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Characterization of C6‐10A glioma cells highly responsive to β‐adrenergic receptor agonist‐induced NGF synthesis/secretion

A subline of rat C6 glioma cells, C6‐10A cells, in which epinephrine can induce nerve growth factor (NGF) synthesis/secretion, was isolated. C6‐10A cells have retained their sensitivity to epinephrine for more than 2 years in a medium containing 0.5% fetal calf serum (FCS) but easily lose it in 10% FCS. C6‐10A cells are S‐100‐ and glial fibrillary acidic protein‐positive, and the doubling time is about 60 h in the medium containing 0.5% FCS and about 20 h in 10% FCS. Epinephrine induced NGF synthesis/secretion prominently in serum‐free cultures of C6‐10A cells and in cultures with a high cell density, but not in serum‐containing cultures. The induction did not occur with parent C6 cells under the appropriate conditions in C6‐10A cells. NGF secretion was induced by catecholaminergic compounds in the following order isoproterenol > epinephrine = norepinephrine » dopamine. The induction caused by epinephrine was blocked by propranolol (α‐blocker) but not by phentolamine (β‐blocker). Various compounds that activate the adenylate cyclase system also induced NGF synthesis/secretion. These results indicate that C6‐10A cells are astrocytes that are highly responsive to β‐adrenergic receptor agonists, which stimulate NGF synthesis/secretion via receptors coupled with adenylate cyclase machinery. These cells may be a useful aid in studying the mechanism of NGF synthesis/secretion.