Effect of basal forebrain neuropeptide Y administration on sleep and spontaneous behavior in freely moving rats.
ABSTRACT Neuropeptide Y (NPY) is present both in local neurons as well as in fibers in the basal forebrain (BF), an area that plays an important role in the regulation of cortical activation. In our previous experiments in anaesthetized rats, significant EEG changes were found after NPY injections to BF. EEG delta power increased while power in theta, alpha, and beta range decreased. The aim of the present experiments was to determine whether NPY infusion to BF can modulate sleep and behavior in freely moving rats. In this study, microinjections were made into the BF. Saline was injected to the control side, while either saline or one of two doses of NPY (0.5 microl, 300-500 pmol) to the treated side. EEG as well as behavioral changes were recorded. Behavioral elements after the NPY injections changed in a characteristic fashion in time and three consecutive phases were defined. In phase I (half hour 2), activated behavioral items (moving, rearing, grooming) appeared frequently. In phase II (half hours 3 and 4) activity decreased, while motionless state increased. Reappearance of activity was seen in phase III (half hours 5 and 6). NPY injections caused sleep-wake changes. The three phases described for behavioral changes were also reflected in the sleep data. During phase I, lower NPY dose increased wakefulness and decreased deep sleep. Reduced behavioral activity seen in phase II was partially reflected in the sleep. In this phase, wakefulness tended to increase in the third half hour, while decreased in the 4th half hour. Deep sleep and total slow wave sleep non-significantly decreased in the third and increased in the 4th half hour. In most cases, wakefulness was elevated again during Phase III, while sleep decreased. Length of single sleep-wake epochs did not change after NPY injections. Our results suggest a role for NPY in the integration of sleep and behavioral stages via the BF.
Full-textDOI: · Available from: Laszlo Detari, Sep 16, 2014
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ABSTRACT: It is known that the sleep-waking cycle is modulated by several molecules that may also regulate food intake, among them several neuropeptides. The cocaine-and-amphetamine-regulated transcript has been studied in relation to food ingestion, but it seems to have several other functions that may include sleep regulation. In this context, we studied the effect of the intracerebroventricular administration of the cocaine-and-amphetamine-regulated transcript (0.15, 0.3, 0.6, 0.9nmol) on the sleep-waking cycle (12-h recordings), as well as its effect on food intake in rats. Additionally, we analyzed the neuronal activity as measured by c-Fos expression induced by the cocaine-and-amphetamine-regulated transcript in neurons of nuclei involved in the regulation of sleep and feeding behavior. Our main finding is that 0.3nmol of the cocaine-and-amphetamine-regulated transcript increases rapid-eye-movement sleep. In addition, our results further support that this neuropeptide triggers satiety; c-Fos expression suggested that the cocaine-and-amphetamine-regulated transcript activates specific hypothalamic nuclei without affecting other brain structures known to be involved in sleep regulation. These data further support the notion that a few neuropeptides are involved in the regulation of both the sleep-waking and the hunger-satiety cycles.Neuropeptides 09/2009; 43(6):499-505. DOI:10.1016/j.npep.2009.08.004 · 2.55 Impact Factor
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ABSTRACT: Biological homeostasis invokes modulatory responses aimed at stabilizing internal conditions. Using tunable photo- and mechano-stimulation, we identified two distinct categories of homeostatic responses during the sleep-like state of C. elegans (lethargus). In the presence of weak or no stimuli, extended motion caused a subsequent extension of quiescence. The neuropeptide Y receptor homolog, NPR-1, and an inhibitory neuropeptide known to activate it, FLP-18, were required for this process. In the presence of strong stimuli, the correlations between motion and quiescence were disrupted for several minutes but homeostasis manifested as an overall elevation of the time spent in quiescence. This response to strong stimuli required the function of the DAF-16/FOXO transcription factor in neurons, but not that of NPR-1. Conversely, response to weak stimuli did not require the function of DAF-16/FOXO. These findings suggest that routine homeostatic stabilization of sleep may be distinct from homeostatic compensation following a strong disturbance.eLife Sciences 12/2014; 3. DOI:10.7554/eLife.04380 · 8.52 Impact Factor
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ABSTRACT: Neuropeptide Y (NPY) is a powerful orexigenic peptide secreted by hypothalamic neurons. The present study investigates how NPY injection into the lateral ventricle modulates masticatory movements and eating behavior. Behavioral experiments showed that cumulative food intake over a 4-h period and latency to eating were increased and decreased, respectively, in NPY-injected rats compared to saline-injected control rats. The feeding time for 2g pellets was shorter in NPY-injected rats and resulted in an increased feeding rate, with more potent effects observed at 1μg compared to 10μg NPY. After injection of 10μg NPY, a greater number of bouts with shorter average bout duration for eating 2g, compared to 1μg NPY, were observed. Furthermore, 10μg NPY injection resulted in prolonged periods of moving and shortened sleep and grooming. Electromyography recordings from the digastric and masseter muscles showed two distinct patterns of bursts corresponding to the gnawing and chewing phases. After the injection of 1μg NPY, the burst magnitude of masseter muscle during the gnawing phase increased, reflecting strong jaw-closing muscle activity. The relative integrated EMG of masseter muscle in both phases was smaller following injection of 10μg NPY in comparison with that of 1μg NPY. The present study indicates that 1μg NPY administration promotes feeding behavior together with increased feeding rate and powerful jaw-closing muscle activity; whereas 10μg NPY administration lowers jaw-closing muscle activity during biting and produces mastication with shorter and more frequent feeding bouts than 1μg NPY. Copyright © 2014 Elsevier B.V. All rights reserved.Behavioural Brain Research 11/2014; 278C:520-526. DOI:10.1016/j.bbr.2014.10.031 · 3.39 Impact Factor