Temperature Stress Reaction

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Ginseng and its extracts can prevent body temperature variations in animals subjected to the stress of cold and heat exposure, although not apparently affecting normal subjects at room temperature. This was realised in 1958 when the Chinese physiologists Sung and Chi published experimental results indicating that powdered P. ginseng root contained active principles with a protective property against temperature stresses. Using male white rats fed either on a normal diet or a normal diet with 5 per cent added ginseng powder, they were able to demonstrate that after 3 weeks the ginseng-fed group were more able to withstand heat stresses of 5-6 minutes at 78-90° C or 60 minutes at -2° C. In an alternative experiment one group of rats received 2.4 ml of 50 per cent ginseng extract one hour before the temperature stress whilst the other (control) group received water only. Ginseng treated rats, on being returned to normal conditions after hot chamber treatment, recovered almost immediately but the control rats similarly treated recovered slowly over 20-60 minutes, either crouching almost stationary or convulsing during the normalisation. The rats were sacrificed after the temperature stress experiments. Analysis of the adrenal glands shewed that the vitamin C content was depleted after hot or cold temperature stress but such depletion was reduced in ginseng treated rats. Thus Sung and Chi had confirmed that ginseng was capable of increasing the nonspecific resistance of animals to temperature stress situations (Hou, 1978).

The increased tolerance to cold as manifested by prolonged survival times was also produced in adrenalectomised mice using alcoholic extracts of ginseng or hydrocortisone (Kim, 1963). In the following year Tsung, Cheng and Tang (1964) subjected 92 animals (white mice) to survival tests either in a hot chamber at 45-47° C or a cold chamber at -2° C; the experiments were terminated when half of the animals had died. The test animals received intraperitoneal injections of 10 ml/kg 50 per cent aqueous extract of ginseng and control animals were similarly given an equal volume of normal saline solution. A comparable alternative experiment involved animals from which the adrenal glands had been surgically removed prior to the experiment. These experiments convincingly confirmed that ginseng extract treatment enabled the test animals to tolerate high and low temperature stresses but the antistress ability was abolished if the adrenal glands were removed. Therefore Tsung et al. concluded that the pituitary gland-adrenal gland system must be implicated in the mechanism of antistress activity.

Using 240 mice, C.C.Kim (1964) observed that the level of total serum protein fell in mice acclimatised to cold conditions although it increased markedly in mice exposed to the cold after treatment with ginseng injections. Exposure to cold also led to a lower serum haemoglobin level and to lower red blood cell counts but ginseng was able to reverse such tendencies, thus countering the cold stress. White blood cell counts too were lower in unprotected experimental animals. Again ginseng had proved effective versus temperature stress.

During the next decade many reports confirmed the effectiveness of ginseng against temperature stress (Hou, 1978) and it was clearly shewn that ginseng countered the fall in body temperature induced by stress (Bao et al., 1984b). Cheng et al. (1986b), also employing mice as test animals and temperature stress conditions at 45° C, observed that the saponins of Chinese red ginseng root and Chinese ginseng stem and leaf inhibited increase in rectal temperature at the alertness stage but, surprisingly, the median lethal time was prolonged by Chinese P. ginseng root and stem but not by P. quinquefolium saponins. This pharmacological variation was probably due to the interspecies variation in saponin composition. In a similar series of experiments involving the saponins of P. ginseng, P. notoginseng and P. quinquefolium, Yan et al. (1987) were able to show that the total saponins of all three species would oppose the reduction of the vitamin C content in stressed rat adrenal gland although only the total saponins of the first two species could reduce the ACTH-induced decrease in adrenal vitamin C and the atrophy of the spleen and thymus gland, confirming the apparent lack of antistress action of P. quinquefolium saponins.

Continuing the study of temperature stress Cheng et al. (1986a), using rats, a temperature of 45° C for 20 minutes and ginseng root saponins, observed a fall of rectal temperature from 40.3° to 39.0° C. Ginseng also reversed the decrease in acetylcholine levels in the brain and markedly increased the plasma corticosterone levels but there was no effect on amino acid levels (gamma-amino-butyric (GABA), glutamic and aspartic acids) in the brain. For mice at 20° C, it was noted that ginseng root saponins (70mg/kg) reduced brain levels of GABA but not glutamate or aspartate. Investigating cold temperature stress the same group (Cheng et al., 1987) observed that for mice kept at -2° C for an hour oral ginseng root saponins (50 or 100 mg/kg) reduced the rate of fall in body temperature. For mice at -4° C brain noradrenaline, 5-hydroxytryptamine (5-HT) and 5-hydroxy-indole-acetic acid (5-HIAA) levels decreased but increased after administration of ginseng root saponins (100 mg/kg). Dopamine levels were unchanged by cold temperature stress. Rats also experienced falls in rectal temperature and plasma corticosterone when confined at -2° C; after administration of ginseng total saponins (70 mg/kg) the rectal temperature remained unchanged but the brain acetylcholine and plasma corticosterone had increased; brain GABA, glutamate and aspartate was unchanged. Yuan et al. (1989) also recorded that heat increased rectal temperature and serum corticosterone levels in mice (45° C for 15 min) but brain 5-HT and noradrenaline decreased and dopamine remained unchanged. Ginseng root saponins (200 mg/ kg by intraperitoneal injection) inhibited the increase in serum corticosterone and the decrease of brain 5-HT and noradrenaline in heat-stressed mice but the dopamine level was unchanged. It was noted that ginseng root saponins produced reduction of body temperature at normal room temperature conditions and inhibited the rise of body temperature under heat environmental conditions. Reserpine, a tranquillising indole alkaloid, neutralised the temperature lowering action of ginseng root saponins at room temperature and at the higher temperatures of heat-stress conditions.

Investigating the mechanism of the protective effects of ginseng root saponins on immunity in heat-stressed mice, Wu et al. (1993) observed that the percentage of lymphocytes and T-lymphocytes in the white blood cells was reduced in a heat environment of 45° C for 15 minutes but the serum corticosterone was increased. If ginseng root saponins (50 or 100 mg/kg-1) were administered intraperitoneally 15 minutes before the heat stress, the suppression of the blood T-lymphocytes was reversed although the increase in serum corticosterone was unaffected. Ginseng root saponins at 50mg/kg-1 also inhibited the reduction of peripheral lymphocytes.

Experimenting with a combined ginseng and multivitamin-mineral preparation and using a cold-hypoxia-restraint animal model, Ratan Kumar et al. (1996) studied cold tolerance and recovery from acute hypothermia with the aim of unravelling the respective roles of ginseng root extract and the vitamin-mineral combination. Male albino Wistar rats were treated by gastric cannula with single doses of P. ginseng root extract (0.1-2.0 ¡g/g) or multivitamin-mineral preparation (1.0-20.0 ¡g/g) or ginseng-multivitamin-mineral preparation (1.122.0 ¡g/g) before transfer to a decompression chamber (5° C, 428 mmHg); the rats were removed when their colonic temperature reached 23° C and were restrained in a recovery chamber at 32±1° C until the colonic temperature returned to 37° C. Adaptogenic activity was calculated in terms of the time for the colonic temperature to fall from normal to 23° C and then to recover to 37° C. Single or multiple doses of the three preparations were assessed for periods of 5 or 30 days. It was concluded that the adaptogenic effect was roughly equal to the sum of the effects of the two components, the ginseng extract inducing the resistance to cooling and the multi-vitamin-mineral combination prompting the more rapid recovery from acute hypothermia.

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