Tadalafil and bergapten mitigate streptozotocin-induced sporadic Alzheimer's disease in mice via modulating neuroinflammation, PI3K/Akt, Wnt/β-catenin, AMPK/mTOR signaling pathways

Antiplatelet therapy as a novel approach in Parkinson's disease: Repositioning Ticagrelor to alleviate rotenone-induced parkinsonism via modulation of ER stress, apoptosis, and autophagy

Cardiovascular diseases, such as myocardial infarction, ischemic stroke, and coronary heart ailments have been closely associated with Parkinson's disease (PD). Despite this established link, the potential neuroprotective impact of the potent antiplatelet agent ticagrelor (Tica) remains unexplored against PD. Thus, we hypothesized that Tica could be repurposed as a therapeutic agent against PD. Rotenone experimental model was adopted in Wistar male rats by administering rotenone subcutaneously on alternate days during a 21-day experimental period and treating a subset of rats with Tica orally for the last 11 consecutive days. The administration of Tica improved motor function (open field test, hanging wire test) and restored striatal histological features. Additionally, Tica opposed the rotenone effect and markedly obliterated the striatal α-synuclein content but enhanced the protein expression of tyrosine hydroxylase and dopamine content. On the molecular level, Tica inhibited striatal endoplasmic reticulum stress (ERS) as evidenced by the downregulation of the ER-resident transmembrane sensor inositol-requiring enzyme 1 alpha and its downstream molecular targets, TNF receptor-associated factor 2 and c-Jun N-terminal kinase, along with a reduction in caspase-3 activity. On the other hand, Tica augmented the autophagy machinery by upregulating the autophagosome markers Beclin-1 and light chain 3-II, while inhibiting the content of cathepsin D. Therefore, the current study is the first to accentuate the neuroprotective potential of Tica in a rat model of PD via modulating the crosstalk between ERS, apoptosis, and autophagy to represent a potential novel therapeutic candidate for managing PD, particularly in patients with or prone to cardiovascular diseases.

Rapamycin mitigates neurotoxicity of fluoride and aluminum by activating autophagy through the AMPK/mTOR/ULK1 pathway in hippocampal neurons and NG108-15 cells

Our previous studies have confirmed that fluoride combined with aluminum (FA) can induce hippocampal neuron damage in the second-generation offspring (F2) of rats; however, the underlying mechanisms remain unclear. In this study, we established an F2 rat model and an NG108-15 cell model to investigate the potential modes of action. The autophagy of F2 rat hippocampal neurons and NG108-15 cells was assessed using transmission electron microscopy and immunofluorescence/immunocytochemistry kit, respectively. Hippocampal morphology was evaluated via hematoxylin-eosin (HE) staining. We measured mRNA levels of AMPK, mTOR, ULK1, and LC3 using quantitative reverse transcription PCR, and protein expressions were analyzed by Western blotting. Following treatment with rapamycin (Rap) in FA-exposed F2 rats and NG108-15 cells, a small number of primary lysosomes and autophagosomes appeared within hippocampal cells, with HE staining indicating a near-normal restoration of pyramidal cell morphology. The quantity, intensity, and volume of green fluorescent spots in the cytoplasm of NG108-15 cells increased as observed through fluorescence microscopy. The mRNA expressions of AMPK, ULK1, and LC3 were upregulated while mTOR expressions were downregulated in NG108-15 cells. Correspondingly, protein levels for AMPK, p-AMPK, ULK1, p-ULK1 along with the LC3-II/LC3-I ratio increased whereas those for mTOR, p-mTOR and p62 decreased significantly. Similar trends regarding both mRNA and protein expression were noted within the hippocampus of F2 rats as well. Activation of the AMPK/mTOR/ULK1 signaling pathway by Rap enhances FA-induced autophagy thereby mitigating neuronal damage.

