Reduction of chronic psychosocial hypertension in mice by decaffeinated tea.

Abstract

SUMMARY The effects of decaffeinated green tea on CBA mice have been contrasted with those of water during 3 to 5 months of exposure to various intensities of social stress. Intensity was modified by using different types of caging: Henry-Stephens complex population cages for maximum stress, open field population cages for intermediate levels, and siblings in standard mouse boxes for minimal stress. Two population densities were used: high, with 16 males and 16 females per population cage; and low, with approximately half this number. In three sets of experiments, 58 comparisons were made between body weight, blood pressure, pulse rate, scarring, blood urea nitrogen (BUN), adrenal and heart weights, plasma corticosterone, adult male mortality, and number of weanlings of those on decaffeinated green tea and matched groups on water. Twenty-five of the comparisons indicated less arousal with the decaffeinated green tea and in none was the water favored. Blood pressure fell from 150 to 133 mm Hg. These results support the proposal that the polyphenols (bioflavonoids) of tea may have a beneficial sedative action. (Hypertension 6: 437-444, 1984) KEY WORDS • blood pressure • adrenal weight • bioflavonoids plasma corticosterone • psychosocial stress A recent authoritative review of the physiology of human essential hypertension presents strong evidence for the etiologic role of repeated arousal of the sympathetic adrenal medullary system during episodes of social interaction. 1 We have long produced psychosocial hypertension in an animal model that applies this principle by using colonies of male and female mice competing for control of territory and nest establishment in Henry-Stephens complex population cages.2 -3 The males develop a blood pressure of 155 to 160 ± 20 mm Hg, which is significantly higher than their normal 125 ± 12 mm Hg. 4These animals also show early arteriosclerosis, 5 and there is an increase in the catecholamine-synthesizing enzymes in the adrenals 6 and in the activity of the renin-angiotensin systems.7 8 A beta-blocker, metoprolol, returns the renin and blood pressure to normal. However, adrenal cortical arousal with elevated plasma corticosterone persists, and a progressive, and often fatal, chronic interstitial nephritis gradually develops.2 9 The mechanism of the nephritis is not decided, but chronic reflux of urine, due to ernotional difficulties in urination with ensuing sensitization to Tamm Horsfall protein, is currently being studied. 10We have examined the effect of various agents on the hypertension developed under continuous psychosocial stress.2 Preliminary observations show no effect of a low salt diet,' but detailed studies of the effects of caffeine show that it intensifies the hormonal and pathophysiological changes that accompany psychosocial stress." Even decaffeinated coffee, which contains a residual 3%, that is, 16 mg/liter of the original 560 mg/liter caffeine content of brewed coffee, has a slight potentiating effect on blood pressure and on the other effects of stress. ...

Green tea consumption in everyday life and mental health

“…Caffeine, a major component found in green tea, is known for its psychoactive effects at low doses 24,34 -36 . A laboratory study reported that the administration of decaffeinated green tea in the drinking water of mice exposed to psychosocial stress resulted in significantly reduced physiological stress markers and behavioural responses 37 . Our results indicated an independent association between perceived mental stress and an increase in the risk of mental ill-health.…”

Possible contribution of green tea drinking habits to the prevention of stroke.

“…In animal experiments, however, several authors reported hypotensive effects of tea after repeated dosage (Henry and Stephens-Larson 1984;Iwata et al 1987;Taniguchi et al 1988). For example, Iwata et al (1987) The major gap between the findings in animal experiments and the present observation is that the hypotensive effects of green tea was positive in animals whereas the apparent reduction in the proportion of those with the disease history is only in the case of stroke and not hypertension in the present epidemiological study.…”

An exposure and risk assessment for fluoride and trace metals in black tea

“…While beneficial effects were investigated against cancer [1,2], vascular diseases [3], hypertension [4], and dental caries [5], tea was associated with dental [6] and skeletal [7] fluorosis, and Alzheimer's disease [8] due to accumulation of fluoride (F) and aluminum (Al), respectively, in the plant. The impact of tea drinks on human health has been observed, and trace elemental content of tea has been investigated in Southern Asian countries where tea is a traditional drink consumed in large quantities, such as in China [9], India [10], Taiwan [11], and Tibet [6] for fluoride, and in China [12], and Thailand [13] for aluminum and other trace elements.…”