Effects of Ginsenosides on Electroencephalogram Power Spectra in Rats

Fen-fang Hong 1,2,#, Gui-lin Tu2,#, Zhao-hui Wang 3, 1Department of Physiology, 2Department of Experimental

Teaching, College of Medicine, Nanchang University, Nanchang, China

# co-author

Da-lei Zhang 1,lei Wu 1, bei Yang 1, Shu-long Yang 1,ξ 3Disease Control Centers of Nanchang Railroad Bureau;

Nanchang, China ξ Corresponding author: slyang@ncu.edu.cn

Abstract—Aim: To investigate the effects of Ginsenosides (GS) on EEG power wave spectra of spontaneous sleep. Method: Adult SD rats were randomly divided into the control, GS 10 and 100 mg/kg groups. After recovery from operation, rats were orally administered GS 10 and 100 mg/kg or water once per day for 6 days. On day 1 and 6 of GS administration, Polygraphic signs of undisturbed sleep-wake activities were recorded for 12h after GS administration. Results: On GS administration day 1, 10 and 100 mg/kg GS enhanced θ power of NREM and wakefulness but reduced θ power of wakefulness and α power during sleep and wakefulness, 10 and 100mg/kg GS lowered θ power of NREM and REM stage, respectively. After 6 days of GS administration, 10 and 100mg/kg GS enhanced δ power during NREM and wakefulness but reduced θ power of wakefulness and α power during sleep and wake state, 10 mg/kg GS also lowered θ power of NREM. The increase of δ power in all stages, the decrease of θ power in NREM and REM sleep and the decrease of α power during NREM and wakefulness were observed in 10mg/kg group; the decrease of θ power during NREM sleep and of α power during wakefulness and the increase of δ power in wakefulness shown in 100mg/kg group. Conclusion: These results demonstrate that GS can regulate extensively cortical EEG power spectra in rats.

Keywords-Ginsenosides; Sleep, Power wave spectra, Electroencephalogram.

I. INTRODUCTION

Sleep is critical in recovery from tiredness and thereby has potent restorative virtues. Previous literatures have displayed that a variety of ginsengs, including its constituent and combination, act a roles in modulation of sleep/sleep disturbance in human and animals [1-2]. Ginseng extract may exert a stabilizing effects on sleep-waking disturbances which possibly accounts for its outstanding health-improving activities [3]. It also relieves sleep disturbances in pre- and postmenopausal women [4]. Morning menopause formula which contains panax ginseng, significantly reduce scores in sleep quality, sleep latency, sleep duration, sleep disturbance, and daytime dysfunction [5] PEC (Panax quinquefolium included) can also improve cognitive-deficiency induced by taking off sleep with force after given orally for 7 days, increase the spontaneous activity, antagonize the inhabitation

induced by Valium, and shorten the sleeping time caused by sodium pentobarbital [6].However, sleep disorders are also the most commonly experienced adverse effects of ginseng [7].

In order to further elucidate the role of GS regulating spontaneous sleep, we examined its effects on power wave spectra using cortical electroencephalogram (EEG) recording.

II. MATERIAL AND METHODS

Adult Sprague Dawley rats (280 and 360 g) were housed individually under ambient temperature of 22±0.5 °C with a relative humidity of 60±2% and an automatically controlled 12h light/12h dark cycle (lights on at 07:00) with free access to food and water. Panax ginseng root saponins for the powder included 95% or more Ginsenosides (GS). Following 6-day acclimation period, under pentobarbital anesthesia (50 mg/kg, i.p.), rat were chronically implanted with transmitters (TA11CTA-F40: Data Sciences International, St. Paul, MN, USA) for recording of EEG and activity via telemetry as described previously [8]. After 7 day post-surgical recovery, rats were randomly divided into the control, GS 10 (low dose) and 100 (high dose) mg/kg groups with each 9 rats. GS were dissolved in distilled water and orally administrated at 7 AM once per day for 6 days. On GS administration day 1(acute) and day 6(chronic), the animals were habituated extensively for freely moving polygraphic recording conditions. Polygraphic signs of undisturbed sleep-wake activities were recorded for 12h after GS administration. Cortical EEG and activity were recorded using telemetric recording procedures similar to previous reports [8-9]. Cortical EEG and activity were amplified, filtered (EEG, 0.5–20 Hz), digitized at a sampling rate of 128 Hz, and recorded by using telemetric recording procedures and SleepSign (Kissei Comtec, Matsumoto, Japan) as described before [8-10].

All data were expressed as means ± SEM and analyzed using SPSS 17.0 software (SPSS, Chicago, IL, USA). Group differences after significant one way ANOVAs were measured by post hoc Stutent’s t-test. P<0.05 was taken as the level of significance.

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III. RESULTS

A. Effects of GS acute administration on EEG power density during NREM, REM, and wakefulness stages

As indicated Table 1, on GS oral day 1, 10 and 100mg/kg

GS raised wave power of NREM (P<0.05) and wake stage (P<0.01) but lowered wave power of wakefulness (P<0.01) and α wave power during the whole sleep (P<0.01) and wake state (P<0.01) , moreover, 10 and 100mg/kg GS deseased wave power of REM and NREM stage (P<0.05) , respectively.

