Characteristics of choline acetyltransferase and cholinesterases in two types of cultured cells from embryonic chick brain

Cells that were mechanically dissociated from the brains of 7-day-old chick embryos were grown in culture for 7–8 days. Two major cell populations were observed: (1) cells that aggregated and sent out processes, (2) flat cells that proliferated rapidly and formed a confluent layer by day 4 of culture. Many of the cells of the first type had the morphological, histochemical and biochemical attributes of neurons. They possessed choline acetyltransferase (ChAc) and acetylcholinesterase (AChEs) activities. The flat cells possessed neither of the activities, but did have butyrylcholinesterase (BuChEs) activity and a choline independent acetylase activity (CIA) that may be carnitine acetyltransferase.The activities of ChAc and AChEs in the cultured neurons increased approximately 9-fold and 5-fold, respectively, over an 8-day period. The patterns of change of these enzymes were not unlike those seen in vivo in intact developing chick brain.The addition of thyroxine (10^?6M) to these cultures increased the activities of neuronal AChEs and flat cell BuChEs by 30–70%.