These findings suggest that LcS may prevent hypersecretion of cortisol and physical symptoms under stressful conditions, possibly through vagal afferent signaling to the brain and reduced stress reactivity in the PVN.

Abstract. Soybean lecithin transphosphatidylated phosphatidylserine (SB-tPS) is already known to improve the learning ability of aged or drug-induced amnesic rodents. In this study, its effect on normal adult rodents was evaluated using several learning tasks. Firstly, three behavioral tests (open-field, Y-maze, and active avoidance test) were consecutively carried out after the daily oral administration of SB-tPS (50 mg / kg per day, for 34 days). Repeated oral administration of SB-tPS did not affect either exploratory behavior in the open-field test or spontaneous alternation behavior in the Y-maze test, while mice pretreated with SB-tPS showed significant enhancement of conditioned avoidance response. Secondly, the brightness discrimination test was used to evaluate the effect of SB-tPS on learning ability. The daily oral administration of SB-tPS (50 mg / kg per day, for 27 days) to normal rats significantly increased the correct response ratio in the brightness discrimination test. Finally, to elucidate the necessity of SB-tPS pretreatment, another active avoidance test was carried out, and no enhancement of conditioned avoidance response was observed in non-pretreated mice. These results suggest that repeated administration of SB-tPS could enhance the learning ability of normal adult rodents as those of aged ones.

Focusing on the beneficial effects of the Yakult -exclusive probiotic strain Lactobacillus casei strain Shirota LcS on the gut environment, we have been studying new functions of LcS involving the braingut axis. In order to maximize the effects of LcS on the brain-gut axis, we have succeeded in increasing the number and concentration of LcS in fermented milk by improving the raw materials and culture techniques. Double-blind, placebo-controlled trials were conducted to examine the effects of this new fermented milk product containing a high count and high density of LcS on psychological and physiological stress responses in healthy medical students under academic examination stress. This revealed that the increased expression of psychological and physical stress markers observed under stress conditions was significantly suppressed in the LcS group relative to the placebo group. In a different trial, daily consumption of LcS maintained sleep quality during the period of increased stress. Based on these results, we have registered the new LcS product as a Food with Functional Claims , allowing its functionality to be shown on the package.