Stress‐induced activation of the immediate early gene Arc (activity‐regulated cytoskeleton‐associated protein) is restricted to telencephalic areas in the rat brain: relationship to c‐fos mRNA

Abstract

Stress-induced activation of the immediate early gene Arc (activity-regulated cytoskeleton-associated protein) is restricted to telencephalic areas in the rat brain: relationship to c-fos mRNA Sheila Ons, Octavi Martí and Antonio ArmarioInstitut de Neurociències and Unitat de Fisiologia Animal, Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain AbstractArc is an effector immediate early gene whose expression is induced in situations of increased neuronal activity. However, there is no report on the influence of stress on Arc expression. Here, we compared the induction of both c-fos and Arc mRNAs in the brain of rats exposed to one of three different stressful situations: novel environment, forced swimming and immobilization. An absent or weak c-fos mRNA signal was observed in control rats, whereas those exposed to one of three stressors showed enhanced c-fos expression in a wide range of brain areas. Constitutive Arc expression was observed in some areas such as cortex, striatum, hippocampus, reticular thalamic nucleus and cerebellar cortex. In response to stressors, a strong induction of Arc was observed, but the pattern was different from that of c-fos. For instance, activation of Arc but not c-fos was observed in the nucleus accumbens after immobilization and in the hippocampus after novel environment. No Arc induction was observed in diencephalic and brainstem areas. The present data show that Arc has a neuroanatomically restricted pattern of induction in the brain after emotional stress. Telencephalic activation suggests that a more intense induction of synaptic plasticity is occurring in this area after exposure to emotional stressors.

Cellular and molecular mechanisms of hippocampal activation by acute stress are age-dependent

“…Kim and Diamond, 30 Pavlides et al, 70 Alfarez et al 71 and Blank et al 72 ). Patterns of Fos expression after stress in adult hippocampus have been described by several groups at both mRNA and protein level, [73][74][75][76] and others have distinguished the effects of novelty from those of stress per se. 77,78 The effects of stress on hippocampal neurons during development have been less studied.…”

Competitive interactions between endogenous LTD and LTP in the hippocampus underlie the storage of emotional memories and stress-induced amnesia

“…Comparable findings were reported regarding the immediate early gene Arc (activity-regulated cytoskeletalassociated protein). Arc activation in the hippocampus is induced by exploration of a novel environment, but not by immobilization stress (Ons et al, 2004;Ramirez-Amaya et al, 2005). Therefore, exposing a rat to a novel environment or reexposing a rat to the fear conditioning context, i.e., retrieving the emotional memory, can induce forms of endogenous LTD/ depotentiation and activate molecular forms of plasticity in the hippocampus.…”

Rotation and immediate-early gene expression in rats treated with the atypical D1 dopamine agonist SKF 83822

“…In the current experiments we therefore examined whether SKF 83822 is able to reproduce two of the best established effects of standard D1 receptor agonists, namely the induction of contralateral rotation and the stimulation of expression of immediate-early genes in rats with unilateral dopamine depleting lesions. Most studies of IEG expression have examined only c-fos; under certain conditions, however, various IEGs appear to be differentially expressed (Ons et al, 2004;Pollack and Fink, 1995;Simpson and Morris, 1995). We thus examined the effects of SKF 83822 on the expression of four different IEGs, all of which have been shown to be sensitive to the effects of typical dopamine D1 agonists, in order to increase our chances of detecting unusual aspects of the response to SKF 83822.…”