Influence of prior experience with homotypic or heterotypic stressor on stress reactivity in catecholaminergic systems

Abstract

Here we review how prior experience with stress alters the response to a subsequent homotypic or heterotypic stressor, focusing on the catecholaminergic systems in the adrenal medulla and the locus coeruleus (LC). The changes in response to homotypic stress differ depending on the stressor applied. With immobilization stress (IMO), transcriptional responses in the adrenal medulla to a single exposure are pronounced and several of the transcription factors and signaling kinases induced or activated are reviewed and compared to the longer term alterations with repeated stress, consistent with persistent activation of gene expression of catecholamine (CA) biosynthetic enzymes. In the LC, transcriptional and post-transcriptional activation of gene expression are shown to be important. Repeated IMO stress triggers further activation of a number of signalling pathways. Neither adrenal medulla nor LC display habituation to long term repeated stress. In contrast, gene expression for CA biosynthetic enzymes habituates to prolonged cold stress in the adrenal medulla and LC, but displays an exaggerated response with exposure to a novel or heterotypic stressor such as IMO. Some of the transcriptional pathways displaying sensitization are described.

Impaired adrenal medullary function in a mouse model of depression induced by unpredictable chronic stress

“…This effect was not observed in rats under immobilization, in which TH mRNA, protein and activity remained elevated even after 41 stressor exposures (Nankova et al, 1994). Different changes in catecholamine biosynthetic enzymes were also observed when chronically stressed animals were exposed to the same (homotypic) or a novel stressor (heterotypic) (Gavrilovic et al, 2008(Gavrilovic et al, , 2013Sabban and Serova, 2007). Nevertheless, an increase in adrenal medulla size induced by chronic stress is often associated with increases in expression, synthesis and activity of catecholamine biosynthetic enzymes [see Kvetnansky et al (2009) for review].…”

“…On the other hand, long time and/or repeated immobilization induce robust and sustained activation of TH, DβH and PNMT mRNA levels, with concomitant increases in protein and enzyme activity, which remain elevated for a long time even after termination of stress stimuli [see Kvetnansky et al (2009) for review]. The activation of adrenal medullary catecholaminergic system also showed to be stressor specific (Sabban and Serova, 2007). For example, cold stress induced an increase of TH mRNA, protein and enzyme activity that returned to baseline after 28 days of exposure to the same stressor (Baruchin et al, 1990).…”

Functional Remodeling of Gap Junction-Mediated Electrical Communication between Adrenal Chromaffin Cells in Stressed Rats

“…As reported previously (Ma and Morilak, 2005;Sabban and Serova, 2007), cold stress exposure sensitizes catecholaminergic systems of the adrenal medulla and the locus ceruleus. An upregulated gap-junctional communication between chromaffin cells might be one endogenous mechanism whereby the adrenomedullary system is sensitized.…”

Antidepressant and Proneurogenic Influence of Environmental Enrichment in Mice: Protective Effects vs Recovery

“…Alternatively, it is possible that the animals performed the final Porsolt with an exacerbated response as the consequence of having been exposed to any stressful stimulus, not necessarily the same stimulus. Both of these possibilities have been demonstrated previously (Rau and Fanselow, 2009;Sabban and Serova, 2007). We addressed this question by including enrichment in the process, because it is not clear whether EE sensitizes the brain to novelty (as it is a paradigm of continuously renovated novelty, increasing the ability to cope with further stressors (Fox et al, 2006)), or alternatively, it desensitizes the brain to novelty, so that the animal might develop a higher threshold to the perception of threat in the environment.…”