Abstract
Glial cells of the central nervous system are activated upon injury and modulate the course of several diseases. The glia population of peripheral nervous system is much less explored in this area. I used satellite glial cells (SGCs) from superior cervical ganglia of P0 to P2 rat pups, to develop an in vitro model to study glia activation in the sympathetic nervous system. Several factors including ATP, endothelin-1, lipopolysaccharides and fractalkine have been reported to activate other glia populations and were tested on SGC cultures. Out of these, LPS showed a relatively better consistency in activating SGCs and was used for most of the experiments. To assess activation of SGCs, the cell lysates were analyzed by western blot to check for GFAP expression, a common glia activation marker. There was only a slight difference in GFAP levels between control and treated cells. Immunocytochemistry was used as an alternative approach to assess SGC activation, comparing cell proliferation between the control and activating conditions. The results suggested cell proliferation to be a better assay than GFAP expression to study SGC activation in cell culture. It is also interesting to look for secretary factors released by SGCs and to observe if this expression profile alters in response to activation. Using western blot, I validated production of neurotrophins such as NGF and BDNF in the SGC culture. The expression of these factors altered non-significantly in response to activation. The young and adult animals may have different protein expression profile. So, more SGC-specific activation protocol/modulator; SGC culture from adult animals; and a better activation marker for SGC might be required to develop a robust in vitro model to study significance and implications of activation of SGCs in sympathetic nervous system function. These inferences would be valuable as the sympathetic neurons innervate several vital organs such as heart and activation of glia may contribute in affecting the sympathetic drive to these organs.