Collagen peptides enhance hippocampal neurogenesis and reduce anxiety related behavior in mice.

The present study examined the effects of enzymatically hydrolyzed collagen peptides on the level of hippocampal neurogenesis and emotional behavior in adult mice. For this purpose, two kinds of enzymatically hydrolyzed collagen peptides, the lower or higher molecular weight peptides (LP: below 2,000, HP: about 30,000) were administered orally to C57BL/6 mice for 4 weeks. As a result, the density of proliferating cells in subgranular zone of hippocampus showed a 1.2-fold increase in LP mice as compared with HP mice. Additionally, LP mice spent less time in closed arms than HP mice in elevated plus maze test to examine anxiety-related behavior. These results suggest that oral administration of the lower molecular weight peptides derived from collagen enhanced the hippocampal neurogenesis and exerted emotional behavior in adult mice.

Volatiles emitted from the roots of Vetiveria zizanioides suppress the decline in attention during a visual display terminal task.

The perennial grass Vetiveria zizanioides (vetiver) is mainly cultivated for its fragrant essential oil. Although the components of the oil and their biological activities have been studied extensively, the effect of the volatiles emitted from the roots of V. zizanioides on humans has so far remained unexplored. We investigated the effects of volatile compounds emitted from the cut roots of V. zizanioides (1.0 g, low-dose conditions; 30 g, high-dose conditions) on individuals during a visual display terminal task. Participants who breathed the volatile compounds emitted under low-dose conditions showed faster reaction times and stimulation of sympathetic nerve activity as measured by electrocardiography. These effects were not observed under high-dose conditions. The total amounnt of volatiles emitted during the experiment was 0.25 µg under low-dose conditions and 1.35 µg under high-dose conditions. These findings indicate that volatile compounds emitted from the roots of V. zizanioides under low-dose conditions may have helped subjects to maintain performance in visual discrimination tasks while maintaining high sympathetic nerve system activity.