Unlocking Hope: Therapeutic Advances and Approaches in Modulating the Wnt Pathway for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are conditions characterized by sensory, motor, and cognitive impairments due to alterations in the structure and function of neurons in the central nervous system (CNS). Despite their widespread occurrence, the exact causes of NDs remain largely elusive, and existing treatments fall short in efficacy. The Wnt signaling pathway is an emerging molecular pathway that has been linked to the development and progression of various NDs. Wnt signaling governs numerous cellular processes, such as survival, polarity, proliferation, differentiation, migration, and fate specification, via a complex network of proteins. In the adult CNS, Wnt signaling regulates synaptic transmission, plasticity, memory formation, neurogenesis, neuroprotection, and neuroinflammation, all essential for maintaining neuronal function and integrity. Dysregulation of both canonical and non-canonical Wnt signaling pathways contributes to neurodegeneration through various mechanisms, such as amyloid-β accumulation, tau protein hyperphosphorylation, dopaminergic neuron degeneration, and synaptic dysfunction, prompting investigations into Wnt modulation as a therapeutic target to restore neuronal function and prevent or delay neurodegenerative processes. Modulating Wnt signaling has the potential to restore neuronal function and impede or postpone neurodegenerative processes, offering a therapeutic approach for targeting NDs. In this article, the current knowledge about how Wnt signaling works in Alzheimer's disease and Parkinson's disease is discussed. Our study aims to explore the molecular mechanisms, recent discoveries, and challenges involved in developing Wnt-based therapies.

Drugs repurposing in the experimental models of Alzheimer's disease

The currently approved drugs for Alzheimer's disease (AD) are only for symptomatic treatment in the early stages of the disease but they could not halt the neurodegeneration, additionally, the safety profile of the recently developed immunotherapy is a big issue. This review aims to explain the importance of the drugs repurposing technique and strategy to develop therapy for AD. We illustrated the biological alterations in the pathophysiology of AD including the amyloid pathology, the Tau pathology, oxidative stress, mitochondrial dysfunction, neuroinflammation, glutamate-mediated excitotoxicity, insulin signaling impairment, wingless-related integration site/β-catenin signaling, and autophagy. Additionally, we demonstrated the different repurposed drugs in the experimental models of AD including the anti-inflammatory, anti-hypertensive, anti-diabetic, antiepileptic, antidepressant and anticancer drugs. Further, we showed the pipeline and FDA approved drugs for AD. The repurposed drugs have a promising therapeutic activity against AD, confirming the value of the drugs repurposing technique to elucidate curative therapy for AD.

Multimodal action of phosphodiesterase 5 inhibitors against neurodegenerative disorders: An update review

Phosphodiesterase type 5 (PDE5) is an enzyme primarily found in the smooth muscle of the corpus cavernosum and also highly expressed in the substantia nigra, cerebellum, caudate, hippocampal regions and cerebellar purkinje cells, responsible for selectively breaking down cyclic guanosine monophosphate (cGMP) into 5'-GMP and regulate intracellular cGMP levels. As a second messenger, cyclic GMP enhances signals at postsynaptic receptors and triggers downstream effector molecules, leading to changes in gene expression and neuronal responses. Additionally, cGMP signaling transduction cascade, present in the brain, is also essential for learning and memory processes. Mechanistically, PDE5 inhibitors share structural similarities with cGMP, competitively binding to PDE5 and inhibiting cGMP hydrolysis. This action enhances the effects of nitric oxide, resulting in anti-inflammatory and neuroprotective effects. Neurodegenerative disorders entail the progressive loss of neuron structure, culminating in neuronal cell death, with currently available drugs providing only limited symptomatic relief, rendering neurodegeneration considered incurable. PDE5 inhibitors have recently emerged as a potential therapeutic approach for neurodegeneration, neuroinflammation, and diseases involving cognitive impairment. This review elucidates the principal roles of 3',5'-cyclic adenosine monophosphate (cAMP) and cGMP signaling pathways in neuronal functions, believed to play pivotal roles in the pathogenesis of various neurodegenerative disorders. It provides an updated assessment of PDE5 inhibitors as disease-modifying agents for conditions such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, cerebral ischemia, Huntington's disease, and neuroinflammation. The paper aims to review the current understanding of PDE5 inhibitors, which concurrently regulate both cAMP and cGMP signaling pathways, positing that they may exert complementary and synergistic effects in modifying neurodegeneration, thus presenting a novel direction in therapeutic discovery. Moreover, the review provides critical about biological functions, therapeutic potentials, limitations, challenges, and emerging applications of selective PDE5 inhibitors. This comprehensive overview aims to guide future academic and industrial endeavors in this field.

Peripheral biomarkers of Parkinson's disease and its correlation with clinical symptoms: a case-control study

BACKGROUND

Inflammation significantly impacts Parkinson's disease (PD), yet the intricate relationship between inflammatory markers and PD remains elusive.

