Sulforaphane Alleviates Lipopolysaccharide-induced Spatial Learning and Memory Dysfunction in Mice: The Role of BDNF-mTOR Signaling Pathway

Chronic restraint stress induces abnormal behaviors in pain sensitivity and cognitive function in mice: the role of Keap1/Nrf2 pathway

Stress is a series of physical and psychological responses to external and internal environmental stimuli. Growing studies have demonstrated the detrimental impacts of acute restraint stress (ARS) and chronic restraint stress (CRS) on animal behavior. However, the related pathogenesis and therapeutic mechanisms remain unclear. Hence, the present study aimed to examine whether unfolded protein response (UPR) and Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2 related factor 2 (Nrf2) pathway are associated with ARS- and CRS- induced abnormal behaviors of pain sensitivity and cognitive function. We here used four behavioral tests to evaluate pain sensitivity and cognitive function in ARS and CRS mice. CRS markedly decreased Paw Withdrawal Mechanical Threshold (PWMT) and Tail-flick Latency (TFL) scores, whereas ARS altered TFL but had no effect on PWMT scores. Additionally, CRS, but not ARS, significantly changed behaviors in nest building behavior and MWMT. Intriguingly, the expression of Keap1 and Nrf2 protein were decreased in the spinal cord and hippocampus in CRS mice, but not in ARS mice. Moreover, neither the ARS nor the CRS groups significantly differed from the control group in terms of endoplasmic reticulum stress (ERS). Taken together, this study demonstrated that CRS could induce abnormal pain sensitivity and cognitive function probably via Keap1/Nrf2 pathway in spinal cord and hippocampus. It is therefore likely that effective intervention of Keap1/Nrf2 pathway may contribute to preventing and treating hyperalgesia and cognitive dysfunction in CRS.

Polysaccharide from Paris polyphylla improves learning and memory ability in D-galactose-induced aging model mice based on antioxidation, p19/p53/p21, and Wnt/β-catenin signaling pathways

The current study aimed to investigate the effects and mechanisms of Paris polyphylla polysaccharide component 1 (PPPm-1) to improve learning and memory in D-galactose-induced aging model mice. We determined the effects of PPPm-1 on the brain, organ index, and behavior in the aging model mice induced by D-galactose to study learning and memory improvement. UV-Vis spectrophotometry helped determine the PPPm-1 effect on antioxidant parameters associated with learning and memory in the brain and related organs of aging mice. Moreover, in the hippocampi of aging model mice, PPPm-1 effect on the mRNA and protein expressions of p19, p53, p21, P16, Rb, Wnt/1, β-catenin, CyclinD1, TCF-4, and GSK-3β were detected using the quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. The results indicated that PPPm-1 could increase the brain and organ indexes, the avoidance latency, the total distance and average speed in the water maze, and the SOD and GSH-PX activities in the brain, liver tissues, and plasma. Moreover, the mRNA and protein expressions of Wnt/1, β-catenin, CyclinD1, and TCF-4 were also elevated in the hippocampi of aging model mice. However, the error times in step-through tests, the MDA content in the brain and liver tissues, the AChE activity in the brain tissue, the protein expressions of P16, Rb in the hippocampi, and the mRNA and protein expressions of p19, p53, p21, and GSK-3β in the hippocampi of aging model mice were significantly decreased. Thus, PPPm-1 significantly enhanced the learning and memory impairment induced by D-galactose in mice. The action mechanisms were associated with anti-oxidative stress, cholinergic nervous system function regulation, LTP enhancement in long-term memory, down-regulated expression of p19/p53/p21 signaling pathway factors, and Wnt/β-catenin signaling pathway activation.

Plausible Role of Stem Cell Types for Treating and Understanding the Pathophysiology of Depression

Major Depressive Disorder (MDD), colloquially known as depression, is a debilitating condition affecting an estimated 3.8% of the population globally, of which 5.0% are adults and 5.7% are above the age of 60. MDD is differentiated from common mood changes and short-lived emotional responses due to subtle alterations in gray and white matter, including the frontal lobe, hippocampus, temporal lobe, thalamus, striatum, and amygdala. It can be detrimental to a person’s overall health if it occurs with moderate or severe intensity. It can render a person suffering terribly to perform inadequately in their personal, professional, and social lives. Depression, at its peak, can lead to suicidal thoughts and ideation. Antidepressants manage clinical depression and function by modulating the serotonin, norepinephrine, and dopamine neurotransmitter levels in the brain. Patients with MDD positively respond to antidepressants, but 10–30% do not recuperate or have a partial response accompanied by poor life quality, suicidal ideation, self-injurious behavior, and an increased relapse rate. Recent research shows that mesenchymal stem cells and iPSCs may be responsible for lowering depression by producing more neurons with increased cortical connections. This narrative review discusses the plausible functions of various stem cell types in treating and understanding depression pathophysiology.

