a 10 s square pulse of white light (0.1 mW*cm−2). (E) Exemplary trace from an optomotor test depicting a larva’s heading (relative to the long axis of a rectangular swimming chamber) as a function of time; during the test, single larvae are presented with gray dots (of variable contrast, diameter, velocity and number) ventrally displayed against a white background via a computer screen beneath the chamber (see Methods). No preferred heading can be detected when the dots remain stationary (OFF); by contrast, larvae swim in the direction of the moving dots when they move along the long axis of the chamber (ON), thereby showing a preferred heading. Following acclimation and baseline recording, dot movements begin automatically when the larva is at one of chamber’s sides (either left or right); dots move towards the chamber’s opposite side and the time elapsed until the larva reaches the end of the chamber (latency) is taken as indicative of response strength. (F) Latency (s) from an optomotor test as a function of dot contrast for larvae pre-treated with E2, NaCl50mM or NaCl100mM.

Mentions: We next asked whether altered locomotion, oxygen consumption or visual reactions could account for the differences in prey-dependent space use observed after NaCl exposure. We first monitored post-exposure levels of locomotor activity in treated and control larvae within a stimulus-deprived environment. For this, larvae pre-incubated in either control or hyperosmotic mediums were placed in a custom-made, vibration-free swimming chamber (10 mm ID, volume: 400 µl) and allowed to swim individually in complete darkness for 600 s under constant temperature (28 ± 0.1°C). We found that NaCl exposure failed to modify post-exposure locomotion (Figure 3A, One-Way ANOVA, F(2,71) = 2.2, p = 0.13); as a result, peak cortisol levels after salt exposure did not account for locomotion variability (Figure 3B, Pearson’s correlation, p = 0.42). To expand the analysis of NaCl effects, we monitored oxygen levels every 5 s for 30 min (as % of air saturated) in a custom-made chamber containing groups of eight freely swimming larvae that had, or had not, been pre-incubated in a hyperosmotic medium (of either NaCl50mM or NaCl100mM). For each measurement, the OCR was approximated as the slope of a linear fit to the oxygen level for 10 min < time < 30 min. Prior to measuring the OCRs of larvae, we measured (twice) the OCR of E2 medium alone. Net OCRs were calculated by subtracting the average OCR of E2 from the OCRs of the larvae. We found that pre-incubation with either NaCl50mM or NaCl100mM did not change net OCRs, as compared to pre-incubation with E2 (Figure 3C, One-Way ANOVA, F(2,23) = 0.26, p = 0.77). Next, because larvae rely on vision for detecting and capturing prey, we set up to detect possible effects of NaCl exposure on their reactions to illumination change and moving visual stimuli. First, we examined motion reactions of control and treated larvae to a sudden illumination change and observed that dark-adapted larvae of either group reacted similarly to a 10 s square pulse of white light (0.1 mW*cm−2). They reduced their locomotor activity similarly when exposed to light (Figure 3D, Two-Way Repeated-Measures ANOVA, Group factor: F(1,36) = 0.41, p = 0.53, Light factor: F(2,36) = 391.7, p < 0.0001, Group X Light factor: F(2,36) = 0.69, p = 0.51). Next, we tested the larvae’s optomotor response, i.e., spontaneous swimming in the direction of large-field displacements in the visual field. For this we presented control and treated larvae with ventrally moving dots of variable contrast, diameter, velocity and number (Figure 3E, see Methods). The results showed that NaCl exposure did not impair the larvae’s optomotor response. Figure 3F shows how dot contrast improved the larvae’s response, and how the response of larvae pre-incubated in either NaCl50mM or NaCl100mM did not differ from that of control larvae (Two-Way ANOVA, Group factor: F(2,54) = 2.49, p = 0.09, Contrast factor: F(1,54) = 69.57, p < 0.0001, Group X Contrast factor: F(2,54) = 0.59, p = 0.56). Similar results arose from varying the diameter, velocity and number of moving dots (data not shown). In sum, locomotion, oxygen consumption and responses to visual inputs appeared unaltered under conditions of elevated HPI-axis activity caused by exposure to hyperosmotic mediums.


