Factors involved in expression of neuron-specific and non-neuronal enolase activity in developing chick brain and in primary cultures of chick neurons

The effect of various factors affecting non-neuronal enolase (NNE) and neuron-specific enolase (NSE) was investigated in developing brain of two different chick strains, in primary cultures of pure neurons and of mixed cultures of neuronal and glial cells. NNE and NSE activities reached their maximum at an earlier stage of brain development in the fast growing Hybro strain than in the Leghorn strain. In pure neurons cultured during 6 days, NNE was stimulated by hydrocortisone in presence or in absence of serum. Dibutyryl cyclic AMP (diBcAMP) stimulated NNE only in serum-free medium. NSE activity was increased by glial cell-conditioned medium in presence of serum and by removal of serum from the medium. Hydrocortisone and diBcAMP had no effect on NSE. In mixed cultures of neurons and glial cells both enolase activities were raised in absence of serum. Hydrocortisone and diBcAMP had no effect. Steroid hormones, insulin and serum albumin also modify both enolase activities in pure neurons and in mixed cultures of neurons and glial cells. Our results suggest that NNE and NSE are regulated separately by various factors involved in nerve cell maturation.