Dabushen decoction ameliorates diabetes-associated cognitive dysfunction in association with changes in...

Diabetes-associated cognitive dysfunction (DCD) is a common and serious central nervous system complication of type 2 diabetes mellitus (T2DM). Dabushen Decoction (DBSD), first recorded in Fu Xing Jue Zang Fu Yong Yao Fa Yao, is a traditional Chinese herbal formula used to tonify the kidney and replenish essence. DBSD has shown potential pharmacological value in the intervention of cognitive dysfunction; however, its neuroprotective mechanisms remain to be systematically elucidated.

This study aimed to validate the mitigating effect of DBSD on DCD and to further investigate its mechanism.

Ultra-high-performance liquid chromatography coupled with Q Exactive Orbitrap high-resolution mass spectrometry (UHPLC-QE/MS) was used to analyze the chemical constituents of DBSD. Network pharmacology analysis was subsequently performed by integrating the SwissTargetPrediction, GeneCards, and OMIM databases. A T2DM rat model was established using a high-fat diet combined with streptozotocin (HFD/STZ), followed by oral administration of DBSD for 8 weeks. The overall pharmacological effects of DBSD were evaluated using the Morris water maze, Y-maze, and glucose and lipid metabolism-related indicators. Nissl staining and immunohistochemistry were used to assess pathological changes in hippocampal neurons, while transmission electron microscopy, ATP measurement, and JC-1 staining were used to evaluate hippocampal mitochondrial ultrastructure and function. ELISA was used to measure oxidative stress and inflammatory markers, and hippocampal proteomics was performed to analyze the potential biological processes involved. Finally, immunofluorescence colocalization and Western blotting were used to evaluate changes in PINK1/Parkin-mediated mitophagy markers.

A total of 22 candidate circulating prototype compounds were putatively annotated by UHPLC-QE/MS. Network pharmacology identified 215 intersecting targets, and GO and KEGG enrichment analyses suggested that these targets were mainly involved in mitochondrial ATP synthesis, oxidative phosphorylation, and metabolic pathways. In vivo experiments showed that DBSD, particularly at the high dose, reduced FBG, FINS, OGTT-AUC, TC, TG, and LDL-C levels, increased HDL-C levels, and enhanced behavioral performance in the Morris water maze, as reflected by a greater number of platform crossings and longer time spent in the target quadrant. Histopathological results showed that DBSD increased the density of Nissl-positive neurons and the percentage of NeuN-positive cells in the hippocampal CA1 region and reduced Aβ immunoreactivity. In addition, DBSD ameliorated mitochondrial and synaptic ultrastructural damage, increased ATP levels, and improved mitochondrial membrane potential. DBSD reduced serum IL-1β, IL-18, and MDA levels as well as hippocampal NLRP3 protein expression, while increasing serum SOD and GSH levels. Proteomic analysis identified 82 shared differentially expressed proteins, which were mainly associated with mitochondrial energy metabolism, mitophagy, and synaptic function. Further validation showed that DBSD increased the percentage of LC3/TOMM20 colocalization-positive cells, significantly upregulated the expression of PINK1, Parkin, Beclin-1 and the LC3B-II/LC3B-I ratio, and downregulated p62, TOMM20, and COX IV protein expression in the hippocampus.

DBSD improved cognitive function in rats with DCD, and its neuroprotective effects may be associated with changes in markers of PINK1/Parkin-mediated mitophagy and improved mitochondrial function.