Samhwangsasim-tang attenuates neuronal apoptosis and cognitive decline through BDNF-mediated activation of tyrosin kinase B and p75-neurotrophin receptors

Lancao decoction alleviates cognitive dysfunction: A new therapeutic drug and its therapeutic mechanism

BACKGROUND

Cognitive dysfunction (CD) is a neurodegenerative disease characterized primarily by the decline of learning and memory abilities. The physiological and pathological mechanisms of CD are very complex, which is mainly related to normal function of the hippocampus. Lancao decoction (LC) is a Chinese medicine formula, which has been used to treat neurodegenerative disorders. However, the potential of LC for the treatment of CD, as well as its underlying mechanisms, is unclear.

PURPOSE

In the study, we aimed to reveal the functional and neuronal mechanisms of LC's treatments for CD in scopolamine-induced mice.

METHODS

Gas chromatography (GC) was used to determine the stability of LC's extraction. CD model was established by the chronic induction of scopolamine (Scop, 1 mg/kg/day) for 1 week. Behavioral tests including morris water maze (MWM) and y-maze were used to evaluate learning and memory abilities of mice after LC's treatments. Immunofluorescence was used to detected the expressions of cFOS, Brdu and Ki67 after LC's treatments. Pharmacological blockade experiments explored the role of α-Amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in LC's treatments for CD and its relationships with regeneration, activities and differentiation of neurons.

RESULTS

The results showed that LC was capable of improving spatial learning and memory and spontaneous alternating abilities in Scop-induced mice, which was similar to donepezil. LC could increase the number of cFOS positive cells, which was used as a marker of neuronal activity to upregulate by neuronal activities in hippocampus, but donepezil did not. Moreover, LC could strengthen neurogenesis and neuro-differentiation by increasing the number of Brdu and Ki67 positive cells in hippocampal dentate gyrus (DG), meanwhile, donepezil could only enhance the number of Ki67 positive cells. Transient inhibition of AMPAR by NBQX blunted the function of LC's treatment for CD and inhibited the enhanced effect of LC on Scop-induced hippocampal neuronal excitability and neurogenesis in mice.

CONCLUSION

To sum up, our study demonstrated that LC had the function of treating CD by enhancing content of acetylcholine (ACh) to activate AMPAR, which further up-regulated neurogenesis and neuronal differentiation to strengthen neuroactivities in hippocampus.

Ginsenoside RK3 promotes neurogenesis in Alzheimer's disease through activation of the CREB/BDNF pathway

ETHNOPHARMACOLOGICAL RELEVANCE

In the ancient book "Shen Nong's Herbal Classic," Panax ginseng CA Mey was believed to have multiple benefits, including calming nerves, improving cognitive function, and promoting longevity. Ginsenosides are the main active ingredients of ginseng. Ginsenoside RK3 (RK3), a rare ginsenoside extracted from ginseng, displays strong pharmacological potential. However, its effect on neurogenesis remains insufficiently investigated.

AIM OF THE STUDY

This study aims to investigate whether RK3 improves learning and memory by promoting neurogenesis, and to explore the mechanism of RK3 action.

MATERIALS AND METHODS

The therapeutic effect of RK3 on learning and memory was determined by the Morris water maze (MWM) and novel object recognition test (NORT). The pathogenesis and protective effect of RK3 on primary neurons and animal models were detected by immunofluorescence and western blotting. Protein expression of cAMP response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway was detected by western blotting.

RESULTS

Our results showed that RK3 treatment significantly improved cognitive function in APPswe/PSEN1dE9 (APP/PS1) mice and C57BL/6 (C57) mice. RK3 promotes neurogenesis and synaptogenesis in the mouse hippocampus. In vitro, RK3 prevents Aβ-induced injury in primary cultured neurons and promotes the proliferation of PC12 as well as the expression of synapse-associated proteins. Mechanically, the positve role of RK3 on neurogenesis was combined with the activation of CREB/BDNF pathway. Inhibition of CREB/BDNF pathway attenuated the effect of RK3.

CONCLUSION

In conclusion, this study demonstrated that RK3 promotes learning and cognition in APP/PS1 and C57 mice by promoting neurogenesis and synaptogenesis through the CREB/BDNF signaling pathway. Therefore, RK3 is expected to be further developed into a potential drug candidate for the treatment of Alzheimer's disease (AD).

Smart Farming Enhances Bioactive Compounds Content of Panax ginseng on Moderating Scopolamine-Induced Memory Deficits and Neuroinflammation

Korean ginseng (Panax ginseng) is a traditional herbal supplement known to have a variety of pharmacological activities. A smart farm system could provide potential standardization of ginseng seedlings after investigating plant metabolic responses to various parameters in order to design optimal conditions. This research was performed to investigate the effect of smart-farmed ginseng on memory improvement in a scopolamine-induced memory deficit mouse model and an LPS-induced microglial cell model. A smart farming system was applied to culture ginseng. The administration of its extract (S2 extract) under specific culture conditions significantly attenuated cognitive and spatial memory deficits by regulating AKT/ERK/CREB signaling, as well as the cortical inflammation associated with suppression of COX-2 and NLRP3 induced by scopolamine. In addition, S2 extract improved the activation of iNOS and COX-2, and the secretion of NO in LPS-induced BV-2 microglia. Based on the HPLC fingerprint and in vitro data, ginsenosides Rb2 and Rd were found to be the main contributors to the anti-inflammatory effects of the S2 extract. Our findings suggest that integrating a smart farm system may enhance the metabolic productivity of ginseng and provides evidence of its potential impact on natural bioactive compounds of medicinal plants with beneficial qualities, such as ginsenosides Rb2 and Rd.

The Role of Neurotrophin Signaling in Age-Related Cognitive Decline and Cognitive Diseases

Neurotrophins are a family of secreted proteins expressed in the peripheral nervous system and the central nervous system that support neuronal survival, synaptic plasticity, and neurogenesis. Brain-derived neurotrophic factor (BDNF) and its high affinity receptor TrkB are highly expressed in the cortical and hippocampal areas and play an essential role in learning and memory. The decline of cognitive function with aging is a major risk factor for cognitive diseases such as Alzheimer’s disease. Therefore, an alteration of BDNF/TrkB signaling with aging and/or pathological conditions has been indicated as a potential mechanism of cognitive decline. In this review, we summarize the cellular function of neurotrophin signaling and review the current evidence indicating a pathological role of neurotrophin signaling, especially of BDNF/TrkB signaling, in the cognitive decline in aging and age-related cognitive diseases. We also review the therapeutic approach for cognitive decline by the upregulation of the endogenous BDNF/TrkB-system.