Therapeutic effects of sulforaphane in ulcerative colitis: effect on antioxidant activity, mitochondrial biogenesis and DNA polymerization

Objectives

Ulcerative colitis (UC), an inflammatory bowel disease, affects mucosal lining of colon leading to inflammation and ulcers. Sulforaphane is a natural compound obtained from cruciferous vegetables. We aimed to investigate potential therapeutic effects of sulforaphane in experimentally induced UC in rats through affection antioxidant activity, mitochondrial biogenesis and DNA polymerization.

Methods

UC was induced in rats via an intracolonic single administration of 2 ml of 4% acetic acid. UC rats were treated with 15 mg/kg sulforaphane. Samples of colon were used to investigate gene expression and protein levels of peroxisome proliferator-activated receptor-gamma coactivator (PGC-1), mitochondrial transcription factor A (TFAM), mammalian target of rapamycin (mTOR), cyclin D1, nuclear factor erythroid 2-related factor-2 (Nrf2), heme Oxygenase-1 (HO-1) and proliferating cell nuclear antigen (PCNA).

Results

UC showed dark distorted Goblet cell nucleus with disarranged mucus granules and no distinct brush border with atypical microvilli. All morphological changes were improved by treating with sulforaphane. Finally, treatment with sulforaphane significantly increased expression of PGC-1, TFAM, Nrf2 and HO-1 associated with reduction in expression of mTOR, cyclin D1 and PCNA.

Conclusion

Sulforaphane could cure UC in rats. The protective activity can be explained by enhancing antioxidant activity, elevating mitochondrial biogenesis and inhibiting DNA polymerization.

Esketamine alleviates postoperative depression-like behavior through anti-inflammatory actions in mouse prefrontal cortex

The rising incidence of postoperative depression (POD) in recent years has placed a heavy burden on patients' physical and mental health. At this point in time, however, POD pathogenesis remains poorly understood and novel therapeutic strategies are being sought. The present study aimed to clarify esketamine's protective effects and possible mechanisms of action in POD. To this avail, we used an animal model of postoperative depression to analyze behavioral, parameters, plus the inflammatory response in serum and in the medial prefrontal cortex (mPFC). Using immunofluorescence staining, we detected the number of microglia and parvalbumin (PV) in mPFC, and determined changes in neuronal dendritic spine density via Golgi staining. Expression of Iba1, PSD95 and NF-κB was examined by Western blot analysis. Our results show that esketamine can significantly improve depression-like symptoms caused by anesthesia and surgery. In addition, esketamine administration reversed the decrease in the density of PV neurons and restored synaptogenesis in mPFC which had been perturbed by inflammation. The evidence obtained suggests esketamine's anti-inflammatory effects may be mediated by the BDNF/TrkB signaling pathway and possibly by attenuation of the nuclear factor κB (NF-κB) pathway. These data warrant further investigations into the interplay of esketamine, and microglia in the modulation of POD symptomatology.

Pharmacological Activation of GPR55 Improved Cognitive Impairment Induced by Lipopolysaccharide in Mice

Our previous research found that activation of GPR55 can alleviate cognitive impairment induced by amyloid-beta 1-42 (Aβ_1-42) and streptozotocin in mice, but the role of GPR55 in the pathogenesis of cognitive impairment remains unknown. Here, we used a lipopolysaccharide (LPS) mouse model to further investigate the role and mechanism of O-1602, a GPR55 agonist, on cognitive dysfunction. ICR mice were treated with an intracerebroventricular (i.c.v.) injection of LPS, followed by cognitive function tests. The expression of GPR55, NF-κB p65, caspase-3, Bax, and Bcl-2 in the hippocampus was examined by Western blotting. Inflammatory cytokines and microglia were detected by ELISA kit and immunohistochemical analyses, respectively. The levels of MDA, GSH, SOD, and CAT were examined by assay kits. Furthermore, TUNEL-staining was used to detect neuronal apoptosis. Our results showed that i.c.v. injection of LPS in mice exhibited impaired performance in the behavior tests, which were ameliorated by O-1602 treatment (2.0 or 4.0 μg/mouse, i.c.v.). Importantly, we found that O-1602 treatment reversed GPR55 downregulation, decreased the expression of NF-κB p65, suppressed the accumulation of proinflammatory cytokines and microglia activation, increased the anti-inflammatory cytokines, and reduced the levels of MDA, increased the levels of GSH, SOD, and CAT in the hippocampus. In addition, O-1602 treatment also significantly reduced Bax and increased Bcl-2 expression as well as decreased caspase-3 activity and TUNEL-positive cells in the hippocampus. These observations indicate that O-1602 may ameliorate LPS-induced cognition deficits via inhibiting neuroinflammation, oxidative stress, and apoptosis mediated by the NF-κB pathway in mice.

