Polysomnography using video electroencephalogram, electro-oculogram and electromyogram monitored continuously by telemetry in cynomolgus monkeys

Abstract

Medication-induced sleep disturbances are a major concern in drug development as a multitude of prescription drugs cause abnormalities at polysomnography. Rodent sleep architecture (nocturnal) differs from larger mammals (diurnal) which present higher translational value. Polysomnography is used in clinical diagnostic but also applicable to cynomolgus monkeys when using telemetry with continuous electroencephalogram (EEG), electro-oculogram (EOG) and electromyogram (EMG) monitoring with video. Sleep stages in cynomolgus monkeys include wake, N1 (somnolence), N2 (includes Spindles and K complexes), N3 (deep sleep with slow waves) and rapid eye movements (REM) and are quantified with automated or manual scoring. Optimal cynomolgus data filters included EOG low pass 5Hz. As observed in humans, cynomolgus present an increased duration of REM sleep the 2nd half of the night. REM sleep was characterized by muscle atonia, high frequency (mostly theta) low amplitude EEG in all animals and EOG activity in most but not all epochs. Total sleep time was 70.3±2.2% of the 12 hour dark cycle. Sleep stages N1, N2, N3 and REM were typically observed in sequence and represented 1.1±0.3%, 65.2±5.3%, 16.0±5.6% and 17.7±2.4% of total sleep time, respectively. Amphetamine (1 and 2 mg/kg, PO) significantly reduced total sleep time and all stages the night of ingestion followed by a rebound during the recovery night. Spectral analysis revealed a significant increase in higher frequency bands after amphetamine. VideoEEG, EOG and EMG by telemetry is a useful non-clinical model to investigate drug induced sleep disturbances. Materials and methods One (1) male Cynomolgus monkey received the following control and test items once by oral gavage within 5 minutes before light off, with a period of at least 2 days between each dose: Reverse osmosis water (0mg/kg) d-amphetamine (2mg/kg) Electroencephalographic, electro-oculographic and electromyographic monitoring was recorded in conscious animals, surgically instrumented with a telemetry transmitter (DSI: D70-EEE), from 1 hour prior to the first dose up to 24 hours following the third dose: Electroencephalograms, electrooculograms and sleep architecture were analyzed using Neuroscore software (DSI). Table 1: Stages of sleep in Cynomolgus monkeys EEG EMG EOG Wake Activated : low amplitude High frequencies Signal +/fast (low amplitude et high frequency) as per activity Signal +/fast (low amplitude et high frequency) as per activity Stage N1 Slowing of EEG (frequency generally theta 4-8 Hz) and amplitude higher than at the Wake Few or no movements Few or no movements Stage N2 Frequency generally theta (4-8 Hz) like N1 but presence spindles (small fast waves of 12-16Hz, duration > 0.5s) and K complexes (slow isolated waves) are needed Few or no movements Few or no movements Stage N3 Slow waves (delta 1-4 Hz) High amplitude (>75μV) Few or no movements Few or no movements Paradoxical Sleep Frequency generally in the theta (4-8 Hz) very regular with low amplitude Weak muscular movement Fast ocular movement Results Table 2: Effects of Amphetamine on sleep architecture in Cynomolgus monkeys Saline Amphetamine Baseline night First night Second night Baseline night First night Second night Wake Mean 20.5% 17.8% 20.0% 20.4% 84.2% 28.3% SD 6.0% 5.0% 5.0% 3.7% 14.5% 9.6% N 1 Mean 0.2% 0.3% 0.2% 0.2% 0.1% 0.1% SD 0.4% 0.6% 0.3% 0.3% 0.1% 0.2% N 2 Mean 55.6% 58.5% 57.0% 55.1% 14.0% 53.6 SD 10.5% 9.7% 10.5% 11.1% 13.8% 12.7% N 3 Mean 8.4% 9.4% 8.2% 10.8% 1.5% 11.5% SD 9.5% 9.7% 9.6% 9.0% 2.3% 9.3% REM Mean 15.2% 14.0% 14.4% 13.8% 0.3% 11.0% SD 3.9% 3.2% 3.2% 2.7% 0.7% 5.5% Fig. 2: Sleep architecture in Cynomolgus monkeys Fig. 1: EOG, EEG and EMG signals during various sleep stages 0 10 20 30 40 50 60 0 5 10 15 20 D u ra ti o n ( m in /h o u r) Zeitgeber time (h) Wake 0 5 10 15 20 0 5 10 15 20 25 30 35 40 D u ra ti o n ( m in /h o u r) Zeitgeber time (h) NREM2 0 5 10 15 20 0 2 4 6 8 10 12 14 16 18 20 A m o u n t o f ti m e ( m in ) Paradoxical (REM) Zeitgeber time (h) 0 5 10 15 20 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 D u ra ti o n ( m in /h o u r) Zeitgeber time (h) NREM1 0 5 10 15 20 0 5 10 15 20 25 D u ra ti o n ( m in /h o u r) Zeitgeber time (h) NREM3