ENZYMATIC-ACTIVITIES DURING DIFFERENTIATION OF THE HUMAN NEUROBLASTOMA-CELLS, LA-N-1 AND LA-N-2

The presence of 10−5 M retinoec acid (RA) in the culture medium of LA‐N‐1, a catecholamonergic cell line, and LA‐N‐2, a cholinergic cell line, enhanced their morphological differentiation. Tyrosine hydroxylase (TH) activity of the LA‐N‐1 cell was increased in the RA‐treated cells compared with control cultures at day 4 and remained elevated. Choline actyltransferase (ChAT) activity in the LA‐N‐2 cells gradually increased until 8 days in vitro (DIV) voth in the untreated control and the RA treated cultures. This activity in control and treated cells decreased gradually to a constant level of activity. The ChAT activity at 8 DIV of RA‐treated La‐N‐2 cells was increased 2.1‐fold (P<0.001) as compared to the control cultures. This increase in ChAT activity was accompanied by a 73% decrease of acetylcholinesterase (AChE) activity in LA‐N‐2 cell by 8DIV. AChE activity of LA‐N‐1 cells was unchanged during the time course of the experiment. Phospholipase‐A2 (PL‐A2)activity in RA‐treated LA‐N‐2cells was increased at day 4 as compared with the control cultures. There were no differnces obseved in phopholipase‐D (PL‐D), choline kinase and FPC‐phosphodiesterases activities in RA‐treated and ‐untreated LA‐N‐1 and LA‐N‐2 cells. Copyright © 1990 Wiley‐Liss, Inc.