Dl-3-n-Butylphthalide Improves Neuroinflammation in Mice with Repeated Cerebral Ischemia-Reperfusion Injury through the Nrf2-Mediated Antioxidant Response and TLR4/MyD88/NF-κB Signaling Pathway

Increasing evidence shows that oxidative stress and neuroinflammation play a crucial role in the pathology of vascular dementia (VD). Previously, we have found that Dl-3-n-butylphthalide (NBP) has antioxidant and anti-inflammatory activities in VD, whereas little is known about its mechanism. Therefore, the objective of our study was to explore the contribution of nuclear factor erythroid-2 related factor 2 (Nrf2) to NBP and its effects on anti-inflammatory activity in a mouse model of VD. Our studies revealed that NBP could effectively mitigate cognitive deficits, neuron cell loss, and apoptosis in mice subjected to repeated cerebral ischemia-reperfusion (RCIR). Additionally, NBP promoted both the expression of brain-derived neurotrophic factor (BDNF) and tyrosine receptor kinase B (TrkB) in hippocampus tissue. NBP exhibited antioxidant activity by enhancing Nrf2 nuclear accumulation, increasing HO-1 and NQO1 expression, enhancing SOD activity, and inhibiting RCIR-induced MDA and 8-iso PGF2α generation in the hippocampus. NBP also significantly inhibited TLR4/MyD88/NF-κB signaling and suppressed microglial proliferation and the production of proinflammatory mediators in RCIR mice. Importantly, the antioxidant, antineuroinflammatory, and neuroprotective effects of NBP above were abolished by Nrf2 knockout. Collectively, these results indicated the effects of NBP on neuroinflammation were strongly associated with the Nrf2 pathway. Modulation of TLR4/MyD88/NF-κB pathway by Nrf2 is involved in the neuroprotective effect of NBP against VD induced by RCIR injury. With antioxidant and anti-neuroinflammatory properties, NBP could be a promising drug candidate for the prevention and/or treatment of VD and other neuroinflammatory disorders.

Frankincense diterpenes as a bio-source for drug discovery

INTRODUCTION

Frankincense (Boswellia sp.) gum resins have been employed as an incense in cultural and religious ceremonies for many years. Frankincense resin has over the years been employed to treat depression, inflammation, and cancer in traditional medicines.

AREAS COVERED

This inclusive review focuses on the significance of frankincense diterpenoids, and in particular, incensole derivatives for establishment future treatments of depression, neurological disorders, and cancer. The authors survey the available literature and furnish an overview of future perspectives of these intriguing molecules.

EXPERT OPINION

Numerous diterpenoids including cembrane, prenylaromadendrane, and the verticillane-type have been isolated from various Boswellia resins. Cembrane-type diterpenoids occupy a crucial position in pharmaceutical chemistry and related industries because of their intriguing biological and encouraging pharmacological potentials. Several cembranes have been reported to possess anti-Alzheimer, anti-inflammatory, hepatoprotective, and antimalarial effects along with a good possibility to treat anxiety and depression. Although some slight drawbacks of these compounds have been noted, including the selectivity of these diterpenoids, there is a great need to address these in future research endeavors. Moreover, it is vitally important for medicinal chemists to prepare libraries of incensole-heterocyclic analogs as well as hybrid compounds between incensole or its acetate and anti-depressant or anti-inflammatory drugs.

Sulforaphane improves cognitive dysfunction after surgery and anesthesia in mice: the role of Keap1-Nrf2 signaling

Anesthesia and surgery are likely causing cognitive dysfunction in patients, especially the elderly. However, the underlying pathogenic mechanisms largely remain unclear. Accumulating evidence suggest that signaling between Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated protein 1 (Keap1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) plays an important role in the pathogenesis and treatment of brain dysfunction, while sulforaphane (SFN), a natural compound acting as an Nrf2 agonist, can improve brain function. In the present study, we used 9-month-old mice to perform tibial fracture surgery under isoflurane general anesthesia. Hierarchical cluster analysis of Morris water maze test (MWMT) analysis was performed to classify mice into post-operative cognitive dysfunction (POCD) versus non-POCD phenotypes. Expression levels of Keap1 and Nrf2 were significantly decreased in the medial prefrontal cortex (mPFC), hippocampus and liver, but not in the nucleus accumbens, muscle and gut of POCD mice compared to control and non-POCD mice. Interestingly, both pretreatment and posttreatment with SFN significantly improved the abnormal behaviors of mice in the MWMT, in parallel with the up-regulated levels of Keap1-Nrf2 signaling in the mPFC, hippocampus and liver. In conclusion, these results suggest that decreased Keap1-Nrf2 signaling in the mPFC, hippocampus and liver may contribute to the onset of POCD, and that SFN exerts facilitating effects on POCD symptoms by increasing Keap1-Nrf2 signaling.