OBJECTIVE

To identify the peripheral biomarkers of PD and its correlation with the motor and non-motor symptoms of PD.

METHODS

79 PD patients and 65 controls were included in this study. Clinical information and the serum levels of IL-8, IL-27, IL-33, β-NGF, AgRP, and TRAILR2 in the participants were collected. Appropriate scales were used to assess the symptoms of PD. For the factors with significant differences in the two groups, multivariable logistic regression was used to determine its relationship with PD. Moreover, spearman correlation was conducted to explore the correlation between the factors and PD related symptoms. The IL-27 level was compared between the cognitively healthy PD group and the mild cognitive impairment in PD (PD-MCI). The serum level of TRAILR2 was positively correlated with age and was not associated with other clinical characteristics related to PD.

RESULTS

Compared to controls, the serum levels of IL-27(P = 0.013) were increased whereas the levels of TRAILR2(P = 0.008) were decreased in PD patients. IL-8, IL-33, β-NGF, and AgRP showed no significant differences between the two groups. After controlling for the other variables, IL-27 was considered as an independent risk factor for PD in the multivariable logistic regression model. The receiver operating characteristic (ROC) curve for diagnosing PD with IL-27 yielded an area under the curve (AUC) of 0.621. Additionally, IL-27 level in PD patients was positively correlated with age, the disease duration, LEDD and negatively correlated with the MoCA scores. However, no significant difference was found in IL-27 levels between cognitively healthy PD and PD-MCI groups.

CONCLUSION

Elevated serum IL-27 was a risk factor for PD and positively correlated with the cognitive decline in PD.

Bergapten attenuates hemorrhagic shock induced multi-organ injury by inhibiting NLRP3 inflammasome activation and pyroptosis

OBJECTIVES

Treatment of hemorrhagic shock (HS) induced multi-organ injury remains a challenge. Bergapten (BeG) is a bioactive coumarin-derived compound, and previous articles have suggested that BeG may serve as a prospective therapeutic modality for HS. This study was designed to investigate the efficacy of BeG in the treatment of HS and its underlying mechanisms.

METHODS

In this research, we established a rat model of HS, following which we assessed the protective effects of BeG on HS induced multi-organ injury. Subsequently, we scrutinized the activation of NLRP3 inflammasomes and pyroptosis in damaged organs. Additionally, we conducted examinations of AMPK and the downstream mitophagy pathway in damaged organs. Finally, we established a hypoxia/reoxygenation (H/R) model in HK-2 cells to simulate the in vitro HS process. Following AMPK inhibition with compound C, we evaluated the levels of mitophagy and cellular pyroptosis in BeG-treated HK-2 cells subjected to H/R.

RESULTS

BeG treatment alleviated HS induced multi-organ injury. Subsequent analyses indicated that the therapeutic effects of BeG were related to the attenuation of NLRP3 inflammasome activation and pyroptosis. Additionally, we found BeG treatment stimulated the phosphorylation of AMPK, thereby enhancing mitophagy. Lastly, we found that the inhibition of AMPK in vitro attenuates BeG's enhancement of mitophagy and its suppression of pyroptosis.

CONCLUSION

Our research indicates that BeG has the potential to alleviate multi-organ injury induced by HS. The protective effect of BeG is likely associated with its promotion of mitophagy through AMPK activation, thereby inhibiting NLRP3 inflammasome-mediated pyroptosis.

Breaking Barriers in Alzheimer's Disease: the Role of Advanced Drug Delivery Systems

Alzheimer's disease (AD), characterized by cognitive impairment, brain plaques, and tangles, is a global health concern affecting millions. It involves the build-up of amyloid-β (Aβ) and tau proteins, the formation of neuritic plaques and neurofibrillary tangles, cholinergic system dysfunction, genetic variations, and mitochondrial dysfunction. Various signaling pathways and metabolic processes are implicated in AD, along with numerous biomarkers used for diagnosis, risk assessment, and research. Despite these, there is no cure or effective treatment for AD. It is critically important to address this immediately to develop novel drug delivery systems (NDDS) capable of targeting the brain and delivering therapeutic agents to modulate the pathological processes of AD. This review summarizes AD, its pathogenesis, related signaling pathways, biomarkers, conventional treatments, the need for NDDS, and their application in AD treatment. It also covers preclinical, clinical, and ongoing trials, patents, and marketed AD formulations.

