Ascorbate Modulates 5-[3H]Hydroxytryptamine Binding to Central 5-HT3 Sites in Bovine Frontal Cortex
Version of Record online: 5 OCT 2006
Journal of Neurochemistry
Volume 50, Issue 5, pages 1505–1512, May 1988
How to Cite
Todd, R. D. and Bauer, P. A. (1988), Ascorbate Modulates 5-[3H]Hydroxytryptamine Binding to Central 5-HT3 Sites in Bovine Frontal Cortex. Journal of Neurochemistry, 50: 1505–1512. doi: 10.1111/j.1471-4159.1988.tb03037.x
- Issue online: 5 OCT 2006
- Version of Record online: 5 OCT 2006
- Received August 24, 1987; revised manuscript received November 24. 1987; accepted November 26, 1987.
- Serotonin binding sites;
- Frontal cortex
Abstract: Ascorbate is present in millimolar concentrations in mammalian brain and can be released from cellular stores by membrane depolarization. We report here that physiologically relevant concentrations of ascorbate modulate 5-[3H]hydroxytryptamine ([3H]5-HT) binding to bovine frontal cortex membranes. Under conditions where [3H]5-HT binding is reversible and saturable, ascorbate causes a concentration-dependent increase in the affinity of [3H]5-HT for central 5-HT3 binding sites. At pH 7.4, increasing ascorbate from 0 to 5.7 mM changes the equilibrium affinity constant (KD) of binding to 5-HT3 sites from 125 nM to 30 nM, without affecting binding site number. These ascorbate-induced effects are pH dependent. At pH 7.1 binding to central 5-HT3 sites is essentially eliminated in the presence of ascorbate. These studies suggest that ascorbate and hydrogen ion concentration interactions may modulate serotonergic function.