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Chronic intake of Panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats
Neuroscience Letters, 111 (1990) 217-221
217
Elsevier Scientific Publishers Ireland Ltd. NSL 06753
Chronic intake of Panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats S u n g Pil Lee l, K a z u k i H o n d a l, Y o u n g H o R h e e 2 a n d S h o j i r o I n o u 6 l 1Institutefor Medical and Dental Engineering, Tokyo Medical and Dental University, Tokyo (Japan) and 2Department of Neuropsychiatry, College of Medicine, Chungbuk National University, Chungju (Korea)
(Received 2 November 1989; Revisedversion received 1 December 1989; Accepted 1 December 1989) Key words: Food deprivation; Ginseng extract; Rat; Slow wave sleep; Wakefulness
The amount of wakefulness and slow wave sleep significantly fluctuated during 48 h food deprivation and subsequent recoveryperiods in freely behaving male rats. In contrast, such fluctuations were significantly less prominent in age-matchedmale rats chronicallytreated with Panax ginseng extract via drinking water. It is speculated that the ginseng extract may exert a stabilizing effect on sleep-wakingdisturbances which possiblyaccounts for its outstanding health-improvingactivities.
The ginseng, P a n a x ginseng, as a herbal medicine is well known for its outstanding effect on the improvement of h u m a n health in general (for reviews, see refs. 9, 14, 24). The ginseng root contains a number of physiologically important constituents [8]. In rats, it is reported that ginseng extract exerts a decrease in blood pressure [19, 21], a suppression of conditioned avoidance response [17, 19, 20, 22] and sound discrimination [20], an inhibition of gastric ulceration [2], a facilitation of sexual behavior [15], and an increase in essential fatty acids [11] and several essential amino acids [12] in serum. On the assumption that the health-improving effect of the ginseng might be, at least in part, related to the maintenance of a normal state of sleep and wakefulness, we have detected an electroencephalographic (EEG) sleep-modulatory effect of P a n a x ginseng extract in adult freely behaving rats [13, 18]. Using the same approach methods, the present study was conducted to evidence a state-modulatory effect of the ginseng on animals raised under a ginseng treatment. Pregnant female rats of the Sprague-Dawley strain, kept on a 12-h light and 12-h dark schedule (lights on: 08.00-20.00 h) under a constant air-conditioned environment o f 25 4- 1°C and 60 4- 6 % relative humidity with free access to rat chow, were
Correspondence: S. Inou6, Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, Tokyo 101, Japan.
0304-3940/90/$ 03.50 © 1990 ElsevierScientific Publishers Ireland Ltd.
218 individually isolated at 17 to 20 days of gestation for delivery and lactation. They were divided into a control group and an experimental group; the former and the latter were given tap water and ginseng water ad libitum, respectively. The ginseng water contained 0.5 mg per ml of Panax ginseng extract (Korean Red Ginseng Extract, Korea Monopoly Corporation). On the 2nd day of delivery, the litter size was adjusted to 8 pups per mother. On 21 days of age, pups of each group were weaned; 4-5 males were housed in a cage where one of the two kinds of water was given as before. At the age of 60-70 days, the males weighing 300-400 g were anesthetized with pentobarbital sodium and implanted with 3 cortical EEG electrodes and 2 nuchal electromyographic (EMG) electrodes according to the technique described in a previous paper [5]. The animals were individually housed in a special cage which enabled continuous monitoring of EEG and EMG. Lead wires of the electrodes were connected with a polygraph (Nihon-Kohden EEG-4317) via a slip ring fixed above the cage. Thus free movement of the rats was guaranteed. Tap water for the control rats and the ginseng water for the experimental rats were given as before. Each cage was placed in a sound-proof, electromagnetically shielded chamber under the same environmental conditions as above. One week was allowed to recover from the surgery. After observing the establishment of circadian rhythms in sleep-waking behavior, the rats of both groups were subjected to experiments for 4 days starting at the onset of the light period. Following 24 h baseline recording on day 1, rat chow was taken away from the cage for 48 h (days 2 3) and returned on day 4. Throughout the period, tap water for the control rats and the ginseng water for the experimental rats were given as before. The daily dose of the ginseng extract around this period was ca. 15 mg, since the daily intake of drinking water was 31 ml in our young adult male rats [7]. This dosage is comparable to that recommended for human use (3 g for a person weighing 60-80 kg). During the 4-day sessions, EEG (bipolarly registered between 2 combinations of the 3 electrodes) and E M G were polygraphically recorded at a paper speed of 0.5 mm/s. Sleep-waking states were visually classified on a large scale digitizer as slow wave sleep (SWS), paradoxical sleep (PS) and wakefulness (W) according to our routinized criteria, numerically stored and processed in a computer system [6]. Intra- and intergroup differences in the data of days 1 4 were statistically analyzed by Student's t-test. There was no difference in the baseline quantity of SWS and W between the control and the ginseng-treated rats except for the amount of diurnal PS (Fig. 1). Food deprivation initially caused an increase in SWS and a decrease in W in both groups during the light and the dark period of day 2. However, the changes were significant only in the control group as compared to the baseline value of day 1 (P<0.001 for both diurnal and nocturnal amounts of W and SWS). The magnitude of the changes was significantly less in the ginseng-treated rats than the control rats (see Fig. 1). On the second day of food deprivation (day 3), the control rats still exhibited an enhancement of diurnal W (P < 0.01, as compared to day 1) and nocturnal SWS (P < 0.001), and a reduction of diurnal PS (P<0.01) and nocturnal W (P<0.001), whereas the
219
Light 500
period
sw~
40O <--r-i
300
E •,_..
