Probing pathways by which rhynchophylline modifies sleep using spatial transcriptomics

Abstract

Background Rhynchophylline (RHY) is an alkaloid component of Uncaria, which are plants extensively used in traditional Asian medicines. Uncaria treatments increase sleep time and quality in humans, and RHY induces sleep in rats. However, like many traditional natural treatments, the mechanisms of action of RHY and Uncaria remain evasive. Moreover, it is unknown whether RHY modifies key brain oscillations during sleep. We thus aimed at defining the effects of RHY on sleep architecture and oscillations throughout a 24-h cycle, as well as identifying the underlying molecular mechanisms. Mice received systemic RHY injections at two times of the day (beginning and end of the light period), and vigilance states were studied by electrocorticographic recordings. Results RHY enhanced slow wave sleep (SWS) after both injections, suppressed paradoxical sleep (PS) in the light but enhanced PS in the dark period. Furthermore, RHY modified brain oscillations during both wakefulness and SWS (including delta activity dynamics) in a time-dependent manner. Interestingly, most effects were larger in females. A brain spatial transcriptomic analysis showed that RHY modifies the expression of genes linked to cell movement, apoptosis/necrosis, and transcription/translation in a brain region-independent manner, and changes those linked to sleep regulation (e.g., Hcrt, Pmch) in a brain region-specific manner (e.g., in the hypothalamus). Conclusions The findings provide support to the sleep-inducing effect of RHY, expose the relevance to shape wake/sleep oscillations, and highlight its effects on the transcriptome with a high spatial resolution. The exposed molecular mechanisms underlying the effect of a natural compound should benefit sleep- and brain-related medicine. Graphical Abstract

Electrocorticographic and Astrocytic Signatures of Stearoyl-CoA Desaturase Inhibition in the Triple Transgenic Mouse Model of Alzheimer’s Disease

“…Absolute and relative activity for the full 24hour recording and 12-hour periods were also calculated for six different frequency bands (i.e., SWA 0.5-5 Hz, Theta 5-9 Hz, Alpha 9-12 Hz, Sigma 12-16 Hz, Beta 16-30 Hz, Gamma 30-50 Hz). In addition, the 24-hour time course of SWA and Theta activity during wakefulness and SWS was calculated using averages per time intervals to which an equal number of epochs contributed and expressed relative to the 24-hour mean activity for each band and each mouse as described previously (Areal et al, 2020;Ballester Roig et al, 2023;Hector et al, 2023).…”

“…For implantation, mice were deeply anesthetized with ketamine/xylazine (120/10 mg/kg, intraperitoneal injection) combined to continuous isoflurane (0.5-2%, inhalation), and were installed in a stereotaxic frame. Mice were implanted with ECoG and EMG electrodes similar to previously described (El Helou et al, 2013;Areal et al, 2020;Ballester Roig et al, 2023). ECoG electrodes (J.I.…”

“…Vigilance states (i.e., wakefulness, SWS, PS) were visually assigned to 4-second epochs using bipolar ECoG (motor -visual cortex) and EMG signals as previously described (Ballester Roig et al, 2023;Hector et al, 2023). Artifacts were simultaneously identified and excluded from spectral and scalefree ECoG analyses.…”

Spatial Transcriptomics: A Powerful Tool in Disease Understanding and Drug Discovery

“…The application of ST has substantial potential for predicting the pathways of action of active constituents in natural remedies. For example, an ST analysis of a mouse brain revealed the molecular pathways influenced by Rhynchophylline, an alkaloid component of Uncaria known for its significant sleep-inducing effects, indicating that Rhynchophylline impacts genes associated with sleep regulation in specific brain regions 126 . Compared to single-component drugs, traditional Chinese medicine (TCM) is characterized by multiple targets, multiple pathways, and holistic regulation, thereby resulting in greater complexity.…”