Functional expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors precedes the development of cholinergic phenotype in embryonic rat septal cells in culture

We examined the development of cholinergic neuronal functions and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) responses in cultured embryonic rat septal cells. Choline acetyltransferase activity was increased from 4 to 6 days in culture and reached a plateau at day 8. Acetylcholine release was increased from 6 to 8 days in culture. AMPA-induced increase in intracellular Ca²⁺ level was observed at 3 days in culture and most of the AMPA-responsive cells coincided with high-K⁺ responsive cells. These results suggest that cholinergic neurons develop their neuronal functions about 8 days under cultured conditions, and functional expression of AMPA receptors precedes the cholinergic functional development.