The Effects of Incensole Acetate on Neuro-inflammation, Brain-Derived Neurotrophic Factor and Memory Impairment Induced by Lipopolysaccharide in Rats

Incensole acetate (IA) is a major component of Boswellia serrata resin that has been shown to have anti-inflammatory, anti-oxidant and neuroprotective properties. The present study determined the effect of IA on lipopolysaccharide (LPS)-induced memory impairment, and hippocampal cytokines and oxidative stress indicators level. We used 32 Wistar rats (220-250 g weight) randomly divided into four groups. The control group, which only received the saline-diluted DMSO (vehicle); LPS group which received LPS and was treated with the vehicle; and two IA-treated groups which received 2.5 or 5 mg/ kg IA before LPS injection. Morris water maze (MWM) and passive avoidance (PA) tests were performed. Finally, the brains were removed and were used to assess cytokines levels and oxidative stress status. Compared to the LPS group, IA administration reduced the time spent and path traveled to reach the hidden platform during 5 days of learning in MWM while increased the time spent in the target quadrant in the probe test. Moreover, IA increased latency while decreased entry number and time spent in the dark chamber of PA test compared to the LPS group. Additionally, pre-treatment with IA attenuated interleukin(IL)-6, tumor necrosis alpha (TNF-α), glial fibrillary acidic protein (GFAP), malondialdehyde (MDA) and nitric oxide (NO) metabolites levels while increased those of IL-10, total thiol, superoxide dismutase (SOD), catalase (CAT) and brain-derived neurotrophic factor (BDNF). Our results indicated that IA improved LPS-induced learning and memory impairments. The observed effects seem to be mediated via a protective activity against neuro-inflammation and brain tissue oxidative damage and through improving BDNF.

Efficacy of Ulinastatin and Sulforaphane Alone or in Combination in Rat Model of Streptozotocin Diabetes Induced Vascular Dementia

Objective

Vascular Dementia (VaD), is associated with metabolic conditions. Diabetes is a major risk factor for the development of VaD. This study investigates the efficacy of ulinastatin (UTI) and sulforaphane (SUL) in streptozotocin (STZ)-diabetes induced vascular endothelium dysfunction and related dementia.

Methods

Single dose STZ (50 mg/kg i.p.) was administered to Albino Wistar rats (male, 200−250 g). Morris water maze and attentional set shifting tests were used to assess the spatial learning, memory, reversal learning, and executive functioning in animals. Body weight, serum glucose, serum nitrite/nitrate, vascular endothelial function, aortic superoxide anion, brains’ oxidative markers (thiobarbituric acid reactive species-TBARS, reduced glutathione-GSH, superoxide dismutase-SOD, and catalase-CAT), inflammatory markers (IL-6, IL-10, TNF-a, and myeloperoxidase-MPO), acetylcholinesterase activity-AChE, blood brain barrier (BBB) permeability and histopathological changes were also assessed. UTI (10,000 U/kg) and SUL (25 mg/kg) were used alone as well as in combination, as the treatment drugs. Donepezil (0.5 mg/kg) was used as a positive control.

Results

STZ-administered rats showed reduction in body weight, learning, memory, reversal learning, executive functioning, impairment in endothelial function, BBB permeability, increase in serum glucose, brains’ oxidative stress, inflammation, AChE-activity, BBB permeability and histopathological changes. Administration of UTI and SUL alone as well as in combination, significantly and dose dependently attenuated the STZ-diabetes-induced impairments in the behavioral, endothelial, and biochemical parameters.

Conclusion

STZ administration caused diabetes and VaD which was attenuated by the administration of UTI and SUL. Therefore, these agents may be studied further for the assessment of their full potential in diabetes induced VaD.

Sulforaphane: A review of its therapeutic potentials, advances in its nanodelivery, recent patents, and clinical trials

Traditionally, herbal supplements have shown an exceptional potential of desirability for the prevention of diseases and their treatment. Sulforaphane (SFN), an organosulfur compound belongs to the isothiocyanate (ITC) group and is mainly found naturally in cruciferous vegetables. Several studies have now revealed that SFN possesses broad spectrum of activities and has shown extraordinary potential as antioxidant, antitumor, anti-angiogenic, and anti-inflammatory agent. In addition, SFN is proven to be less toxic, non-oxidizable, and its administration to individuals is well tolerated, making it an effective natural dietary supplement for clinical trials. SFN has shown its ability to be a promising future drug molecule for the management of various diseases mainly due to its potent antioxidant properties. In recent times, several newer drug delivery systems were designed and developed for this potential molecule in order to enhance its bioavailability, stability, and to reduce its side effects. This review focuses to cover numerous data supporting the wide range of pharmacological activities of SFN, its drug-related issues, and approaches to improve its physicochemical and biological properties, including solubility, stability, and bioavailability. Recent patents and the ongoing clinical trials on SFN are also summarized.

