Neural plasticity is affected by stress and heritable variation in stress coping style

Here we use a comparative model to investigate how behavioral and physiological traits correlate with neural
plasticity. Selection for divergent post-stress cortisol levels in rainbow trout (Oncorhynchus mykiss) has
yielded low- (LR) and high responsive (HR) lines. Recent reports show low behavioral flexibility in LR compared
to HR fish and we hypothesize that this divergence is caused by differences in neural plasticity. Genes
involved in neural plasticity and neurogenesis were investigated by quantitative PCR in brains of LR and HR
fish at baseline conditions and in response to two different stress paradigms: short-term confinement (STC)
and long-term social (LTS) stress. Expression of proliferating cell nuclear antigen (PCNA), neurogenic differentiation
factor (NeuroD) and doublecortin (DCX) was generally higher in HR compared to LR fish. STC stress
led to increased expression of PCNA and brain-derived neurotrophic factor (BDNF) in both lines, whereas LTS
stress generally suppressed PCNA and NeuroD expression while leaving BDNF expression unaltered. These
results indicate that the transcription of neuroplasticity-related genes is associated with variation in coping
style, while also being affected by STC – and LTS stress in a biphasic manner. A higher degree of neural plasticity
in HR fish may provide the substrate for enhanced behavioral flexibility