Vinpocetine mitigates aluminum-induced cognitive impairment in socially isolated rats

Vinpocetine and Lactobacillus Attenuated Rotenone-Induced Parkinson's Disease and Restored Dopamine Synthesis in Rats through Modulation of Oxidative Stress, Neuroinflammation, and Lewy Bodies Inclusion

Parkinson's disease (PD) is the main neurodegenerative disorder affecting motor activity, there are different pathophysiological pathways contributing to its development including oxidative stress, neuroinflammation, Lewy's bodies accumulation, and impaired autophagy. Vinpocetine is an herbal extract with antioxidant and anti-inflammatory activities that may counteract pathophysiologic neurodegeneration pathways. Moreover, Lactobacillus is a probiotic that can modulate the gut-brain axis and provide the body with the needed precursors of antioxidants and anti-inflammatory mediators. In the current study PD was induced experimentally in Sprague Dawley rats with rotenone (2.5 mg/kg, i.p, daily) for 60 days, vinpocetine; Vinpo (20 mg/kg, orally, daily) and Lactobacillus; Lacto (2.7 × 108 CFU/ml, orally, daily) were applied as protective treatment. Vinpocetine and Lactobacillus treatment significantly ameliorated motor function by increasing distance traveled and rearing frequency in the open field test with a concomitant increase in falling time from both the accelerating rotarod and the wire screen test. Moreover, vinpocetine and Lactobacillus treatment upregulates tyrosine hydroxylase expression (the rate-limiting enzyme in dopamine synthesis), leading to enhanced dopamine synthesis and improved dopaminergic function with regression of histopathological hallmarks. Antioxidant GSH levels were significantly increased after vinpocetine and Lactobacillus treatment with a significant decrease in MDA content in brain homogenates. Furthermore, vinpocetine and Lactobacillus treatment significantly decreased striatal inflammatory markers; nitrite, IL-1β and TNF-α. Proteinopathies were regressed with a substantial decrease in striatal α-synuclein and tau content. In conclusion, vinpocetine and Lactobacillus treatment reduced rotenone neurotoxicity with improved dopamine release and motor activity with correction of oxidative burden, neuro-inflammation, and proteinopathy.

GC/MS and LC-ESI-MS Analysis of Conocarpus erectus Leaves Extract via Regulating Amyloid-β-Peptide, Tau Protein, Neurotransmitters, Inflammation and Oxidative Stress against AlCl3-Induced Alzheimer's Disease in Rats

This study investigated the therapeutic effect of Conocarpus erectus leaves methanolic extract against AlCl3 -induced Alzheimer's disease (AD) in rats comparing with Donepezil-hydrochloride as a reference drug. The bioactive compounds of C. erectus leaves were isolated and identified by GC/MS and LC-ESI-MS analysis. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), amyloid-β-peptide (Aβ-peptide), tau protein, acetylcholinesterase (AChE), serotonin (5-HT), dopamine (DA) and nor-adrenaline (NE) levels were estimated. The neuromuscular strength, memory behavior and histopathological examination of cerebral cortex region were also conducted. Forty-three compounds were characterized from the non-polar fraction of C. erectus L. leaves extract and nineteen compounds were identified from the defatted extract. AlCl3- induction caused significant elevation of brain oxidative stress, Aβ-peptide, tau protein, IL-6, TNF-α and AChE levels. A significant decrease in 5-HT, ND and DA levels were noticed. Additionally, AlCl3 reduced neuromuscular strength and compromised memory function. Treatment of AlCl3- induced rats with C. erectuse extract ameliorated these selected parameters by variable degrees. In conclusion, C. erectus protects against AlCl3- induced AD in rats through its antioxidant, anti-inflammatory, and antineural damage. [Correction added on 3 December 2024, after first online publication: The term "antineutron" was corrected to "antineural" in the preceding sentence.]. It could be considered as a new nutraceutical agent for attenuating symptoms associated with Alzheimer's disease.

