An international team of researchers representing several institutions in Japan and the US has published promising findings that may stand to benefit people living with the specter of Alzheimer’s and other neuro degenerative diseases, as well as age-related cognitive decline.
In their paper published in PNAS, “Leptin in hippocampus mediates benefits of mild exercise by an antioxidant on neurogenesis and memory,” Yook and colleagues present results from a series of experiments murine and in vitro that elucidate the role of leptin in cognitive function. Leptin is a hormone that is produced in adipose tissue and in the hippocampus, the part of the brain where memory and spatial learning are processed.
Certain dietary supplements
The relationship between exercise and improved cognitive function is well established. Likewise, certain dietary supplements, for example, docasahexaenoic acid (DHA) have also show promise in improving cognition; also in slowing or halting cognitive decline. The effect of both exercise and supplementation with an antioxidant; so on plasticity and cognitive function within the hippocampus has until now been largely unexplored, however.
The first experiment examined the performance; so of four groups of wild-type mice on standard tests used to evaluate murine memory and spatial learning. The mice comprise the following groups: sedentary with placebo (SE+PL); mild exercise with placebo (ME+PL); sedentary with astaxanthin (SE+AX); and mild exercise with astaxanthin (ME+AX). The SE+PL group perform the worst while the ME+PL and SE+AX groups both performed better.
Finally, to establish whether or not LEP is require to achieve the synergistic effect seen with the AX+ME, Yook and colleagues repeated their earlier mouse experiment on ob/obknockout; so using LEP-deficient animals bred for obesity and diabetes research. They found that LEP deficiency did indeed play a role, as these mice perform poorly relative to the wild-type; so thus indicating LEP as the crucial component of the AX+ME synergy observed in the prior experiment.
The synergistic effects
To further confirm the mediative effect of LEP in the brain; so the scientists inject the ob/ob with LEP over the course of four weeks, finding that the synergistic effects of AX and ME were restore in these mice. The researchers also observed increased levels of proteins pIGF1R and pP13K in ME+PL and ME+AX groups; so independently of whether or not the mice were wild-type or knockout.
While the results shown here in murine models are certainly promising; what might this mean in a clinical context for humans? For one thing, ME (mild exercise) for humans has characterized in this paper as that which is typical of a yoga or tai chi session; which puts it within reach of many people. Another factor is the ready availability of the relatively inexpensive nutritional supplement astaxanthin.
Ultimately, the authors conclude “our findings advance the notion that ME combined with a dietary antioxidant such as AX, which induces endogenous h-LEP, may be an effective non pharmacological strategy for preventing or improving cognitive function and brain health, and for slowing cognitive decline. This strategy may be particularly useful in vulnerable individuals, including the elderly.”