200
ILl
100
PS
,7,
,7,
Day2
I-
- --'------~
[~ 3
Day4
Day3
Day4
Dark p e r i o d 500 400 0
300
1-200 100"
PS
DayI
Day2
Fig. 1. Changes in the diurnal (top) and nocturnal (bottom) amount of wakefulness (W), slow wave sleep (SWS) and paradoxical sleep (PS) before (day 1), during (days 2-3) and after (day 4) food deprivation. S.E.M. is shown by vertical lines, otherwise it is too short to indicate. Statistical differencebetween the control rats (open, n=8) and the ginseng-treated rats (filled,n= 10): *P<0.05, **P<0.01, ***P<0.001 (Student's t-test).
ginseng-treated rats showed significant changes only in diurnal SWS (P < 0.05) and W ( P < 0.05). The difference in the nocturnal amount of W and SWS was significant between the two groups (Fig. 1). When food was restituted at the light onset of day 4, the hourly amount of W was greatly elevated due to feeding behavior, which lasted throughout the light period in the control rats (Fig. 2, top). On the contrary, such an enhancement of W was only episodic in the ginseng-treated rats (Fig. 2, bottom). The significant increase in W resulted in a rebound during the subsequent dark period, the magnitude of which was also less in the ginseng-treated rats. Thus, in both groups, the amount of all parameters was significantly different from the respective baseline value of day 1 (P<0.001 for diurnal W, SWS and PS, P<0.01 for nocturnal W and PS, and P < 0 . 0 5 for nocturnal SWS in the control rats; P<0.001 for diurnal W and SWS, P
220
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-
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Control
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~
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I----
~
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30 Z/Z 2o
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* ** *
08
CLOCK
*20 m I N E
Fig. 2. Time course changes in the hourly amount of wakefulness before (day 1, open) and after (day 4, filled) food deprivation in the control rats (n = 8) and the ginseng-treated rats (n = 10). Vertical lines indicate S.E.M. Statistical difference between days 1 and 4 in the same group is shown inside the graphs, and that between the two groups on day 4 is indicated below. *P< 0.05, **P< 0.01, ***P< 0.001 (Student's t-test). out that, during starvation, the availability o f endogenous substrates at the cellular level seems to play an essential role in the regulation o f sleep-waking states [3]. The fact that the ginseng extract prevented the fluctuations caused by food deprivation may indicate that some constituents o f the ginseng extract promoted the availability o f substrates or inhibited the inavailability o f them, eventually bringing about stabilized sleep--waking behaviors even after food restitution. From another point o f view, it may be postulated that such changes are non-specifically dependent on a normalized state o f body health owing to ginseng intake. A normalization o f sleep and wakefulness observed in chronically ginseng-treated rats in our previous study [13, 18] may indicate such a possibility. In conclusion, it seems likely that the health-improving activities o f Panax ginseng may be, at least in part, related to a stabilization o f sleep and wakefulness or vice versa. This research was partially supported by funds from the N i h o n Seimei Foundation to S.I. and from the Ministry o f Education o f Korea to Y.H.R. 1 Borbely, A.A., Sleep in the rat during food deprivation and subsequent restitution of food, Brain Res., 124 (1977) 457-471.
