Loganin substantially ameliorates molecular deficits, pathologies and cognitive impairment in a mouse model of Alzheimer's disease

Nicotinamide adenine dinucleotide treatment confers resistance to neonatal ischemia and hypoxia: effects on neurobehavioral phenotypes

JOURNAL/nrgr/04.03/01300535-202412000-00031/figure1/v/2024-04-08T165401Z/r/image-tiff Neonatal hypoxic-ischemic brain injury is the main cause of hypoxic-ischemic encephalopathy and cerebral palsy. Currently, there are few effective clinical treatments for neonatal hypoxic-ischemic brain injury. Here, we investigated the neuroprotective and molecular mechanisms of exogenous nicotinamide adenine dinucleotide, which can protect against hypoxic injury in adulthood, in a mouse model of neonatal hypoxic-ischemic brain injury. In this study, nicotinamide adenine dinucleotide (5 mg/kg) was intraperitoneally administered 30 minutes before surgery and every 24 hours thereafter. The results showed that nicotinamide adenine dinucleotide treatment improved body weight, brain structure, adenosine triphosphate levels, oxidative damage, neurobehavioral test outcomes, and seizure threshold in experimental mice. Tandem mass tag proteomics revealed that numerous proteins were altered after nicotinamide adenine dinucleotide treatment in hypoxic-ischemic brain injury mice. Parallel reaction monitoring and western blotting confirmed changes in the expression levels of proteins including serine (or cysteine) peptidase inhibitor, clade A, member 3N, fibronectin 1, 5'-nucleotidase, cytosolic IA, microtubule associated protein 2, and complexin 2. Proteomics analyses showed that nicotinamide adenine dinucleotide ameliorated hypoxic-ischemic injury through inflammation-related signaling pathways (e.g., nuclear factor-kappa B, mitogen-activated protein kinase, and phosphatidylinositol 3 kinase/protein kinase B). These findings suggest that nicotinamide adenine dinucleotide treatment can improve neurobehavioral phenotypes in hypoxic-ischemic brain injury mice through inflammation-related pathways.

Loganin exerts neuroprotective effect by inhibiting neuronal pyroptosis in rat with cerebral haemorrhage

Intracerebral haemorrhage (ICH) presents significant challenges in clinical management because of the high morbidity and mortality, necessitating novel therapeutic approaches. This study aimed to assess the neuroprotective effects of loganin in a rat ICH model. Sprague-Dawley rats were used, subjected to a collagenase-induced ICH model, followed by loganin treatment at doses of 2.5, 5 and 10 mg/kg. Neurological functions were evaluated using the modified neurological severity score (mNSS) and a rotarod test. Results indicated a significant improvement in neurological functions in loganin-treated groups, evident from the mNSS and rotarod tests, suggesting dose-dependent neuroprotection. Loganin also effectively reduced the blood-brain barrier (BBB) permeability and cerebral oedema. Additionally, it mitigated cellular pyroptosis, as shown by terminal deoxynucleotidyl transferase dUTP nick-end labelling staining and western blot analysis, which indicated reduced levels of pyroptosis markers in treated rats. Furthermore, loganin's regulatory effects on the adenosine A2A receptor and myosin light chain kinase pathways were observed, potentially underpinning its protective mechanism against ICH. The study concludes that loganin exhibits significant neuroprotective properties in a rat ICH model, highlighting its potential as a novel therapeutic strategy. Despite promising results, the study needs further research to determine loganin's therapeutic potential in human ICH patients. This research paves the way for further exploration into loganin's clinical applications, potentially revolutionizing treatment strategies for patients suffering from intracerebral haemorrhage.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

The behavioral, pathological and therapeutic features of the triple transgenic Alzheimer's disease (3 × Tg-AD) mouse model strain

As a classic animal model of Alzheimer's disease (AD), the 3 × Tg-AD mouse not only recapitulates most of anatomical hallmarks observed in AD pathology but also displays cognitive alterations in memory and learning tasks. The 3 × Tg-AD can better show the two characteristics of AD, amyloid β (Aβ) and neurofibrillary tangles (NFT). Therefore, 3 × Tg-AD strain is widely used in AD pathogenesis research and new drug development of AD. In this paper, the construction methods, pathological changes, and treatment characteristics of 3 × Tg-AD mouse models commonly used in AD research are summarized and commented, hoping to provide reference for researchers to choose and establish experimental patterns.

