Forebrain and midbrain astrocytes promote neuritogenesis in cultured chromaffin cells

Adrenal chromaffin cells from immature or adult rats were grown in one of the following 'in vitro' conditions: (1) on coverslips placed on top of confluent, fetal, regional glia cultures; (2) in conditioned media from similar confluent cultures; (3) after direct seeding on top of such confluent cultures. Astroglia was obtained from cerebral cortex, septum, striatum and ventral mesen-cephalon from El6-17 pregnant-dated rats. All regions succesfully generated conditions for the early (less than 24 h) expression of neuritogenesis in about 15% of cells, which was more apparent in immature adrenal cell dissociates than in adult ones. The former grew long neurites compared with their adult counterparts. In addition to the known effects of glioma conditioned medium and isolated trophic factors described by other authors, it is concluded that adrenal chromaffin cells are responsive to the neuritogenic activity of (central) astroglial diffusible factor(s) in non-supplemented, defined culture media conditioned by astrocytes from various brain regions. Additionally, evidence is offered that adult chromaffin cells show a reduced responsiveness towards such astroglial factor(s). Possible implications for cell trasplantation chimeras are discussed.