In Vitro Effects of Chronic Spirolide Treatment on Human Neuronal Stem Cell Differentiation and Cholinergic System Development

Spirolides (SPX) aline toxins, produced by dinoflagellates that act as potent antagonists of nicotinic acetylcholine receptors. These compounds are not toxic tor humans, and since there are no reports of human intoxications caused by this group of toxins.they are not yet currently regulated in Europe. Currently 13-desinethyl spirolide C, 13,19-didesmethyl spirolide C, and 20 -methyl spirolide G are commercially available as reference materials. Previous work in our laboratory has demonstrated that after 4 days of treatment of primary mice cortical neurons with 13-desmethyl spirolide C, the compound ameliorated the glutamate induced toxicity and increased acetylcholine levels and the expression of the acetylcholine synthesizing enzyme being useful both in vitro and in vivo to decrease the brain pathology associated with Alzheimer's disease. In this work, we aimed to extend the study of the neuronal effects of spirolides in human neuronal cells. To this end, human neuronal progenitor cells CTX0E16 were employed to evaluate the in vitro effect of spirolides on neuronal development. The results presented here indicate that long-term, exposure (30 days) of human neuronal stem cells to SPX, compounds, at concerarations up to 50 nM, ameliorated the MPP*-induced neurotoxicity and increased the expression of neuritic and dendritic marker's, the levels of the choline acetyltransferase enzyme and the protein levels of the alpha 7 subunit of nicotinic acetylcholine receptors. These effects are presumably due to the, previously described interaction of these compounds with nicotinic receptors containing both alpha 7 and alpha 4 subunits. All together, these data emphasize, the idea that SPX could be attractive lead molecules against neuroclegenerative disorders,