Discrepancy of synaptic and microtubular protein phosphorylation in the hippocampus of APP/PS1 and MAPT×P301S transgenic mice at the early stage of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, and is caused by multiple pathological factors, such as the overproduction of β-amyloid (Aβ) and the hyperphosphorylation of tau. However, there is limited knowledge of the mechanisms underlying AD pathogenesis and no effective biomarker for the early diagnosis of this disorder. Thus in this study, a quantitative phosphoproteomics analysis was performed to evaluate global protein phosphorylation in the hippocampus of Aβ overexpressing APP/PS1 transgenic mice and tau overexpressing MAPT×P301S transgenic mice, two in vivo AD model systems. These animals, up to ten weeks old, do not exhibit cognitive dysfunctions and are widely used to simulate early-stage AD patients. The number of differentially phosphorylated proteins (DPPs) was greater for APP/PS1 transgenic mice than for MAPT×P301S transgenic mice. The function of the DPPs in APP/PS1 transgenic mice was mainly related to synapses, while the function of the DPPs in MAPT×P301S transgenic mice was mainly related to microtubules. In addition, an AD core network was established including seven phosphoproteins differentially expressed in both animal models, and the function of this core network was related to synapses and oxidative stress. The results of this study suggest that Aβ and tau induce different protein phosphorylation profiles in the early stage of AD, leading to the dysfunctions in synapses and microtubule, respectively. And the detection of same DPPs in these animal models might be used for early AD diagnosis.

Loganin reduces neuroinflammation and promotes functional recovery after spinal cord injury through inhibiting NF-κB/NLRP3 signalling

The highly disabling nature of spinal cord injuries (SCI) and high cost of treatment and rehabilitation impose a burden on families and society. Loganin has potential medicinal value in alleviating neuroinflammation. This study aimed to explore whether loganin can be used to reduce SCI-induced neuroinflammation and elucidate the molecular mechanisms underlying its action. An SCI rat model was developed to assess whether loganin promotes motor recovery after SCI. The anti-inflammatory effects of loganin on the dorsal horn of the spinal cord were identified by haematoxylin-eosin and immunohistochemical staining. The inflammatory effects of loganin were characterised using a lipopolysaccharide (LPS)-induced neuroinflammatory model in BV2 cells. For mechanistic exploration, the signalling pathways and target proteins of loganin action were predicted using bioinformatics and computational biology and then validated in cellular inflammation models. Loganin promoted animal motor recovery after SCI at the behavioural level, and it inhibited M1 differentiation of microglia and reduced NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated inflammatory responses at the tissue level. Loganin inhibited LPS-induced inflammation in BV2 cells, and bioinformatics and computational biology suggested that loganin acts on the p65 protein through the nuclear factor kappa-B (NF-κB)/NLRP3 signalling pathway. This was validated in a cellular model in which p65 trans-overexpression eliminated the downregulation of inflammatory factors by loganin. In conclusion, loganin reduces neuroinflammatory responses and promotes motor recovery after SCI. Loganin inhibits the NF-κB/NLRP3 signalling pathway by targeting the p65 protein to achieve repair.

Four undescribed iridoid glycosides with antidiabetic activity from fruits of Cornus officinalis Sieb. Et Zucc

Four novel iridoid glycosides neocornuside E-H (1-4), together with nine known ones (5-13), were isolated from fruits of Cornus officinalis. Their chemical structures were determined on the basis of spectroscopic analyses and comparing of the literature data. All of the isolated compounds were evaluated for their antidiabetic activity in insulin resistant HepG2 cells. Compounds 2, 4, 5, 8, and 12 exhibited antidiabetic activities with EC₅₀ values of 40.12, 2.54, 70.43, 15.31, and 4.86 μM, respectively. Flow Sight cytometry analysis indicated that compounds 2, 4, 5, 8, and 12 improved the ability of 2-NBDG uptake of insulin-induced HepG2 cells.