TABLE 1 EFFECTS OF GS ACUTE ADMINISTRATION ON EEG POWER DENSITY DURING NREM, REM, AND WAKEFULNESS STAGES

Stage Group wave wave wave

Control 29.62±2.04 13.96±1.40 23.49±0.91

NREM GS 10 mg/kg 59.47±10.40* 10.41±1.87 7.64±1.67***

GS 100 mg/kg 62.84±11.49* 9.02±2.22* 11.32±3.66**

Control 24.11±2.75 21.59±1.36 30.85±2.33

REM GS 10 mg/kg 30.02±7.27 16.76±1.53* 19.35±1.03***

GS 100 mg/kg 45.77±6.33** 18.28±3.17 16.89±2.18***

Control 23.21±1.98 24.38±2.14 29.52±1.85

Wake GS 10 mg/kg 47.82±7.63** 14.67±2.53** 11.39±1.72***

GS 100 mg/kg 70.89±4.93*** 8.81±0.81*** 10.66±1.91***

The values are expressed as mean ± S.E.M. of EEG

power densities in three selected frequency bands in the NREM sleep, REM sleep, and wakefulness stages. Group differences after significant one way ANOVAs were measured by post hoc Stutent’s t-test. * P<0.05, ** P<0.01 and *** P<0.001 compared to control.

B. Effects of GS chronic administration on EEG power density during NREM, REM, and wakefulness stages

In Table 2, following 6 days of GS treatment, 10 and

100mg/kg GS increased wave power during NREM (P<0.05) and wake stage (P<0.01) but lowered wave power of wakefulness (P<0.05) and α wave power during the whole sleep (P<0.05) and wake state (P<0.01) , 10mg/kg GS also decreased wave power of NREM sleep (P<0.01).

TABLE 2 EFFECTS OF GS CHRONIC ADMINISTRATION ON EEG POWER DENSITY DURING NREM, REM, AND WAKEFULNESS STAGES

Stage Group wave wave wave

Control 31.47±0.70 14.41±1.24 24.32±1.12

NREM GS 10 mg/kg 61.38±8.93** 8.83±1.63** 7.13±1.32***

GS100 mg/kg 58.84±9.61* 11.34±1.82 11.11±2.97***

Control 21.17±2.91 19.92±1.95 32.16±4.33

REM GS 10 mg/kg 28.35±3.32 18.98±0.63 22.53±2.18*

GS 100 mg/kg 24.29±4.59 27.56±4.27 20.54±1.29**

Control 25.52±2.73 23.44±1.60 29.76±1.75

Wake GS 10 mg/kg 49.56±6.90** 16.39±2.31* 11.21±1.15***

GS 100 mg/kg 52.09±8.36** 15.63±1.81** 13.30±2.58***

The values are expressed as mean ± S.E.M. of EEG power densities in three selected frequency bands in the NREM sleep, REM sleep, and wakefulness stages. Group differences after significant one way ANOVAs were measured by post hoc Stutent’s t-test. * P<0.05, ** P<0.01 and *** P<0.001 compared to control.

IV. DISCUSSION

It is well known that total sleep amount and frequency depends on the activity patterns of cortical EEG waves [11]. Several pure saponins isolated from Panax ginseng C. A. Meyer also create moderate depressant actions on the EEG, the behavior and EEG arousal response induced by electrical stimulation of the mid brain in cats [12]. Standardized Ginseng Extract G115 has been shown to produce a desynchronizing effect on the electrocorticogram [13]. However, there are few reports about the role of GS in EEG power density in human or animals. Here we further analyzed the effects of GS on wave band in rats. Although low dose GS didn’t alter sleep architecture and sleep-wake cycle following its acute oral intake, we noted that both low and high dose GS treatment enhanced delta activity of NREM and wakefulness stage but reduced theta activity of wakefulness and alpha activity of the whole sleep and wakefulness stage; however, low and high dose GS lowered respectively theta activity in REM and NREM sleep. Following 6 days of GS administration, both low and high dose GS enhanced delta wave power during NREM and wake stage but reduced thetaactivity of wakefulness and alpha activity of the whole sleep and wake state, low but not high dose GS lowered thetaactivity of NREM sleep. Quantitative EEG analysis allows the extraction of important functional parameters such as slow-wave activity (SWA, or delta activity) in NREM sleep, encompassing components of the EEG signal in the frequency range (0.5–4.5 Hz) [14], REM sleep and waking are characterized in animals (i.e. rodents) by a pronounced activity in the theta (6–9 Hz) frequency range, but the functional significances of slow waves and REM sleep regulation are still unknown. From our experiments, there were extensive regulations in GS action on power density though no dose or time-depend trends existed between low and high dose GS. These findings are interesting and imply

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that the regulations of GS on EEG wave band and sleep behavior may be far more complicated than present openion.

Totally, present study demonstrated that marked regulations of GS action on power density were existed, suggesting that GS modulate EEG power spectra following acute and chronic GS administration. These findings provide a new viewpoint for treating sleep disorder such as insomnia with traditional Chinese medicine herb.

ACKNOWLEDGMENT This work was supported by Educational Commission of

Jiangxi Province of China No. 2008GJJ09038 and Foundation of Nanchang University No 300304 .

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