Researchers from Johns Hopkins University have found that hydrogen sulfide, a gas that smells like rotten eggs, may protect brain cells from Alzheimer's disease in mice.
The growing field of gasotransmission shows that gases are integral for cellular messaging in the body- and particularly for the brain. Hydrogen sulfide is created in small amounts in the body to help regulate functions, including cell metabolism and blood vessel dilation. Recent studies have shown that hydrogen sulfide levels in the brain decrease with age, and especially for those with Alzheimer's disease.
As such, in the present research, scientists set out to study the mechanisms behind this process in those with Alzheimer's. To do so, they genetically engineered mice to have a condition that mimics human Alzheimer's. They then injected them with a hydrogen-sulfide-carrying compound that slowly released passenger hydrogen sulfide molecules while making its way through their bodies. The mice were then tested for memory, and motor function changes over 12 weeks.
In the end, the researchers found that hydrogen sulfide was able to reverse some of the behavioral outcomes from Alzheimer's disease. Mice treated with hydrogen sulfide improved by 50% in cognitive and motor function in comparison to untreated mice. They were also better able to remember locations of platform exits and appeared more physically active than their untreated counterparts.
In a series of biochemical experiments, the researchers discovered the underlying process for these changes. In the presence of healthy levels of hydrogen sulfide, a common enzyme known as glycogen synthase β (GSK3β) acts as a signaling molecule, adding chemical markers to other proteins that then alter their function. In the absence of hydrogen sulfide, however, GSK3β is over-attracted to a brain protein known as Tau, which then tangles and clumps inside of nerve cells.
As these clumps of Tau expand, they block communication between nerves, leading them to die. This ultimately leads to a loss in cognitive ability, memory, and motor function characterized by Alzheimer's.
The researchers now hope to continue studying the effects of sulfur groups on conditions such as Alzheimer's disease in other cells and organ systems. They also plan on investigating novel delivery models for the gas.
Sources: Neuroscience News, PNAS