The novel effects of
gangliosides from human brain on the number of nuclei of nerve cells and neurite outgrowth were studied in cultures of human
neuroblastoma cell lines GOTO and NB-1.
Ganglioside GQ1b at a nanomolar level stimulated cell proliferation and neurite outgrowth during culture for 24 hours, as reported previously [J Biochem 94: 303-306, 1983]. Although the neurite promoting activity of GQ1b was similar to those of total human brain
gangliosides (GS) and
nerve growth factor (
NGF), its activity on cell proliferation did not persist on longer culture; that is, the number of GQ1b-treated cells rapidly decreased to the control level during culture for 48 or 72 hours. In contrast, on treatment with GS or
NGF, the number of cell nuclei increased continuously during prolonged culture. These results showed that either some other molecular species of
ganglioside(s) than GQ1b or other substances such as
proteins present in the GS fraction were responsible for the long-term activity. Studies on the GS fraction after its treatment with
proteases and neuraminidases revealed that
ganglioside GD1a (20 ng/ml) had the ability to prolong the activity of GQ1b. Namely, GQ1b and GD1a
gangliosides cooperated in maintaining the number of nuclei in long-term cultures of
neuroblastoma cell lines.