GFAP IMMUNOREACTIVITY IN TRIGEMINAL GANGLION SATELLITE CELLS AFTER TOOTH INJURY IN RATS

Glial fibrillary acidic protein (GFAP) is a member of a heterogeneous group of intermediate filaments in glial cells of both the central and peripheral nervous systems. We demonstrate here that satellite cells in the trigeminal ganglion (TG) increase immunoreactivity (IR) for GFA P in response to dental injury. The satellite cell reaction was most o ften confined to the somatotopic region of the ganglion that correspon ded to the zone of damage in the periphery, although in some cases it was seen to spread out from a focal center in the maxillary region to neighboring zones corresponding to cell bodies that innervate other ti ssues such as the cornea, We used two methods to demonstrate that the increase in satellite cell GFAP-IR was site specific and injury relate d, First, by altering the site of the pulp exposure from the maxillary molars to the mandibular molars, we could change the site of satellit e cell reaction in the TG. Second, we used combined retrograde transpo rt of DiI from the molar pulp and GFAP immunofluorescence to show dire ct correspondence between neurons that innervate the molars and neuron s that are encircled by GFAP-IR satellite cells. The satellite cell GF AP-IR was seen at 3 and 7 days, the longest time point examined here. This GFAP response in satellite cells around injured sensory neurons w ill be a useful tool in future studies of mechanisms in trigeminal pai n and neuron-support cell interactions. We conclude that a GFAP-IR sat ellite cell reaction is induced in TG by an injury to the molar pulp i n a site specific manner at 3-7 days. (C) 1995 Academic Press, Inc.