The behavior of larval zebrafish reveals stressor-mediated anorexia during early vertebrate development.

De Marco RJ, Groneberg AH, Yeh CM, Treviño M, Ryu S - Front Behav Neurosci (2014)

Locomotion, oxygen consumption and visual responses remain unaltered after stressor stress. (A) Locomotor activity of larvae pre-incubated with E2, NaCl50mM and NaCl100mM swimming individually in darkness at 28°C (±0.1°C). (B) Average locomotion (over 600 s) plotted against whole body cortisol for larvae pre-treated with E2, NaCl50mM and NaCl100mM. (C) Net oxygen consumption rates (OCRs) of groups of (eight) larvae pre-treated with E2, NaCl50mM or NaCl100mM. (A,C: sample size in parentheses). (D) Swim velocity of single dark-adapted larvae pre-treated with E2, NaCl50mM or NaCl100mM before, during and after a 10 s square pulse of white light (0.1 mW*cm−2). (E) Exemplary trace from an optomotor test depicting a larva’s heading (relative to the long axis of a rectangular swimming chamber) as a function of time; during the test, single larvae are presented with gray dots (of variable contrast, diameter, velocity and number) ventrally displayed against a white background via a computer screen beneath the chamber (see Methods). No preferred heading can be detected when the dots remain stationary (OFF); by contrast, larvae swim in the direction of the moving dots when they move along the long axis of the chamber (ON), thereby showing a preferred heading. Following acclimation and baseline recording, dot movements begin automatically when the larva is at one of chamber’s sides (either left or right); dots move towards the chamber’s opposite side and the time elapsed until the larva reaches the end of the chamber (latency) is taken as indicative of response strength. (F) Latency (s) from an optomotor test as a function of dot contrast for larvae pre-treated with E2, NaCl50mM or NaCl100mM.
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Related In: Results  -  Collection

