Expression patterns of c-Fos early gene and phosphorylated ERK in the rat brain following 1-h immobilization stress: concomitant changes induced in association with stress-related sleep rebound

Abstract

An immobilization stress (IS) of 1 h applied at the beginning of the dark phase is followed by a sleep rebound. During the restraint, serotonin released by the dorsal raphe nucleus within the arcuate area stimulates the availability of corticotropin-like intermediate lobe peptide (CLIP or ACTH18-39). Three hours after the restraint, CLIP, through its hypnogenic properties, contributes to the sleep rebound that follows the IS. Here, we immunohistochemically evaluated protein expression of the immediate early gene, c-Fos and phosphorylated extracellular signal-regulated kinase (p-ERK) in hypothalamic (preoptic area [POA], paraventricular nucleus [PVN], arcuate nucleus [ARC]) and brain stem (dorsal raphe [DR], locus coeruleus [LC]) nuclei involved in the acute response to stress and the subsequent stress-related sleep rebound (recovery period). Immediately after the 1-h restraint, c-Fos and p-ERK expression increased in all structures studied, particularly in PVN and LC. Three hours later, the number of p-ERK- and c-Fos-positive neurons was reduced in PVN and LC (p < 0.001) as well as in DR (p < 0.01) compared to control animals. In contrast, both c-Fos and p-ERK expression in POA neurons (p < 0.01) and c-Fos expression in ARC neurons (p < 0.001) were increased 3 h after the IS. The marked activation observed in PVN and LC nucleus immediately after the IS confirms that these structures are clearly reactive to stress. However, the high activity observed in POA and ARC neurons during the recovery period, not described to date, highlights the particular part played by these structures in the stress-related sleep rebound. An unbalance in the above processes may contribute to pathological outcomes, such as anxiety and depression.

Conditioned effects of ethanol on the immune system

“…C-Fos is a general marker of neural activity and the PVN is a key structure in the regulation of autonomic responses to stress and aversive stimulation, and also shows changes after chronic ethanol exposure. Keshavarzy et al 42 and Acevedo et al 43 observed significant Fos immunoreactivity in the PVN after a single exposure to restraint stress, whereas Lee et al 44 found increased levels of NGFIB, a protein involved in inflammatory processes, after chronic vapor ethanol exposure. Chronic ethanol treatment in Experiment 3 did not induce specific changes in C-Fos activity in the PVN, but reduced C-Fos levels in HPC, when given intraperitoneally.…”

Localisation and stress-induced plasticity of GABAA receptor subunits within the cellular networks of the mouse dorsal raphe nucleus

“…With a view to investigating potential GABA A R plasticity in adaptive, rather than maladaptive responses to stressful experiences, we deliberately used a mild restraint stress protocol which does not induce a chronic stress phenotype (Buynitsky and Mostofsky 2009) nor anxiogenic-like behaviour (Seifi et al 2014). However, this protocol has been shown to robustly engage the DRN-serotonergic system, amongst other brain regions (Shoji and Mizoguchi 2010;Keshavarzy et al 2014). Animals were divided into stress and control experimental groups 1 week prior to the start of the experiment in order to allow adaptation to the new cage environment before commencing the stress.…”

ERK1/2 Phosphorylation in the Rat Supraoptic Nucleus, Dorsal Raphe Nucleus, and Locus Coeruleus Neurons Following Noxious Stimulation to the Hind Paw

“…Regarding the three areas analyzed in this study, also these areas, the SON, the DRN, and the LC are involved in pain processing [10,11,12,13,18]. The SON and the DRN, as the PVN, are areas where stress and opioid responses converge [7,18,19]. The DRN and the LC, as the PVN, are involved in the descending modulation of nociception [20,21].…”

“…The time course of ERK1/2 staining in response to a noxious thermal stimulation of the rat hind paw has been documented, appearing within minutes and lasting for more than 30 min [3]. Overall, the advantage of the pERK1/2 histochemistry over c-fos staining is the much faster response we get as compared to the response obtained from the former method [7]. …”