Baical skullcap and its effects on sleep-wake regulation.
Chang H, Yi P, Cheng C, Lu C, Hsiao Y, Tsai Y, Li C, Chang F. 2011. Biphasic effects of baicalin, an active constituent of Scutellaria baicalensis Georgi, in the spontaneous sleep-wake regulation. J Ethnopharmacol 135;359-68.
The dried root of Scutellaria baicalensis has been used for many years in traditional Chinese medicine (TCM) and Western herbal medicine. Whilst most Western herbalists use it for its anti-allergic effects, this herb also possesses a range of therapeutic activities, including anti-inflammatory, antipyretic, antibacteria, antihypertensive and sedative.
Application for its sedative effects on the central nervous system has been limited in clinical practice. Baicalin, one of the active compounds in the herb has been shown to have anxiolytic effects via activation of GABAA receptors. Other studies have shown that inflammatory cytokines and tumour necrosis factor (TNF-[alpha]) modulate sleep cycles. This study was designed to determine whether the GABAA receptor activation and/or the suppression of pro-inflammatory cytokines mediate baicalin induced sleep alterations.
Male Sprague-Dawley rats were surgically implanted with three electroencephalogram (EEG) screw electrodes (on the right hemisphere of the frontal and parietal lobes and the left hemisphere of the occipital lobe) and a guide cannulae into the lateral ventricle. After seven days' recovery they were divided into five groups.
* Group 1 was used to demonstrate the effect of baicalin during light period. An undisturbed control recording was measured on the first day, then rats received vehicle (0.5% DMSO), 50 [micro]M baicalin and 100 [micro]M baicalin over the following consecutive days. EEG and sleep recordings were obtained for 23 h every day.
* Group 2 had the same dosage schedule and recordings except that they received the substances 20 minutes prior to the dark period and recordings began from dark onset.
* Group 3 was designed to measure involvement of IL-1[beta] in baicalin induced sleep alteration.
* Group 4 was administered either DMSO or 100 [micro]M baicalin 20 mins prior to light onset and then their hypothalamus, hippocampus and cerebral cortex dissected.
* Group 5 was employed to demonstrate GABA involvement in baicalin induced sleep alteration.
Overall the results demonstrated that administration of baicalin 20 min prior to the beginning of the light periods significantly suppressed short wave sleep (SWS) during the first hour after injection. Rebound enhancement of this phase of sleep was seen after 4 hours. Wakefulness was enhanced in the hour after baicalin. REM sleep was not affected.
When administered 20 min prior to the dark period, baicalin enhanced SWS during the following 8-10 hours of darkness and at higher doses significantly enhanced the period of time spent in REM sleep also.
This shows the importance of circadian rhythms when dosing baical skullcap to enhance sleep.
Results may be due to the herb's ability to suppress IL-1s induced SWS enhancement during light hours (via a blockade effect rather than affecting production) and by interactions with GABAA receptors.
Tessa Finney-Brown MNHAA