Enhancement of memory and emotional functions by long-term ingestion of protease-treated porcine liver extract in mice

The relationship between diet and brain functions has garnered attention. Previous studies have shown that ingesting a protease-treated porcine liver decomposition product (PLDP) improves cognitive function in humans. In this study, we investigated the effects of PLDP ingestion on cognitive and emotional functions in mice. Mice were fed a PLDP-enhanced diet for 16 weeks and subjected to various behavioral assessments. PLDP ingestion enhanced long-term memory in Barnes maze test. Moreover, mice fed the PLDP diet exhibited reduced anxiety- and depression-like behaviors as evidenced by their performance in open-field, elevated plus maze, marble-burying, and forced swim tests. They also increased locomotor activity. RNA sequencing analysis of the brain tissue revealed substantial changes in gene expression, particularly in pathways associated with learning, memory, and anxiety regulation. Collectively, these results suggest that PLDP induces changes in gene expression associated with brain function, potentially contributing to the enhancement of cognitive function and psychological health. Furthermore, our findings not only enhance our understanding of the relationship between nutrition and brain function but also indicate the potential of interventions utilizing dietary components, such as PLDP, to support cognitive function and psychological health. Mice were fed a PLDP-enhanced diet for 16 weeks Total RNA was extracted from mouse brains following behavioral experiments using TRIZOL reagent (Thermo Fisher Scientific, Waltham, USA), according to the manufacturer's instructions. Samples were subjected to TruSeq Stranded mRNA library preparation (Illumina) and sequenced on a NovaSeq 6000 (2 ×150 bp; Illumina, San Diego, CA, USA) for a 6-Gb coverage. In total, 2303 differentially expressed genes (1,271 upregulated and 1,032 downregulated genes) with p-values < 0.05 were further analyzed using Qiagen Ingenuity Pathway Analysis (IPA) software (QIAGEN, Valencia, CA, USA).