Serotonergic characteristics of rainbow trout divergent in stress responsiveness

In stream-spawning salmonid fishes there is a considerable variation in the timing of when fry leave the spawning nests and establish a feeding territory. The timing of emergence from spawning nests appears to be related to behavioural and physiological traits, e.g. early emerging fish are bolder and more aggressive. In the present study, emerging Atlantic salmon (Salmo salar L.) alevins were sorted into three fractions: early, intermediate and late emerging. At the parr stage, behaviour, stress responses, hindbrain monoaminergic activity and forebrain gene expression were explored in fish from the early and late emerging fractions (first and last 25%). The results show that when subjected to confinement stress, fish from the late emerging fraction respond with a larger activation of the brain serotonergic system than fish from the early fraction. Similarly, in late emerging fish, stress resulted in elevated expression of mRNA coding for serotonin 1A receptors (5-HT 1A ), GABA-A receptor-associated protein and ependymin, effects not observed in fish from the early emerging fraction. Moreover, fish from the early emerging fraction displayed bolder behaviour than their late emerging littermates. Taken together, these results suggest that time of emergence, boldness and aggression are linked to each other, forming a behavioural syndrome in juvenile salmon. Differences in brain gene expression between early and late emerging salmon add further support to a relationship between stress coping style and timing of emergence. However, early and late emerging salmon do not appear to differ in hypothalamus-pituitary-interrenal (HPI) axis reactivity, another characteristic of divergent stress coping styles.

Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Natural selection constrains personality and brain gene expression differences in Atlantic salmon (Salmo salar)

Thörnqvist

Höglund

Winberg

2015

“…lower post-stress cortisol), as well as lower brain serotonergic and higher dopaminergic activity, while reactive individuals exhibit the opposite behavioural and physiological profile (Koolhaas et al, 2007(Koolhaas et al, , 2010(Koolhaas et al, , 1999. Notably, while differences between coping styles in terms of behaviour, hypothalamic-pituitary-interrenal (HPI) axis reactivity (the fish's HPA equivalent) and monoaminergic activity in multifunctional brain regions, such as the telencephalon, hypothalamus and brainstem, have been reported in fish (Johansen et al, 2012;Schjolden et al, 2006;Silva et al, 2014;Øverli et al, 2001, 2007, a more precise, region-specific, characterisation of telencephalic areas is still lacking. Region-specific studies of functional subdivisions and limbic nuclei are notoriously difficult in fish, as a result of their relatively small size.…”

Section: Introductionmentioning

confidence: 99%

How do individuals cope with stress? Behavioural, physiological and neuronal differences between proactive and reactive coping styles in fish

Vindas

Gorissen

Höglund

et al. 2017

Despite the use of fish models to study human mental disorders and dysfunctions, knowledge of regional telencephalic responses in nonmammalian vertebrates expressing alternative stress coping styles is poor. As perception of salient stimuli associated with stress coping in mammals is mainly under forebrain limbic control, we tested regionspecific forebrain neural (i.e. mRNA abundance and monoamine neurochemistry) and endocrine responses under basal and acute stress conditions for previously characterised proactive and reactive Atlantic salmon. Reactive fish showed a higher degree of the neurogenesis marker proliferating cell nuclear antigen ( pcna) and dopamine activity under basal conditions in the proposed hippocampus homologue (Dl) and higher post-stress plasma cortisol levels. Proactive fish displayed higher post-stress serotonergic signalling (i.e. higher serotonergic activity and expression of the 5-HT 1A receptor) in the proposed amygdala homologue (Dm), increased expression of the neuroplasticity marker brain-derived neurotropic factor (bdnf ) in both Dl and the lateral septum homologue (Vv), as well as increased expression of the corticotropin releasing factor 1 (crf 1 ) receptor in the Dl, in line with active coping neuro-profiles reported in the mammalian literature. We present novel evidence of proposed functional equivalences in the fish forebrain with mammalian limbic structures.

“…The role of most of these elements is well known, whereas the function of some others, such as the brain monoaminergic neurotransmitters, is not yet clear. For instance, the activity of central monoaminergic systems increases after exposure to different types of stressors, such as handling, isolation, predator exposure, pollutant exposure or crowding (Gesto et al, 2008;Gesto et al, 2009;Schjolden et al, 2006;Weber et al, 2012;Winberg and Nilsson, 1993), with the response of the serotonergic activity being especially consistent. However, the causes and consequences of these increased activities within the stress response along with the dynamics of the monoaminergic response to stress are not well known.…”

Section: Introductionmentioning

confidence: 99%

The response of brain serotonergic and dopaminergic systems to an acute stressor in rainbow trout: a time-course study

Gesto

López‐Patiño

Hernández

et al. 2013

114

SUMMARYThe brain monoaminergic neurotransmitter systems are known to be involved in the integrated response to stress in vertebrates. However, present knowledge about the timing of their actions as well as their specific roles in the regulation of the endocrine axes that drive the stress response is incomplete. This is partly because of the complexity of the reciprocal interactions among the monoaminergic systems and other biochemical effectors of the stress response such as corticotropin-releasing factor (CRF), arginine vasotocin (AVT), adrenocorticotropic hormone (ACTH) and corticosteroids. In this study, we show for the first time in teleost fish (rainbow trout) the short-and mid-term time course of the response of the forebrain serotonergic and dopaminergic activities after exposure to an acute stressor. Other stress markers like the plasma levels of cortisol, glucose and lactate were also monitored, providing a context in which to precisely locate the monoaminergic activation within the fish acute stress response. Our results show that acute stress induced a rapid increase in forebrain serotonergic activity, which became elevated after only 15 s of chasing. Several hours after stress, serotonergic activity recovered its basal levels, in parallel with the recovery of other stress markers such as plasma catecholamines and cortisol. Dopaminergic activity was also increased after stress, but only in the telencephalon and only after 20 min. The increase in serotonergic activity happened before the elevation of plasma catecholamines, suggesting that this monoamine system could have a key role in triggering the initial steps of the activation of not only the hypothalamus-pituitary-inter-renal axis but also the brain-sympathetic-chromaffin axis in fish. Supplementary material available online at