co-released with classical neurotransmitters

Actions terminated by macrophages

synthesised as a large precursor molecule at the cell soma and transported (potentially long distance) to release sites in dense core vesicles

slow postsynaptic effects

Release requires a less intense stimulus and initially less calcium entry but ultimately neuropeptide release requires higher concentrations of Ca2+

neuropeptides are synthesised from precursors, NPs uesed only once

NPs present at much lower concentrations in vesicles (10mM compared with 100mM)

Neuropeptides have much lower affinity for receptors

A single precursor molecule can only give rise to one bioactive peptide

Pro-lactin undergoes a single cleavage in order to form its corresponding neuropeptide

Neuropeptides are synthesised from much larger precursor molecules of at least 90 amino acids long

Substance P coexists with the excitatory neurotransmitter glutamate in primary afferents that respond ot painful stimulation

Substance P is also associated with anxiety, stress, neurogenesis, nausea

co-localises with neuropeptide Y - associated with excitatory signals

Signalling mediated through neuropeptin 1 receptors (NP1) - G protein coupled receptors