Preparation of Deer Brain Peptide Chelated with Zinc and Its Effect on Improving Memory Impairment in Insomnia Mice Induced by Para-Chlorophenylalanine

Background/Objectives: Chronic insomnia commonly induces progressive memory decline, severely compromising human daily life and work capability. At present, there are no safe long-term available agents that can concurrently relieve insomnia symptoms and rescue accompanying memory dysfunction. This study aimed to optimize the preparation of deer brain peptides (DBPP) and zinc-chelated DBPP (Zn-DBPP), and explore their protective effects and molecular mechanism against insomnia-caused memory impairment, hoping to develop novel functional candidates for related neurological disorders. Methods: Single-factor experiments combined with response surface methodology were used to optimize the synthesis process of DBPP and Zn-DBPP. A para-chlorophenylalanine-induced insomnia mouse model was established. The structural characteristics, amino acid composition, and antioxidant activity of the products were verified via multiple spectroscopic and biochemical assays. Pentobarbital sodium sleep test and Morris water maze test assessed behavioral changes. Hippocampal neuronal morphology and BDNF-TrkB pathway expression were detected by histological staining, immunofluorescence and Western blotting. Results: The optimized DBPP achieved a hydrolysis rate of 43.89%, and Zn-DBPP possessed a zinc content of 143.37 mg/g. Successful zinc chelation, rich amino acid components, and strong antioxidant capacity were confirmed in Zn-DBPP. In vivo results showed that Zn-DBPP elevated brain zinc levels, improved learning and memory deficits, and restored hippocampal neuronal damage in insomniac mice. Mechanically, Zn-DBPP alleviated memory impairment by upregulating the BDNF-TrkB signaling pathway. Conclusions: The optimized Zn-DBPP exhibits excellent neuroprotective effects against insomnia-induced memory dysfunction. This work provides a reliable theoretical basis for the application of Zn-DBPP as a promising functional food or drug candidate for intervening in insomnia and cognitive decline.