Emerging phosphodiesterase inhibitors for treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) cause progressive loss of neuron structure and ultimately lead to neuronal cell death. Since the available drugs show only limited symptomatic relief, NDs are currently considered as incurable. This review will illustrate the principal roles of the signaling systems of cyclic adenosine and guanosine 3',5'-monophosphates (cAMP and cGMP) in the neuronal functions, and summarize expression/activity changes of the associated enzymes in the ND patients, including cyclases, protein kinases, and phosphodiesterases (PDEs). As the sole enzymes hydrolyzing cAMP and cGMP, PDEs are logical targets for modification of neurodegeneration. We will focus on PDE inhibitors and their potentials as disease-modifying therapeutics for the treatment of Alzheimer's disease, Parkinson's disease, and Huntington's disease. For the overlapped but distinct contributions of cAMP and cGMP to NDs, we hypothesize that dual PDE inhibitors, which simultaneously regulate both cAMP and cGMP signaling pathways, may have complementary and synergistic effects on modifying neurodegeneration and thus represent a new direction on the discovery of ND drugs.

Gastrodin regulates the TLR4/TRAF6/NF-κB pathway to reduce neuroinflammation and microglial activation in an AD model

BACKGROUND

Gastrodia elata (Orchidaceae) is a medicinal plant used in traditional Chinese medicine. The rhizomes contain numerous active components, of which Gastrodin (p-hydroxymethylphenyl-B-D-glucopyranoside) forms the basis of the traditional medicine Gastrodiae Rhizoma. Gastrodin is also found in other medicinal plants and has neuroprotective, antioxidant, and anti-inflammatory effects. Neuroinflammation plays a crucial role in neurodegeneration. Research indicates that consuming meals and drinks containing Gastrodiaelata can enhance cognitive functioning and memory in elderly patients. The mechanisms relevant to the problem have not been completely understood.

PURPOSE

The aim was to examine the in vivo and in vitro anti-neuroinflammatory effects of Gastrodin.

STUDY DESIGN

The neuroprotective effects of Gastrodin on the TLR4/TRAF6/NF-κB pathway and Stat3 phosphorylation in LPS-treated C57BL/6 mice and BV-2 cells were investigated.

METHODS

1. C57BL/6 mice were assigned to model, gastrodin, donepezil, and control groups (n = 10 per group). The Gastrodin group received 100 mg/kg/d for five days, and the Dopenezil group 1.3 mg/kg/d. A neuroinflammation model was established by administering intraperitoneal injections of 2 mg/kg LPS to all groups, excluding the control. To induce microglial activation in Gastrodin-treated mouse microglial BV-2 cells, 1 µg/ml LPS was introduced for 24 h Morris water mazes were utilized to evaluate learning and spatial memory. Expression and subcellular localization of TLR4/TRAF6/NF-κB axis-related proteins and p-Stat3, Iba-1, GFAP, iNOS, and CD206 were assessed by immunofluorescence, western blots, and ELISA. qRT-PCR was performed to determine and measure IL-1β, TNF-α, cell migration, and phagocytosis. Overexpression of TRAF6 was induced by transfection, and the effect of Gastrodin on IL-1β and p-NF-κB p65 levels was assessed.

RESULTS

1. In mice, gastrodin treatment mitigated LPS-induced deficits in learning and spatial memory, as well as reducing neuroinflammation in the hippocampus, expression of TLR4/TRAF6/NF-κB pathway proteins, activation of microglia and astrocytes, and phosphorylation of Stat3. 2. Gastrodin pretreatment improved LPS-induced inflammation in vitro, reducing expression of TLR4/TRAF6/NF-κB-associated proteins and p-Stat3, inducing microglial transformation from M1 to M2, and inhibiting migration and phagocytosis. Overexpression of TRAF6 inhibited the Gastrodin-induced effects.

CONCLUSION

Gastrodin suppresses neuroinflammation and microglial activation by modifying the TLR4/TRAF6/NF-κB pathway and Stat3 phosphorylation.

