How do individuals cope with stress? Behavioural, physiological and neuronal differences between proactive and...

Area of Science:

• Neuroscience
• Comparative Psychology
• Endocrinology

Background:

• Understanding stress coping mechanisms in non-mammalian vertebrates is crucial for comparative studies of mental health.
• Fish models offer insights into conserved neural pathways underlying stress and behavior.

Purpose of the Study:

• To investigate region-specific forebrain neural and endocrine responses in proactive versus reactive Atlantic salmon under basal and acute stress.
• To explore potential functional equivalences between fish and mammalian limbic systems in stress coping.

Main Methods:

• Characterization of proactive and reactive Atlantic salmon.
• Measurement of neural markers (mRNA abundance, neurochemistry) and plasma cortisol levels.
• Region-specific analysis of forebrain responses in homologues of mammalian limbic structures.

Main Results:

• Reactive fish showed higher neurogenesis marker (proliferating cell nuclear antigen) and dopamine activity in the Dl (hippocampus homologue) and elevated post-stress cortisol.
• Proactive fish displayed enhanced post-stress serotonergic signaling in the Dm (amygdala homologue) and increased brain-derived neurotrophic factor (BDNF) and corticotropin-releasing factor 1 receptor expression in the Dl.
• These findings align with active coping neuro-profiles observed in mammals.

Conclusions:

• Atlantic salmon exhibit distinct regional forebrain adaptations related to their stress coping styles.
• Evidence suggests functional conservation of limbic-like structures and stress response pathways between fish and mammals.
• This study advances our understanding of the neurobiological underpinnings of stress coping across vertebrate evolution.