Dataset Information

Dim light at night disturbs the daily sleep-wake cycle in the rat.

ABSTRACT: Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12?h light (150-200lux):12?h dark (LD) schedule or a 12?h light (150-200 lux):12?h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily rhythms of REM and NREM sleep, with a further decrease over the following days. LDim diminished the rhythms of 1) the circadian 16-19?Hz frequency domain within the NREM sleep EEG, and 2) SCN clock gene expression. LDim also induced internal desynchronization in locomotor activity by introducing a free running rhythm with a period of ~25?h next to the entrained 24?h rhythm. LDim did not affect body weight or glucose tolerance. In conclusion, we introduce the first rodent model for disturbed circadian control of sleep due to LAN. We show that internal desynchronization is possible in a 24?h L:D cycle which suggests that a similar desynchronization may explain the association between LAN and human insomnia.

SUBMITTER: Stenvers DJ

PROVIDER: S-EPMC5071835 | biostudies-other | 2016 Oct

REPOSITORIES: biostudies-other

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Dim light at night disturbs the daily sleep-wake cycle in the rat.

Stenvers Dirk Jan DJ van Dorp Rick R Foppen Ewout E Mendoza Jorge J Opperhuizen Anne-Loes AL Fliers Eric E Bisschop Peter H PH Meijer Johanna H JH Kalsbeek Andries A Deboer Tom T

Scientific reports 20161020

Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12 h light (150-200lux):12 h dark (LD) schedule or a 12 h light (150-200 lux):12 h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily ...[more]

PMID: 27762290

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Project description:Sleep is critical for hippocampus-dependent memory consolidation. However, the underlying mechanisms of synaptic plasticity are poorly understood. The central controversy is on whether long-term potentiation (LTP) takes a role during sleep and which would be its specific effect on memory. To address this question, we used immunohistochemistry to measure phosphorylation of Ca2+/calmodulin-dependent protein kinase II (pCaMKII?) in the rat hippocampus immediately after specific sleep-wake states were interrupted. Control animals not exposed to novel objects during waking (WK) showed stable pCaMKII? levels across the sleep-wake cycle, but animals exposed to novel objects showed a decrease during subsequent slow-wave sleep (SWS) followed by a rebound during rapid-eye-movement sleep (REM). The levels of pCaMKII? during REM were proportional to cortical spindles near SWS/REM transitions. Based on these results, we modeled sleep-dependent LTP on a network of fully connected excitatory neurons fed with spikes recorded from the rat hippocampus across WK, SWS and REM. Sleep without LTP orderly rescaled synaptic weights to a narrow range of intermediate values. In contrast, LTP triggered near the SWS/REM transition led to marked swaps in synaptic weight ranking. To better understand the interaction between rescaling and restructuring during sleep, we implemented synaptic homeostasis and embossing in a detailed hippocampal-cortical model with both excitatory and inhibitory neurons. Synaptic homeostasis was implemented by weakening potentiation and strengthening depression, while synaptic embossing was simulated by evoking LTP on selected synapses. We observed that synaptic homeostasis facilitates controlled synaptic restructuring. The results imply a mechanism for a cognitive synergy between SWS and REM, and suggest that LTP at the SWS/REM transition critically influences the effect of sleep: Its lack determines synaptic homeostasis, its presence causes synaptic restructuring.

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Dim light at night disturbs the daily sleep-wake cycle in the rat.

Publications

Dim light at night disturbs the daily sleep-wake cycle in the rat.

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