Evaluation of Anti-inflammatory Nutraceuticals in LPS-induced Mouse Neuroinflammation Model: An Update

It is known that peripheral infections, accompanied by inflammation, represent significant risk factors for the development of neurological disorders by modifying brain development or affecting normal brain aging. The acute effects of systemic inflammation on progressive and persistent brain damage and cognitive impairment are well documented. Anti-inflammatory therapies may have beneficial effects on the brain, and the protective properties of a wide range of synthetic and natural compounds have been extensively explored in recent years. In our previous review, we provided an extensive analysis of one of the most important and widely-used animal models of peripherally induced neuroinflammation and neurodegeneration - lipopolysaccharide (LPS)-treated mice. We addressed the data reproducibility in published research and summarized basic features and data on the therapeutic potential of various natural products, nutraceuticals, with known anti-inflammatory effects, for reducing neuroinflammation in this model. Here, recent data on the suitability of the LPS-induced murine neuroinflammation model for preclinical assessment of a large number of nutraceuticals belonging to different groups of natural products such as flavonoids, terpenes, non-flavonoid polyphenols, glycosides, heterocyclic compounds, organic acids, organosulfur compounds and xanthophylls, are summarized. Also, the proposed mechanisms of action of these molecules are discussed.

Sulforaphane enhances long-term potentiation and ameliorate scopolamine-induced memory impairment

Increases in human life expectancy have led to increases in the prevalence of senile dementia and neurodegenerative diseases. This is a major problem because there are no curative treatments for these diseases, and patients with unmanaged cognitive and neurodegenerative symptoms experience many social problems. Sulforaphane is a type of organosulfur compound known as an isothiocyanate. It is derived from glucoraphanin, a compound found in cruciferous vegetables such as broccoli, brussels sprouts, and cabbages, via an enzymatic reaction that is triggered by plant damage (e.g., chewing). Sulforaphane exhibits activity against cancer, inflammation, depression, and severe cardiac diseases. It can also alleviate oxidative stress and neural dysfunction in the brain. However, there is insufficient knowledge about the electrophysiological and behavioral basis of the effects of sulforaphane on learning and memory. Therefore, we evaluated whether acute sulforaphane administration affected long-term potentiation (LTP) in organotypic cultured rat hippocampal tissues. We also measured the effect of sulforaphane on the performance of three behavioral tests, the Y-maze test, the passive avoidance test, and the Morris water maze, which assess short-term memory, avoidance memory, and short and long-term spatial memory, respectively. We found that sulforaphane increased the total field excitatory postsynaptic potential (fEPSP) in a dose-dependent manner after high frequency stimulation and attenuated scopolamine-induced interference of the fEPSP in the hippocampal CA1 area. Sulforaphane also restored cognitive function and inhibited memory impairment as indicated by the alleviation of the negative neurological effects of scopolamine, i.e, a lowered ratio of spontaneous alternation in the Y-maze, a reduced step-through latency in the passive avoidance test, and an increased navigation time in the Morris water maze. These results indicate that sulforaphane can effectively prevent the attenuation of LTP and cognitive abilities induced by cholinergic and muscarinic receptor blockade. Further research is warranted to explore the potential therapeutic and prophylactic utility of sulforaphane for improving learning and memory, especially in those suffering from neurodegenerative disorders.

Role of mTOR-Regulated Autophagy in Synaptic Plasticity Related Proteins Downregulation and the Reference Memory Deficits Induced by Anesthesia/Surgery in Aged Mice

