Adaptation of the hypothalamic-pituitary-adrenal axis and glucose to repeated immobilization or restraint stress is not influenced by associative signals

Cristina Rabasa, Raúl Delgado-Morales, Cristina Muñoz-Abellán, Roser Nadal, Antonio Armario

Research output: Contribution to journalReview articleResearchpeer-review

17 Citations (Scopus)

Abstract

Repeated exposure to the same stressor very often results in a reduction of some prototypical stress responses, namely those related to the hypothalamic-pituitary-adrenal (HPA) and sympatho-medullo-adrenal (SMA) axes. This reduced response to repeated exposure to the same (homotypic) stressor (adaptation) is usually considered as a habituation-like process, and therefore, a non-associative type of learning. However, there is some evidence that contextual cues and therefore associative processes could contribute to adaptation. In the present study we demonstrated in two experiments using adult male rats that repeated daily exposure to restraint (REST) or immobilization on boards (IMO) reduced the HPA (plasma levels of ACTH and corticosterone) and glucose responses to the homotypic stressor and such reduced responses remained intact when all putative cues associated to the procedure (experimenter, way of transporting to the stress room, stress boxes, stress room and colour of the restrainer in the case of REST) were modified on the next day. Therefore, the present results do not favour the view that adaptation after repeated exposure to a stressor may involve associative processes related to signals predicting the imminence of the stressors, but more studies are needed on this issue. © 2010 Elsevier B.V.
Original languageEnglish
Pages (from-to)232-239
JournalBehavioural Brain Research
Volume217
Issue number1
DOIs
Publication statusPublished - 2 Feb 2011

Keywords

  • ACTH
  • Classical conditioning
  • Context
  • Corticosterone
  • Habituation
  • HPA axis

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