A QUANTITATIVE-ANALYSIS OF THE GLIAL-CELL REACTION IN PRIMARY SENSORYTERMINATION AREAS FOLLOWING SCIATIC-NERVE INJURY AND TREATMENT WITH NERVE GROWTH-FACTOR IN THE ADULT-RAT

The time course of the astroglial cell reaction in the nucleus gracili s and the spinal cord dorsal horn was examined following sciatic nerve transection in the adult rat with qualitative and quantitative analys is of glial fibrillary acidic protein immunoreactivity and in situ hyb ridization for its mRNA. In addition, the potential effect of exogenou s nerve growth factor (NGF) was examined on the astroglial and microgl ial cells in the spinal cord dorsal horn at certain time points follow ing sciatic nerve transection. An increase in glial fibrillary acidic protein immunoreactivity as well as mRNA labelling was observed from 1 day after lesioning, with a peak at about 1 week and 2 days after les ioning, respectively, followed by a decline. However, NGF application during 1, 2 and 4 weeks following nerve transection did not result in any significantly reduced astroglial or microglial activity. Our resul ts show that the astroglial cell response in the nucleus gracilis and the spinal cord dorsal horn is rapid in comparison with previously des cribed central degenerative changes following peripheral nerve lesions (transganglionic degeneration), that the astroglial cell reaction dev elops concomitantly with the microglial cell reaction previously descr ibed and that the ''signal'' from the axotomized neurons which induces these reactions can not be prevented by exogenous NGF applied to the peripheral nerve.