Temporal Appearance of Enhanced Innate Anxiety in Alzheimer Model Mice

The prevalence of Alzheimer's disorder (AD) is increasing worldwide, and the co-morbid anxiety is an important, albeit often neglected problem, which might appear early during disease development. Animal models can be used to study this question. Mice, as prey animals, show an innate defensive response against a predator odor, providing a valuable tool for anxiety research. Our aim was to test whether the triple-transgenic mice model of AD shows signs of innate anxiety, with specific focus on the temporal appearance of the symptoms. We compared 3xTg-AD mice bearing human mutations of amyloid precursor protein, presenilin 1, and tau with age-matched controls. First, separate age-groups (between 2 and 18 months) were tested for the avoidance of 2-methyl-2-thiazoline, a fox odor component. To test whether hypolocomotion is a general sign of innate anxiety, open-field behavior was subsequently followed monthly in both sexes. The 3xTg-AD mice showed more immobility, approached the fox odor container less often, and spent more time in the avoidance zone. This effect was detectable already in two-month-old animals irrespective of sex, not visible around six months of age, and was more pronounced in aged females than males. The 3xTg-AD animals moved generally less. They also spent less time in the center of the open-field, which was detectable mainly in females older than five months. In contrast to controls, the aged 3xTg-AD was not able to habituate to the arena during a 30-min observation period irrespective of their sex. Amyloid beta and phospho-Tau accumulated gradually in the hippocampus, amygdala, olfactory bulb, and piriform cortex. In conclusion, the early appearance of predator odor- and open space-induced innate anxiety detected already in two-month-old 3xTg-AD mice make this genetically predisposed strain a good model for testing anxiety both before the onset of AD-related symptoms as well as during the later phase. Synaptic dysfunction by protein deposits might contribute to these disturbances.

Research progress in traditional Chinese medicine in the treatment of Alzheimer's disease and related dementias

Alzheimer's disease (AD) is the world's leading cause of dementia and has become a huge economic burden on nations and families. However, the exact etiology of AD is still unknown, and there are no efficient medicines or methods to prevent the deterioration of cognition. Traditional Chinese medicine (TCM) has made important contributions in the battle against AD based on the characteristics of multiple targets of TCM. This study reviewed the treatment strategies and new discoveries of traditional Chinese medicine in current research, which may be beneficial to new drug researchers.

Proteomic examination of Cornus officinalis stimulated 1.1B4 human pancreatic cells reveals activation of autophagy and Keap1/Nrf2 pathway

Type 1 diabetes (T1D) is an autoimmune disease initiated by genetic predisposition and environmental influences culminating in the immunologically mediated destruction of pancreatic β-cells with eventual loss of insulin production. Although T1D can be accurately predicted via autoantibodies, therapies are lacking that can intercede autoimmunity and protect pancreatic β-cells. There are no approved interventional modalities established for this purpose. One such potential source for clinical agents of this use is from the frequently utilized Cornus officinalis (CO) in the field of ethnopharmacology. Studies by our lab and others have demonstrated that CO has robust proliferative, metabolic, and cytokine protective effects on pancreatic β-cells. To identify the molecular mechanism of the biological effects of CO, we performed a proteomic and phosphoproteomic analysis examining the cellular networks impacted by CO application on the 1.1B4 pancreatic β-cell line. Our label-free mass spectrometry approach has demonstrated significant increased phosphorylation of the selective autophagy receptor of p62 (Sequestosome-1/SQSTM1/p62) and predicted activation of the antioxidant Kelch-like ECH-associated protein 1 (Keap1)/Nuclear factor-erythroid factor 2-related factor 2 (Nrf2) pathway. Further validation by immunoblotting and immunofluorescence revealed markers of autophagy such as increased LC3-II and decreased total p62 along with nuclear localization of Nrf2. Both autophagy and the Keap1/Nrf2 pathways have been shown to be impaired in human and animal models of T1D and may serve as an excellent potential therapeutic target stimulated by CO.