Postoperative cognitive dysfunction increases mortality and morbidity in perioperative patients and has become a major concern for patients and caregivers. Previous studies demonstrated that synaptic plasticity is closely related to cognitive function, anesthesia and surgery inhibit synaptic function. In central nervous system, autophagy is vital to synaptic plasticity, homeostasis of synapticproteins, synapse elimination, spine pruning, proper axon guidance, and when dysregulated, is associated with behavioral and memory functions disorders. The mammalian target of rapamycin (mTOR) negatively regulates the process of autophagy. This study aimed to explore whether rapamycin can ameliorate anesthesia/surgery-induced cognitive deficits by inhibiting mTOR, activating autophagy and rising synaptic plasticity-related proteins in the hippocampus. Aged C57BL/6J mice were used to establish POCD models with exploratory laparotomy under isoflurane anesthesia. The Morris Water Maze (MWM) was used to measure reference memory after anesthesia and surgery. The levels of mTOR phosphorylation (p-mTOR), Beclin-1 and LC3-II were examined on postoperative days 1, 3 and 7 by western blotting. The levels of synaptophysin (SYN) and postsynaptic density protein 95 (PSD-95) in the hippocampus were also examined by western blotting. Here we showed that anesthesia/surgery impaired reference memory and induced the activation of mTOR, decreased the expression of autophagy-related proteins such as Beclin-1 and LC3-II. A corresponding decline in the expression of neuronal/synaptic, plasticity-related proteins such as SYN and PSD-95 was also observed. Pretreating mice with rapamycin inhibited the activation of mTOR and restored autophagy function, also increased the expression of SYN and PSD-95. Furthermore, anesthesia/surgery-induced learning and memory deficits were also reversed by rapamycin pretreatment. In conclusion, anesthesia/surgery induced mTOR hyperactivation and autophagy impairments, and then reduced the levels of SYN and PSD-95 in the hippocampus. An mTOR inhibitor, rapamycin, ameliorated anesthesia/surgery-related cognitive impairments by inhibiting the mTOR activity, inducing activation of autophagy, enhancing SYN and PSD-95 expression.

Effects of Gestational Inflammation with Postpartum Enriched Environment on Age-Related Changes in Cognition and Hippocampal Synaptic Plasticity-Related Proteins

Increasing evidence indicates that exposure to inflammation during pregnancy intensifies the offspring’s cognitive impairment during aging, which might be correlated with changes in some synaptic plasticity-related proteins. In addition, an enriched environment (EE) can significantly exert a beneficial impact on cognition and synaptic plasticity. However, it is unclear whether gestational inflammation combined with postnatal EE affects the changes in cognition and synaptic plasticity-related proteins during aging. In this study, pregnant mice were intraperitoneally injected with lipopolysaccharides (LPS, 50 μg/kg) or normal saline at days 15–17 of pregnancy. At 21 days after delivery, some LPS-treated mice were randomly selected for EE treatment. At the age of 6 and 18 months, Morris water maze (MWM) and western blotting were, respectively, used to evaluate or measure the ability of spatial learning and memory and the levels of postsynaptic plasticity-related proteins in the hippocampus, including postsynaptic density protein 95 (PSD-95), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) GluA1 subunit, and Homer-1b/c. The results showed that 18-month-old control mice had worse spatial learning and memory and lower levels of these synaptic plasticity-related proteins (PSD-95, GluA1, and Homer-1b/c) than the 6-month-old controls. Gestational LPS exposure exacerbated these age-related changes of cognition and synaptic proteins, but EE could alleviate the treatment effect of LPS. In addition, the performance during learning and memory periods in the MWM correlated with the hippocampal levels of PSD-95, GluA1, and Homer-1b/c. Our results suggested that gestational inflammation accelerated age-related cognitive impairment and the decline of PSD-95, GluA1, and Homer-1b/c protein expression, and postpartum EE could alleviate these changes.

Sulforaphane mitigates LPS-induced neuroinflammation through modulation of Cezanne/NF-κB signalling

AIM

Neuroinflammation is a potent pathological process of various neurodegenerative diseases. Sulforaphane (SFN) is a natural product and acts as a neuroprotective agent to suppress inflammatory response in brain. The present study investigated the protective effect of Sulforaphane (SFN) on lipopolysaccharide (LPS)-induced neuroinflammation.

MATERIALS AND METHODS

Rats were divided into three groups: control group, LPS group and LPS + SFN group. Morris water maze test was carried out to evaluate the spatial memory and learning function of rats. The inflammatory cytokines levels in hippocampal tissues, plasma were measured by ELISA. The western blot was used to detect Cezanne/NF-κB signalling. For in vitro study, the Cezanne siRNA and scrambled control were transfected into BV2 cells, and then treated with or without 20 μM SFN before exposed to LPS. The inflammatory cytokines levels and Cezanne/NF-κB signalling were detected by ELISA and western blot, respectively. Co-IP assay were applied to investigate the regulation of Cezanne on ubiquitination of TRAF6 and RIP1.

KEY FINDINGS

SFN improved LPS-induced neurocognitive dysfunction in rats. It inhibited the neuroinflammation and activation of NF-κB pathway induced by LPS. The modulation of TRAF6 and RIP1 ubiquitination by Cezanne was playing a pivotal role in relation to the mechanism of SFN inhibiting NF-κB pathway.

SIGNIFICANCE

The results of our study demonstrated that SFN could attenuate LPS-induced neuroinflammation through the modulation of Cezanne/NF-κB signalling.

