Exposure to stress can affect the establishment of dominance hierarchies. In our model, a social hierarchy established by two male rats during a first encounter is not maintained 1 week later. If one of the two rats is stressed, the stressed rat becomes subordinate and the hierarchy that is formed is maintained. In this study, we investigated the changes in the expression of oxytocin (Otr) and vasopressin (V1aR) receptor genes in the medial amygdala (MeA) and the lateral septum (LS) in the hours following hierarchy establishment under both stressed and basal conditions. We found that the potentiation of a social hierarchy induced by stress is accompanied by social status- and region-specific changes in the expression of Otr mRNA in the MeA 3 h after the social encounter. At this time point, no evidence was found for the regulation of V1aR mRNA in any of the brain regions examined. Results from pharmacological experiments involving the microinfusion of a specific OTR antagonist immediately after the acquisition of a subordinate status under basal, non-stress conditions suggested a role for this receptor in the MeA on the long-term establishment of the subordinate status. Altogether, these findings highlight a role for the oxytocinergic system in the mechanisms through which stress facilitates the long-term establishment of a social hierarchy.

Stress can affect the establishment and maintenance of social hierarchies. In the present study, we investigated the role of increasing corticosterone levels before or just after a first social encounter between two rats of a dyad in the establishment and the long-term maintenance of a social hierarchy. We show that pre-social encounter corticosterone treatment does not affect the outcome of the hierarchy during a first encounter, but induces a long-term memory for the hierarchy when the corticosterone-injected rat becomes dominant during the encounter, but not when it becomes subordinate. Post-social encounter corticosterone leads to a long-term maintenance of the hierarchy only when the subordinate rat of the dyad is injected with corticosterone. This corticosterone effect mimics previously reported actions of stress on the same model and, hence, implicates glucocorticoids in the consolidation of the memory for a recently established hierarchy.

Citation for published version (APA): Havekes, R., Timmer, M., & Van der Zee, E. A. (2007). Regional differences in hippocampal PKA immunoreactivity after training and reversal training in a spatial Y-maze task. Hippocampus, 17(5), 338-348. https://doi.org/10.1002/hipo.20272 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. It is suggested that the hippocampus functions as a comparator by making a comparison between the internal representation and actual sensory information from the environment (for instance, comparing a previously learned location of a food reward with an actual novel location of a food reward in a Y-maze). However, it remains unclear to what extent the various hippocampal regions contribute to this comparator function. One of the proteins known to be crucially involved in the formation of hippocampus-dependent long-term memory is the adenosine 3 0 ,5 0 cyclic monophosphate dependent protein kinase (PKA). Here, we examined region-specific changes in immunoreactivity (ir) of the regulatory IIa,b subunits of PKA (PKA RIIa,b-ir) in the hippocampus during various stages of spatial learning in a Y-maze reference task. Thereafter, we compared changes in hippocampal PKA RIIa,b-ir induced by training and reversal training in which the food reward was relocated to the previously unrewarded arm. We show that: (1) There was a clear correlation between behavioral performance and elevated PKA RIIa,b-ir during the acquisition phase of both training and reversal training in area CA3 and dentate gyrus (DG), (2) PKA RIIa,b-ir was similarly enhanced in area CA1 during the acquisition phase of reversal training, but did not correlate with behavioral performance, (3) PKA RIIa,b-ir did not change during training or reversal training in the subiculum (SUB), (4) No changes in PKA RIIa,b protein levels were found using Western blotting, and (5) AMPA receptor phosphorylation at serine 845 (S845p; the PKA site on the glutamate receptor 1 subunit (GluR1)), was enhanced selectively during the acquisition phase of reversal training. These findings reveal that training and reversal training induce region-specific changes in hippocampal PKA RIIa,b-ir and suggest a differential involvement of hippocampal subregions in match-mismatch detection in case of Y-maze reference learning. Alterations in AMPA receptor regulation at the S845 site seems specifically related to the novelty detector function of the hippocampus important for match...

In about one-third of vignette cases, inflammatory bowel disease treatment propositions made by practicing gastroenterologists diverged from expert recommendations. Practicing gastroenterologists may experience difficulty in applying recommendations in daily practice.

This paper reviews how multi-facility observations are coordinated today and concludes that the process will be insufficient for the flood of transient follow-up campaigns expected in the era of gravity wave, cosmic ray and neutrino detectors, and the LSST. Improvement is also required in the coordinated observation of steady sources, and in the optimization of synchronized surveys.Study of the efforts currently underway to resolve the problems shows much good work but a lack of overall coordination. We suggest that, even without a master plan, the various separate components that have been built, plus new ones not yet considered, could be assembled to make a web 'platform' that would be a useful aid to coordinated observing in the future.A pilot use-case is used to develop a plan for that platform and a simplified prototype has been constructed.