Sound mind, sound body – connection

A protein known to strengthen certain functions of the brain has now been shown to help strengthen the heart.

The protein is known as BDNF (brain-derived neurotrophic factor). Scientists were already aware of some of its many properties – the protein acts as a natural antidepressant, bolsters learning and memory, nourishes blood vessels and helps keep nerve cells healthy. Now a research team at John Hopkins University has found the protein also plays a significant role in maintaining heart muscle vitality.

BDNF, they discovered, controls the ability of heart muscle cells to ‘beat’ – in other words, contract and relax properly. It does so by binding to a particular cell receptor on heart cells known as tropomyosin receptor kinase B, or TrkB. TrkB’s job is to receive chemical signals from BDNF and then transmit those signals internally within the cell. The study, published in the Proceedings of the National Academy of Sciences, showed that cells from a failing heart had faulty TrkB receptors which poorly transmitted BDNF’s signals. This meant the cells contracted weakly, pumped blood less efficiently and took longer to relax after each beat.

The researchers pointed out that BDNF abnormalities alone were not cause for significant concern. But when chronic BDNF deficiency or cell insensitivity was compounded by stressors such as endurance training or high blood pressure, it can contribute to heart disease.

“[T]hese findings show that any abnormality in the way BDNF communicates with its receptor appears to unlock a cascade of chemical glitches that eventually leads to poor cardiac function,” says lead investigator Dr Ning Feng, a cardiology fellow at John Hopkins University School of Medicine.

The results could help us discover new treatments for certain kinds of heart failure such as chemotherapy-induced heart failure. Some chemotherapy treatments involve blocking receptors such as TrkB to stop the growth of tumours. Abnormalities in BDNF, paired with its antidepressant properties, could also better explain the biochemical relationship between depression and heart disease which can occur together.

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