Differential Effect of Repeated Lipopolysaccharide Treatment and Aging on Hippocampal Function and Biomarkers of Hippocampal Senescence

Markers of brain aging and cognitive decline are thought to be influenced by peripheral inflammation. This study compared the effects of repeated lipopolysaccharide (LPS) treatment in young rats to age-related changes in hippocampal-dependent cognition and transcription. Young Fischer 344 X Brown Norway hybrid rats were given intraperitoneal injections once a week for 7 weeks with either LPS or vehicle. Older rats received a similar injection schedule of vehicle. Old vehicle and young LPS rats exhibited a delay-dependent impairment in spatial memory. Further, LPS treatment reduced the hippocampal CA3-CA1 synaptic response. RNA sequencing, performed on CA1, indicated an increase in genes linked to neuroinflammation in old vehicle and young LPS animals. In contrast to an age-related decrease in transcription of synaptic genes, young LPS animals exhibited increased expression of genes that support the growth and maintenance of synapses. We suggest that the increased expression of genes for growth and maintenance of synapses in young animals represents neuronal resilience/recovery in response to acute systemic inflammation. Thus, the results indicate that repeated LPS treatment does not completely recapitulate the aging phenotype for synaptic function, possibly due to the chronic nature of systemic inflammation in aging and resilience of young animals to acute treatments.

Anesthesia and surgery induce cognitive dysfunction in elderly male mice: the role of gut microbiota

It is well known that the incidence of postoperative cognitive dysfunction (POCD) is high in elderly patients. The pathogenesis and therapeutic mechanisms of POCD, however, have not yet been completely elucidated. The effects of gut microbiota, particularly in terms of regulating brain function, have gradually attracted increasing attention. In this study, we investigated the potential role of gut microbiota in POCD in aged male mice and attempted to determine whether alterations in gut microbiota would be helpful in the diagnosis of POCD. POCD and non-POCD mice were classified by hierarchical cluster analysis of behavioral results. Additionally, α- and β-diversity of gut microbiota showed a differential profile between the groups. In total, 24 gut bacteria were significantly altered in POCD mice compared with those in non-POCD mice, in which 13 gut bacteria were significantly correlated with escape latency in the Morris water maze test (MWMT). Remarkably, receiver operating characteristic curves revealed that the Dehalobacteriaceae family and Dehalobacterium genus are potentially important bacteria for the diagnosis of POCD. These findings indicate that alterations in the composition of gut microbiota are probably involved in the pathogenesis of POCD in aged mice. Novel therapeutic strategies regulating specific gut bacteria may be helpful for the prevention and treatment of POCD.

Adipose-derived mesenchymal stem cells protect against CMS-induced depression-like behaviors in mice via regulating the Nrf2/HO-1 and TLR4/NF-κB signaling pathways

Increasing studies show that inflammatory processes may be involved in depressive disorders. Nuclear factor erythroid-2 related factor 2 (Nrf2) modulates tissue microglial M1 phenotypic changes to the M2 phenotype, which is implicated in protection against inflammatory diseases. We have reported that the adipose-derived mesenchymal stem cells (ADSCs) display anti-inflammatory activity. In this study we explored whether the mechanism of anti-inflammatory activity of ADSCs was related to Nrf2. ADSCs were isolated from mouse fat pads and intravenously administered to chronic mild stress (CMS)-exposed C57BL/6 mice at the dose of 1 × 10⁶ once a week for 3 weeks. We showed that ADSC administration significantly remedied CMS-induced depressive-like behaviors in sucrose preference test, tail suspension test, and forced swim test accompanied by suppressing microglial activation and the expression of inflammatory factors including MCP-1, TNF-α, IL-1β, and IL-6. Furthermore, ADSC administration promoted both the expression of BDNF and TrkB, and promoted Nrf2/HO-1 signaling but suppressed TLR4/NF-κB signaling in brain tissue. In order to elucidate the role of Nrf2/HO-1 signaling in ADSC-caused neuroprotection, Nrf2-modified ADSCs were cocultured with BV2 microglial cells, then exposed to lipopolysaccharide (LPS). Downregulation of Nrf2 in ADSCs decreased the protective effects of ADSCs against LPS-induced microglial activation and M1 polarization. Nrf2 overexpression in ADSCs markedly suppressed LPS-induced TLR4 and NF-κB expression in microglial cells. These results suggest a possible antidepressive mechanism correlated with microglial polarization for anti-inflammatory agents, which may provide a new microglia-targeted strategy for depression therapy.

