TY - JOUR
T1 - Acute exposure of rats to a severe stressor alters the circadian pattern of corticosterone and sensitizes to a novel stressor
T2 - Relationship to pre-stress individual differences in resting corticosterone levels
AU - Belda, Xavier
AU - Fuentes, Silvia
AU - Labad, Javier
AU - Nadal, Roser
AU - Armario, Antonio
N1 - Funding Information:
This work was supported by Spanish grants to AA and/or RN from Ministerio de Economía y Competitividad ( SAF2017-83430-R ) and Generalitat de Catalunya ( SGR2017-457 ). RN was a recipient of an ICREA-ACADEMIA award (Generalitat de Catalunya, 2015–2019). JL received an Intensification of the Research Activity Grant by the Health Department of the Generalitat de Catalunya (SLT006/17/00012; 2018-2019). The UAB animal facility received funding from 2015FEDER7S-20IU16-001945.
Publisher Copyright:
© 2020 Elsevier Inc.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/11
Y1 - 2020/11
N2 - Traumatic events have been proposed to be associated with hypo-activity of the hypothalamic-pituitary-adrenal (HPA) axis, but data in animal models exposed to severe stressors are controversial and have important methodological concerns. Individual differences in resting or stress levels of corticosterone might explain some of the inconsistencies. We then studied this issue in male rats exposed to 2 h immobilization on boards (IMO), a severe stressor. Thirty-six rats were blood sampled under resting conditions four times a day on three non-consecutive days. Then, they were assigned to control (n = 14) or IMO (n = 22) to study the HPA response to IMO, the stressor-induced alterations in the circadian pattern of corticosterone (CPCORT), and the behavioral and HPA responsiveness to an open-field. Individual differences in pre-IMO resting corticosterone were inconsistent, but averaging data markedly improved consistency. The CPCORT was markedly altered on day 1 post-IMO (higher trough and lower peak levels), less altered on day 3 and apparently normal on day 7. Importantly, when rats were classified in low and high resting corticosterone groups (LCORT and HCORT, respectively), on the basis of the area under the curve (AUC) of the averaged pre-IMO data, AUC differences between LCORT and HCORT groups were maintained in controls but disappeared in IMO rats during the post-IMO week. Open-field hypo-activity and corticosterone sensitization were similar in LCORT and HCORT groups nine days after IMO. A single IMO exposure causes long-lasting HPA alterations, some of them dependent on pre-stress resting corticosterone levels, with no evidence for post-IMO resting corticosterone hypo-activity.
AB - Traumatic events have been proposed to be associated with hypo-activity of the hypothalamic-pituitary-adrenal (HPA) axis, but data in animal models exposed to severe stressors are controversial and have important methodological concerns. Individual differences in resting or stress levels of corticosterone might explain some of the inconsistencies. We then studied this issue in male rats exposed to 2 h immobilization on boards (IMO), a severe stressor. Thirty-six rats were blood sampled under resting conditions four times a day on three non-consecutive days. Then, they were assigned to control (n = 14) or IMO (n = 22) to study the HPA response to IMO, the stressor-induced alterations in the circadian pattern of corticosterone (CPCORT), and the behavioral and HPA responsiveness to an open-field. Individual differences in pre-IMO resting corticosterone were inconsistent, but averaging data markedly improved consistency. The CPCORT was markedly altered on day 1 post-IMO (higher trough and lower peak levels), less altered on day 3 and apparently normal on day 7. Importantly, when rats were classified in low and high resting corticosterone groups (LCORT and HCORT, respectively), on the basis of the area under the curve (AUC) of the averaged pre-IMO data, AUC differences between LCORT and HCORT groups were maintained in controls but disappeared in IMO rats during the post-IMO week. Open-field hypo-activity and corticosterone sensitization were similar in LCORT and HCORT groups nine days after IMO. A single IMO exposure causes long-lasting HPA alterations, some of them dependent on pre-stress resting corticosterone levels, with no evidence for post-IMO resting corticosterone hypo-activity.
KW - Aggregated data
KW - Circadian rhythm
KW - Hypercorticosteronemia
KW - Hypocorticosteronemia
KW - Hypothalamic-pituitary-adrenal axis
KW - Immobilization stress
KW - Individual differences
KW - PTSD
UR - http://www.scopus.com/inward/record.url?scp=85092060099&partnerID=8YFLogxK
U2 - 10.1016/j.yhbeh.2020.104865
DO - 10.1016/j.yhbeh.2020.104865
M3 - Article
C2 - 32991887
AN - SCOPUS:85092060099
SN - 0018-506X
VL - 126
JO - Hormones and Behavior
JF - Hormones and Behavior
M1 - 104865
ER -