Vinpocetine alleviates the abdominal aortic aneurysm progression via VSMCs SIRT1-p21 signaling pathway

Abdominal aortic aneurysm (AAA) is a degenerative disease that caused mortality in people aged >65. Senescence plays a critical role in AAA pathogenesis. Advances in AAA repair techniques have occurred, but a remaining priority is therapies to limit AAA growth and rupture. Our Previous study found cyclic nucleotide phosphodiesterase 1C (PDE1C) exacerbate AAA through aggravate vascular smooth muscle cells (VSMCs) senescence by downregulating Sirtuin1 (SIRT1) expression and activity. Vinpocetine as a selective inhibitor of PDE1 and a clinical medication for cerebral vasodilation, it is unclear whether vinpocetine can rely on SIRT1 to alleviate AAA. This study showed that pre-treatment with vinpocetine remarkably prevented aneurysmal dilation and reduced aortic rupture in elastase-induced AAA mice. In addition, the elastin degradation, MMP (matrix metalloproteinase) activity, macrophage infiltration, ROS production, collagen fibers remodeling, and VSMCs senescence were decreased in AAA treated with vinpocetine. While these effects were unable to exert in VSMCs-specific SIRT1 knockout AAA mice. Accordingly, we revealed that vinpocetine suppressed migration, proliferation, and senescence in VSMCs. Moreover, vinpocetine reduced SIRT1 degradation by inhibiting lysosome-mediated autophagy. In conclusion, this study indicated that vinpocetine may be as a potential drug for therapy AAA through alleviate VSMCs senescence via the SIRT1-dependent pathway.

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.

Review on anti-alzheimer drug development: approaches, challenges and perspectives

Alzheimer is an irreversible progressive neurodegenerative disease that causes failure of cerebral neurons and disability of the affected person to practice normal daily life activities. There is no concrete evidence to identify the exact reason behind the disease, so several relevant hypotheses emerged, highlighting many possible therapeutic targets, such as acetylcholinesterase, cholinergic receptors, N-methyl d-aspartate receptors, phosphodiesterase, amyloid β protein, protein phosphatase 2A, glycogen synthase kinase-3 beta, β-secretase, γ-secretase, α-secretase, serotonergic receptors, glutaminyl cyclase, tumor necrosis factor-α, γ-aminobutyric acid receptors, and mitochondria. All of these targets have been involved in the design of new potential drugs. An extensive number of these drugs have been studied in clinical trials. However, only galantamine, donepezil, and rivastigmine (ChEIs), memantine (NMDA antagonist), and aducanumab and lecanemab (selective anti-Aβ monoclonal antibodies) have been approved for AD treatment. Many drugs failed in the clinical trials to such an extent that questions have been posed about the significance of some of the aforementioned targets. On the contrary, the data of other drugs were promising and shed light on the significance of their targets for the development of new potent anti-alzheimer drugs.

Adipose tissue-derived mesenchymal stem cells ameliorate cognitive impairment in Alzheimer's disease rat model: Emerging role of SIRT1

Alzheimer's disease (AD) is a complex form of neurodegenerative dementia. Growing body of evidence supports the cardinal role of sirtuin1 (SIRT1) in neurodegeneration and AD development. Recently, adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark for a wide array of regenerative medicine applications, including neurodegenerative disorders. Therefore, the present study aimed to investigate the therapeutic potential of Ad-MSCs in AD rat model, and to explore the possible implication of SIRT1. Ad-MSCs were isolated from rat epididymal fat pads and properly characterized. Aluminum chloride was used to induce AD in rats, and afterward, a group of AD-induced rats received a single dose of Ad-MSCs (2 × 106 cell, I.V per rat). One month after Ad-MSCs transplantation, behavioral tests were done, brain tissues were collected, then histopathological and biochemical assessments were performed. Amyloid beta and SIRT1 levels were determined by enzyme-linked immunosorbent assay. Whereas expression levels of neprilysin, BCL2 associated X protein, B-cell lymphoma-2, interleukin-1β, interleukin-6, and nerve growth factor in hippocampus and frontal cortex brain tissues were assessed using reverse transcriptase quantitative polymerase chain reaction. Our data demonstrated that transplantation of Ad-MSCs alleviated cognitive impairment in AD rats. Additionally, they exhibited anti-amyloidogenic, antiapoptotic, anti-inflammatory, as well as neurogenic effects. Furthermore, Ad-MSCs were found to possibly mediate their therapeutic effects, at least partially, via modulating both central and systemic SIRT1 levels. Hence, the current study portrays Ad-MSCs as an effective therapeutic approach for AD management and opens the door for future investigations to further elucidate the role of SIRT1 and its interrelated molecular mediators in AD.

