Maternal programming of offspring hypothalamic-pituitary-interrenal axis in wild sockeye salmon (Oncorhynchus nerka)

- Functioning of the progeny HPI axis is influenced by maternal stressor exposure.
- The cortisol response of progeny reared from stressed mothers was attenuated.
- These progeny also had higher constitutive mRNA abundance of MC2R, StAR and GR2.

In fishes, maternal exposure to a stressor can influence offspring size and behavior. However, less is known about how maternal stress influences physiological processes in offspring, such as function of the hypothalamic-pituitary-interrenal (HPI) axis. We examined the impact of chronic maternal exposure to an acute chase stressor on the stress response/HPI activity of progeny in wild sockeye salmon (Oncorhynchus nerka). Resting plasma cortisol and brain preoptic area (POA) corticotropin-releasing factor (CRF) mRNA levels did not vary between offspring reared from undisturbed, control females and offspring reared from females exposed to the stressor. However, resting levels of POA glucocorticoid receptors (GR1 and GR2), and head kidney melanocortin 2 receptor (MC2R), steroidogenic acute regulatory protein (StAR), and cytochrome P450 side chain cleavage enzyme (P450scc) were elevated in offspring reared from stressor-exposed females. Offspring reared from stressor-exposed females had lower plasma cortisol levels 1-h after an acute chase stressor compared to cortisol levels in offspring reared from control females. In offspring reared from chased females, mRNA levels of genes associated with cortisol biosynthesis were reduced in the head kidney post-chase. In offspring reared from control females, mRNA levels in the head kidney did not vary pre- to post-chase. Together, the results of the present study suggest maternal programming of progeny with respect to baseline and stressor-induced mediators of HPI axis activity.