The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 8 No.
1 • January 2005
Green Tea Polyphenols as Acetylcholinesterase Inhibitors for Memory Improvement
A recent paper reports that in 4–5-week-old male ICR rats fed a regular chow diet supplemented with 0.2% by weight of green tea polyphenols for 7 days, the animals had improved memory in the step-through latency test after pretreatment with scopolamine. Scopolamine is a muscarinic cholinergic receptor blocker that causes memory deficits as a result of reduced cholinergic neurotransmission. Memory is assessed via a test (step-through latency) in which the animals are placed in a box with two compartments, one light and one dark. During training, the animals are placed in the lighted compartment, and when they enter the dark compartment (which they normally prefer), they receive a shock. Their ability to remember this later is the basis for memory assessment. Increased latency in the treated animals, i.e., delayed entry into the dark compartment (as compared to nontreated animals) after previous shock, is a measure of the memory-enhancing effects of acetylcholinesterase inhibitors. The authors found that “Chronic administration of TP [green tea polyphenols] significantly increased latency time.” They found that “TP administration dramatically inhibited AChE [acetylcholinesterase] activity (71% inhibition) as compared to the control. … The concentration required for 50% enzyme inhibition (IC50) was 248 µg/ml.”
This may be yet another mechanism for beneficial effects from green tea polyphenols.
- Kim et al. Effects of green tea polyphenol on cognitive and acetylcholinesterase activities. Biosci Biotechnol Biochem 68(9):1977-9 (2004).