Long term tea intake attenuates brain monoamine metabolism in rats

ABSTRACT

Tea is one of the most popular caffeine containing beverages consumed all over the world for increasing work performance and as a social drink. In the present study effects of long term intake of tea administration are monitored on the activity and brain monoamine levels in rats. Animals taking tea as sole source of liquid exhibited a significant increase in the home cage activity after one week which was normalized after four weeks of treatment. No effect of tea was observed on the activity of rats in an open field. Four weeks of tea intake did not alter plasma tryptophan [TRP] levels but increased plasma glucose levels. The concentration of TRP and 5-hydroxytryptamine [5-HT, serotonin] but not 5-hydroxyindole acetic acid [5-HIAA] decreased in the brain. Brain levels of dopamine [DA], dihydroxyphenyl acetic acid [DOPAC] and homovanillic acid [HVA] were also significantly attenuated in tea-treated rats. The findings are explained in terms of tea increasing activity in a familiar but not novel environment. Decrease in brain monoamine metabolism following long term tea administration may be involved in the lowering of mood observed in the consumers