Hua Sui

The effects of the Chinese medicine ZiBu PiYin recipe on the hippocampus in a rat model of diabetes-associated cognitive decline: a proteomic analysis

Aims/hypothesisIncreasing evidence suggests that diabetes is associated with an enhanced risk of cognitive decline. The precise mechanisms underlying diabetes-associated cognitive decline (DACD) remain unclear. Here we investigated the molecular changes associated with DACD using a comparative proteomics study of hippocampus in a rat model of type 2 diabetes. In addition, we tested the effects of the Chinese medicine ZiBu PiYin recipe (ZBPYR) on DACD.MethodsThe hippocampus was dissected from control, diabetic and diabetic rats treated with ZBPYR (DM/ZBPYR). Soluble proteins were separated using fluorescence-based difference gel electrophoresis. Protein spots were visualised with fluorescent dyes and spot density was compared between each pair of groups. Proteins of interest were identified using mass spectrometry. Proteins of specific interest were also tested by western blot and real-time PCR analysis.ResultsWe found 13 spots that were altered between control and diabetes groups, and 12 spots that were changed between diabetes and DM/ZBPYR groups. The identities of nine proteins were determined by mass spectrometry. The identified proteins were largely involved in energy metabolism, cytoskeleton regulation and oxidative stress. The protein alterations observed in the diabetes group were ameliorated to varying degrees following ZBPYR treatment.Conclusions/interpretationThe protein changes identified in hippocampus from a rat model of type 2 diabetes suggest that specific cellular alterations contribute to DACD. The Chinese medicine ZBPYR was found to affect multiple targets and partially repaired the original cellular balance. This study may provide important insights into the molecular events underlying DACD and allow the identification of novel therapeutic targets.

ZiBuPiYin recipe protects db/db mice from diabetes-associated cognitive decline through improving multiple pathological changes.

Multiple organ systems, including the brain, which undergoes changes that may increase the risk of cognitive decline, are adversely affected by diabetes mellitus (DM). Here, we demonstrate that type 2 diabetes mellitus (T2DM) db/db mice exhibited hippocampus-dependent memory impairment, which might associate with a reduction in dendritic spine density in the pyramidal neurons of brain, Aβ1-42 deposition in the prefrontal cortex (PFC) and hippocampus, and a decreased expression of neurostructural proteins including microtubule-associated protein (MAP2), a marker of dendrites, and postsynaptic density 95 (PSD95), a marker of excitatory synapses. To investigate the effects of the ZiBuPiYin recipe (ZBPYR), a traditional Chinese medicine recipe, on diabetes-related cognitive decline (DACD), db/db mice received daily administration of ZBPYR over an experimental period of 6 weeks. We then confirmed that ZBPYR rescued learning and memory performance impairments, reversed dendritic spine loss, reduced Aβ1-42 deposition and restored the expression levels of MAP2 and PSD95. The present study also revealed that ZBPYR strengthened brain leptin and insulin signaling and inhibited GSK3β overactivity, which may be the potential mechanism or underlying targets of ZBPYR. These findings conclude that ZBPYR prevents DACD, most likely by improving dendritic spine density and attenuating brain leptin and insulin signaling pathway injury. Our findings provide further evidence for the effects of ZBPYR on DACD.

Endoplasmic Reticulum Stress Impairs Insulin Receptor Signaling in the Brains of Obese Rats

The incidence of obesity is increasing worldwide. It was reported that endoplasmic reticulum stress (ERS) could inhibit insulin receptor signaling by activating c-Jun N-terminal kinase (JNK) in the liver. However, the relationship between ERS and insulin receptor signaling in the brain during obesity remains unclear. The aim of the current study was to assess whether ERS alters insulin receptor signaling through the hyper-activation of JNK in the hippocampus and frontal cortex in the brains of obese rats. Obesity was induced using a high fat diet (HFD). The Morris water maze test was then performed to evaluate decreases in cognitive function, and western blot was used to verify whether abnormal insulin receptor signaling was induced by ERS in HFD rats exhibiting cognitive decline. In addition, to determine whether ERS activated JNK and consequently impaired insulin receptor signaling, SH-SY5Y cells were treated with the JNK inhibitor, SP600125, followed by tunicamycin or thapsigargin, and primary rat hippocampal and cortical neurons were transfected with siRNA against IRE1α and JNK. We found that the expression of phosphorylation of PKR-like kinase (PERK), phosphorylation of α subunit of translation initiation factor 2 (eIF2α), and phosphorylation of inositol-requiring kinase-1α (IRE-1α) were increased in the brains of rats with HFD when compared with control rats. The level of serine phosphorylation of insulin receptor substrate-1 (IRS-1) was also increased, while protein kinase B (PKB/Akt) was reduced. ERS was also found to inhibit insulin receptor signaling via the activation of JNK in SH-SY5Y cells, primary rat hippocampal, and cortical neurons. These results indicate that ERS was increased, thereby resulting in impaired insulin receptor signaling in the hippocampus and frontal cortex of obese rats.