Natural polyphenol: Their pathogenesis-targeting therapeutic potential in Alzheimer's disease

Alzheimer's disease (AD) is a detrimental neurodegenerative disease affecting the elderly. Clinically, it is characterized by progressive memory decline and subsequent loss of broader cognitive functions. Current drugs provide only symptomatic relief but do not have profound disease-modifying effects. There is an unmet need to identify novel pharmacological agents for AD therapy. Neuropathologically, the characteristic hallmarks of the disease are extracellular senile plaques containing amyloid β-peptides and intracellular neurofibrillary tangles containing hyperphosphorylated microtubule-associated protein tau. Simultaneously, oxidative stress, neuroinflammation and mitochondrial dysfunction in specific brain regions are early events during the process of AD pathologic changes and are associated with Aβ/tau toxicity. Here, we first summarized probable pathogenic mechanisms leading to neurodegeneration and hopefully identify pathways that serve as specific targets to improve therapy for AD. We then reviewed the mechanisms that underlie disease-modifying effects of natural polyphenols, with a focus on nuclear factor erythroid 2-related factor 2 activators for AD treatment. Lastly, we discussed challenges in the preclinical to clinical translation of natural polyphenols. In conclusion, there is evidence that natural polyphenols can be therapeutically useful in AD through their multifaceted mechanism of action. However, more clinical studies are needed to confirm these effects.

Molecular interplay between phytoconstituents of Ficus Racemosa and neurodegenerative diseases

Neurodegenerative diseases (NDs) are a significant global health concern, primarily affecting middle and older populations. Recently, there has been growing interest in herbal therapeutics as a potential approach to address diverse neuropathological conditions. Despite the widespread prevalence of NDs, limited phytochemical has been reported for their promising therapeutic potential with distinct underlying mechanisms. Additionally, the intricate molecular pathways influenced by herbal phytoconstituents, particularly in neurodegenerative disorders, are also not well documented. This report explores the phytoconstituents of Ficus racemosa (F. racemosa), an unfamiliar plant of the Moraceae family, for their potential interactions with pathological pathways of NDs. The influential phytoconstituents of F. racemosa, including polyphenols, glycosides, terpenoids, and furocoumarin, have been reported for targeting diverse pathological states. We proposed the most convincing molecular interplay between leading phytoconstituents and detrimental signalling cascades. However, extensive research is required to thoroughly understand the phytochemical persuaded intricate molecular pathway. The comprehensive evidence strongly suggests that F. racemosa and its natural compounds could be valuable in treating NDs. This points towards an exciting path for future research and the development of potential treatments based on a molecular level.

Deciphering the Mysterious Relationship between the Cross-Pathogenetic Mechanisms of Neurodegenerative and Oncological Diseases

The relationship between oncological pathologies and neurodegenerative disorders is extremely complex and is a topic of concern among a growing number of researchers around the world. In recent years, convincing scientific evidence has accumulated that indicates the contribution of a number of etiological factors and pathophysiological processes to the pathogenesis of these two fundamentally different diseases, thus demonstrating an intriguing relationship between oncology and neurodegeneration. In this review, we establish the general links between three intersecting aspects of oncological pathologies and neurodegenerative disorders, i.e., oxidative stress, epigenetic dysregulation, and metabolic dysfunction, examining each process in detail to establish an unusual epidemiological relationship. We also focus on reviewing the current trends in the research and the clinical application of the most promising chemical structures and therapeutic platforms that have a modulating effect on the above processes. Thus, our comprehensive analysis of the set of molecular determinants that have obvious cross-functional pathways in the pathogenesis of oncological and neurodegenerative diseases can help in the creation of advanced diagnostic tools and in the development of innovative pharmacological strategies.

Development of a Rapid LC-MS/MS Method for Simultaneous Quantification of Donepezil and Tadalafil in Rat Plasma: Its Application in a Pharmacokinetic Interaction Study after Oral Administration in Rats

This study aimed to establish a simple and sensitive analytical method to simultaneously quantify donepezil (DPZ) and tadalafil (TAD) in rat plasma using lansoprazole (LPZ) as an internal standard (IS) by using liquid chromatography tandem mass spectrometry. The fragmentation pattern of DPZ, TAD, and IS was elucidated using multiple reaction monitoring in electrospray ionization positive ion mode for the quantification of precursor to production at m/z 380.1 → 91.2 for DPZ, m/z 390.2 → 268.1 for TAD, and m/z 370.3 → 252.0 for LPZ. The extracted DPZ and TAD from plasma using acetonitrile-induced protein precipitation was separated using Kinetex C18 (100 × 2.1 mm, 2.6 µm) column with a gradient mobile phase system consisting of 2 mM ammonium acetate and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min for 4 min. The selectivity, lower limit of quantification, linearity, precision, accuracy, stability, recovery, and matrix effect of this developed method was validated according to the guidelines of the U.S. Food and Drug Administration and the Ministry of Food and Drug Safety of Korea. The established method achieved acceptance criteria in all validation parameters, ensuring reliability, reproducibility, and accuracy, and was successfully implemented in a pharmacokinetic study on the co-administration of DPZ and TAD orally in rats.