Punicalagin's Protective Effects on Parkinson's Progression in Socially Isolated and Socialized Rats: Insights into Multifaceted Pathway

Parkinson's disease (PD) is a gradual deterioration of dopaminergic neurons, leading to motor impairments. Social isolation (SI), a recognized stressor, has recently gained attention as a potential influencing factor in the progress of neurodegenerative illnesses. We aimed to investigate the intricate relationship between SI and PD progression, both independently and in the presence of manganese chloride (MnCl2), while evaluating the punicalagin (PUN) therapeutic effects, a natural compound established for its cytoprotective, anti-inflammatory, and anti-apoptotic activities. In this five-week experiment, seven groups of male albino rats were organized: G1 (normal control), G2 (SI), G3 (MnCl2), G4 (SI + MnCl2), G5 (SI + PUN), G6 (MnCl2 + PUN), and G7 (SI + PUN + MnCl2). The results revealed significant changes in behavior, biochemistry, and histopathology in rats exposed to SI and/or MnCl2, with the most pronounced effects detected in the SI rats concurrently exposed to MnCl2. These effects were associated with augmented oxidative stress biomarkers and reduced antioxidant activity of the Nrf2/HO-1 pathway. Additionally, inflammatory pathways (HMGB1/RAGE/TLR4/NF-ᴋB/NLRP3/Caspase-1 and JAK-2/STAT-3) were upregulated, while dysregulation of signaling pathways (PI3K/AKT/GSK-3β/CREB), sustained endoplasmic reticulum stress by activation PERK/CHOP/Bcl-2, and impaired autophagy (AMPK/SIRT-1/Beclin-1 axis) were observed. Apoptosis induction and a decrease in monoamine levels were also noted. Remarkably, treatment with PUN effectively alleviated behaviour, histopathological changes, and biochemical alterations induced by SI and/or MnCl2. These findings emphasize the role of SI in PD progress and propose PUN as a potential therapeutic intervention to mitigate PD. PUN's mechanisms of action involve modulation of pathways such as HMGB1/RAGE/TLR4/NF-ᴋB/NLRP3/Caspase-1, JAK-2/STAT-3, PI3K/AKT/GSK-3β/CREB, AMPK/SIRT-1, Nrf2/HO-1, and PERK/CHOP/Bcl-2.

The protective effects of sesamol and/or the probiotic, Lactobacillus rhamnosus, against aluminum chloride-induced neurotoxicity and hepatotoxicity in rats: Modulation of Wnt/β-catenin/GSK-3β, JAK-2/STAT-3, PPAR-γ, inflammatory, and apoptotic pathways

Introduction: Aluminium (Al) is accumulated in the brain causing neurotoxicity and neurodegenerative disease like Alzheimer's disease (AD), multiple sclerosis, autism and epilepsy. Hence, attenuation of Al-induced neurotoxicity has become a "hot topic" in looking for an intervention that slow down the progression of neurodegenerative diseases. Objective: Our study aims to introduce a new strategy for hampering aluminum chloride (AlCl3)-induced neurotoxicity using a combination of sesamol with the probiotic bacteria; Lactobacillus rhamnosus (L. rhamnosus) and also to test their possible ameliorative effects on AlCl3-induced hepatotoxicity. Methods: Sprague-Dawley male rats were randomly divided into five groups (n = 10/group) which are control, AlCl3, AlCl3 + Sesamol, AlCl3 + L. rhamnosus and AlCl3 + Sesamol + L. rhamnosus. We surveilled the behavioral, biochemical, and histopathological alterations centrally in the brain and peripherally in liver. Results: This work revealed that the combined therapy of sesamol and L. rhamnosus produced marked reduction in brain amyloid-β, p-tau, GSK-3β, inflammatory and apoptotic biomarkers, along with marked elevation in brain free β-catenin and Wnt3a, compared to AlCl3-intoxicated rats. Also, the combined therapy exerted pronounced reduction in hepatic expressions of JAK-2/STAT-3, inflammatory (TNF-α, IL-6, NF-κB), fibrotic (MMP-2, TIMP-1, α-SMA) and apoptotic markers, (caspase-3), together with marked elevation in hepatic PPAR-γ expression, compared to AlCl3 -intoxicated rats. Behavioral and histopathological assessments substantiated the efficiency of this combined regimen in halting the effect of neurotoxicity. Discussion: Probiotics can be used as an add-on therapy with sesamol ameliorate AlCl3 -mediated neurotoxicity and hepatotoxicity.

