While humans are living longer, the prevalence of dementia is also on the rise. And many researchers believe factors such as stress, accumulation of toxic waste products as well as inflammation accelerate aging in the brain.
However, scientists are also learning that certain mechanisms can protect the brain from deterioration and even repair defective structures.
For example, in a study of mice, European researchers have recently discovered a previously unknown function of the cannabinoid-1 receptor (CB1). A receptor is a protein that can bind to other substances, triggering a chain of signals.
Cannabinoids such as THC — the active agent in marijuana — and endocannabinoids formed by the body bind to the CB1 receptors.
The existence of this receptor is also the reason for the intoxicating effect of hashish and marijuana and perhaps the upbeat feeling of a runner’s high after intense exercise.
Not only does the CB1 receptor have an addictive potential, but it also plays a role in the degeneration of the brain.
“If we switch off the receptor using gene technology, mouse brains age much faster,” said Önder Albayram, a doctoral student at the Institute of Molecular Psychiatry at the University of Bonn in Germany and principal author of the study. “This means that the CB1 signal system has a protective effect for nerve cells.”
The researchers studied mice in different age categories – young six-week-old animals, middle-aged ones at five months, and those of an advanced age at 12 months.
The animals had to master various tasks used to assess the ability to learn and remember – first, they had to find a submerged platform in the pool. Once the mice knew its location, the platform was moved, and the animals had to find it again.
The animals in which the CB1 receptor had been switched off by genetic engineering (the “knockout” mice) clearly differed from the other group.
“The knock-out mice showed clearly diminished learning and memory capacity,” Albayram said. Thus, animals that did not have the receptor were less successful in their search for the platform. They also showed a clear loss of nerve cells in the hippocampus, a brain structure critical to forming and storing memories.
Furthermore, researchers found inflammation processes in the brain and as the mice advanced in age, the degenerative processes became increasingly noticeable.
The animals with the intact CB1 receptor, to the contrary, did clearly better with regard to their learning and memory capabilities, as well as the health of their nerve cells.
The processes in the mouse brains have a surprising number of parallels with age-related changes in human brains, Albayram said. “So the endocannabinoid system may also present a protective mechanism in the aging of the human brain.”
Nevertheless, additional research is required to better understand the mechanism by which CB1 receptors protect the brain from inflammation processes. Then, based on these signal chains, it might be possible to develop substances for new drug therapies, he said.
Source: University of Bonn