Long-term plasticity of postsynaptic GABA(A)-receptor function in the adult brain: insights from the oxytocin neurone

The subunit switching of ligand-gated receptors is a potentially important mechanism through which synaptic plasticity can be achieved in the nervous system. Although established in an activity-dependent manner for neurotrans mission that is mediated by excitatory amino acids, there is much less dire ct evidence for a role of subunit switching in long-term plasticity of GABA (A) receptors in the adult. We argue that the hypothalamic oxytocin neurone s, which exhibit marked plasticity through each reproductive cycle, provide an excellent model of both presynaptic and postsynaptic long-term plastici ty of GABA-mediated transmission in the mature nervous system. The postsyna ptic plasticity involves GABA(A)-receptor-subunit switching in an activity- independent manner. It also has profound effects on the electrical behaviou r of the oxytocin neurones and, thus, the neural control of pregnancy and l actation.