221 2 Chang, W.A. and Kim, C., Influence of Panax ginseng upon gastric ulceration produced by restraint, J. Cath. Med. Coll., 27 (1974) 249-255. 3 Danguir, J. and Nicolaidis, S., Dependence of sleep on nutrients' availability, Physiol. Behav., 22 (1979) 735-740. 4 Dewasmes, G., Buchet, C., Geloen, A. and Le Maho, Y., Sleep changes in emperor penguins during fasting, Am. J. Physiol., 256 (1989) R476~R480. 5 Honda, K. and Inou6, S., Establishment ofa bioassay method for the sleep-promoting substance, Rep. Inst. Med. Dent. Eng., 12 (1978) 81-85. 6 Honda, K. and Inou6, S., Effects of sleep-promoting substance on sleep-waking patterns of male rats, Rep. Inst. Med. Dent. Eng., 15 (1981) 115-123. 7 Honda, K. and Inou6, S., Sleep-promoting effects of a bracket fungus, Fomes japonicus. In W.P. Koella, F. Ob~il, H. Schulz, P. Visser (Eds.), Sleep '86, Fischer, Stuttgart, 1988, pp. 338-339. 8 Hou, J.P., The chemical constituents of ginseng plants, Comp. Med. East West, 5 (1977) 123-145. 9 Hu, S.Y., A contribution to our knowledge of ginseng, Am. J. Chin. Med., 5 (1977) 1-23. 10 Jacobs, B.L. and McGinty, D.J., Effects of food deprivation on sleep and wakefulness in the rat, Exp. Neurol., 30 (1971) 212 222. I l Kim, A.E. and Kim, C.C., Effect of ginseng on the serum fatty acid composition in the rats, J. Cath. Med. Coll., 37 (1984) 55--61. 12 Lee, B.K. and Kim, C.C., Change of the serum composition in the rats receiving ginseng, J. Cath. Med. Coll., 37 (1984) 47-53. 13 Lee, S.P., Rhee, Y.H., Honda, K. and Inou6, S., Effect of the ginseng extract on sleep in unrestrained rats, Jpn. J. Psychiat. Neurol., 43 (1989) in press. 14 Li, C.P. and Li, R.C., An introductory note to ginseng, Am. J. Chin. Med., 1 (1973) 249~61. 15 Lim, S.Y. and Kim, C.C., Influence upon male rats' sexual behavior of ginseng administered before and after mature state, J. Cath. Med. Coll., 35 (1982) 9-14. 16 MacFadyen, U.M., Oswald, I. and Lewis, S.A., Starvation and human slow-wave sleep, J. Appl. Physiol., 35 (1973) 391-394. 17 Nabata, H., Saito, H. and Takagi, K., Pharmacological studies of neutral saponins (GNS) of Panax ginseng root, Jpn. J. Pharmacol., 23 (1973) 29-41. 18 Rhee, Y.H., Lee, S.P., Honda, K. and Inou6, S., Panax ginseng extract modulates sleep in unrestrained rats, submitted. 19 Saito, H., Morita, M. and Takagi, K., Pharmacological studies of Panax ginseng leaves, Jpn. J. Pharmacol., 23 (1973) 43-56. 20 Saito, H., Tsuchiya, M., Naka, S. and Takagi, K., Effects of Panax ginseng root on conditioned response in rats, Jpn. J. Pharmacol., 27 (1977) 509-516. 21 Takagi, K., Saito, H. and Nabata, H., Pharmacological studies of Panax ginseng root: estimation of pharmacological actions of Panax ginseng root, Jpn. J. Pharmacol., 22 (1972) 245-259. 22 Takagi, K., Saito, H. and Tsuchiya, M., Pharmacological studies on Panax ginseng root: pharmacological properties of a crude saponin fraction, Jpn. J. Pharmacol., 22 (1972) 33%346. 23 Walker, L.E., Walker, J.M., Palca, J.W. and Berger, R.J., A continuum of sleep and shallow torpor in fasting doves, Science, 221 (1983) 195-196. 24 Yamamura, Y., Kumagai, A., Oura, H., Okuda, T., Morisawa, S. and Yamamoto, M. (Eds.), Medicinal Ginseng: Progress in its Basic and Clinical Studies, Kyoritsu Shuppan, Tokyo, 1989, 282 pp.
