Journal of Neuroimmunology Journal of Neuroimmunology 65 ( 1996) 49-53 Characterisation of a functional polyamine site on rat mast cells: association with a NMDA receptor macrocomplex W.M. Purcell * , KM. Doyle, C. Westgate, C.K. Attenvill zyxwvutsrqponmlkjihgfedcbaZ Cellular Toxicology Unit, Division of Biosciences, University of Hertfordshire, College Lane, Harfeki, Hem. AL10 9AB, UK Received 8 August 1995; accepted 12 December 1995 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON Abstract Polyamines can modulate activation of N-methyl-D-aspattate (NMDA) receptors by binding to a specific polyamine site associated with a NMDA receptor macrocomplex. Polyamines induce histamine release from mast cells, although the mechanism had not been defined. We have examined whether spermine, a natural polyamine, and compound 48/80, regarded as a synthetic polyamine, activate mast cells by a polyamine site associated with a NMDA receptor macrocomplex. Spexrnine induced secretion of histamine from rat peritoneal mast cells and rat brain mast cells in a concentration-dependent manner. Rat peritoneal mast cells were used as a model system to explore the effects of NMDA antagonists on polyamine-induced histamine release. Ifenprodil, MKSOl and arcaine inhibited histamine secretion from mast cells exposed to polyamines; the percentage inhibition was greater against spermine than compound 48/80. These data support the proposal that spermine (and possibly compound 48/80) induce histamine release from mast cells by interacting with a specific polyamine site on a NMDA receptor complex. Keywords: Mast cells; Histamine; NMDA receptor, Polyamines; Spermine; Compound 48/80, Brain 1. Introduction Mast cells may be triggered to undergo exocytotic secretory processes by ligands other than immunoglobulin E (IgE; Purcell et al., 1989). ‘Neuroactive’ non-IgE-depen- dent ligands, including neurotrophic factors such as nerve growth factor (NGF) and neuropeptides, for example sub- stance P, trigger release of potent vasoactive and inflam- matory mediators from rat peritoneal mast cells (RPMC) and rat brain mast cells (RBMC; Purcell and Atterwill, 1995). These observations reveal ‘cross-talk’ between im- mune and neural cells in the periphery and central nervous system by common mediators, and this ‘neuroimmune axis’ appears to be implicated in a range of neuropatholog- ical states (Purcell and Atterwill, 1995). Polyamines, such as spermine and spermidine, are poly- cationic compounds present in virtually all cells and are involved in the growth, division and differentiation of many cell types. Various stressors induce an altered distri- bution of polyamines in the tissues (Williams et al., 1991). l Corresponding author. Phone + 44 (1707) 284 597; Fax + 44 (1707) 285 046, E-mail w.m.purcell@herts.ac.uk 0165-5728/%/$15.00 Q 19% Elsevier Science B.V. All rights reserved SSDIOl65-5728(95)00182-4 The natural polyamines induce release of histamine from RPMC in a concentration- and energy-dependent process, with a rank order of potency of spermine > spermidine > putrescine (Bueb et al., 1991). Compound 48/80 (C48/80), the condensation product of p-methoxy-N- methylphenethylamine with formaldehyde is regarded as a synthetic polyamine, and is a classic mast cell secreta- gogue (Paton, 1951). Whether mast cells isolated from rat brain thalamic tissue (RBMC) are likewise responsive, in terms of histamine release, to spermine and C48/80 had not been determined and was addressed in the present study. However, the mechanism by which polyamine com- pounds trigger secretion from mast cells remains to be elucidated. It has variously been suggested that they inter- act with mast cells via direct stimulation of G-proteins (Bueb et al., 1991) or with ill-defined polyamine ‘recep- tors’ (Read et al., 1982). We have explored the possibility that spermine triggers histamine release from RPMC via interaction with a polyamine site associated with a N- methyl-n-aspartate (NMDA) receptor complex. The NMDA receptor complex has regulatory sites for various ligands, including glutamate, glycine, Mg’+, Zr?+ and polyamines. Spermine can modulate activation of the macrocomplex