New insights on the potential effect of vinpocetine in Parkinson's disease: one of the neglected warden and baffling topics

Vinpocetine (VPN) is an ethyl apovincaminate that has anti-inflammatory and antioxidant effects by inhibiting the expression of nuclear factor kappa B (NF-κB) and phosphodiesterase enzyme 1 (PDE-1). VPN is used in the management of stroke, dementia, and other neurodegenerative brain diseases. VPN may be effective in treating Parkinson's disease (PD). Therefore, this review aimed to clarify the mechanistic role of VPN in the management of PD. VPN has protective and restorative effects against neuronal injury by reducing neuroinflammation, and improvement of synaptic plasticity and cerebral blood flow. VPN protects dopaminergic neurons by reducing oxidative stress, lipid peroxidation, glutamate neurotoxicity, and regulation of Ca+ 2 overloads. VPN can alleviate PD neuropathology through its anti-inflammatory, antioxidant, antiapoptotic and neurogenic effects. VPN through inhibition of PDE1 improves cyclic adenosine monophosphate (cAMP)/cyclic guanosine monophosphate (cGMP) signaling in the dopaminergic neurons of the substantia nigra (SN). VPN improves PD neuropathology through PDE1 inhibition with a subsequent increase of the cAMP/cGMP signaling pathway. Therefore, increasing cAMP leads to antioxidant effects, while augmentation of cGMP by VPN leads to anti-inflammatory effects which reduced neurotoxicity and development of motor severity in PD. In conclusion, this review indicated that VPN could be effective in the management of PD.

Assessment of Anti-Alzheimer Pursuit of Jambolan Fruit Extract and/or Choline against AlCl3 Toxicity in Rats

Jambolan fruit extract and choline were investigated for Aluminum tri chloride (AlCl₃)-induced Alzheimer's disease in rats. Thirty-six male "Sprague Dawley" rats weighing (150 ± 10 g) were allocated into six groups; the first group was fed a baseline diet and served as a negative control. Alzheimer's disease (AD) was induced in Group 2 rats by oral administration of AlCl₃ (17 mg/kg body weight) dissolved in distilled water (served as a positive control). Rats in Group 3 were orally supplemented concomitantly with both 500 mg/kg BW of an ethanolic extract of jambolan fruit once daily for 28 days and AlCl₃ (17 mg/kg body weight). Group 4: Rivastigmine (RIVA) aqueous infusion (0.3 mg/kg BW/day) was given orally to rats as a reference drug concomitantly with oral supplementation of AlCl₃ (17 mg/kg body weight) for 28 days. Group 5 rats were orally treated with choline (1.1 g/kg) concomitantly with oral supplementation of AlCl₃ (17 mg/kg body weight). Group 6 was given 500 mg/kg of jambolan fruit ethanolic extract and 1.1 g/kg of choline orally to test for additive effects concurrently with oral supplementation of AlCl₃ (17 mg/kg bw) for 28 days. Body weight gain, feed intake, feed efficiency ratio, and relative brain, liver, kidney, and spleen weight were calculated after the trial. Brain tissue assessment was analyzed for antioxidant/oxidant markers, biochemical analysis in blood serum, a phenolic compound in Jambolan fruits extracted by high-performance liquid chromatography (HPLC), and histopathology of the brain. The results showed that Jambolan fruit extract and choline chloride improved brain functions, histopathology, and antioxidant enzyme activity compared with the positive group. In conclusion, administering jambolan fruit extract and choline can lower the toxic impacts of aluminum chloride on the brain.

Role of aluminum exposure on Alzheimer's disease and related glycogen synthase kinase pathway

Aluminum (Al) is an environmentally abundant metal that is not essential for life. There is considerable evidence that Al as a neurotoxic xenobiotic may play a role in the pathogenesis of neurodegenerative diseases like Alzheimer's disease (AD). Exposure to aluminum has been shown to cause neuronal damage that resembles the symptoms of AD. In this review, we will summarize recent data about Al as the possible risk of incidence of AD. Then glycogen synthase kinase-3 beta (GSK3β) contributes to the hyperphosphorylation of Tau protein, the main component of neurofibrillary tangles, one of the hallmarks of AD as one of the mechanisms behind Al neurotoxicity will be covered. Overall, there is still a need for epidemiological studies and more in vivo and in vitro studies to determine the exact mechanisms of its neurotoxicity and the role of GSK3β in both Al toxic effect and AD.

Research Progress on the Etiology and Pathogenesis of Alzheimer's Disease from the Perspective of Chronic Stress

Due to its extremely complex pathogenesis, no effective drugs to prevent, delay progression, or cure Alzheimer's disease (AD) exist at present. The main pathological features of AD are senile plaques composed of β-amyloid, neurofibrillary tangles formed by hyperphosphorylation of the tau protein, and degeneration or loss of neurons in the brain. Many risk factors associated with the onset of AD, including gene mutations, aging, traumatic brain injury, endocrine and cardiovascular diseases, education level, and obesity. Growing evidence points to chronic stress as one of the major risk factors for AD, as it can promote the onset and development of AD-related pathologies via a mechanism that is not well known. The use of murine stress models, including restraint, social isolation, noise, and unpredictable stress, has contributed to improving our understanding of the relationship between chronic stress and AD. This review summarizes the evidence derived from murine models on the pathological features associated with AD and the related molecular mechanisms induced by chronic stress. These results not only provide a retrospective interpretation for understanding the pathogenesis of AD, but also provide a window of opportunity for more effective preventive and identifying therapeutic strategies for stress-induced AD.