Rat hippocampal proteomic alterations following intrahippocampal injection of amyloid beta peptide (1–40)

Amyloid beta peptide 1-40 (Aβ(1-40)) is closely associated with the progressive neuronal loss and cognitive decline observed in Alzheimers disease (AD). This study aimed to establish a proteomic strategy for the profiling of AD tissues for disease-specific changes in protein abundance. Intrahippocampal injection of Aβ(1-40) induced spatial memory and learning decline in rats. Proteomic analysis revealed the changes in protein expression in the rat hippocampus treated with Aβ(1-40). Four proteins of interest which was in abundance was significantly altered in Aβ(1-40)-treated rats were identified by peptide mass fingerprint (PMF). These proteins corresponded to synapsin Ib, protein disulfide-isomerase A3 precursor, tubulin β chain and ATP synthase β subunit. Our results provide new insights into the relationship between Aβ and the pathogenesis of AD, and suggest potential targets for the therapy of AD.

Role of the SNK-SPAR pathway in the development of Alzheimer's disease

Alzheimers disease (AD) is characterized by the presence of senile plaques and neurofibrillary tangles in the brain. The beta‐amyloid peptide (Aβ) is the primary constituent of the senile plaques, and has been proposed to be a key contributor to the neurodegeneration observed in AD. The molecular mechanisms underlying dendritic spine damage that is induced by Aβ toxicity in AD patients remain largely unknown. It has been suggested previously that the SNK‐SPAR signaling pathway is involved in activity‐dependent remodeling of synapses. The relationship between the SNK‐SPAR pathway and Aβ‐induced excitotoxicity, however, is poorly understood. The present study investigated the effects of bilateral intrahippocampal injection of Aβ peptide 1–40 (Aβ1–40) on learning and memory in the rat, and explored the mechanisms underlying the effects of this injection. We reported that bilateral injection of Aβ1–40 in rats resulted in impaired performance in the step‐down passive avoidance and Morris water maze tasks. Then we examined mRNA and protein expression levels in the different brain regions one week after injection with Aβ1–40 and found that the SNK‐SPAR signaling pathway was possibly involved in dendritic spine damage in the different brain regions of Aβ‐treated rats. These results demonstrate that the SNK‐SPAR pathway may possibly play a crucial role in Aβ‐induced excitotoxic damage in the central nervous system by regulating synaptic stability.

Decreased expression of spine-associated Rap guanosine triphosphatase-activating protein (SPAR) in glutamate-treated primary hippocampal neurons

Spine-associated Rap guanosine triphosphatase-activating protein (SPAR) is an important regulator of activity-dependent remodeling of synapses. It is also critically involved in both mature dendritic spine formation and the maintenance of spine maturity. Glutamate is a major neurotransmitter of the brain, and is involved in all aspects of cognitive function, as it is the primary transmitter utilized by the cortical and hippocampal pyramidal neurons. Glutamate has also been associated with neuronal dendritic spine damage. The precise molecular mechanisms underlying dendritic spine damage following glutamate-induced neurotoxicity remain unknown. In the current study, we measured mRNA and protein expression levels of SPAR and serum-inducible kinase (SNK) in primary hippocampal neurons following glutamate treatment. Expression of SPAR and SNK was altered by glutamate treatment, indicating that the SPAR and SNK signaling pathways may be involved in the damage to dendritic spines in hippocampal neurons following excitotoxicity induced by glutamate.

Effects of Zibu Piyin Recipe (滋补脾阴方药) on SNK-SPAR pathway in neuron injury induced by glutamate

