ESTRAINT-INDUCED fra-2 AND c-fos EXPRESSION IN THE RAT OREBRAIN: RELATIONSHIP TO STRESS DURATION

bstract—The protein product of the fra-2 gene (Fra-2), a os-family member, can compete with Fos protein for particpation in activating protein-1 (AP-1) transcription factor omplexes and each protein can contribute different transctivational consequences to an AP-1 complex. To date, here is limited characterization of fra-2 mRNA expression n the rat forebrain. We examined basal and restraint-inuced mRNA expression (in situ hybridization) of fra-2 in he rat forebrain and compared its temporal–spatial pattern o c-fos. In contrast to the very low basal expression of c-fos, ra-2 basal expression was moderately high throughout corex and some subcortical structures, including prominent asal expression in the hypothalamic paraventricular nuleus (PVN). Restraint-induced fra-2 expression was quantied in the prefrontal cortex (PFC), lateral septum (LS) and VN. Maximal fra-2 gene induction in the PFC and LS was elayed (60 min) after restraint onset with respect to c-fos (15 in), whereas in the PVN, fra-2 mRNA increased within 15 in of restraint. Additionally we compared c-fos and fra-2 ene expression in rats given shorter or longer restraint urations, but equal total time from stress onset to sample ollection, to determine the extent to which the kinetics of ene induction matched that of a hypothalamic–pituitary– drenal axis hormone response. Rats given 45 min recovery fter 15 min restraint showed less c-fos expression in the VN, less fra-2 expression in the prelimbic and infralimbic FC, and no difference in the LS compared with rats retrained for 60 min. Thus, the expression of both genes was ensitive to stressor duration, but this sensitivity varied with rain region. Differential basal and stress-induced expresion patterns of the fra-2 and c-fos genes are likely to have mportant functional consequences for AP-1 transcription actor dependent regulation of neural plasticity. Published by lsevier Ltd on behalf of IBRO.