Vinpocetine and coenzyme Q10 combination alleviates cognitive impairment caused by ionizing radiation by improving mitophagy

OBJECTIVE

This research was designed to ascertain the effect and mechanism of vinpocetine (VIN) and coenzyme Q10 (CoQ10) combination on cognitive impairment induced by ionizing radiation (IR).

METHODS

Cognitive impairment in mice was induced by 9-Gy IR, and they were intraperitoneally injected with VIN, CoQ10, or VIN + CoQ10. Then novel object recognition and Morris water maze tests were used to detect cognitive function. The number of hippocampal neurons and BrdU⁺Dcx⁺ cells was observed by Nissl and immunofluorescence staining. Mitochondrial respiratory complex I, adenosine triphosphate (ATP), and mitochondrial membrane potential (MMP) were evaluated, as well as oxidative stress injury. Mitophagy in hippocampal neurons was evaluated by observing the ultrastructure of hippocampal neurons and assessing the expression of mitophagy-related proteins.

RESULTS

IR reduced novel object discrimination index, the time for platform crossing, and the time spent in platform quadrant, in addition to neuron loss, downregulated levels of mitochondrial respiratory complex I, ATP, and MMP, aggravated oxidative stress injury, increased expression of LC3 II/I, Beclin1, PINK1, and parkin, and decreased P62 expression. VIN or CoQ10 treatment mitigated cognitive dysfunction, neurons loss, mitochondrial damage, and oxidative stress injury, and enhanced mitophagy in hippocampal neurons. VIN and CoQ10 combination further protected against IR-induced cognitive dysfunction than VIN or CoQ10 alone.

CONCLUSION

VIN combined with CoQ10 improved neuron damage, promoted mitophagy, and ameliorated cognitive impairment in IR mice.

Potential role of IP3/Ca2+ signaling and phosphodiesterases: Relevance to neurodegeneration in Alzheimer's disease and possible therapeutic strategies

Despite large investments by industry and governments, no disease-modifying medications for the treatment of patients with Alzheimer's disease (AD) have been found. The failures of various clinical trials indicate the need for a more in-depth understanding of the pathophysiology of AD and for innovative therapeutic strategies for its treatment. Here, we review the rational for targeting IP3 signaling, cytosolic calcium dysregulation, phosphodiesterases (PDEs), and secondary messengers like cGMP and cAMP, as well as their correlations with the pathophysiology of AD. Various drugs targeting these signaling cascades are still in pre-clinical and clinical trials which support the ideas presented in this article. Further, we describe different molecular mechanisms and medications currently being used in various pre-clinical and clinical trials involving IP3/Ca⁺² signaling. We also highlight various isoforms, as well as the functions and pharmacology of the PDEs broadly expressed in different parts of the brain and attempt to unravel the potential benefits of PDE inhibitors for use as novel medications to alleviate the pathogenesis of AD.

Necrostatin-1 Relieves Learning and Memory Deficits in a Zebrafish Model of Alzheimer's Disease Induced by Aluminum

Aluminum (Al) is considered one of the environmental risk factors for Alzheimer's disease (AD). The present study aims to establish a zebrafish AD model induced by Al and explore if necrostation-1 (Nec-1), a specific inhibitor of necroptosis, is effective in relieving learning and memory deficits in the zebrafish AD models. We treated adult zebrafish with aluminum trichloride at various doses for 1 month, followed by a T-maze test to evaluate learning and memory performance. Al concentration, levels of acetylcholine (Ach), and AD-related protein and gene expression in the brain tissue were evaluated in the zebrafish AD models. Our results demonstrated that in the brain tissue of Al-treated zebrafish, Al accumulated, Ach levels decreased, and AD-related genes and proteins increased. As a result, the learning and memory performance of Al-treated zebrafish was impaired. This suggested that a zebrafish AD model was established. To test the effect of Nec-1 on the zebrafish AD model, we added Nec-1 into the culture medium of the Al-treated adult zebrafish. The results demonstrated that Nec-1 could relive the learning and memory deficits, enhance Ach levels and the numbers of neural cells, and impact necroptosis-related gene expression. We concluded that Nec-1 could reverse Al-induced learning and memory impairment and had potential theoretical value in the zebrafish AD model.