217
Elsevier Scientific Publishers Ireland Ltd. NSL 06753
Chronic intake of Panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats S u n g Pil Lee l, K a z u k i H o n d a l, Y o u n g H o R h e e 2 a n d S h o j i r o I n o u 6 l 1Institutefor Medical and Dental Engineering, Tokyo Medical and Dental University, Tokyo (Japan) and 2Department of Neuropsychiatry, College of Medicine, Chungbuk National University, Chungju (Korea)
(Received 2 November 1989; Revisedversion received 1 December 1989; Accepted 1 December 1989) Key words: Food deprivation; Ginseng extract; Rat; Slow wave sleep; Wakefulness
The amount of wakefulness and slow wave sleep significantly fluctuated during 48 h food deprivation and subsequent recoveryperiods in freely behaving male rats. In contrast, such fluctuations were significantly less prominent in age-matchedmale rats chronicallytreated with Panax ginseng extract via drinking water. It is speculated that the ginseng extract may exert a stabilizing effect on sleep-wakingdisturbances which possiblyaccounts for its outstanding health-improvingactivities.
The ginseng, P a n a x ginseng, as a herbal medicine is well known for its outstanding effect on the improvement of h u m a n health in general (for reviews, see refs. 9, 14, 24). The ginseng root contains a number of physiologically important constituents [8]. In rats, it is reported that ginseng extract exerts a decrease in blood pressure [19, 21], a suppression of conditioned avoidance response [17, 19, 20, 22] and sound discrimination [20], an inhibition of gastric ulceration [2], a facilitation of sexual behavior [15], and an increase in essential fatty acids [11] and several essential amino acids [12] in serum. On the assumption that the health-improving effect of the ginseng might be, at least in part, related to the maintenance of a normal state of sleep and wakefulness, we have detected an electroencephalographic (EEG) sleep-modulatory effect of P a n a x ginseng extract in adult freely behaving rats [13, 18]. Using the same approach methods, the present study was conducted to evidence a state-modulatory effect of the ginseng on animals raised under a ginseng treatment. Pregnant female rats of the Sprague-Dawley strain, kept on a 12-h light and 12-h dark schedule (lights on: 08.00-20.00 h) under a constant air-conditioned environment o f 25 4- 1°C and 60 4- 6 % relative humidity with free access to rat chow, were
Correspondence: S. Inou6, Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, Tokyo 101, Japan.
0304-3940/90/$ 03.50 © 1990 ElsevierScientific Publishers Ireland Ltd.
218 individually isolated at 17 to 20 days of gestation for delivery and lactation. They were divided into a control group and an experimental group; the former and the latter were given tap water and ginseng water ad libitum, respectively. The ginseng water contained 0.5 mg per ml of Panax ginseng extract (Korean Red Ginseng Extract, Korea Monopoly Corporation). On the 2nd day of delivery, the litter size was adjusted to 8 pups per mother. On 21 days of age, pups of each group were weaned; 4-5 males were housed in a cage where one of the two kinds of water was given as before. At the age of 60-70 days, the males weighing 300-400 g were anesthetized with pentobarbital sodium and implanted with 3 cortical EEG electrodes and 2 nuchal electromyographic (EMG) electrodes according to the technique described in a previous paper [5]. The animals were individually housed in a special cage which enabled continuous monitoring of EEG and EMG. Lead wires of the electrodes were connected with a polygraph (Nihon-Kohden EEG-4317) via a slip ring fixed above the cage. Thus free movement of the rats was guaranteed. Tap water for the control rats and the ginseng water for the experimental rats were given as before. Each cage was placed in a sound-proof, electromagnetically shielded chamber under the same environmental conditions as above. One week was allowed to recover from the surgery. After observing the establishment of circadian rhythms in sleep-waking behavior, the rats of both groups were subjected to experiments for 4 days starting at the onset of the light period. Following 24 h baseline recording on day 1, rat chow was taken away from the cage for 48 h (days 2 3) and returned on day 4. Throughout the period, tap water for the control rats and the ginseng water for the experimental rats were given as before. The daily dose of the ginseng extract around this period was ca. 15 mg, since the daily intake of drinking water was 31 ml in our young adult male rats [7]. This dosage is comparable to that recommended for human use (3 g for a person weighing 60-80 kg). During the 4-day sessions, EEG (bipolarly registered between 2 combinations of the 3 electrodes) and E M G were polygraphically recorded at a paper speed of 0.5 mm/s. Sleep-waking states were visually classified on a large scale digitizer as slow wave sleep (SWS), paradoxical sleep (PS) and wakefulness (W) according to our routinized criteria, numerically stored and processed in a computer system [6]. Intra- and intergroup differences in the data of days 1 4 were statistically analyzed by Student's t-test. There was no difference in the baseline quantity of SWS and W between the control and the ginseng-treated rats except for the amount of diurnal PS (Fig. 1). Food deprivation initially caused an increase in SWS and a decrease in W in both groups during the light and the dark period of day 2. However, the changes were significant only in the control group as compared to the baseline value of day 1 (P<0.001 for both diurnal and nocturnal amounts of W and SWS). The magnitude of the changes was significantly less in the ginseng-treated rats than the control rats (see Fig. 1). On the second day of food deprivation (day 3), the control rats still exhibited an enhancement of diurnal W (P < 0.01, as compared to day 1) and nocturnal SWS (P < 0.001), and a reduction of diurnal PS (P<0.01) and nocturnal W (P<0.001), whereas the
219
Light 500
period
sw~
40O <--r-i
300
E •,_..
