Tenuifolin ameliorates chronic restraint stress-induced cognitive impairment in C57BL/6J mice

Integrating Network Pharmacology and Component Analysis to Study the Potential Mechanisms of Qi-Fu-Yin Decoction in Treating Alzheimer's Disease

Purpose

To elucidate the potential mechanisms of QFY for the treatment of Alzheimer's Disease (AD), and explore the effective substances of QFY.

Materials and Methods

UPLC-LTQ-Orbitrap-MS was used to identify the chemical constituents of the serum samples and the cerebrospinal fluid samples of rats after QFY administration. Network pharmacology was used to predict potential targets and pathways of QFY against AD. The AD mice model was established by subcutaneous injection of D-gal for 8 consecutive weeks. New object recognition (NOR) and Morris water maze test (MWM) were used to evaluate the learning and memory abilities of mice. Moreover, the levels of TNF-α, IL-1β, and IL-18 in the brain hippocampus of mice were determined by ELISA. The expression of Bax, Bcl-2, Caspase-1, PSD95, SYP, ICAM-1 and MCP-1 proteins in the hippocampus was detected by Western blotting. Furthermore, qRT-PCR was used to detect the gene expressions of PSD95, SYP, M1 and M2 polarization markers of microglia, including iNOS, CD16, ARG-1, and IL-10 in the hippocampus.

Results

A total of 51 prototype compounds were detected in rat serum and 15 prototype components were identified in rat cerebrospinal fluid. Behavioral experiments revealed that QFY significantly increased the recognition index, decreased the escape latency, increased the platform crossing times and increased the residence time in the target quadrant. QFY also could alleviate the ultrastructural pathological changes in the hippocampus of AD mice. Meanwhile, QFY treatment suppressed the expression of inflammatory factors, such as TNF-α, IL-1β, and IL-18. QFY improved the synaptic plasticity of the hippocampus in D-gal model mice by significantly increasing the expression of proteins and mRNAs of PSD95 and SYP.

Conclusion

QFY could effectively improve the learning and memory impairment of D-gal-induced AD mice by inhibiting the excessive activation of microglia, enhancing the expression of M2 microglia, inhibiting the increase of inflammatory factors, cell adhesion factors and chemokines, anti-apoptosis, and improving synaptic plasticity.

Memory impairments in rodent depression models: A link with depression theories

More than 80% of depressed patients struggle with learning new tasks, remembering positive events, or concentrating on a single topic. These neurocognitive deficits accompanying depression may be linked to functional and structural changes in the prefrontal cortex and hippocampus. However, their mechanisms are not yet completely understood. We conducted a narrative review of articles regarding animal studies to assess the state of knowledge. First, we argue the contribution of changes in neurotransmitters and hormone levels in the pathomechanism of cognitive dysfunction in animal depression models. Then, we used numerous neuroinflammation studies to explore its possible implication in cognitive decline. Encouragingly, we also observed a positive correlation between increased oxidative stress and a depressive-like state with concomitant memory deficits. Finally, we discuss the undeniable role of neurotrophin deficits in developing cognitive decline in animal models of depression. This review reveals the complexity of depression-related memory impairments and highlights the potential clinical importance of gathered findings for developing more reliable animal models and designing novel antidepressants with procognitive properties.

Tenuifolin ameliorates the sleep deprivation-induced cognitive deficits

Tenuifolin (TEN), a natural neuroprotective compound obtained from the Polygala tenuifolia Willd plant, has improved cognitive symptoms. However, the impact of TEN on memory impairments caused by sleep deprivation (SD) is unclear. Accordingly, the objective of this study was to investigate the mechanisms behind the preventative benefits of TEN on cognitive impairment caused by SD. TEN (10 and 20 mg/kg) and Huperzine A (0.1 mg/kg) were given to mice through oral gavage for 28 days during the SD process. The results indicate that TEN administrations improve short- and long-term memory impairments caused by SD in the Y-maze, object identification, and step-through tests. Moreover, TEN stimulated the generation of anti-inflammatory cytokines (interleukin-10), lowered the production of pro-inflammatory cytokines (interleukin-1β, interleukin-6, and interleukin-18), and activated microglia, improving antioxidant status in the hippocampus. TEN treatments significantly boosted the expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 while considerably decreasing the expression of NOD-like receptor thermal protein domain associated protein 3 and caspase-1 p20. Additionally, TEN restored the downregulation of the brain-derived neurotrophic factor signaling cascade and the impaired hippocampal neurogenesis induced by SD. When considered collectively, our data suggest that TEN is a potentially effective neuroprotective agent for cognition dysfunction.

The effects of stress on avoidance in rodents: An unresolved matter

In the face of a possible threat, a range of physiological (e.g., increased heart rate) and behavioral (e.g., avoidance or escape) responses are recruited. Here, we will focus on avoidance, in its persistent form one of the core symptoms of anxiety disorders and obsessive-compulsive disorder. The initial goal of fear and avoidance responses is to increase survival, but if they become persistent or overgeneralize, they can disrupt normal daily functioning, and ultimately even result in anxiety-related disorders. Relatedly, acute stress responses promote adaptation and survival, while chronic stress has been found to aggravate pathophysiology. Thus, stress might trigger the transition from adaptive to maladaptive responses, e.g., from goal-directed to persistent avoidance. Animal models are prime tools to unravel if and how stress influences avoidance. This is typically done by performing stress inductions prior to the assessment of (passive or active) avoidance behavior. Despite its clinical relevance, the current literature on this topic is fragmented, and an overall conclusion is lacking. In this Review, we first recapitulate the state of the art regarding stress and active as well as passive avoidance procedures. We then summarize the behavioral effects of acute and chronic stress on active and passive avoidance, and discuss the main neurobiological findings of the field. Finally, we highlight possible reasons for the largely contradictory findings in the literature and we propose strategies to further unravel the effect of stress on avoidance behavior. A deeper understanding of this currently unresolved matter may provide further insights in the etiology and treatment of anxiety-related disorders.

Roles of traditional chinese medicine regulating neuroendocrinology on AD treatment

The incidence of sporadic Alzheimer's disease (AD) is increasing in recent years. Studies have shown that in addition to some genetic abnormalities, the majority of AD patients has a history of long-term exposure to risk factors. Neuroendocrine related risk factors have been proved to be strongly associated with AD. Long-term hormone disorder can have a direct detrimental effect on the brain by producing an AD-like pathology and result in cognitive decline by impairing neuronal metabolism, plasticity and survival. Traditional Chinese Medicine(TCM) may regulate the complex process of endocrine disorders, and improve metabolic abnormalities, as well as the resulting neuroinflammation and oxidative damage through a variety of pathways. TCM has unique therapeutic advantages in treating early intervention of AD-related neuroendocrine disorders and preventing cognitive decline. This paper reviewed the relationship between neuroendocrine and AD as well as the related TCM treatment and its mechanism. The advantages of TCM intervention on endocrine disorders and some pending problems was also discussed, and new insights for TCM treatment of dementia in the future was provided.