Phosphodiesterase inhibitor, Vinpocetine, guards against doxorubicin induced cardiotoxicity via modulation of HIF/VEGF and cGMP/cAMP/SIRT signaling pathways

Purpose: Doxorubicin (DOX) is a widely used chemotherapeutic agent complicated with cardiotoxic adverse effects. Up till now, there are no researches discussing the role of vinpocetine (VIN) in DOX cardiotoxicity. Thus, the aim of our work was to study this effect and explore the different involved mechanisms.

Methods:

50 male Wistar albino rats were subjected to DOX toxicity via administration of single i.p. Dose (15 mg/kg) on the 4th day with or without co-administration of VIN (10, 20, 30 mg/kg/day) orally for 5 days.

Results:

Our data revealed that VIN succeeded in protecting the heart against DOX induced damage as manifested by significant decrease of cardiac enzymes, hypoxia inducible factor alpha (HIF-1α), vascular endothelial growth factor-A (VEGF-A), tissue malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α) and caspase3 levels. Furthermore, VIN given group showed marked improvement of the histopathological changes of cardiac injury, total antioxidant capacity (TAC), elevation of reduced glutathione (GSH), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP) and sirtuin-1 (SIRT-1).

Conclusion:

We concluded that VIN could ameliorate DOX induced cardiac damage and this effect may be attributed to modulation of HIF/VEGF signaling pathway, up-regulation of cGMP/cAMP/SIRT pathway, inhibition of phosphodiesterase enzyme, besides its anti-apoptotic, anti-inflammatory, and anti-oxidant properties.

Roflumilast ameliorates cognitive deficits in a mouse model of amyloidogenesis and tauopathy: Involvement of nitric oxide status, Aβ extrusion transporter ABCB1, and reversal by PKA inhibitor H89

The biological cascade of second messenger-cyclic adenosine monophosphate (cAMP) -as a molecular mechanism implicated in memory and learning regulation has captured the attention of neuroscientists worldwide. cAMP triggers its foremost effector, protein kinase A (PKA), resulting in the activation of innumerable downstream targets. Roflumilast (ROF), a phosphodiesterase 4 inhibitor, has demonstrated a greater efficiency in enhancing cAMP signaling in various neurological disorders. This study was conducted to identify various downstream targets of PKA as mechanistic tools through which ROF could hinder the progressive cognitive impairment following central streptozotocin (STZ) administration in mice. Animals were injected with STZ (3 mg/kg/i.c.v) once. Five hours later, mice received ROF (0.4 mg/kg) with or without the PKA inhibitor, H89, for 21 days. ROF highly preserved the structure of hippocampal neurons. It improved the ability of mice to develop short-term memories and retrieve spatial memories in Y-maze and Morris water maze tests, respectively. ROF enhanced the gene expression of ABCB1 transporters and pregnane X receptors (PXR), and hampered Aβ accumulation in hippocampus. Simultaneously, it interfered with the processes of tau phosphorylation and nitration. This effect was associated with an upsurge in hippocampal arginase activity as well as a decline in glycogen synthase kinase-3β activity, nitric oxide synthase (NOS) activity, and inducible NOS expression. Contrariwise, ROF's beneficial effects were utterly abolished by co-administration of H89. In conclusion, boosting PKA, by ROF, modulated PXR/ABCB1 expression and arginase/NOS activities to restrict the main post-translational modifications of tau, Aβ deposition and, accordingly, cognitive deterioration of sporadic Alzheimer's disease.

Pomegranate juice reverses AlCl3-Induced neurotoxicity and improves learning and memory in female mice

BACKGROUND

Aluminum is a neurotoxic element that can accumulate in the brain and cause neurodegenerative disorders. In addition, the antioxidants found in pomegranate juice (PJ) are much more than those existing in other fruits. It was proven to provide protection against neurodegenerative diseases.

OBJECTIVES

This experiment aimed to clarify the amelioration efficiency of PJ against aluminum chloride-induced neurobehavioral and biochemical disorders in female mice.

METHODS

The female mice were given oral administrations for 35 days as follows. The control group received tap water, the PJ groups received 20% and 40% pomegranate juice, the aluminum chloride (AlCl₃) group was treated with 400 mg/kg AlCl₃, and the last two groups received AlCl₃ + 20% PJ and AlCl₃ + 40% PJ, respectively. The neurobehavioral features were assessed by shuttle box, T-maze, and Morris water maze devices. Furthermore, the neurotransmitters and oxidative indicators in the brains of the female mice were determined at the end of experiment.

