Cell density and exogenous CNTF affect CNTF mRNA levels in glial cell cultures

Regulation of CNTF mRNA was investigated in primary cortical astrocytes cultured from newborn rats and in C6 glioma cells. Northern blot analysis indicated that semi-confluent astrocyte cell cultures. CNTF added to confluent astrocyte cultures down-regulated CNTF message in a dose-dependent fashion. In contrast, when CNTF was given to semi-confluent astrocyte cultures the level of CNTF mRNA was up-regulated. C6 glioma cells also showed a cell density-dependent expression of CNTF: cells from confluent cultures expressed detectable amounts of CNTF mRNA whereas those from semi-confluent cultures did not. Thus, CNTF mRNA expression by astroglial and glioma cells is regulated by cell contact and exogenous CNTF in vitro.