Comparing Hippocampal Structures To Investigate Probiotic-mediated Neuroprotection

Probiotics have been hypothesized to have neuroprotective effects. We sought to investigate this in the present study by studying the effects of probiotics during a nutritional recovery period following a high-fat diet (HFD). HFD has been previously shown to reduce hippocampal volume in rodents, so adult male rats were given HFD for one month, after which they displayed hippocampal memory impairments, suggestive of reduced hippocampal structure. They were subsequently switched back to a control diet and given daily yogurt samples, which either contained probiotics or not (the yogurt given to the control group was filtered to remove any microorganisms, whereas the probiotic group received unfiltered yogurt). After 4 weeks of diet recovery and probiotic supplementation, probiotic rats had stronger recovery of hippocampal memory and the rats were sacrificed to collect brain samples. Their brains were sectioned at 40um, stained with cresyl violet to stain brain area architecture and fixed onto microscope slides. For each brain, the sizes of the following hippocampal structures were measured: dentate gyrus, CA3, and CA1/2 by tracing a representative series of sections containing these areas. Results suggest that despite memory differences between control and probiotic rats, there was no volume difference in the dentate gyrus, CA3, and CA1/2. This shows that although probiotic supplementation improves behavior, it likely does so without producing whole-scale changes to brain structure