RESULTS

Significant effects of AlCl₃ were observed on female mice in the body weight, during the behavioral tasks (shuttle box, T-maze, and Morris water maze), and in neurotransmitters and oxidative stress parameters. Pomegranate juice, especially at low concentrations, induced remarkable improvements in body weight, spatial memory and learning during T-maze, Morris water maze and shuttle box tasks, as well as in neurotransmitters and oxidative biomarkers in the AlCl₃-treated female mice.

CONCLUSION

PJ reversed AlCl₃-induced neurotoxicity and improved learning and memory in female mice. However, PJ contains a group of antioxidants that may be considered double-edged swords in the cellular redox status especially at high doses.

New insights into the effects of vinpocetine against neurobehavioral comorbidities in a rat model of temporal lobe epilepsy via the downregulation of the hippocampal PI3K/mTOR signalling pathway

OBJECTIVES

As one of the most frequent worldwide neurological disorders, epilepsy is an alteration of the central nervous system (CNS) characterized by abnormal increases in neuronal electrical activity. The mammalian target of rapamycin (mTOR) signalling pathway has been investigated as an interesting objective in epilepsy research. Vinpocetine (VNP), a synthesized derivative of the apovincamine alkaloid, has been used in different cerebrovascular disorders. This study aimed to examine the modulatory effects of VNP on neurobehavioral comorbidities via the mTOR signalling pathway in a lithium-pilocarpine (Li-Pil) rat model of seizures.

METHODS

In male Wistar rats, seizures were induced with a single administration of pilocarpine (60 mg/kg; i.p.) 20 hours after the delivery of a single dose of lithium (3 mEq/kg; i.p.). VNP (10 mg/kg; i.p.) was administered daily for 14 consecutive days before Li-Pil administration.

KEY FINDINGS

VNP had a protective effect against Li-Pil-induced seizures. VNP improved both the locomotor and cognitive abilities, moreover, VNP exerted a neuroprotective action, as verified histologically and by its inhibitory effects on hippocampal glutamate excitotoxicity, mTOR pathway, and inflammatory and apoptotic parameters.

CONCLUSIONS

VNP is a valuable candidate for epilepsy therapy via its modulation of the mechanisms underlying epileptogenesis with emphasis on its modulatory effect on mTOR signalling pathway.

Inhibition of PDE1-B by Vinpocetine Regulates Microglial Exosomes and Polarization Through Enhancing Autophagic Flux for Neuroprotection Against Ischemic Stroke

Exosomes contribute to cell–cell communications. Emerging evidence has shown that microglial exosomes may play crucial role in regulation of neuronal functions under ischemic conditions. However, the underlying mechanisms of microglia-derived exosome biosynthesis are largely unknown. Herein, we reported that the microglial PDE1-B expression was progressively elevated in the peri-infarct region after focal middle cerebral artery occlusion. By an oxygen-glucose-deprivation (OGD) ischemic model in cells, we found that inhibition of PDE1-B by vinpocetine in the microglial cells promoted M2 and inhibited M1 phenotype. In addition, knockdown or inhibition of PDE1-B significantly enhanced the autophagic flux in BV2 cells, and vinpocetine-mediated suppression of M1 phenotype was dependent on autophagy in ischemic conditions. Co-culture of BV2 cells and neurons revealed that vinpocetine-treated BV2 cells alleviated OGD-induced neuronal damage, and treatment of BV2 cells with 3-MA abolished the observed effects of vinpocetine. We further demonstrated that ischemia and vinpocetine treatment significantly altered microglial exosome biogenesis and release, which could be taken up by recipient neurons and regulated neuronal damage. Finally, we showed that the isolated exosome per se from conditioned BV2 cells is sufficient to regulate cortical neuronal survival in vivo. Taken together, these results revealed a novel microglia-neuron interaction mediated by microglia-derived exosomes under ischemic conditions. Our findings further suggest that PDE1-B regulates autophagic flux and exosome biogenesis in microglia which plays a crucial role in neuronal survival under cerebral ischemic conditions.

