Ingestion of theanine, an amino acid in tea, suppresses psychosocial stress in mice.

The antistress effect of theanine (γ-glutamylethylamide), an amino acid in tea, was investigated using mice that were psychosocially stressed from a conflict among male mice in conditions of confrontational housing. Two male mice were housed in the same cage separated by a partition to establish a territorial imperative. When the partition was removed, the mice were co-housed confrontationally.

Theanine intake improves the shortened lifespan, cognitive dysfunction and behavioural depression that are induced by chronic psychosocial stress in mice.

To evaluate the psychosocial effect on lifespan and cognitive function, this study investigated the effect of confrontational housing on mice because conflict among male mice is a psychosocial stress. In addition, it investigated the anti-stress effect of theanine (γ-glutamylethylamide), an amino acid in tea. Mice were housed under confrontation.

Protection of brain and pancreas from high-fat diet: effects of catechin and caffeine.

To investigate the effect of a high-fat diet on brain and pancreas functions, we used SAMP10 mice that have characteristics of brain atrophy and cognitive dysfunction with aging. Simultaneously, we investigated the effect of green tea catechin consumption on high-fat diet feeding, because green tea catechin has been reported to improve brain atrophy, brain dysfunction and obesity. The body weight of mice fed a high-fat diet from 2 to 12 months was higher than that of the control, although the calorie intake was not.

Daily ingestion of green tea catechins from adulthood suppressed brain dysfunction in aged mice.

Oxidative damage is believed to be an important cause of senescence. We have previously found that green tea catechins (GT-catechin), potent antioxidants, decrease oxidative damage to DNA and suppress brain dysfunction in aged senescence-accelerated mice (SAMP10) when ingested from the age of 1 month to the age of 12 months. To clarify the effect of GT-catechin on suppression of brain senescence, we investigated the effect of starting period to ingest GT-catechin.