Dale’s principle

Dale's principle, named after Sir Henry Dale, is a concept in neuroscience stating that a neuron releases the same neurotransmitter at all of its axon terminals. This principle is fundamental to understanding how nerve impulses are transmitted chemically across synapses.123

Neurotransmitter release occurs at synapses, the junctions between neurons or between neurons and other cells like muscles or glands. When an electrical impulse (action potential) reaches the end of a neuron (presynaptic terminal), it triggers the release of neurotransmitters stored in vesicles. These chemicals then cross the synaptic cleft and bind to receptors on the next cell (postsynaptic cell), influencing its activity, either by exciting or inhibiting it.3

While Dale's principle applies to the presynaptic neuron, the postsynaptic cell can respond differently to the same neurotransmitter depending on the type of receptor it possesses. This complexity allows for the intricate and varied responses of the nervous system.13