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Figure 3: Locomotion, oxygen consumption and visual responses remain unaltered after stressor stress. (A) Locomotor activity of larvae pre-incubated with E2, NaCl50mM and NaCl100mM swimming individually in darkness at 28°C (±0.1°C). (B) Average locomotion (over 600 s) plotted against whole body cortisol for larvae pre-treated with E2, NaCl50mM and NaCl100mM. (C) Net oxygen consumption rates (OCRs) of groups of (eight) larvae pre-treated with E2, NaCl50mM or NaCl100mM. (A,C: sample size in parentheses). (D) Swim velocity of single dark-adapted larvae pre-treated with E2, NaCl50mM or NaCl100mM before, during and after a 10 s square pulse of white light (0.1 mW*cm−2). (E) Exemplary trace from an optomotor test depicting a larva’s heading (relative to the long axis of a rectangular swimming chamber) as a function of time; during the test, single larvae are presented with gray dots (of variable contrast, diameter, velocity and number) ventrally displayed against a white background via a computer screen beneath the chamber (see Methods). No preferred heading can be detected when the dots remain stationary (OFF); by contrast, larvae swim in the direction of the moving dots when they move along the long axis of the chamber (ON), thereby showing a preferred heading. Following acclimation and baseline recording, dot movements begin automatically when the larva is at one of chamber’s sides (either left or right); dots move towards the chamber’s opposite side and the time elapsed until the larva reaches the end of the chamber (latency) is taken as indicative of response strength. (F) Latency (s) from an optomotor test as a function of dot contrast for larvae pre-treated with E2, NaCl50mM or NaCl100mM.
Mentions: We next asked whether altered locomotion, oxygen consumption or visual reactions could account for the differences in prey-dependent space use observed after NaCl exposure. We first monitored post-exposure levels of locomotor activity in treated and control larvae within a stimulus-deprived environment. For this, larvae pre-incubated in either control or hyperosmotic mediums were placed in a custom-made, vibration-free swimming chamber (10 mm ID, volume: 400 µl) and allowed to swim individually in complete darkness for 600 s under constant temperature (28 ± 0.1°C). We found that NaCl exposure failed to modify post-exposure locomotion (Figure 3A, One-Way ANOVA, F(2,71) = 2.2, p = 0.13); as a result, peak cortisol levels after salt exposure did not account for locomotion variability (Figure 3B, Pearson’s correlation, p = 0.42). To expand the analysis of NaCl effects, we monitored oxygen levels every 5 s for 30 min (as % of air saturated) in a custom-made chamber containing groups of eight freely swimming larvae that had, or had not, been pre-incubated in a hyperosmotic medium (of either NaCl50mM or NaCl100mM). For each measurement, the OCR was approximated as the slope of a linear fit to the oxygen level for 10 min < time < 30 min. Prior to measuring the OCRs of larvae, we measured (twice) the OCR of E2 medium alone. Net OCRs were calculated by subtracting the average OCR of E2 from the OCRs of the larvae. We found that pre-incubation with either NaCl50mM or NaCl100mM did not change net OCRs, as compared to pre-incubation with E2 (Figure 3C, One-Way ANOVA, F(2,23) = 0.26, p = 0.77). Next, because larvae rely on vision for detecting and capturing prey, we set up to detect possible effects of NaCl exposure on their reactions to illumination change and moving visual stimuli. First, we examined motion reactions of control and treated larvae to a sudden illumination change and observed that dark-adapted larvae of either group reacted similarly to a 10 s square pulse of white light (0.1 mW*cm−2). They reduced their locomotor activity similarly when exposed to light (Figure 3D, Two-Way Repeated-Measures ANOVA, Group factor: F(1,36) = 0.41, p = 0.53, Light factor: F(2,36) = 391.7, p < 0.0001, Group X Light factor: F(2,36) = 0.69, p = 0.51). Next, we tested the larvae’s optomotor response, i.e., spontaneous swimming in the direction of large-field displacements in the visual field. For this we presented control and treated larvae with ventrally moving dots of variable contrast, diameter, velocity and number (Figure 3E, see Methods). The results showed that NaCl exposure did not impair the larvae’s optomotor response. Figure 3F shows how dot contrast improved the larvae’s response, and how the response of larvae pre-incubated in either NaCl50mM or NaCl100mM did not differ from that of control larvae (Two-Way ANOVA, Group factor: F(2,54) = 2.49, p = 0.09, Contrast factor: F(1,54) = 69.57, p < 0.0001, Group X Contrast factor: F(2,54) = 0.59, p = 0.56). Similar results arose from varying the diameter, velocity and number of moving dots (data not shown). In sum, locomotion, oxygen consumption and responses to visual inputs appeared unaltered under conditions of elevated HPI-axis activity caused by exposure to hyperosmotic mediums.

Bottom Line: Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish.We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established.The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging.

View Article: PubMed Central - PubMed

Affiliation: Developmental Genetics of the Nervous System, Max Planck Institute for Medical Research Heidelberg, Germany.

ABSTRACT
The relationship between stress and food consumption has been well documented in adults but less so in developing vertebrates. Here we demonstrate that an encounter with a stressor can suppress food consumption in larval zebrafish. Furthermore, we provide indication that food intake suppression cannot be accounted for by changes in locomotion, oxygen consumption and visual responses, as they remain unaffected after exposure to a potent stressor. We also show that feeding reoccurs when basal levels of cortisol (stress hormone in humans and teleosts) are re-established. The results present evidence that the onset of stress can switch off the drive for feeding very early in vertebrate development, and add a novel endpoint for analyses of metabolic and behavioral disorders in an organism suitable for high-throughput genetics and non-invasive brain imaging.

No MeSH data available.


Related in: MedlinePlus