AD−1 Small Molecule Improves Learning and Memory Function in Scopolamine-Induced Amnesic Mice Model through Regulation of CREB/BDNF and NF-κB/MAPK Signaling Pathway

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

Dendrobium nobile Lindl ameliorates learning and memory deficits in scopolamine-treated mice

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium nobile Lindl (DNL), a valued time-honored herb, possesses immune-boosting and age-delaying properties, has been widely used to treat hyperglycemia and neurological diseases, and is probably a potential drug for improving learning and memory. Scopolamine (Scop), an antagonist for muscarinic receptors, potentially impairing intelligence and memory.

AIM OF THE STUDY

This investigation aimed to assess the efficacy of DNL in alleviating scopolamine-induced cognitive deficits in mice and its mechanisms.

MATERIALS AND METHODS

We utilized the open-field test, novel object recognition test (NOR), and Morris water maze test (MWM) to assess the potential of DNL in ameliorating learning and memory dysfunction caused by scopolamine in mice. Enzyme-linked immunosorbent assay (ELISA) was employed to measure Choline acetyltransferase (ChAT) content and Acetylcholinesterase (AChE) activities in the brain, and oxidative stress-related factors in the serum, including Malondialdehyde (MDA), Superoxide dismutase (SOD), and glutathione (GSH) content.

RESULTS

Scopolamine injection significantly reduced the discrimination index of mice in the NOR test and impaired their performance in the MWM test, as demonstrated by longer escape latency, fewer target crossings, and less time spent in the target quadrant in the MWM. After 25 days of administration, DNL increased the discrimination index of the scopolamine-treated mice in the NOR test. DNL reduced the escape latency in the MWM test in the model mice. DNL increased the target crossing number and the percentage of time spent in the target quadrant in the MWM test. ELISA experiments indicated that DNL decreased the AChE activities, increased the ChAT activities, and modulated oxidative stress makers (GSH, SOD, and MDA) in scopolamine-induced mice.

CONCLUSIONS

DNL may improve the learning and memory in mice treated with scopolamine, possibly by modulating oxidative stress and impaired cholinergic function.

The Neuropharmacological Evaluation of Seaweed: A Potential Therapeutic Source

The most common neurodegenerative diseases (NDDs), such as Alzheimer's disease (AD) and Parkinson's disease (PD), are the seventh leading cause of mortality and morbidity in developed countries. Clinical observations of NDD patients are characterized by a progressive loss of neurons in the brain along with memory decline. The common pathological hallmarks of NDDs include oxidative stress, the dysregulation of calcium, protein aggregation, a defective protein clearance system, mitochondrial dysfunction, neuroinflammation, neuronal apoptosis, and damage to cholinergic neurons. Therefore, managing this pathology requires screening drugs with different pathological targets, and suitable drugs for slowing the progression or prevention of NDDs remain to be discovered. Among the pharmacological strategies used to manage NDDs, natural drugs represent a promising therapeutic strategy. This review discusses the neuroprotective potential of seaweed and its bioactive compounds, and safety issues, which may provide several beneficial insights that warrant further investigation.

Diverse signaling mechanisms and heterogeneity of astrocyte reactivity in Alzheimer's disease

Alzheimer's disease (AD) affects various brain cell types, including astrocytes, which are the most abundant cell types in the central nervous system (CNS). Astrocytes not only provide homeostatic support to neurons but also actively regulate synaptic signaling and functions and become reactive in response to CNS insults through diverse signaling pathways including the JAK/STAT, NF-κB, and GPCR-elicited pathways. The advent of new technology for transcriptomic profiling at the single-cell level has led to increasing recognition of the highly versatile nature of reactive astrocytes and the context-dependent specificity of astrocyte reactivity. In AD, reactive astrocytes have long been observed in senile plaques and have recently been suggested to play a role in AD pathogenesis and progression. However, the precise contributions of reactive astrocytes to AD remain elusive, and targeting this complex cell population for AD treatment poses significant challenges. In this review, we summarize the current understanding of astrocyte reactivity and its role in AD, with a particular focus on the signaling pathways that promote astrocyte reactivity and the heterogeneity of reactive astrocytes. Furthermore, we explore potential implications for the development of therapeutics for AD. Our objective is to shed light on the complex involvement of astrocytes in AD and offer insights into potential therapeutic targets and strategies for treating and managing this devastating neurodegenerative disorder.

Standardized extract of Glehnia Littoralis abrogates memory impairment and neuroinflammation by regulation of CREB/BDNF and NF-κB/MAPK signaling in scopolamine-induced amnesic mice model

Mild cognitive impairment is a typical symptom of early Alzheimer's disease (AD). Glehnia littoralis (G. littoralis), a medicinal halophyte plant commonly used to treat strokes, has been shown to possess some therapeutic qualities. In this study, we investigated the neuroprotective and anti-neuroinflammatory effects of a 50% ethanol extract of G. littoralis (GLE) on lipopolysccharide (LPS)-stimulated BV-2 cells and scopolamine-induced amnesic mice. In the in vitro study, GLE treatment (100, 200, and 400 µg/mL) markedly attenuated the translocation of NF-κB to the nucleus concomitantly with the significant mitigation of the LPS-induced production of inflammatory mediators, including NO, iNOS, COX-2, IL-6, and TNF-α. In addition, the GLE treatment suppressed the phosphorylation of MAPK signaling in the LPS-stimulated BV-2 cells. In the in vivo study, mice were orally administered with the GLE (50, 100, and 200 mg/kg) for 14 days, and cognitive loss was induced via the intraperitoneal injection of scopolamine (1 mg/kg) from 8 to 14 days. We found that GLE treatment ameliorated memory impairment and simultaneously improved memory function in the scopolamine-induced amnesic mice. Correspondingly, GLE treatment significantly decreased the AChE level and upregulated the protein expression of neuroprotective markers, such as BDNF and CREB, as well as Nrf2/HO-1 and decreased the levels of iNOS and COX-2 in the hippocampus and cortex. Furthermore, GLE treatment attenuated the increased phosphorylation of NF-κB/MAPK signaling in the hippocampus and cortex. These results suggest that GLE has a potential neuroprotective activity that may ameliorate learning and memory impairment by regulating AChE activity, promoting CREB/BDNF signaling, and inhibiting NF-κB/MAPK signaling and neuroinflammation.