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Withdrawal from psychostimulants increases anxiety states, and amphetamine-treated rats show increased CRF2 receptors in the serotonergic cell body region, the dorsal raphe nucleus (dRN). In the current study, amphetamine (2.5 mg/kg, ip, 14 days) pre-treated rats spent less time in open arms of the elevated plus maze compared saline pre-treated rats at both 24 hours or 2 weeks of withdrawal, and CRF2 receptor antagonism (ASV-30; 2 μg/0.5 μl) within the dRN reversed the effects of amphetamine withdrawal on anxiety-like behavior. Overall, results suggest that CRF2 receptor antagonism may be a novel pharmacological target for anxiety states during drug withdrawal.

Hypoxia and inflammation are coincidental events in a diverse range of disease states including tumor growth, ischemia, and chronic inflammation. Hypoxia contributes to the development of inflammation, at least in part through the activation and/or potentiation of NF-kappaB, a master regulator of genes involved in innate immunity, inflammation, and apoptosis. NF-kappaB can be activated through two distinct signaling pathways termed the canonical and noncanonical pathways, respectively. The canonical pathway is activated through the IKKalpha/beta/gamma complex, while the noncanonical pathway involves NIK-mediated activation of IKKalpha homodimers. In the current study, we have investigated the relative roles of these two pathways in hypoxia-dependent NF-kappaB activation. Lymphotoxin alpha1beta2 (LTalpha1beta2) activated both the canonical and noncanonical NF-kappaB signaling pathways in HeLa cells. Sustained hypoxia enhanced basal and LTalpha1beta2-induced NF-kappaB activity in a manner that was dependent upon the canonical but not the noncanonical signaling pathway. Intermittent hypoxia activated NF-kappaB in a manner that was also primarily dependent upon the canonical pathway. Knockdown of the p65 subunit of the canonical NF-kappaB pathway was sufficient to abolish the effects of hypoxia on LTalpha1beta2-induced NF-kappaB activity. Furthermore, in synovial biopsies obtained at arthroscopy from patients with active inflammatory arthritis, the canonical pathway was preferentially activated in those patents with lower joint pO2 values. In summary, we hypothesize that hypoxia enhances NF-kappaB activity primarily through affecting the canonical pathway.

NFκB is a master regulator of innate immunity and inflammatory signalling. Microenvironmental hypoxia has long been identified as being coincident with chronic inflammation. The contribution of microenvironmental hypoxia to NFκB-induced inflammation has more recently been appreciated. Identification of the co-regulation of NFκB and hypoxia inducible factor (HIF) pathways by 2-oxoglutarate-dependent hydroxylase family members has highlighted an intimate relationship between NFκB inflammatory signalling and HIF-mediated hypoxic signalling pathways. Adding another layer of complexity to our understanding of the role of NFκB inflammatory signalling by hypoxia is the recent recognition of the contribution of basal NFκB activity to HIF-1α transcription. This observation implicates an important and previously unappreciated role for NFκB in inflammatory disease where HIF-1α is activated. The present review will discuss recent literature pertaining to the regulation of NFκB inflammatory signalling by hypoxia and some of the inflammatory diseases where this may play an important role. Furthermore, we will discuss the potential for prolyl-hydroxylase inhibitors in inflammatory disease. NFκ κBThe transcription factor NFκB has been investigated for its diverse range of functions in innate immunity, stress responses, cell survival and development. It is also the master regulator of the inflammatory response [1]. An in-depth review of the NFκB pathway is beyond the scope of the present article, and there are several excellent reviews dedicated specifically to this topic [2,3].Briefly, the NFκB family comprises five members: p65, Rel B, cRel, p50 and p52. These proteins share a highly conserved Rel homology domain. In order to bind DNA and modulate gene expression, family members form homodimers or heterodimerswith the exception of Rel B, which will only form heterodimers with p50 or p52 [4]. The most commonly encountered dimer complex is the p50-p65 dimer [5]. There are two primary activation pathways for NFκB: the canonical pathway, which is predominantly dependent on inhibitor of κB kinase (IKK) beta, and the IKKα-dependent noncanonical pathway [6].Under resting conditions, NFκB is bound to its co-repressor molecule IκB in the cytosol, with which it interacts through multiple ankyrin repeats. A nuclear localisation sequence of the p65 protein is masked and it remains predominantly sequestered in the cytosolic compartment. Upon stimulation IκBα is phosphorylated at serine 32 and serine 36, targeted for ubiquitination and thereafter degraded proteolytically by the 26S proteosome [7]. A nuclear localisation sequence of NFκB is then revealed, and this is free to translocate and accumulate in the nucleus where it can become transcriptionally active by binding to specific κB sites within the promoter regions of its target genes [8]. The stimulus for IκBα to release the inhibition of NFκB has been identified as phosphorylation by the 700 kDa IKKα/β/γ protein complex.Genes induced by NFκB include those responsible for encodi...

Post-weaning social isolation of rats is utilized as a model of early life stress. We have previously demonstrated that rats exposed to post-weaning social isolation exhibit greater anxiety-like behaviors as adults. Furthermore, these rats exhibit greater density of corticotropin-releasing factor (CRF) type 2 receptors in the dorsal raphe nucleus. Therefore, we examined whether antagonism of CRF2 receptors in the dorsal raphe nucleus reverses the effects of post-weaning social isolation on anxiety states. Male rats were reared in isolation or in groups from day of weaning (postnatal day [PND] 21) to mid-adolescence (PND42) and then allowed to develop to early adulthood housed in groups. At PND62, rats were either infused with vehicle, the CRF1 receptor antagonist antalarmin (0.25-0.5 μg) or the CRF2 receptor antagonist antisauvagine-30 (2 μg) into the dorsal raphe nucleus, 20 minutes prior to being introduced to the elevated plus maze. Isolation-reared rats showed reduced open arm behavior compared to group-reared rats, confirming the anxiogenic effects of post-weaning social isolation. Infusion of the CRF2 receptor antagonist, but not the CRF1 receptor antagonist, into the dorsal raphe nucleus of isolation-reared rats increased open arm behavior when compared to that of group-reared rats. Overall, the findings suggest that CRF2 receptors within the dorsal raphe nucleus mediate anxiety-like states following post-weaning social isolation, and CRF2 receptors may represent an important target for the treatment of anxiety disorders following early life stressors.