Meeting Abstract

P1.125  Monday, Jan. 4  Influence of melatonin, glutamate, and melatonin receptor antagonists on neurite growth in crustacean X-organ cells TILDEN, Andrea*; KUSEMA, Escar; LANGTON, Ruth; MYERS, Jennifer; Colby College; Colby College; Colby College; Colby College artilden@colby.edu

Melatonin is a neuromodulatory hormone with well-studied roles in the regulation of vertebrate circadian physiology. Few studies have been conducted in invertebrates, though it has been determined that they do produced melatonin. Previous studies in our lab have shown that melatonin enhances neurite growth in cultured crustacean X-organ cells, and that luzindole, an inhibitor of both MT1 and MT2 melatonin receptors, also influenced neurite growth. In the current studies, we explored the cellular role of melatonin in crustacean neurite growth. To further determine the melatonin receptor type located in X-organ cells, we treated the cells with pertussis toxin, an inhibitor of MT1 receptor-coupled Gi (inhibitory G protein) activity. Pertussis toxin did not influence neurite growth. Prazosin, an MT3 receptor antagonist, inhibited melatonin-induced neurite outgrowth. Glutamate at high (10 mM) concentrations has neurite growth-inhibiting effects on X-organ cells, and at higher (50 mM) concentrations is excitotoxic. In prior studies, we showed that melatonin has neuroprotective effects against oxidative stress. Treatment with melatonin and non-lethal levels of glutamate had cytotoxic effects, causing necrosis in all cells within 24 hr of treatment, suggesting an interactive effect of the two modulators.