Modulation of intracellular calcium in early neural cells by non-NMDA ionotropic glutamate receptors.

Non-NMDA ionotropic receptor channels were longtime thought to be impermeable to calcium. There is now increasing evidence that this is not a general feature. Neural cells bearing non-NMDA receptors permeable to divalent cations can be found not only in the adult CNS, but also at surprisingly early stages of development (well before the onset of synaptogenesis). Since modulation of cytosolic calcium is known to trigger numerous transcription, translation, and post-translation mechanisms, molecules acting at non-NMDA ionotropic receptors may profoundly affect the fate of individual cells, brain regions, and finally the whole nervous system. However, present knowledge of transduction mechanisms and possible roles (ranging from transcription of immediate early genes to regulation of cell survival) is still very fragmentary. These receptors can be activated and modulated by endogenous molecules, but also by exogenous naturally occurring or pharmaceutical substances. If significant amounts of these substances can pass the human placental barrier, their consumption or accidental intake during pregnancy may constitute a risk for the developing embryonic and foetal CNS.