Neurotrophins and Other Growth Factors in the Pathogenesis of Alzheimer’s Disease

The involvement of the changed expression/function of neurotrophic factors in the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD), has been suggested. AD is one of the age-related dementias, and is characterized by cognitive impairment with decreased memory function. Developing evidence demonstrates that decreased cell survival, synaptic dysfunction, and reduced neurogenesis are involved in the pathogenesis of AD. On the other hand, it is well known that neurotrophic factors, especially brain-derived neurotrophic factor (BDNF) and its high-affinity receptor TrkB, have multiple roles in the central nervous system (CNS), including neuronal maintenance, synaptic plasticity, and neurogenesis, which are closely linked to learning and memory function. Thus, many investigations regarding therapeutic approaches to AD, and/or the screening of novel drug candidates for its treatment, focus on upregulation of the BDNF/TrkB system. Furthermore, current studies also demonstrate that GDNF, IGF1, and bFGF, which play roles in neuroprotection, are associated with AD. In this review, we introduce data demonstrating close relationships between the pathogenesis of AD, neurotrophic factors, and drug candidates, including natural compounds that upregulate the BDNF-mediated neurotrophic system.

Inhibition of VDAC1 Rescues Aβ 1-42-Induced Mitochondrial Dysfunction and Ferroptosis via Activation of AMPK and Wnt/β-Catenin Pathways

Beta-amyloid (Aβ) accumulation in the brains of Alzheimer's disease (AD) patients leads to mitochondrial dysfunction and ferroptosis in neurons. Voltage-dependent anion channel 1 (VDAC1) is a major protein in the mitochondrial outer membrane. It has been reported that VDAC1 associated with mitochondrial dysfunction and ferroptosis. However, the mechanism by which VDAC1 regulates mitochondrial dysfunction and ferroptosis of neurons in AD remains unclear. This study is aimed at investigating the mechanism of action of VDAC1 in mitochondrial dysfunction and ferroptosis in neurons of the AD model. In this study, we determined cell viability after treatment with Aβ _1-42 via the MTT assay. The SOD, MDA, ROS, and MMP production was measured via the SOD kit, MDA kit, DCFDA staining, and JC-1 staining. The memory abilities of mice were detected via the Morris water maze test. The expression of AMPK/mTOR, Wnt/β-catenin, and GPX4 regulated by VDAC1 was detected via western blotting. Our present study showed that PC12 cells had decreased cell viability, increased LDH release, and decreased GPX4 expression after Aβ _1-42 treatment. Meanwhile, Aβ _1-42 induced MMP and SOD downregulation and increased MDA and ROS generation in PC12 cells. In addition, the expression of VDAC1 is increased in the brain tissue of AD mice and Aβ _1-42-treated PC12 cells. Further investigation of the role of VDAC1 in regulating AD found that all effects induced by Aβ _1-42 were reversed by inhibition of VDAC1. Additionally, inhibition of VDAC1 activates the AMPK/mTOR and Wnt/β-catenin pathways. Taken together, these findings demonstrate that inhibition of VDAC1 alleviates mitochondrial dysfunction and ferroptosis in AD neurons by activating AMPK/mTOR and Wnt/β-catenin.

From attention-deficit hyperactivity disorder to sporadic Alzheimer's disease-Wnt/mTOR pathways hypothesis

