Enzymolysis peptides from Mauremys mutica plastron improve the disorder of neurotransmitter system and facilitate sleep-promoting in the PCPA-induced insomnia mice

Ethnopharmacology relevancy: For many centuries, Mauremys mutica is highly valued as a food homologous Chinese herbal medicine. It has been considered useful to sedate, nourish brain and promote sleep. However, the animal experimental evidence of its sleep-promoting activity is missing in literature. Aim of the study: In this study, PCPA-induced insomnia model was used to explore the sleep-promoting mechanism of enzymolysis peptides from PMM, and its main composition and chemical structure were analyzed. Materials and methods: Experiments were performed using PCPA-induced insomnia model, all animals were intraperitoneally injected with PCPA (350 mg/kg.d) for two days. The sleep-promoting effect evaluated using measuring content of 5-HT, GABA, DA, IL-1, BDNF and expression of 5-HT1A receptor and GABAA receptor alpha 1-subunit in mice brain. Primary structure of peptides was identified by HPLC-ESI-QqTOF-MS/MS. Results: Compared with the model group, the content of 5-HT, GABA, IL-1, BDNF in mice brain of PMM peptide groups was increased to varying degrees, the content of DA was decreased, and the gene transcription and protein expression of 5-HT1A receptor and GABAA receptor alpha 1-subunit were almost all returned to normal levels. In addition, the primary structures of most abundant nine typical peptides in PMM peptides were identified. Conclusions: The results showed that PMM peptides could improve the disorder of neurotransmitter system, restore compensatory over-expression 5-HT1A receptor and GABAA receptor alpha 1-subunit, and have a good sleep-promoting effect. The specific amino acid composition, sequence and glycosylation modification of PMM peptides may be the key reason for their activity, which lays a foundation for the subsequent development of sleeppromoting peptide products.

Automated summary

Through experiments on PCPA-induced insomnia model, enzymolysis peptides from PMM were found to improve neurotransmitter system disorder, restore over-expression of 5-HT1A receptor and GABAA receptor alpha 1-subunit, and show a good sleep-promoting effect. The unique amino acid composition, sequence, and glycosylation modification of PMM peptides may be the key factors for their activity, providing a basis for the development of sleep-promoting peptide products.