Hypocretin (orexin) and dynorphin are neuromodulators that play an important role in regulating affect and motivation. Orexin is critical for reward and is implicated in drug seeking, whereas dynorphin mediates negative mood and is implicated in depressive-like states. Considering these opposing effects, reports that both peptides are expressed in the same neurons and are coreleased are counterintuitive. Here, we demonstrate that orexin and dynorphin are coexpressed within the same synaptic vesicles and that this colocalization has a profound influence on reward, drug taking, and impulsive-like behavior. The fact that orexin occludes the depressive-like antireward effects of dynorphin significantly changes how we view the functional role of orexin in the brain.
Posted on: Tue, 25 Mar 2014 23:56:37 +0000
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