Agmatine: a novel neurotransmitter?

Current evidence is consistent with an hypothesis that agmatine meets many criteria for a neurotransmitter-neuromodulator. It is synthesized, stored, and released in brain; is contained in neurons and axon terminals with a heterogeneous distribution; interacts with cell-specific receptors; and elicits biological actions within the central nervous system. Its role in normal brain function, however, has not yet been established, in part because of the absence of agents that selectively affect its biosynthesis or degradation.