Maternal temperature exposure impairs emotional and cognitive responses and triggers dysregulation of neurodevelopment genes in fish

Fish are sensitive to temperature, but the intergenerational consequences of maternal exposure to high temperature on offspring behavioural plasticity and underlying mechanisms are unknown. Here we show that a thermal maternal stress induces impaired emotional and cognitive responses in offspring rainbow trout (Oncorhynchus mykiss). Thermal stress in mothers triggered the inhibition of locomotor fear-related responses upon exposure to a novel environment and decreased spatial learning abilities in progeny. Impaired behavioural phenotypes were associated with the dysregulation of several genes known to play major roles in neurodevelopment, including auts2 (autism susceptibility candidate 2), a key gene for neurodevelopment, more specifically neuronal migration and neurite extension, and critical for the acquisition of neurocognitive function. In addition, our analysis revealed the dysregulation of another neurodevelopment gene (dpysl5) as well as genes associated with human cognitive disorders (arv1, plp2). We observed major differences in maternal mRNA abundance in the eggs following maternal exposure to high temperature indicating that some of the observed intergenerational effects are mediated by maternally-inherited mRNAs accumulated in the egg. Together, our observations shed new light on the intergenerational determinism of fish behaviour and associated underlying mechanisms. They also stress the importance of maternal history on fish behavioural plasticity

Brief Exposure to Sensory Cues Elicits Stimulus-Nonspecific General Sensitization in an Insect

The effect of repeated exposure to sensory stimuli, with or without reward is well known to induce stimulus-specific modifications of behaviour, described as different forms of learning. In recent studies we showed that a brief single pre-exposure to the female-produced sex pheromone or even a predator sound can increase the behavioural and central nervous responses to this pheromone in males of the noctuid moth Spodoptera littoralis. To investigate if this increase in sensitivity might be restricted to the pheromone system or is a form of general sensitization, we studied here if a brief pre-exposure to stimuli of different modalities can reciprocally change behavioural and physiological responses to olfactory and gustatory stimuli. Olfactory and gustatory pre-exposure and subsequent behavioural tests were carried out to reveal possible intra- and cross-modal effects. Attraction to pheromone, monitored with a locomotion compensator, increased after exposure to olfactory and gustatory stimuli. Behavioural responses to sucrose, investigated using the proboscis extension reflex, increased equally after pre-exposure to olfactory and gustatory cues. Pheromone-specific neurons in the brain and antennal gustatory neurons did, however, not change their sensitivity after sucrose exposure. The observed intra- and reciprocal cross-modal effects of pre-exposure may represent a new form of stimulus-nonspecific general sensitization originating from modifications at higher sensory processing levels

Tester les capacités cognitives des animaux d'élevage pour appréhender leur univers mental

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Conséquences de l'âge au sevrage sur les réactions émotionnelles des porcelets

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Influence de la mixité et de la familiarité dans le groupe sur le comportement agressif des porcelets sevrés à 28 jours

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Consequences of weaning piglets at 21 and 28 days on growth, behaviour and hormonal responses

International audienceA recent European Directive raised the minimum weaning age of piglets to 28 days, although weaning at 21 days is still allowed (but not necessarily practiced) in batch breeding conditions. The aim of the present study was to determine the consequences of weaning at 3 and 4 weeks on animal weight gain, behaviour and stress neuro-endocrine responses, compared to sow-reared piglets. Three groups of Large-White piglets were compared: six litters of seven to eight piglets weaned at 21 days (W21 group), six litters of seven to eight piglets weaned at 28 days (W28 group) and six litters of eight suckling piglets reared by the sow for 40 days (C group). Piglets were regularly weighed from birth to 75 days. Each weaned group was observed for 2 h/day for 7 days (between d − 1 and d + 12 after weaning) at the same time as the control group. The specific behavioural parameters assessed by direct observation were position, activity and social interaction. Urine was collected to measure glucocorticoid (cortisol and cortisone) and catecholamine (adrenaline and noradrenaline) levels. Compared to nursed piglets, weaning at 21 or 28 days induced a reduction in growth rate, as well as behavioural and hormonal changes. Early behavioural changes included an increase of vocalisations and of lying in litter cohesion; later changes included an increase of aggressive and nosing behaviour. Endocrine changes included a reduction in catecholamine (mainly noradrenaline) and cortisone levels in urine. Comparison of W21 and W28 showed that some of these changes were more intense and lasted longer with early weaning. Endocrine changes and certain behaviour (litter cohesion, vocalisations) could be related to food intake deficits, as measured by the greater reduction in growth rate in early-weaned animals. Changes in active behaviour (increase of aggressive and nosing behaviour) appeared earlier after weaning in the youngest animals. This study shows that weaning at 21 days has more negative consequences on growth rate and stress endocrine responses than weaning at 28 days. However, piglets weaned at both 21 and 28 days showed behavioural disturbances, but often with different kinetics

Agonistic behaviour of piglets reduced by single-sex grouping at weaning

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Egg cortisol exposure enhances fearfulness in larvae and juvenile rainbow trout

We investigated the effects of an early boost of cortisol exposure inrainbow trout (Oncorhynchus mykiss) eggs during fertilisation on subsequentbehavioural responses when exposed to a sudden stimulus in larvaeand juveniles. At 55 d post-fertilisation (dpf), treatment had no effect onhigh accelerations occurring after a sudden event. At 146 dpf, these highaccelerations were more frequent in cortisol-treated fish than in controls.At 146 dpf also, swimming activity was increased in cortisol-treated fishboth before and after the sudden stimulus. This study underlines theimportant behavioural modifications in both larvae and juveniles, linkedto a change in the surrounding environment of the embryo. Indeed, fishexposed to cortisol as eggs showed a higher level of fearfulness later in life.Our findings are of major interest for stress management in an aquaculturecontext and also allow for a better understanding of the long-lastingeffects of a permanent and/or acute stress – mediated by cortisol – thatcould be encountered by females, affecting population’s life historytrajectory

Grouper les porcelets par sexe au sevrage réduit les comportements agressifs

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Evaluation de l'importance relative des changements d'environnement et/ou de groupe social au sevrage chez le porcelet : mesures comportementales, zootechniques et hormonales

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