Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom; The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom; The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom
Geneva University Hospitals (HUG), Division of Psychiatric Specialties, Geneva, Switzerland; University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom; The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom; Sir Jules Thorn Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, United Kingdom; The Kavli Institute for Nanoscience Discovery, Oxford, United Kingdom; University Hospital of Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland; Centre for Experimental Neurology, University of Bern, Bern, Switzerland
Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools for remote control of targeted cell populations using chemical actuators that bind to modified receptors. Despite the popularity of DREADDs in neuroscience and sleep research, potential effects of the DREADD actuator clozapine-N-oxide (CNO) on sleep have never been systematically tested. Here, we show that intraperitoneal injections of commonly used CNO doses (1, 5, and 10 mg/kg) alter sleep in wild-type male laboratory mice. Using electroencephalography (EEG) and electromyography (EMG) to analyse sleep, we found a dose-dependent suppression of rapid eye movement (REM) sleep, changes in EEG spectral power during non-REM (NREM) sleep, and altered sleep architecture in a pattern previously reported for clozapine. Effects of CNO on sleep could arise from back-metabolism to clozapine or binding to endogenous neurotransmitter receptors. Interestingly, we found that the novel DREADD actuator, compound 21 (C21, 3 mg/kg), similarly modulates sleep despite a lack of back-metabolism to clozapine. Our results demonstrate that both CNO and C21 can modulate sleep of mice not expressing DREADD receptors. This implies that back-metabolism to clozapine is not the sole mechanism underlying side effects of chemogenetic actuators. Therefore, any chemogenetic experiment should include a DREADD-free control group injected with the same CNO, C21, or newly developed actuator. We suggest that electrophysiological sleep assessment could serve as a sensitive tool to test the biological inertness of novel chemogenetic actuators.
