Current biology : CB
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Current biology : CB · Nov 2012
Two dopaminergic neurons signal to the dorsal fan-shaped body to promote wakefulness in Drosophila.
The neuronal circuitry underlying sleep is poorly understood. Although dopamine (DA) is thought to play a key role in sleep/wake regulation, the identities of the individual DA neurons and their downstream targets required for this process are unknown. ⋯ These experiments define a novel arousal circuit at the single-cell level. Because the dorsal fan-shaped body promotes sleep, these data provide a key link between wake and sleep circuits. Furthermore, these findings suggest that inhibition of sleep centers via monoaminergic signaling is an evolutionarily conserved mechanism to promote arousal.
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Current biology : CB · Nov 2012
Direct activation of sleep-promoting VLPO neurons by volatile anesthetics contributes to anesthetic hypnosis.
Despite seventeen decades of continuous clinical use, the neuronal mechanisms through which volatile anesthetics act to produce unconsciousness remain obscure. One emerging possibility is that anesthetics exert their hypnotic effects by hijacking endogenous arousal circuits. A key sleep-promoting component of this circuitry is the ventrolateral preoptic nucleus (VLPO), a hypothalamic region containing both state-independent neurons and neurons that preferentially fire during natural sleep. ⋯ Cumulatively, this work demonstrates that anesthetics are capable of directly activating endogenous sleep-promoting networks and that such actions contribute to their hypnotic properties.