200
ILl
100
PS
,7,
,7,
Day2
I-
- --'------~
[~ 3
Day4
Day3
Day4
Dark p e r i o d 500 400 0
300
1-200 100"
PS
DayI
Day2
Fig. 1. Changes in the diurnal (top) and nocturnal (bottom) amount of wakefulness (W), slow wave sleep (SWS) and paradoxical sleep (PS) before (day 1), during (days 2-3) and after (day 4) food deprivation. S.E.M. is shown by vertical lines, otherwise it is too short to indicate. Statistical differencebetween the control rats (open, n=8) and the ginseng-treated rats (filled,n= 10): *P<0.05, **P<0.01, ***P<0.001 (Student's t-test).
ginseng-treated rats showed significant changes only in diurnal SWS (P < 0.05) and W ( P < 0.05). The difference in the nocturnal amount of W and SWS was significant between the two groups (Fig. 1). When food was restituted at the light onset of day 4, the hourly amount of W was greatly elevated due to feeding behavior, which lasted throughout the light period in the control rats (Fig. 2, top). On the contrary, such an enhancement of W was only episodic in the ginseng-treated rats (Fig. 2, bottom). The significant increase in W resulted in a rebound during the subsequent dark period, the magnitude of which was also less in the ginseng-treated rats. Thus, in both groups, the amount of all parameters was significantly different from the respective baseline value of day 1 (P<0.001 for diurnal W, SWS and PS, P<0.01 for nocturnal W and PS, and P < 0 . 0 5 for nocturnal SWS in the control rats; P<0.001 for diurnal W and SWS, P
220
, 50
-
,
40-
eE
Control
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I----
~
Ginseng
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D
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30 Z/Z 2o
io o co,,t,ot
* ** *
08
CLOCK
*20 m I N E
Fig. 2. Time course changes in the hourly amount of wakefulness before (day 1, open) and after (day 4, filled) food deprivation in the control rats (n = 8) and the ginseng-treated rats (n = 10). Vertical lines indicate S.E.M. Statistical difference between days 1 and 4 in the same group is shown inside the graphs, and that between the two groups on day 4 is indicated below. *P< 0.05, **P< 0.01, ***P< 0.001 (Student's t-test). out that, during starvation, the availability o f endogenous substrates at the cellular level seems to play an essential role in the regulation o f sleep-waking states [3]. The fact that the ginseng extract prevented the fluctuations caused by food deprivation may indicate that some constituents o f the ginseng extract promoted the availability o f substrates or inhibited the inavailability o f them, eventually bringing about stabilized sleep--waking behaviors even after food restitution. From another point o f view, it may be postulated that such changes are non-specifically dependent on a normalized state o f body health owing to ginseng intake. A normalization o f sleep and wakefulness observed in chronically ginseng-treated rats in our previous study [13, 18] may indicate such a possibility. In conclusion, it seems likely that the health-improving activities o f Panax ginseng may be, at least in part, related to a stabilization o f sleep and wakefulness or vice versa. This research was partially supported by funds from the N i h o n Seimei Foundation to S.I. and from the Ministry o f Education o f Korea to Y.H.R. 1 Borbely, A.A., Sleep in the rat during food deprivation and subsequent restitution of food, Brain Res., 124 (1977) 457-471.
