Astrocytes possess a diverse assortment of ionotropic transmitter receptors, which enable these glial cells to respond to many of the same signals that act on neurones. Ionotropic receptors mediate neurone-driven signals to astroglial cells in various brain areas including neocortex, hippocampus and cerebellum. Glutamate and ATP are the major neurotransmitters responsible for signalling in neuronal-glial networks. Recent studies have found functional NMDA receptors in brain macroglia, in astrocytes and oligodendrocytes. Glial and neuronal NMDA receptors are functionally and structurally different; the glial receptors are weakly sensitive to the extracellular magnesium block, which may indicate a predominant expression of the NR3 receptor subunit. The ionotropic purinergic neuronal-glial transmission is mediated through both P2Y metabotropic and P2X ionotropic purinoceptors. The P2Y1,2 receptors are ubiquitously expressed in astroglia and their activation trigger intracellular Ca²⁺ signalling. The ionotropic receptors are much more territorially restricted; P2X-medaited responses were hitherto found only in cortical astrocytes. Cortical astrocytes express P2X1/5 purinoceptors that are characterised by very high sensitivity to ATP (EC50 ~ 50 nM) and weak desensitization. In the cortex, astroglial NMDA and P2X1/5 receptors are activated upon physiological synaptic transmission. Spontaneous synaptic currents were also readily recorded from cortical astrocytes, indicating the close proximity of glial membranes to the sites of neurotransmitter release from the neuronal terminals. Activation of ionotropic receptors trigger rapid signalling events in astroglia; these events, represented by local Ca²⁺ or Na⁺ signals provide the mechanism for fast neuronal-glial signalling at the level of individual synapse.