neurosecretion

Most neurons whisper to the cell next door, releasing a chemical across a tiny gap. A neuron doing neurosecretion does something bolder: instead of speaking only to a neighbor, it dumps its chemical message straight into the bloodstream, broadcasting to the whole body at once. The neuron has become, in effect, a tiny gland cell with a long electrical wire attached.

In neurosecretion, hormones are made in the cell body, packaged into granules, and shipped down the axon to nerve endings that sit against blood capillaries. An electrical impulse arriving at the ending triggers calcium entry, which fuses the granules with the membrane and releases the hormone into the blood. The posterior pituitary works exactly this way, with oxytocin and vasopressin released from the tips of hypothalamic neurons.

The concept was established by Ernst and Berta Scharrer in the 1930s and 1940s and was controversial at first, because it broke the assumption that neurons only signal locally. It is the structural basis for treating the brain as an endocrine organ.