Sleep is believed to play an important role in memory consolidation. We induced sleep on demand by expressing the temperature-gated nonspecific cation channel Transient receptor potential cation channel (UAS-TrpA1) in neurons, including those with projections to the dorsal Fan-Shaped body (FB). When the temperature was raised to 31°C, flies entered a quiescent state that meets the criteria for identifying sleep. When sleep was induced for 4 hours after a massed-training protocol for courtship conditioning that is not capable of inducing long-term memory (LTM) by itself, flies develop an LTM. Activating the dorsal FB in the absence of sleep did not result in the formation of LTM after massed training.

Background Extended wakefulness disrupts acquisition of short term memories in mammals. However, the underlying molecular mechanisms triggered by extended waking and restored by sleep are unknown. Moreover, the neuronal circuits that depend on sleep for optimal learning remain unidentified. Results Learning was evaluated using Aversive Phototaxic Suppression (APS). In this task, flies learn to avoid light that is paired with an aversive stimulus (quinine /humidity). We demonstrate extensive homology in sleep deprivation induced learning impairment between flies and humans. Both 6 h and 12 h of sleep deprivation are sufficient to impair learning in Canton-S (Cs) flies. Moreover, learning is impaired at the end of the normal waking-day in direct correlation with time spent awake. Mechanistic studies indicate that this task requires intact mushroom bodies (MBs) and requires the Dopamine D1-like receptor (dDA1). Importantly, sleep deprivation induced learning impairments could be rescued by targeted gene expression of the dDA1 receptor to the MBs. Conclusion These data provide direct evidence that extended wakefulness disrupts learning in Drosophila. These results demonstrate that it is possible to prevent the effects of sleep deprivation by targeting a single neuronal structure and identify cellular and molecular targets adversely affected by extended waking in a genetically tractable model organism.

SUMMARY Given the role that sleep plays in modulating plasticity, we hypothesized that increasing sleep would restore memory to canonical memory mutants without specifically rescuing the causal molecular-lesion. Sleep was increased using three independent strategies: activating the dorsal Fan Shaped Body (FB), increasing the expression of Fatty acid binding protein (dFabp) or by administering the GABA-A agonist 4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridine-3-ol (THIP). Short-term memory (STM) or Long-term memory (LTM) was evaluated in rutabaga (rut) and dunce (dnc) mutants using Aversive Phototaxic Suppression (APS) and courtship conditioning. Each of the three independent strategies increased sleep and restored memory to rut and dnc mutants. Importantly, inducing sleep also reverses memory defects in a Drosophila model of Alzheimer’s disease. Together these data demonstrate that sleep plays a more fundamental role in modulating behavioral plasticity than previously appreciated and suggests that increasing sleep may benefit patients with certain neurological disorders.

The addition of diffusion-weighted images with a b-value of 2,000 s/mm2 to T2WI can improve the diagnostic performance of MR imaging in prostate cancer detection.

Starvation, which is common in the wild, appears to initiate a genetic program that allows fruitflies to remain awake without the sleepiness and cognitive impairments that typically follow sleep deprivation.

To explore the mechanisms of adrenomedullin-induced vasorelaxation, we tested the effects of adrenomedullin on renal function in rats in vivo and measured the release of endothelium-derived nitric oxide from isolated perfused rat kidney (using a chemiluminescence assay) and the diameters of the glomerular arterioles in the hydronephrotic kidney. Adrenomedullin decreased blood pressure in a dose-dependent manner (3 nmol/kg: -29 +/- 2% [SEM]; P < .01) and slightly increased the glomerular filtration rate and urinary sodium excretion (+108%; P < .05). These changes were associated with significant increases in urinary excretion of cyclic AMP (+54%; P < .05). Adrenomedullin decreased renal vascular resistance (10(-7) mol/L adrenomedullin: -41 +/- 2%; P < .001) and increased release of nitric oxide (+5.1 +/- 0.7 fmol/min per gram kidney weight; P < .001) in the isolated kidney. This increase in nitric oxide release was abolished by the inhibitor NG-monomethyl-L-arginine, and it also reversed the decrease in renal vascular resistance seen with adrenomedullin. Renal responses of deoxycorticosterone acetate-salt hypertensive rats to adrenomedullin were significantly smaller than those of control rats for both release of nitric oxide (10(-7) mol/L adrenomedullin: +0.8 +/- 0.2 fmol/min per gram kidney weight; P < .01 versus control) and renal vasodilation (-28 +/- 6%; P < .05). Videomicroscopic analysis revealed that adrenomedullin increased the diameters of both afferent and efferent arterioles (3 nmol/kg: +11%; P < .05). Thus, adrenomedullin-induced renal vasodilation is partially endothelium dependent and is attenuated in deoxycorticosterone acetate-salt hypertension, probably due to endothelial damage.

Drosophila melanogaster is increasingly being used to model human conditions that are associated with cognitive deficits including fragile-X syndrome, Alzheimer’s disease, Parkinson’s disease, sleep loss, etc. With few exceptions, cognitive abilities that are known to be modified in these conditions in humans have not been evaluated in fly models. One reason is the absence of a simple, inexpensive and reliable behavioral assay that can be used by laboratories that are not expert in learning and memory. Aversive phototaxic suppression (APS) is a simple assay in which flies learn to avoid light that is pairedwith an aversive stimulus (quinine/humidity). However, questions remain about whether the change in the fly’s behavior reflects learning an association between light and quinine/humidity or whether the change in behavior is because of nonassociative effects of habituation and/or sensitization. We evaluated potential effects of sensitization and habituation on behavior in the T-maze and conducted a series of yoked control experiments to further exclude nonassociative effects and determine whether this task evaluates operant learning. Together these experiments indicate that a fly must associate the light with quinine/humidity to successfully complete the task. Next, we show that five classic memory mutants are deficient in this assay. Finally, we evaluate performance in a fly model of neurodegenerative disorders associated with the accumulation of Tau. These data indicate that APS is a simple and effective assay that can be used to evaluate fly models of human conditions associated with cognitive deficits.

These data indicate that sleep plays an important and phylogenetically conserved role in the developing brain.