The noradrenaline system consists of around 15,000 neurons, primarily in the locus coeruleus. This is diminutive compared to the more than 100 billion neurons in the brain. As with dopaminergic neurons in the substantia nigra,  neurons in the locus coeruleus tend to be melanin-pigmented. Noradrenaline is released from the neurons, and acts on adrenergic receptors. Noradrenaline is often released steadily so that it can prepare the supporting glial cells for calibrated responses. Despite containing a relatively small number of neurons, when activated, the noradrenaline system plays major roles in the brain including involvement in suppression of the neuroinflammatory response, stimulation of neuronal plasticity through LTP, regulation of glutamate uptake by astrocytes and LTD, and consolidation of memory.