Developmental origins of central norepinephrine neuron diversity

Central norepinephrine producing neurons comprise a diverse population of cells differing in anatomical location, connectivity, function and response to disease and environmental insult. At present, the mechanisms that generate this diversity are unknown. Here we elucidate the lineal relationship between molecularly distinct progenitor populations in the developing mouse hindbrain and mature norepinephrine neuron subtype identity. We have identified four genetically separable subpopulations of mature norepinephrine neurons differing in their anatomical location, axon morphology and efferent projection pattern. One of the subpopulations revealed an unexpected projection to the prefrontal cortex, challenging the long-held belief that the locus coeruleus (LoC) is the sole source of norepinephrine projections to the cortex. These findings reveal the embryonic origins of central norepinephrine neurons and provide for the first time multiple molecular points of entry for future study of individual norepinephrine circuits in complex behavioral and physiological processes including arousal, attention, mood, memory, appetite, and homeostasis.