ObjectiveTo investigate the relationship between the excitotoxicity and serum-inducible kinase (SNK) and spine-associated Rap GTPase-activating protein (SPAR) pathway in primary hippocampal neuron injury induced by glutamate and furthermore, to explore the molecular mechanism of neuroprotection of Zibu Piyin Recipe (滋补脾阴方药, ZBPYR) and the relationship between ZBPYR and the morphological regulation of dendritic spines.MethodsThe serum containing ZBPYR was prepared by seropharmacology. Reverse transcription and polymerase chain reaction (RT-PCR) was used to detect the expression of mRNA for SNK, SPAR, postsynaptic density protein 95 (PSD-95) and N-methyl-D-aspartate (NMDA) receptor subunits (NR1, NR2A and NR2B) in primary rat hippocampal neuron cultures after pretreatment with 10 μmol/L glutamate and ZBPYR serum.ResultsZBPYR serum pretreatment resulted in a significant down-regulation of glutamate-induced SNK mRNA expression (P<0.05). Significant up-regulation was seen on the mRNA expression of SPAR and PSD-95 (P<0.05). All these changes were dose-dependent. The mRNA expression of NR1, NR2A and NR2B was down-regulated to different degrees (P<0.05).ConclusionThe mechanism of effect of ZBPYR on glutamate-induced excitotoxicity may be related to the regulation of SNK-SPAR signal pathway. ZBPYR may play a role in protecting and maintaining the normal morphology and structure of dendritic spines, which may be achieved by inhibiting the excessive activation of NMDA receptors.

Plasma Metabolomic Profiling of Patients with Diabetes-Associated Cognitive Decline

Diabetes related cognitive dysfunction (DACD), one of the chronic complications of diabetes, seriously affect the quality of life in patients and increase family burden. Although the initial stage of DACD can lead to metabolic alterations or potential pathological changes, DACD is difficult to diagnose accurately. Moreover, the details of the molecular mechanism of DACD remain somewhat elusive. To understand the pathophysiological changes that underpin the development and progression of DACD, we carried out a global analysis of metabolic alterations in response to DACD. The metabolic alterations associated with DACD were first investigated in humans, using plasma metabonomics based on high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and multivariate statistical analysis. The related pathway of each metabolite of interest was searched in database online. The network diagrams were established KEGGSOAP software package. Receiver operating characteristic (ROC) analysis was used to evaluate diagnostic accuracy of metabolites. This is the first report of reliable biomarkers of DACD, which were identified using an integrated strategy. The identified biomarkers give new insights into the pathophysiological changes and molecular mechanisms of DACD. The disorders of sphingolipids metabolism, bile acids metabolism, and uric acid metabolism pathway were found in T2DM and DACD. On the other hand, differentially expressed plasma metabolites offer unique metabolic signatures for T2DM and DACD patients. These are potential biomarkers for disease monitoring and personalized medication complementary to the existing clinical modalities.

Deciphering bacterial community changes in zucker diabetic fatty rats based on 16S rRNA gene sequences analysis

The aim of the present pilot study was deciphering bacterial community changes in Zucker diabetic fatty rats (ZDF rats), a model of type 2 diabetes. Recent studies unmasked that the status of gastrointestinal tract microbiota has a marked impact on nutrition-related syndromes such as obesity and type-2 diabetes (T2D). In this study, samples taken from the gastrointestinal tracts (GI tracts) of ZDF and their lean littermates (ZL rats) were subjected to 16S rRNA gene sequence-based analysis to examine the characteristic bacterial communities, including those located in the stomach, duodenum, jejunum, ileum, cecum and feces. Results revealed that the Firmicutes/Bacteroidetes ratio was increased and greater numbers of Lactobacillus were detected along GI tracts in ZDF rats compared to ZL rats. In conclusion, this work is the first study to systematically characterize bacterial communities along ZDF rat GI tract and provides substantial evidence supporting a prospective strategy to alter the GI microbial communities improving obesity and T2D.

ZiBuPiYin recipe improves cognitive decline by regulating gut microbiota in Zucker diabetic fatty rats

Numerous researches supported that microbiota can influence behavior and modulate cognitive function through “microbiota-gut-brain” axis. Our previous study has demonstrated that ZiBuPiYin recipe (ZBPYR) possesses excellent pharmacological effects against diabetes-associated cognitive decline. To elucidate the role of ZBPYR in regulating the balance of gut microbiota to improve psychological-stress-induced diabetes-associated cognitive decline (PSDACD), we compared blood glucose, behavioral and cognitive functions and diversity of the bacterial community among experimental groups. The Zucker diabetic fatty (ZDF) rats with PSDACD exhibited behavioral and cognitive anomalies showing as increased anxiety- and depression-like behaviors and decreased learning and memory abilities. High-throughput sequencing of the bacterial 16S rRNA gene revealed that Roseburia and Coprococcus were decreased in ZDF rats with PSDACD compared with control group. Notably, these changes were reversed by ZBPYR treatment. Our findings indicate that ZBPYR might prevent PSDACD by maintaining the compositions of gut microbiota, which could be developed as a new therapy for T2D with PSDACD.