Age and circadian rhythm‐dependent effects of M1 muscarinic acetylcholine receptor positive allosteric modulators and donepezil on sleep‐wake architecture and arousal

Abstract

AbstractBackgroundDegeneration of basal forebrain cholinergic signaling in aging and Alzheimer's disease (AD) is linked with abnormalities in arousal, sleep/wake architecture, and cognition. While acetylcholinesterase inhibitors (AChEIs) are approved for the treatment of AD, they produce dose‐limiting adverse effects due to nonselective activation of peripheral muscarinic acetylcholine receptors (mAChRs). Selectively targeting the M1 mAChR using M1 positive allosteric modulators (PAMs) has shown promise for boosting cognitive performance and arousal across preclinical species. We evaluate the effects of the M1 PAM VU0453595 on arousal and sleep/wake architecture in aged and young mice across both the active and inactive phases of the circadian cycle. We hypothesize that dosing an M1 PAM during the active phase in aged mice will produce a greater enhancement of arousal and wakefulness, normalizing deficits observed in aged mice.MethodUtilizing electroencephalography, we examined the effects of the M1 PAM VU0453595 in comparison with the AChEI Donepezil on sleep‐wake architecture and state dependent spectral power in young and aged C57/BL6 mice following dosing in either the active or inactive phases of the circadian cycle.ResultWhen compared to young mice, aged mice displayed several alterations in normal sleep‐wake architecture; in the inactive phase, reductions in rapid eye movement (REM) sleep, while in the active phase increases in non‐REM (NREM) sleep and decreases in wakefulness. Aged mice also displayed reductions in slow delta power during NREM sleep and increased delta power during wake. In young mice, dosing with both compounds increased wakefulness and arousal during wake in the inactive phase, with reduced effects in the active phase. In the aged mice VU0453595 increased arousal during wake in the inactive phase, and both wakefulness and arousal during wake when dosed in the active phase. Donepezil in contrast produced increased wakefulness in the inactive period, but reduced wakefulness in the active period and limited effects on arousal during wake.ConclusionThe M1 PAM VU0453595 produced increases in wakefulness and arousal in aged mice during the active phase, suggesting that selective M1 PAMs may be suitable for dosing during the active phase in aging and AD populations to normalize disruptions in wakefulness and arousal.