Hourly Rhythms in Brain Cells Regulate Stress Activation and Deactivation

Recent research conducted by the University of Otago has uncovered a fascinating aspect of brain function related to stress regulation. The study reveals that specific stress-controlling neurons in the brain activate and deactivate in regular, approximately hourly cycles, even when no stressors are present. This rhythmic activity appears to influence overall alertness and activity patterns, acting like a natural wake-up signal that also correlates with increases in stress hormones such as cortisol.

Led by Associate Professor Karl Iremonger from Otago's Department of Physiology and Center for Neuroendocrinology, the research utilized advanced optical techniques, specifically photometry, to monitor brain cell activity in freely moving mice and rats over 24-hour periods. This method involved shining light into various parts of the brain to track neural activity and its relationship with sleep, wakefulness, and hormone levels.

A particular group of neurons, known as corticotropin-releasing hormone (CRH) neurons, were identified as key players in generating these daily stress hormone rhythms. These neurons exhibit a cyclical pattern of activation and suppression roughly once an hour, which aligns with the sleep-wake cycle. Interestingly, artificially stimulating these neurons altered animal behavior, making resting animals more hyperactive.

The findings suggest that these cyclical neural patterns may be central to maintaining normal stress hormone levels and activity rhythms. Disruptions in this rhythm could potentially impact mood and sleep, offering new insights into mental health issues related to stress dysregulation. The research paves the way for future studies on how normal and abnormal stress patterns influence mental health, with potential therapeutic implications. Drugs targeting CRH neuron activity could become useful in treating stress-related disorders.

This pioneering study enhances our understanding of the neural underpinnings of stress regulation and could lead to innovative approaches to managing stress-related conditions and improving overall mental health.

Source: https://medicalxpress.com/news/2025-08-brain-cells-stress-hourly.html