Rat supraoptic neurons are resistant to glutamate neurotoxicity.

Magnocellular neurosecretory cells of the supraoptic nucleus (SON) are thought to be endogenously resistant to glutamate toxicity. In this study, we sought physiological and morphological evidence of this resistance in rats that received multiple peri-nuclear injections of ibotenate. In this preparation, ibotenate produced a large necrotic zone encompassing the SON but not within the nucleus itself. Extracellular recordings in vivo from 68 'spared' SON neurons from lesioned rats revealed normal patterns of electrical activity. Intracellular analysis in vitro from 13 'spared' SON neurons indicated that their intrinsic membrane properties, osmosensitivity and spontaneous synaptic activity did not differ significantly from that of controls. We conclude that SON neurons retain both a morphological and a physiological resistance to glutamate neurotoxicity.