Effects of Dietary Supplementation with In Vitro-Cultivated Arboreal Medicinal Mushrooms on Long-Term Memory and Anxiety-Like Behavior of Male Mice

Health-promoting effects of medicinal mushrooms have been postulated for centuries in folk medicine in Asia and Europe and are currently being verified by scientific research. Lion's mane (Hericium erinaceus, HE) is an arboreal medicinal mushroom that has been shown to improve short-term memory of healthy mice, and to modulate stress-coping strategies of rodents. HE shares bioactive compounds with other arboreal medicinal mushrooms such as the pink oyster mushroom (Pleurotus djamor, PDJ) and agarikon (Fomitopsis officinalis, FO), but their effects in vivo have not been investigated. The aim of this study was to compare the effects of dietary supplementation with HE, FO, or PDJ on long-term memory, anxiety-like behavior, and hippocampal gene expression of healthy male mice. CD-1 mice were fed with either control or mushroom-supplemented (2 mg/g of dry chow) diets for 40 days and underwent object novelty recognition and elevated plus maze tests before hippocampi collection. Only HE-supplemented animals displayed long-term memory (one sample t-test against chance level of novelty preference ratio). Supplementation had no effect on anxiety-like behavior, but its effect on the frequency of arm visits of the elevated plus maze apparatus was modulated by the amount of ingested food - an effect that was absent in control animals. We also observed that mice with higher weight gain had lower expression of Gsk3 beta and Mtor in their hippocampi. We discuss the relevance of these results for rodent behavioral studies of dietary mushroom supplementation.