Insulin-Like Growth Factor (IGF2 or IGF II) Significantly Enhances Memory Retention and Prevents Forgetting

Scientists at the Mount Sinai School of Medicine Department of Neuroscience report that, in rats, the administration of insulin-like growth factor II (IGF-II, also known as IGF2) significantly enhances memory retention and prevents forgetting.

Inhibitory avoidance learning (shocking the rat when walked into a dark area of their cage) leads to an increase in hippocampal expression of IGF-II, which requires the transcription factor CCAAT enhancer binding protein β and is essential for memory consolidation.

Furthermore, injections of recombinant IGF-II into the hippocampus after either training or memory retrieval significantly enhance memory retention and prevent forgetting. To be effective, IGF-II needs to be administered within a sensitive period of memory consolidation.

The scientists propose that IGF-II may represent a novel target for cognitive enhancement therapies.

IGF2 has been known as a growth promoting hormone during gestation.

IGF-II is a neutral peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like and mitogenic (cellular division) activities. The growth factor has a major, but not absolute, dependence on somatotropin. IGF2 is believed to be a major fetal growth factor in contrast to INSULIN-LIKE GROWTH FACTOR I, which is a major growth factor in adults.

There are other Insulin Growth Factors …
The IGF “axis” is also commonly referred to as the Growth Hormone/IGF1 Axis. Insulin-like growth factor 1 (IGF-1) is mainly secreted by the liver as a result of stimulation by growth hormone (GH). IGF-1 is important for both the regulation of normal physiology, as well as a number of pathological states, including cancer. The IGF axis has been shown to play roles in the promotion of cell proliferation and the inhibition of cell death (apoptosis).

Insulin-like growth factor 2 (IGF-2) is thought to be a primary growth factor required for early development while IGF-1 expression is required for achieving maximal growth. Gene knockout studies in mice have confirmed this, though other animals are likely to regulate the expression of these genes in distinct ways. While IGF-2 may be primarily fetal in action it is also essential for development and function of organs such as the brain, liver and kidney.