CELLULAR ANALYSIS OF S100ß AND FIBROBLAST GROWTH FACTOR-2 IN THE DORSAL ROOT GANGLIA AND SCIATIC NERVE OF RODENTS. FOCUS ON PARACRINE ACTIONS OF ACTIVATED SATELLITE CELLS AFTER AXOTOMY

Abstract

The role of satellite cells, a type of peripheral glia, in the paracrine mechanisms related to neuronal maintenance and plasticity in the dorsal root ganglia (DRG) needs to be further investigated. This study employed immunohistochemistry and image analysis to investigate basic fibroblast growth factor (bFGF, FGF-2) and S100ß immunoreactivities in the DRG and sciatic nerve of the rat and mouse. Well-characterized antibodies against bovine (residues 1–24) and rat (residues 1–23) FGF-2 were employed. Furthermore, the state of satellite cell reaction and changes in the FGF-2/S100ß immunoreactivity were analyzed after axotomy of rat sciatic nerve. Scattered neurons and the majority of the satellite cells of the rat DRG and also Schwann cells of the rat sciatic nerve stained for S100ß. In the mouse, strong S100ß was encountered in the majority of sensory neurons and Schwann cells. Moderate FGF-2 (residues 1–24) immunoreactivity was found in scattered small size neurons of the rat DRG. A strong FGF-2 (residues 1–23) immunoreactivity was achieved in the satellite cells of rat DRG. Both FGF-2 antisera showed strong labeling in the mouse DRG sensory neurons. Activated satellite cells of the axotomized DRG possessed increased amount of FGF-2 and S100ß immunoreactivity as demonstrated by quantitative image analysis. The proximal stump of the lesioned rat sciatic nerve showed increased FGF-2 (residues 1–24 and 1–23) in the Schwann cells, myelin sheaths, and neuronal fibers, without changes in the level of S100ß immunoreactivity. Results suggested a possible interaction between FGF-2 and S100ß in activated satellite cells of the DRG, which might trigger paracrine actions in the axotomized sensory neurons.