CIE Spotlight: Acute stress decreases corticosterone-binding globulin for 24 hours and a second stressor during this time increases sleep disruptions in Mountain White-crowned Sparrows

Ondi C.
Ondi C.

Title: Acute stress decreases corticosterone-binding globulin for 24 hours and a second stressor during this time increases sleep disruptions in Mountain White-crowned Sparrows

Authors: Malisch, J. L.; Johnson, E.; Doan, P.; Tang, A.; Humphries, T. J.; Crino, O. L.; Breuner, C. W.

Source: INTEGRATIVE AND COMPARATIVE BIOLOGY, 56 E136-E136; 1 MAR 2016

Brief summary of the paper: Corticosterone-binding globulin (CBG) is a potential potent modulator of the glucocorticoid (GC) response to stress. CBG binds the majority of circulating GCs, increasing GC solubility in plasma, while potentially sequestering GCs from receptors.

For a given concentration of GC, higher CBG levels reduce free GC (unbound) while lower CBG levels increase free GC levels, and therefore increase GC binding to receptors. CBG levels can fluctuate acutely (within 60 min) in some species, while other species have a delayed CBG response to acute stress.

24 hours following standardized stressors, both rats and Japanese quail have a significant reduction in circulating free GC, leading to a significant increase in free baseline GC a full 24 hours after the acute stressor.

Here we examine the effect of acute stress on GC, CBG, and free GC over a longer timeframe, up to 72 hours following the stressor in a free-living vertebrate, the Mountain White-crowned Sparrow, Zonatrichia oriantha leucophrys (WCSP).

We found a decrease in CBG and an increase in free GC 24 hours following acute stress. We also explored potential behavioral ramification of experiencing a second stressor while CBG is depressed. WCSP acutely stressed twice within 24 hours had an increase in the number of sleep disruptions compared to a single-stressor. Furthermore, WCSP acutely stressed prior to inclement weather also experienced more sleep disruptions as compared to WCSP that were not acutely stressed prior to the storm.

This research is particularly relevant because of climate change with increased frequency and intensity of snow storms later into the WCSP breeding season.