NGFI-C EXPRESSION IS AFFECTED BY PHYSIOLOGICAL STIMULATION AND SEIZURES IN THE SOMATOSENSORY CORTEX

NGFI-C is an early response gene which encodes a Cys(2)/His(2) zinc fi nger protein. NGFI-C has previously been demonstrated to be inducible in PC12 cells after NGF stimulation. This study sought to localize thi s gene in somatosensory cortex, and investigate its possible induction by physiological and seizure stimuli. To determine if NGFI-C message levels are affected by stimulation, RT-PCR was performed on mRNA extra cts from somatosensory cortex. NGFI-C mRNA levels were increased to le vels four-fold over baseline after a seizure. In a paradigm used as a model of experience-dependent plasticity, vibrissae stimulation also i ncreased the level of NGFI-C expression in the contralateral barrel co rtex to 180% of control levels. In situ analysis using digoxigenin-lab elled cRNA probes demonstrated NGFI-C containing neurons throughout la yers 2 through 6 in somatosensory cortex. A higher cell density was se en after stimulation. Qualitatively, staining was more intense in post -seizure and post-stimulus cortex than in control cortex. Analysis of related zinc finger expression in serial sections revealed that NGFI-C is expressed in a distinct but overlapping cell populations relative to NGFI-A, Krox 20, and Egr-3. These studies demonstrate the inducible nature of NGFI-C message in response to a physiological vibrissae sti mulus, as well as to seizures. However, the levels and pattern of expr ession differ between these two stimuli.