OBJECTIVE Pain sensations in the periphery are carried by primary sensory neurons whose cell bodies lay in the dorsal root ganglia (DRG).The present study focuses on examining the interactions between DRG neurons and gilal cells in vitro in relation to their roles as detectors of tissue damage.METHODS Acutely dissociated DRG cells were isolated from adult SD rats, and plated on poly-DL-omithine and laminin-coated tissue culture plates.Responses in 3 cell groups were compared over time in culture: mixed DRG cells (45% neurons on plating), neuron-eeniched cells (70% neurons on plating) and glial cells (99% glial cells on plating).Cell proliferation was determined by counting cells, protein assay and MTT assay.[3H] cAMP production in the presence of specific receptor agonists and antagonists was assayed to detect Gs-coupled receptors.Gilal acidic fibrillary protein (GFAP) , glutamine synthase (GS) and Toll-like receptor 4 (TLR4) mRNA and protein expression were determined by real time PCR and immunocyto-chemistry, respectively.RESULTS The presence of Gs-coupled β2AR, CGRP, EP4 and IP receptors were identified in glial cell preparations although only CGRP receptors have been reported on satellite glial cells in vivo.Furthermore, IP receptor-stimulated adenylyl cyclase activity in glial cells was significantly inhibited by the presence of DRG neurons.DRG neurons did not overtly affect glial cell proliferation or the expression of GFAP (classical markers of glial cell activation), but appeared to inhibit the expression of TLR4 and prevent the loss of GS in glial cells.CONCLUSION Time-dependent changes occur in DRG glial cells in vitro with regard to the expression of TLR4, Gs-coupled receptors and glial cell markers, and all these changes are influenced by the presence of DRG neurons.Whether similar neuron-glial interactions occur in vivo remains to be determined.