Corticosterone levels reflect variation in metabolic rate, independent of ‘stress’

Abstract

Variation in glucocorticoid hormones (GCs) is often interpreted as reflecting ‘stress’, but this interpretation is subject of intense debate. GCs induce gluconeogenesis, and we hypothesized therefore that GC variation can be explained by changes in current and anticipated metabolic rate (MR). Alternatively, GC levels may respond to psychological ‘stress’ over and above its effect on metabolic rate. We tested these hypotheses in captive zebra finches, by inducing an increase in MR using a psychological stressor (noise), and compared its effect on corticosterone (CORT, the primary avian GC) with the effect induced by a decrease in ambient temperature increasing MR to a similar extent. We found the increase in CORT induced by the psychological stressor to be indistinguishable from the level expected based on the noise effect on MR. We further found that a handling and restraint stressor that increased CORT levels also resulted in increased blood glucose levels, corroborating a key assumption underlying our hypothesis. Thus, GC variation primarily reflected variation in energy expenditure, independently of psychological stress. GC levels have many downstream effects besides glucose mobilization, and we propose that these effects can be interpreted as adjustments of physiological functions to the metabolic level at which an organism operates.

Zebra finches show spatial avoidance of near but not far distance traffic noise

“…Without being able to pinpoint down the lowest threshold of negative impact yet, the combined evidence from our and other studies suggests that for sound levels from 70 dB(A) and higher (<15 m to the highway), traffic noise may affect communication, foraging, physiology and reproduction (Cynx et al, 1998;Potvin & MacDougall-Shackleton, 2015;Potvin et al, 2016;Villain et al, 2016;Dorado-Correa et al, 2018). Wild birds of other species that were chronically exposed to anthropogenic noise were found to have altered glucocorticoid levels (Kleist et al, 2018; but see Crino et al, 2013), which in turn will raise energy demands (Jimeno et al, 2018). In combination with raised vigilance levels in noisy conditions (Quinn et al, 2006;Chan et al, 2010), this may further impact fitness prospects in noisy areas.…”

Effects of early life glucocorticoid exposure on metabolism in zebrafish (Danio rerio) larvae

“…Earlier we have observed that following cortisol (van den Bos et al, 2019a), but not dexamethasone (Althuizen, 2019a) treatment, baseline levels of cortisol were higher, suggesting higher baseline HPI-axis activity. Higher levels of cortisol have been shown to be associated with higher levels of oxygen consumption or metabolic rate (De Boeck et al, 2001;Jimeno et al, 2017Jimeno et al, , 2018, which could explain the data. As this is normally also associated with increased levels of glucose through stimulation of GR (De Boeck et al, 2001;Jimeno et al, 2017Jimeno et al, , 2018Wendelaar Bonga 1997) we expected increased expression of genes related to gluconeogenesis and glucose transport.…”

“…In earlier experiments we have found that at 5 days post-fertilisation (dpf) baseline cortisol levels are increased following cortisol treatment for 6 hours post fertilisation (hpf) but not following dexamethasone (a potent GR-agonist (Rupprecht et al, 1993) to assess the role of GR more specifically) treatment (Althuizen, 2018;van den Bos et al, 2019a), suggesting a higher hypothalamus-pituitary-interrenal cells (HPI-axis) activity. Higher cortisol levels have been shown to be associated with increased respiration rate (oxygen consumption and CO 2 production) and plasma glucose levels through stimulation of GR (De Boeck et al, 2001;Jimeno et al, 2017Jimeno et al, , 2018Wendelaar Bonga, 1997). Hence, we hypothesized that oxygen consumption and gene-expression were stronger in cortisol-treated than in control-treated or dexamethasone-treated subjects at 5 dpf.…”

Investigating the behaviors of corticosterone hormone in different solvents by using DFT calculations and experimental data

“…Reasonable correlations were found among the predicted IR, Raman and UV spectra with the corresponding experimental ones [56]. The calculations of gap values [54] and some descriptors were performed, as suggested by Parr and Pearson [59][60][61][62][63][64][65][66][67][68], because the prediction of reactivities and behaviours in the three media are of interest for this hormone with anti-inflammatory and immunosuppressive properties [20,21,23,27,[30][31][32][35][36][37][39][40][41][42][43][44].…”

“…The IUPAC name of corticosterone is (11β)-11,21-dihydroxypregn-4-ene-3,20-dione although it is also known as 11β,21-dihydroxyprogesterone or simply as 17-deoxycortisol . The adrenal gland produces this hormone with antiinflammatory and immunosuppressive properties [20,21,23,27,[30][31][32][35][36][37][39][40][41][42][43][44]. So far, there are a lot of articles related to structural, chemical and biological studies on glucocorticoids, from experimental studies by using spectroscopic and electrochemical techniques up to different theoretical studies because these species present dual regulation effects on the immune function which are strongly dependent on the concentration.…”