Growth Hormone Boosts Brain Power

A protein involved in cell growth and repair also helps improve memory, according to research published today in the journal Nature. Researchers hope that the findings will point towards new therapeutic targets for Alzheimer’s and other neurodegenerative diseases, and will shed light on the still mysterious process of memory formation.

The protein, called insulin-like growth factor II (IGF-II), is most active during development, but it is also enriched in the hippocampus, a brain structure that is vital to memory. To test its role in memory, researchers from Mt Sinai School of Medicine first taught rodents to fear a darkened box by giving them a mild shock when they entered it. They animals will remember this shock for weeks, as evidenced by their reluctance to return to the box. Animals injected with IGF-II remembered this pairing more strongly and kept the memory longer than those that weren’t given the drug. Animals given a compound to block the action of the protein, which researchers found naturally rises after learning, forgot to fear the box.

According to ScienceNow:

“Their hesitation, or latency, more than doubled,” says neuroscientist Cristina Alberini, who led the research. “It’s a very potent effect.”

IGF-II improved a rodent’s memory only when administered in a precise window of time—roughly within 24 hours after the foot shock—which coincides with a stage in the learning process called “memory consolidation.” That’s a poorly understood transition period when a memory is still malleable but becoming more established and robust.

The results may also contribute to developing memory-boosting drugs. The fact that IGF-II is naturally occurring and can cross the blood-brain barrier makes it a promising candidate for treating memory-impairing diseases or even forgetfulness, Alberini notes. But any clinical applications are a long way off, as one key question remains unanswered—namely, how exactly IGF-II boosts memory. Preliminary results suggest the growth factor strengthens the connections between nerve cell synapses during consolidation, says Alberini. Her team’s next steps will explore the mechanism, in hopes of one day putting IGF-II to work in humans.