A growth factor that stops forgetting in lab rats

A new study funded by the US National Institutes of Health (NIH) has shown that a natural growth factor, IGF-II, helps rats remember and prevents forgetting of shocks and pain. Injected into the memory areas of the brain, it improves long-term memory.

Earlier studies had suggested that insulin-like growth factor II (IGF-II) has a positive effect on memory. This is the first time a natural substance that strongly boosts memory, and that easily crosses the blood–brain barrier, has been examined in detail, which may promise future treatments.

The researchers say this gives a better understanding of how remembering and forgetting work, and the discovery may have important clinical uses, such as treating memory loss after trauma.

Strong memories depend on making new proteins and on structural changes in the connections between brain cells. These changes strengthen a memory and happen during a limited time after learning, when the memory is consolidated, and again after it is recalled (revision).

The researchers trained the rats with a method called inhibitory avoidance: rats learned to avoid a dark area by receiving mild electric shocks to their feet. The more the rats avoided the dark, the better they had learned.