Owning a rat with poor memory is not a common problem. Rats age relatively rapidly and so as their memories decline with advancing years they are already on borrowed time and long-term care is not likely to be a problem. However absurd this seems, it does illustrate a useful feature of animal models, that is to say the shorter lifespan of the animals can accelerate the effects of disease and as such data can be collected in a much shorter timescale when compared to studying humans. If it takes a lifetime of poor diet to cause an effect, that effect may take 50 years to be observable in humans, but in rats the effect occurs in months or weeks. For all their shortcomings, rats have provided useful nutritional data that has undoubtedly advanced the understanding of humans nutrition. In particular, rats are inquisitive little fellows and as such are quite well suited to testing the effects of nutrition of cognition, particularly spatial learning. In fact rats love mazes and will happily run through them to provide a useful model for learning.
Rat maze experiments are a favourite of researchers because they are cheap, easy to set up and provide a useful amount of data that is often of publishable quality. Many studies have investigated the effects of nutrients on rats and how these nutrients affect maze running. Green tea has been investigated for its memory enhancing effects and in this regard rats have been fed green tea extract and then provided with a suitable maze to investigate changes to their spatial learning. In one study1, rats were fed green tea in their water bottles for 26 week, which for a rat is a considerable part of their lives. The green tea extract contained a number of catechin compound found naturally in green tea including 63 % epigallocatechin gallate, 11 % epicatechin, 6% epigallocatechin and 6% epicatechin gallate. Relative to the control rats, who did not receive any green tea, the treatment rats showed significant improvements in memory related learning, as measured by improved maze learning ability.
The benefit of green tea on memory are often credited to the caffeine content of the drink. Caffeine has been investigated for its cognitive ability and many studies attest to its ability to improve a number of different types of cognition. Evidence certainly suggests that caffeine has short term effects on cognition, but the long term effects of green tea on memory may be due to the present of antioxidants in the tea plant. The evidence for this came when the researchers tested the antioxidant status of the rats fed green tea and found that they had significantly higher antioxidant status and significantly lower lipid peroxidation rates in their plasma compared to control rats. Evidence suggests that lipid peroxidation of the brain is a significant factor in age related memory decline and that having a high antioxidant status may be beneficial at preventing declining cognition with age. The methodology in the study suggests that caffeine was not present in the green tea extract and so the benefits are likely to have come from the antioxidants.
RdB
