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Mild Neonatal Hypoxia Modifies the Reactivity of the Glucocorticoid System in Adult Rats, Promoting Improved Learning
Sofiya Potapova1, Diana Safarova2, Ekaterina Tyulkova2
1Laboratory of Regulation of Brain Neuronal Functions, Pavlov Institute of Physiology, Russian Academy of Sciences, Makarova Emb. 6, Saint-Petersburg, 199034, Russia. sofiya-potapova@mail.ru.
Neurochemical Research
|January 7, 2026
Summary
Neonatal hypoxia (NH) acts as conditioning, altering adult stress responses. This study shows NH preconditioning leads to lasting behavioral adaptations and modified hypothalamic-pituitary-adrenal (HPA) regulation in rats.
Area of Science:
- Neuroscience
- Endocrinology
- Developmental Biology
Background:
- Mild neonatal hypoxia (NH) can condition stress systems.
- Understanding long-term effects of early-life stress on HPA axis regulation is crucial.
Purpose of the Study:
- To investigate if neonatal hypobaric hypoxia induces lasting changes in hypothalamic-pituitary-adrenal (HPA) axis regulation and adult behavior in rats.
- To explore the molecular and physiological adaptations following neonatal conditioning.
Main Methods:
- Male Wistar rats underwent three 2-hour hypobaric hypoxia sessions on postnatal days 8-10.
- Adult behavioral tests (startle, Morris water maze, Barnes maze, recognition, forced swim) were performed.
- Biochemical analyses included plasma/adrenal corticosterone (CORT), ACTH, brain CORT, CRH/POMC/GR/11β-HSD2 protein, and gene expression.
Main Results:
- Neonatal hypoxia resulted in a calmer phenotype with increased startle latency and improved memory in the Morris water maze.
- Hypothalamic CRH and pituitary/plasma ACTH were reduced, suggesting post-transcriptional regulation.
- While basal CORT was unchanged, the stress-induced CORT response was larger and sustained; amygdala CORT levels decreased.
Conclusions:
- Neonatal hypoxia acts as developmental preconditioning, inducing persistent behavioral and HPA axis alterations in adulthood.
- Adult rats exhibited reduced resting HPA drive but efficient stress mobilization.
- Findings highlight the long-term adaptive capacity of stress systems to early-life conditioning.
