Researchers at the University of California have released a new study in The Journal of Neuroscience which gives an insight into the mechanisms of cognitive decline, and also identifies potential strategies to reverse it. Using lab rats, the scientists were able to reverse the process where aged brain cells lose the fibres that are responsible for receiving neural impulses, a change which is believed to be at the root of cognitive decline.
While we tend to think that there’s nothing much we can do about aging, this new study suggests that this may not be the case. By studying the dendrites in rats’ brains, the researchers were looking for evidence of dendritric retraction. This process, where the dendrites decline, normally occurs during middle age in both rats and humans. They team wanted to see whether this process had already started in middle aged rats and whether it was possible to reverse its effects using ampakine, a compound which has already been shown to improve age-related cognitive conditions in rats. Ampakines have also been shown to increase the production of a key growth factor in the brain.
For their study, the researches put male rats in cages where there was plenty of space, a large running wheel and lots of things to keep the rats occupied. Half of the rats were given an oral dose of ampakine on a daily basis for 3 months, while the others were given a placebo. The researchers monitored the rats’ activity during this time, conducting behavioural tests as the rats explored their new environment. When the 3 months were up, the researchers examined the rats’ hippocampus, the area of the brain associated with memory and learning. These samples were then compared to samples from the brains of adolescent rats.
The findings of the study showed that the middle-aged rats that had taken the placebo had fewer and shorter dendritic branches compared to the adolescent rats. However, the brains of the rats who had taken the ampakine were almost identical to those of the younger rats, in terms of the length of the dendrites and the amount of dendritic branches. Furthermore, the rats who had been given ampakine exhibited more of the small spines on their dendrites that are responsible for receiving signals from other neurons, than both the untreated or adolescent rats, together with enhanced signalling between the neurons.
In terms of behavioural differences, the treated rats had shown predictable patterns in their new environment after only two days, while the untreated group continued to explore their new surroundings in a random manner. This showed that the treated rats had developed better memories of the area and had also developed more strategies to explore it, a fact which led the scientists to suggest that the ampakine had reversed the effects of aging in this part of the brain.
However, while these results are very promising, there is still a lot of work to be done before human testing can begin, including finding out the effects of ampakine on female rats and those beyond middle age.
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