Alzheimer's disease (AD) is the most common neurodegenerative disorder with the majority of patients classified as sporadic AD (sAD), in which etiopathogenesis remains unresolved. Though sAD is argued to be a polygenic disorder, apolipoprotein E (APOE) ε4, was found three decades ago to pose the strongest genetic risk for sAD. Currently, the only clinically approved disease-modifying drugs for AD are aducanumab (Aduhelm) and lecanemab (Leqembi). All other AD treatment options are purely symptomatic with modest benefits. Similarly, attention-deficit hyperactivity disorder (ADHD), is one of the most common neurodevelopmental mental disorders in children and adolescents, acknowledged to persist in adulthood in over 60% of the patients. Moreover, for ADHD whose etiopathogenesis is not completely understood, a large proportion of patients respond well to treatment (first-line psychostimulants, e.g., methylphenidate/MPH), however, no disease-modifying therapy exists. Interestingly, cognitive impairments, executive, and memory deficits seem to be common in ADHD, but also in early stages of mild cognitive impairment (MCI), and dementia, including sAD. Therefore, one of many hypotheses is that ADHD and sAD might have similar origins or that they intercalate with one another, as shown recently that ADHD may be considered a risk factor for sAD. Intriguingly, several overlaps have been shown between the two disorders, e.g., inflammatory activation, oxidative stress, glucose and insulin pathways, wingless-INT/mammalian target of rapamycin (Wnt/mTOR) signaling, and altered lipid metabolism. Indeed, Wnt/mTOR activities were found to be modified by MPH in several ADHD studies. Wnt/mTOR was also found to play a role in sAD and in animal models of the disorder. Moreover, MPH treatment in the MCI phase was shown to be successful for apathy including some improvement in cognition, according to a recent meta-analysis. In several AD animal models, ADHD-like behavioral phenotypes have been observed indicating a possible interconnection between ADHD and AD. In this concept paper, we will discuss the various evidence in human and animal models supporting the hypothesis in which ADHD might increase the risk for sAD, with common involvement of the Wnt/mTOR-pathway leading to lifespan alteration at the neuronal levels.

Exploring the role of interleukin-27 as a regulator of neuronal survival in central nervous system diseases

Interleukin-27 is a pleiotropic cytokine that is involved in tissue responses to infection, cell stress, neuronal disease, and tumors. Recent studies in various tissues indicate that interleukin-27 has complex activating and inhibitory properties in innate and acquired immunity. The availability of recombinant interleukin-27 protein and mice with genetic deletions of interleukin-27, its receptors and signaling mediators have helped define the role of interleukin-27 in neurodegenerative diseases. Interleukin-27 has been well-characterized as an important regulator of T cell activation and differentiation that enhances or suppresses T cell responses in autoimmune conditions in the central nervous system. Evidence is also accumulating that interleukin-27 has neuroprotective activities in the retina and brain. Interleukin-27 is secreted from and binds to infiltrating microglia, macrophage, astrocytes, and even neurons and it promotes neuronal survival by regulating pro- and anti-inflammatory cytokines, neuroinflammatory pathways, oxidative stress, apoptosis, autophagy, and epigenetic modifications. However, interleukin-27 can have the opposite effect and induce inflammation and cell death in certain situations. In this review, we describe the current understanding of regulatory activities of interleukin-27 on cell survival and inflammation and discuss its mechanisms of action in the brain, spinal cord, and retina. We also review evidence for and against the therapeutic potential of interleukin-27 for dampening harmful neuroinflammatory responses in central nervous system diseases.

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.

The Interplay between cGMP and Calcium Signaling in Alzheimer's Disease

Cyclic guanosine monophosphate (cGMP) is a ubiquitous second messenger and a key molecule in many important signaling cascades in the body and brain, including phototransduction, olfaction, vasodilation, and functional hyperemia. Additionally, cGMP is involved in long-term potentiation (LTP), a cellular correlate of learning and memory, and recent studies have identified the cGMP-increasing drug Sildenafil as a potential risk modifier in Alzheimer's disease (AD). AD development is accompanied by a net increase in the expression of nitric oxide (NO) synthases but a decreased activity of soluble guanylate cyclases, so the exact sign and extent of AD-mediated imbalance remain unclear. Moreover, human patients and mouse models of the disease present with entangled deregulation of both cGMP and Ca2+ signaling, e.g., causing changes in cGMP-mediated Ca2+ release from the intracellular stores as well as Ca2+-mediated cGMP production. Still, the mechanisms governing such interplay are poorly understood. Here, we review the recent data on mechanisms underlying the brain cGMP signaling and its interconnection with Ca2+ signaling. We also discuss the recent evidence stressing the importance of such interplay for normal brain function as well as in Alzheimer's disease.

