The relationship between anxiety and sleep–wake behavior after stressor exposure in the rat

Abstract

Disturbed sleep is a common subjective complaint among individuals diagnosed with anxiety disorders. In rodents, sleep is often recorded after exposure to various foot-shock paradigms designed to induce an anxiety state. Although differences in sleep-wake architecture are noted, the relationship to specific level of anxiety is often assumed or absent. Utilizing the elevated plus maze (EPM) after exposure to escapable shock (ES), inescapable shock (IS) or fear conditioning (FC), resulting differences in sleep architecture were compared to an objective measure of anxiety. Male Wistar rats were implanted with EEG, EMG and hippocampal theta electrodes to record sleep-wake behavior. After recovery and recording of baseline sleep, rats were exposed to one of five manipulations: ES, IS, FC, or control (CES or CIS; utilizing either chamber with no shock exposure). Shortly after experimental manipulation, the EPM was employed to quantify traditional and ethological measures of anxiety and polygraphic signs of sleep-wake behavior were recorded continuously for 6h. Although no significance was observed in EPM measurements across groups, profound differences in sleep architecture were present. Individual correlation analysis revealed no differences in anxiety level and total percentage of time spent in sleep-wake states. These results indicate that differences in sleep architecture after foot-shock exposure may not be simply due to increased anxiety. Rather, individual anxiety may be exacerbated by disrupted sleep. To fully understand the relationship between anxiety and sleep-wake behavior, a more objective analysis of anxiety after stressor exposure is mandated.

Effects of eszopiclone and zolpidem on sleep–wake behavior, anxiety-like behavior and contextual memory in rats

“…The elevated plus-maze (EPM) is the most extensively used behavioral paradigm to measure anxiety in the rodent model [9, 42, 53]. Anxiety-related behavior reflects a conflict between the rodent’s desire to explore a novel environment and its innate preference to protected areas [106].…”

“…The percentage of time spent on the open arm is increased and decreased with anxiolytic and anxiogenic substances, respectively [3, 70, 78]. When used appropriately, the EPM is the most effective and popular animal model to observe and quantify anxiety within the rodent model [53, 77]. …”

“…The rodent model is also frequently employed to measure the changes in sleep-wake architecture after experimental manipulation of fear-inducing stress [41, 43, 53, 56, 99]. Classical fear conditioning, the most common paradigm, utilizes an unconditioned foot-shock presented with a conditioned stimulus to measure the acquisition, expression and/or extinction of fear [43, 53, 68, 99].…”

“…Classical fear conditioning, the most common paradigm, utilizes an unconditioned foot-shock presented with a conditioned stimulus to measure the acquisition, expression and/or extinction of fear [43, 53, 68, 99]. Neuroimaging techniques, such as fMRI, have afforded researchers the opportunity to examine the similarities between structures involved in the acquisition and expression of fear in humans and rodents [25].…”

A novel system allowing long-term simultaneous video-electroencephalography recording, drug infusion and blood sampling in rats

“…epilepsy, psychosis, sleep and anaesthesia (Feng and Ma, 2002;Maclean and Datta, 2007;McKenna et al, 2007;Lu et al, 2008). Video-EEG (vEEG) allows simultaneous recording of the animals' behaviour, and is a particularly valuable tool to investigate the acute and long-term pharmacodynamic effects of drugs on pathological features such as epileptic seizures but is also highly relevant to a variety of neuropsychopharmacological studies where a correlation of behaviour with cerebral EEG is important .…”