Writing in the peer-review journal Neuroscience, scientists from Iran report that probiotic supplements reduced the moderate disturbances of learning and memory observed in diabetic lab rats.
“Our findings from the behavioral and electrophysiological experiments open a window for concomitant evaluation of the learning and memory and, hippocampal synaptic plasticity in diabetes and how the probiotics generate similar positive effects on both phenomena,” wrote the researchers from Isfahan University of Medical Sciences and Kashan University of Medical Sciences.
“Additionally, these data imply on the necessity of an optimal function of the microbiome–gut–brain axis in the behavioral as well as electrophysiological aspects of brain action.”
According the FAO/WHO, probiotics are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host".
Numerous animal studies have indicated the effect of the gut-brain axis, and the potential role of probiotics to modify performance and mood. The first human study to report that chronic intake of a fermented milk product with probiotics can alter brain activity in humans was published earlier this year in Gastroenterology (doi: 10.1053/j.gastro.2013.02.043).
Scientists from Danone Research and UCLA used a fermented milk product containing five different probiotic strains and found an effect on parts of the brain linked to emotion and sensation.
Commenting independently on that Danone-UCLA study, Prof Glenn Gibson, a world-renowned expert in pre- and probiotics at the University of Reading in the UK, told us: "There is evidence that the gut to brain axis exists, with positive and negative potential outcomes. However, modulating it like this is a big step forward."
The Iranian scientists gave lab animals an injection of streptozocin to induce diabetes and then fed them a normal diet with or without probiotics (Lactobacillus acidophilus (ATCC 4356), Bifidobacterium lactis (DSM 10140), and Lactobacillus fermentum (ATCC 9338)) for eight months. A non-diabetic group of lab animals was used as the control group, and these were also fed with a normal diet with or without probiotics.
Results showed that, compared to the control animals, the diabetic animals fed the normal diet without probiotics displayed decreases in learning capability and maze navigation. This supported previous findings that diabetes can produce moderate disturbances of learning and memory.
However, probiotics were associated with a ‘marked’ influence in the maze test in both control and diabetic animals.
In addition, diabetic animals receiving the probiotics showed an improved in spatial performance in a hidden platform test.
Commenting on the potential mechanism, the researchers note that this could be related to a reduction in oxidative stress following probiotic supplementation, a proposal supported by enhanced activation of superoxide dismutase, and decreased levels of glucose and 8-OHdG factor, a marker of oxidative stress.
“From the present results we concluded that probiotics efficiently reverse deteriorated brain functions in the levels of cognitive performances and their proposed synaptic mechanisms in diabetes mellitus,” they wrote.
Volume 240, Pages 287-296, doi: 10.1016/j.neuroscience.2013.02.055
“Probiotics treatment improves diabetes-induced impairment of synaptic activity and cognitive function: Behavioral and electrophysiological proofs for microbiome-gut-brain axis”
Authors: Davari S, Talaei SA, Alaei H, Salami M.