Neurotransmitter synthesis by SN6 cell lines, a family of hybrid cell lines of embryonic septal origin.

Previously, we reported the presence of multiple neurotransmitters in subclones of SN6, a septal cholinergic hybrid cell line. To obtain information concerning the functionality of these transmitters, we measured transmitter contents, activities of transmitter-producing enzymes, and the effect of serum-free culture medium in two different batches (SN6.1.6 and SN6.10.2.2) and two subclones of the SN6 cell line (SN6.2a and SN6.1b). Except for SN6.1b, SN6 cell lines and subclones had basically the same neurotransmitter characteristics. Among the transmitters, only acetylcholine seemed to be functional. Monoamine oxidase was missing and activity of aromatic amino acid decarboxylase was diminished in SN6 cell lines. Even in serum-containing medium, SN6.1b had a more mature morphology than the other cell lines, and it contained choline acetyltransferase and acetylcholine but not tyrosine hydroxylase or catecholamines. Similar characteristics were acquired by the mother cell line in response to serum-free conditions. Thus, SN6.1b is the most mature of these central cholinergic neuronal cell lines, at least with regard to neurotransmitter profiles.