STRESS-INDUCED EXPRESSION OF IMMEDIATE-EARLY GENES IN THE BRAIN AND PERIPHERAL ORGANS OF THE RAT

Stress causes rapid and transient expression of immediate early genes (IEGs) in the brain, and the monitoring of IEGs has enabled the visual ization of the neurocircuitry of stress. Previous studies have postula ted that stressors can be divided into two categories; processive and systemic. The neural circuits of brain activation differ between the t wo kinds of stressors. For example, processive stressors, such as immo bilization (IMO), induce c-fos mRNA first in the cortical and limbic a reas and then in the paraventricular hypothalamic nucleus (PVH), while c-fos expression in the PVH precedes that in other areas in animals s ubjected to systemic stressors. We further show that prior exposure to IMO stress for 6 days, or implantation of corticosterone pellets supp resses the induction of c-fos, fos B, jun B and NGFI-B, but not that o f NGFI-A in the rat PVH. Plasma glucocorticoid may be an important fac tor regulating stress-induced IEG expression. It is well known that AP -I and glucocorticoid receptors (GR) interact and suppress each other. Thus, decreased AP-1 levels in chronically stressed animals may help enhance the negative feedback effects of GR and prevent hypersecretion of glucocorticoid, which is implicated in the pathogenesis of stress- related diseases. IMO stress induces rapid expression of c-fos, c-jun and NGFI-A mRNAs in the heart and stomach. These were observed in the ventricular myocardium and coronary arteries, and in the epithelium, s mooth muscles and arteries of the stomach after 30 min of IMO. IEG exp ression in the peripheral organs may provide a molecular basis for str ess-induced psychosomatic disorders. (C) 1997 Elsevier Science Ireland Ltd.