Stimulus-specific induction of an Egr-1 transgene in rat brain.

Regulated expression of Egr-1 (Zif268/NGFIA) in a variety of brain networks suggests a diversity of roles in neuronal plasticity. Here, we aimed to determine whether an egr-1 transgene would mediate transcriptional responses to different pharmacological and physiological stimuli in the brain of transgenic rats. Constitutive transgene expression was observed in the cortex, CA1 hippocampal area and pituitary, recapitulating expression of egr-1. Transgene induction was stimulus-specific. Metrazole induced widespread expression in the dentate gyrus, CA2 and CA3 areas, amygdala, and ventromedial nucleus. In contrast, induction following a light stimulus was restricted to the hypothalamic suprachiasmatic and periventricular nuclei. Our studies have provided novel insights into the differential regulation of egr-1, and facilitated approaches to the genetic manipulation of Egr-1-regulated neuronal systems.