ROCK and PDE-5 Inhibitors for the Treatment of Dementia: Literature Review and Meta-Analysis

Dementia is a disease in which memory, thought, and behavior-related disorders progress gradually due to brain damage caused by injury or disease. It is mainly caused by Alzheimer’s disease or vascular dementia and several other risk factors, including genetic factors. It is difficult to treat as its incidence continues to increase worldwide. Many studies have been performed concerning the treatment of this condition. Rho-associated kinase (ROCK) and phosphodiesterase-5 (PDE-5) are attracting attention as pharmacological treatments to improve the symptoms. This review discusses how ROCK and PDE-5 affect Alzheimer’s disease, vascular restructuring, and exacerbation of neuroinflammation, and how their inhibition helps improve cognitive function. In addition, the results of the animal behavior analysis experiments utilizing the Morris water maze were compared through meta-analysis to analyze the effects of ROCK inhibitors and PDE-5 inhibitors on cognitive function. According to the selection criteria, 997 publications on ROCK and 1772 publications on PDE-5 were screened, and conclusions were drawn through meta-analysis. Both inhibitors showed good improvement in cognitive function tests, and what is expected of the synergy effect of the two drugs was confirmed in this review.

Insulin and liraglutide attenuate brain pathology in diabetic mice by enhancing the Wnt/β‑catenin signaling pathway

Insulin and liraglutide have been demonstrated to control blood glucose and exert neuroprotective effects. However, the impact of liraglutide or insulin alone or in combination on brain pathology in type 1 diabetes mellitus (T1DM) and their underlying mechanisms are unclear. In the present study, diabetes mellitus (DM) was induced via intraperitoneal injection of streptozotocin in mice and subsequently mice were treated with insulin, liraglutide, a combination of the two drugs or saline. Changes in body weight and blood glucose were assessed weekly. The pathological changes in the brain tissue and the apoptosis of neurons were assessed using H&E staining and TUNEL staining. The mRNA and protein expression levels of apoptosis-related proteins were detected using reverse transcription-quantitative PCR (RT-qPCR) and western blotting, respectively. Moreover, Ki67 protein expression was analyzed using immunohistochemistry and the mRNA and protein expression levels of Wnt/β-catenin signaling pathway-related proteins were examined using RT-qPCR and western blotting, respectively. The results of the present study suggested that DM mice developed hyperglycemia and weight loss and also exhibited significantly increased neural cell apoptosis and significantly reduced numbers of Ki67-positive cells. Liraglutide significantly decreased blood glucose levels in DM mice, whereas both insulin and the combination of the two drugs failed to control blood glucose well. Insulin, liraglutide and their combination also failed to control body weight well, but significantly attenuated brain pathological changes and activation of the pro-apoptotic proteins Caspase-3 and Bax, which may have resulted in the significant increase in the expression levels of Wnt/β-catenin signaling pathway-associated molecules such as Wnt3a and S9-pGSK-3β. Liraglutide also promoted the protein expression of the neurogenesis marker of Ki67 and the antiapoptotic factor Bcl-2. These results suggested that insulin and liraglutide may improve brain damage via upregulation of the Wnt/β-catenin signaling pathway and could be of therapeutic relevance for improvement of cognitive impairment in patients with DM.

How do phosphodiesterase-5 inhibitors affect cancer? A focus on glioblastoma multiforme

Since the discovery of phosphodiesterase-5 (PDE5) enzyme overexpression in the central nervous system (CNS) malignancies, investigations have explored the potential capacity of current PDE5 inhibitor drugs for repositioning in the treatment of brain tumors, notably glioblastoma multiforme (GBM). It has now been recognized that these drugs increase brain tumors permeability and enhance standard chemotherapeutics effectiveness. More importantly, studies have highlighted the promising antitumor functions of PDE5 inhibitors, e.g., triggering apoptosis, suppressing tumor cell growth and invasion, and reversing tumor microenvironment (TME) immunosuppression in the brain. However, contradictory reports have suggested a pro-oncogenic role for neuronal cyclic guanosine monophosphate (cGMP), indicating the beneficial function of PDE5 in the brain of GBM patients. Unfortunately, due to the inconsistent preclinical findings, only a few clinical trials are evaluating the therapeutic value of PDE5 inhibitors in GBM treatment. Accordingly, additional studies should be conducted to shed light on the precise effect of PDE5 inhibitors in GBM biology regarding the existing molecular heterogeneities among individuals. Here, we highlighted and discussed the previously investigated mechanisms underlying the impacts of PDE5 inhibitors in cancers, focusing on GBM to provide an overview of current knowledge necessary for future studies.