Epinephrine also called adrenaline is more of a hormone than a neurotransmitter. Hormones are used for signaling by being released into the blood stream. Adrenaline or epinephrine produced by adrenal gland, acts as a hormone. Adrenaline or epinephrine does not have its own receptor, since its chemical composition is quite similar to noradrenaline or norepinephrine, epinephrine stimulates norepinephrine receptors and acts as neurotransmitter. While norepinephrine is primarily a neurotransmitter. A neurotransmitter is used for direct signaling between the neurons generally by physical contact at synapse.