Sildenafil ameliorates Alzheimer disease via the modulation of vascular endothelial growth factor and vascular cell adhesion molecule-1 in rats

Alzheimer disease (AD) is a chronic neurodegenerative disease with multi-pathways pathogenesis. Sildenafil is a selective phosphodiesterase-5 inhibitor with a potential benefit in the treatment of AD. This study investigated the possible mechanisms underlying the effect of sildenafil in AD with emphasis on vascular endothelial growth factor (VEGF), and vascular cell adhesion molecule-1 (VCAM-1). Twenty-four adult male rats were classified into four groups; control group: received vehicles, sildenafil-control: received sildenafil (15 mg/kg/day, p.o.), AD group received Aluminum (25 mg/kg/day, p.o.), AD-treated group: received sildenafil (15 mg/kg/day, p.o.) for 6 weeks. AD was assessed by memory performance test and confirmed by histopathological examination and immunostaining of, neurogenesis marker nestin and α-synuclein. The levels of VEGF-A, VCAM-1, oxidative stress markers and TNF-α in brain tissue were evaluated. AD rats showed histopathological evidences of AD; along with increased latency time in the memory test. There was a decrease in VEGF-A, and an increase in VCAM-1, TNF-α, and oxidative stress markers. Immunohistochemical study showed a significant increase in α-synuclein and a significant decrease in nestin expressions in brain tissues. Sildenafil administration ameliorated the histopathological changes and decreased latency time. Such effect was associated with a decrease in VCAM-1, TNF-α and oxidative stress as well as an increase in VEGF-A. Sildenafil caused a significant increase in nestin and a decrease in α-synuclein immunostaining. These findings suggested a protective effect of sildenafil via modulation of VEGF-A, and VCAM-1.

Phosphodiesterase Inhibitors for Alzheimer's Disease: A Systematic Review of Clinical Trials and Epidemiology with a Mechanistic Rationale

BACKGROUND

Preclinical studies, clinical trials, and reviews suggest increasing 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) with phosphodiesterase inhibitors is disease-modifying in Alzheimer's disease (AD). cAMP/protein kinase A (PKA) and cGMP/protein kinase G (PKG) signaling are disrupted in AD. cAMP/PKA and cGMP/PKG activate cAMP response element binding protein (CREB). CREB binds mitochondrial and nuclear DNA, inducing synaptogenesis, memory, and neuronal survival gene (e.g., brain-derived neurotrophic factor) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). cAMP/PKA and cGMP/PKG activate Sirtuin-1, which activates PGC1α. PGC1α induces mitochondrial biogenesis and antioxidant genes (e.g.,Nrf2) and represses BACE1. cAMP and cGMP inhibit BACE1-inducing NFκB and tau-phosphorylating GSK3β.

OBJECTIVE AND METHODS

We review efficacy-testing clinical trials, epidemiology, and meta-analyses to critically investigate whether phosphodiesteraseinhibitors prevent or treat AD.

RESULTS

Caffeine and cilostazol may lower AD risk. Denbufylline and sildenafil clinical trials are promising but preliminary and inconclusive. PF-04447943 and BI 409,306 are ineffective. Vinpocetine, cilostazol, and nicergoline trials are mixed. Deprenyl/selegiline trials show only short-term benefits. Broad-spectrum phosphodiesterase inhibitor propentofylline has been shown in five phase III trials to improve cognition, dementia severity, activities of daily living, and global assessment in mild-to-moderate AD patients on multiple scales, including the ADAS-Cogand the CIBIC-Plus in an 18-month phase III clinical trial. However, two books claimed based on a MedScape article an 18-month phase III trial failed, so propentofylline was discontinued. Now, propentofylline is used to treat canine cognitive dysfunction, which, like AD, involves age-associated wild-type Aβ deposition.

CONCLUSION

Phosphodiesterase inhibitors may prevent and treat AD.

Role of vinpocetine in ischemic stroke and poststroke outcomes: A critical review

Vinpocetine (VPN) is a synthetic ethyl-ester derivative of the alkaloid apovincamine from Vinca minor leaves. VPN is a selective inhibitor of phosphodiesterase type 1 (PDE1) that has potential neurological effects through inhibition of voltage-gated sodium channel and reduction of neuronal calcium influx. VPN has noteworthy antioxidant, anti-inflammatory, and anti-apoptotic effects with inhibitory effect on glial and astrocyte cells during and following ischemic stroke (IS). VPN is effective as adjuvant therapy in the management of epilepsy; it reduces seizure frequency by 50% in a dose of 2 mg/kg/day. VPN improves psychomotor performances through modulation of brain monoamine pathway mainly on dopamine and serotonin, which play an integral role in attenuation of depressive symptoms. VPN recover cognitive functions and spatial memory through inhibition of hippocampal and cortical PDE1 with augmentation of cyclic adenosin monophosphate and cyclic guanosin monophosphate ratio, enhancement of cholinergic neurotransmission, and inhibition of neuronal inflammatory mediators. Therefore, VPN is an effective agent in the management of IS and plays an integral role in the prevention and attenuation of poststroke epilepsy, depression, and cognitive deficit through direct cAMP/cGMP-dependent pathway or indirectly through anti-inflammatory and antioxidant effects.