Formation of olfactory memories mediated by nitric oxide

摘要: Sheep learn to recognize the odours of their lambs within two hours giving birth, and this learning involves synaptic changes olfactory bulb1,2. Specifically, mitral cells become increasingly responsive learned odour, which stimulates release both glutamate GABA (γ-aminobutyric acid) neurotransmitters from reciprocal synapses between excitatory inhibitory granule cells1. Nitric oxide (NO) has been implicated in plasticity other regions brain as a result its modulation cyclic GMP levels3,4,5,6,7. Here we investigate possible role NO learning. We find that neuronal enzyme nitric synthase (nNOS) is expressed cells, whereas guanylyl cyclase subunits are required for stimulation cGMP formation8 only cells. Immediately after levels rise, inducing formation cGMP, potentiate at mitral-to-granule cell synapses. Inhibition nNOS or activity prevents potentiation memory. The effects inhibition can be reversed by infusion into bulb. Once memory formed, however, cannot impair either recall neurochemical evoked lamb odour. therefore seems act retrograde and/or intracellular messenger, being released modulating contentrations. propose resulting functional circuitry bulb underlie memories.