221 2 Chang, W.A. and Kim, C., Influence of Panax ginseng upon gastric ulceration produced by restraint, J. Cath. Med. Coll., 27 (1974) 249-255. 3 Danguir, J. and Nicolaidis, S., Dependence of sleep on nutrients' availability, Physiol. Behav., 22 (1979) 735-740. 4 Dewasmes, G., Buchet, C., Geloen, A. and Le Maho, Y., Sleep changes in emperor penguins during fasting, Am. J. Physiol., 256 (1989) R476~R480. 5 Honda, K. and Inou6, S., Establishment ofa bioassay method for the sleep-promoting substance, Rep. Inst. Med. Dent. Eng., 12 (1978) 81-85. 6 Honda, K. and Inou6, S., Effects of sleep-promoting substance on sleep-waking patterns of male rats, Rep. Inst. Med. Dent. Eng., 15 (1981) 115-123. 7 Honda, K. and Inou6, S., Sleep-promoting effects of a bracket fungus, Fomes japonicus. In W.P. Koella, F. Ob~il, H. Schulz, P. Visser (Eds.), Sleep '86, Fischer, Stuttgart, 1988, pp. 338-339. 8 Hou, J.P., The chemical constituents of ginseng plants, Comp. Med. East West, 5 (1977) 123-145. 9 Hu, S.Y., A contribution to our knowledge of ginseng, Am. J. Chin. Med., 5 (1977) 1-23. 10 Jacobs, B.L. and McGinty, D.J., Effects of food deprivation on sleep and wakefulness in the rat, Exp. Neurol., 30 (1971) 212 222. I l Kim, A.E. and Kim, C.C., Effect of ginseng on the serum fatty acid composition in the rats, J. Cath. Med. Coll., 37 (1984) 55--61. 12 Lee, B.K. and Kim, C.C., Change of the serum composition in the rats receiving ginseng, J. Cath. Med. Coll., 37 (1984) 47-53. 13 Lee, S.P., Rhee, Y.H., Honda, K. and Inou6, S., Effect of the ginseng extract on sleep in unrestrained rats, Jpn. J. Psychiat. Neurol., 43 (1989) in press. 14 Li, C.P. and Li, R.C., An introductory note to ginseng, Am. J. Chin. Med., 1 (1973) 249~61. 15 Lim, S.Y. and Kim, C.C., Influence upon male rats' sexual behavior of ginseng administered before and after mature state, J. Cath. Med. Coll., 35 (1982) 9-14. 16 MacFadyen, U.M., Oswald, I. and Lewis, S.A., Starvation and human slow-wave sleep, J. Appl. Physiol., 35 (1973) 391-394. 17 Nabata, H., Saito, H. and Takagi, K., Pharmacological studies of neutral saponins (GNS) of Panax ginseng root, Jpn. J. Pharmacol., 23 (1973) 29-41. 18 Rhee, Y.H., Lee, S.P., Honda, K. and Inou6, S., Panax ginseng extract modulates sleep in unrestrained rats, submitted. 19 Saito, H., Morita, M. and Takagi, K., Pharmacological studies of Panax ginseng leaves, Jpn. J. Pharmacol., 23 (1973) 43-56. 20 Saito, H., Tsuchiya, M., Naka, S. and Takagi, K., Effects of Panax ginseng root on conditioned response in rats, Jpn. J. Pharmacol., 27 (1977) 509-516. 21 Takagi, K., Saito, H. and Nabata, H., Pharmacological studies of Panax ginseng root: estimation of pharmacological actions of Panax ginseng root, Jpn. J. Pharmacol., 22 (1972) 245-259. 22 Takagi, K., Saito, H. and Tsuchiya, M., Pharmacological studies on Panax ginseng root: pharmacological properties of a crude saponin fraction, Jpn. J. Pharmacol., 22 (1972) 33%346. 23 Walker, L.E., Walker, J.M., Palca, J.W. and Berger, R.J., A continuum of sleep and shallow torpor in fasting doves, Science, 221 (1983) 195-196. 24 Yamamura, Y., Kumagai, A., Oura, H., Okuda, T., Morisawa, S. and Yamamoto, M. (Eds.), Medicinal Ginseng: Progress in its Basic and Clinical Studies, Kyoritsu Shuppan, Tokyo, 1989, 282 pp.