Sympathetic neuron density differentially regulates transmitter phenotypic expression in culture.

AUTOR(ES)

Adler, J E

RESUMO

The effects of cell density and aggregation on expression of transmitter traits were examined in dissociated, pure sympathetic neuron cultures, grown in fully defined, serum-free medium. After 1 week at a density of 7-8 X 10(3) neurons per 35-mm dish, moderate levels of tyrosine hydroxylase (tyrosine 3-monooxygenase, EC 1.14.16.2) activity and substance P were detected. When neuron density was increased 4-fold, a 4-fold increase in tyrosine hydroxylase activity was observed; i.e., there was no change in tyrosine hydroxylase activity per neuron. In contrast, substance P increased 30-fold, corresponding to a 7-fold increase in substance P per neuron. Choline O-acetyltransferase (EC 2.3.1.6) activity, not detected at low cell densities, was first detectable at a concentration of 15,000 neurons per dish and increased 6-fold when this cell concentration was doubled. Medium conditioned by high-density cultures failed to reproduce these effects on low-density cultures, suggesting that diffusible factors are not involved in the density-dependent differential regulation. Time-lapse phase-contrast microscopy of high-density cultures showed neuronal migration and progressive aggregation, which did not occur in low-density cultures. Our observations suggest that cell contact may mediate differential expression of transmitter traits.

Documentos Relacionados

• Phenotypic plasticity in adult sympathetic neurons: changes in neuropeptide expression in organ culture.
• Cell density determines epithelial migration in culture.
• Phenotypic modulation of gonococcal lipooligosaccharide in acidic and alkaline culture.
• The role of 5-hydroxytryptamine as a transmitter between identified leech neurones in culture.
• Dilute passage promotes expression of genetic and phenotypic variants of human immunodeficiency virus type 1 in cell culture.