Substance P Receptors on O‐2A Progenitor Cells and Type‐2 Astrocytes In Vitro

Bradykinin- and substance P (SP)-stimulated second messenger studies in isolated subsets of neuroglia showed bradykinin-stimulated synthesis of phosphoinositides (PI) in type-1 astrocytes and oligodendrocytes. SP-stimulated PI accumulation was restricted to oligodendrocyte/type-2 astrocyte progenitor cells and type-2 astrocytes. These data were confirmed by analysis of calcium transients in single cells. In a regional study, SP-stimulated PI accumulation in primary astrocyte cultures was restricted to white matter. We conclude that regional heterogeneity in the expression of peptide receptors in cultures of primary astrocytes arises from a restricted distribution on subsets of macroglia. SP receptors restricted on cells of the oligodendrocyte/type-2 astrocyte type-2 lineage in vitro, coupled with in vivo observations by others, suggests that SP receptor expression is conserved on subsets of macroglia in vitro and possibly reactive astrocytes in vivo.