D-Ribose-L-cysteine attenuates lipopolysaccharide-induced memory deficits through inhibition of oxidative stress, release of proinflammatory cytokines, and nuclear factor-kappa B expression in mice

D-Ribose-L-cysteine (DRLC), an analog of cysteine that boosts glutathione (GSH) content, has been reported to mitigate oxidative stress-mediated diseases. This study seeks to evaluate the effects of DRLC on memory deficits and the biochemical and histo-morphological changes induced by lipopolysaccharide (LPS) in mice. Male Swiss mice (n = 10) were pre-treated orally with three doses of DRLC (25 mg/kg, 50 mg/kg, and 100 mg/kg), donepezil (1 mg/kg), or vehicle (saline) for 30 min prior to the intraperitoneal injection of LPS (0.25 mg/kg) daily for 7 days. Memory functions were evaluated using the Y-maze, object recognition, and social recognition tests. The specific brain regions (prefrontal cortex and hippocampus) were evaluated to determine oxidative stress biomarkers (malondialdehyde, GSH, and catalase), acetyl-cholinesterase activity, proinflammatory cytokines (tumor necrosis factor-α and interleukin-6), expression of nuclear factor-kappa B (NF-κB), and neuronal cell morphology. DRLC (25-100 mg/kg) reversed the memory deficits in the LPS-treated mice (p < 0.05). The increased oxidative stress and proinflammatory cytokines in the brain regions of the LPS-treated mice were significantly (p < 0.05) reduced by DRLC. DRLC (50 mg/kg and 100 mg/kg) also reduced acetyl-cholinesterase activity and decreased NF-κB expression in the brains of LPS-treated mice. Finally, it attenuated the cytoarchitectural distortions and loss of neuronal cells of the prefrontal cortex and hippocampus that were induced by LPS in mice. The results of this study suggest that DRLC attenuates memory deficit induced by LPS in mice through mechanisms related to the inhibition of oxidative stress, release of proinflammatory cytokines, and expression of NF-κB in mice.

Autophagy Dysfunction and mTOR Hyperactivation Is Involved in Surgery: Induced Behavioral Deficits in Aged C57BL/6J Mice

Autophagy is crucial for cell survival, development, division, and homeostasis. The mammalian target of rapamycin (mTOR), which is the foremost negative controller of autophagy, plays a key role in many endogenous processes. The present study investigated whether rapamycin can ameliorate surgery-induced cognitive deficits by inhibiting mTOR and activating autophagy in the hippocampus. Both adult and aged C57BL/6J mice received an intraperitoneal injection of rapamycin (10 mg/kg/day) for 5 days per week for one and a half months. Mice were then subjected to partial hepatectomy under general anesthesia. Behavioral performance was assessed on postoperative days 3, 7, and 14. Hippocampal autophagy-related (Atg)-5, phosphorylated mTOR, and phosphorylated p70S6K were examined at each time point. Brain derived neurotrophic factor (BDNF), synaptophysin, and tau hyperphosphorylation (T396) in the hippocampus were also examined. Surgical trauma and anesthesia exacerbated spatial learning and memory impairment in aged mice on postoperative days 3 and 7. Following partial hepatectomy, the levels of phosphorylated mTOR, phosphorylated 70S6K, and phosphorylated tau were all increased in the hippocampus. A corresponding decline in BDNF and synaptophysin were observed. Rapamycin treatment restored autophagy function, attenuated phosphorylation of tau protein, and increased BDNF and synaptophysin expression in the hippocampus of surgical mice. Furthermore, surgery and anesthesia induced spatial learning and memory impairments were also reversed by rapamycin treatment. Autophagy impairments and mTOR hyperactivation were detected along with surgery-induced behavioral deficits. Inhibiting the mTOR signaling pathway with rapamycin successfully ameliorated surgery-related cognitive impairments by sustaining autophagic degradation, inhibiting tau hyperphosphorylation, and increasing synaptophysin and BDNF expression.

Potential link between the RagA-mTOR-p70S6K axis and depressive-behaviors during bacterial liposaccharide challenge

BACKGROUND

Bacterial infection is a potential risk factor for depression. However, little is known about the mechanistic link between bacterial endotoxin and depressive-like behaviors. The aim of the present study was to clarify whether liposaccharide (LPS) could induce depressive-like behaviors in mice via sequentially activating small GTPase RagA, mammalian target of rapamycin (mTOR), and p70S6K.

METHODS

C57BL/6 N mice were treated with 0.83 mg/kg LPS by intraperitoneal injection for 24 h. The animals were assessed for depressive-like behaviors by forced swim test and tail suspension test. The expression levels of RagA, mTOR, and p70S6K were determined in mice, primary cortical neurons, neural stem cells, and PC12 cells.

RESULTS

LPS effectively induced depressive-like behaviors in mice. Biochemical examination revealed that LPS not only upregulated RagA expression but also activated mTOR/p70S6K pathway in mouse brains. LPS challenge also achieved a similar effect in primary cortical neurons, neural stem cells, and PC12 cells. Following the silencing of RagA expression with specific siRNA, LPS failed to induce mTORC1 translocation to the lysosomal membranes in PC12 cells. These results suggested that LPS might sequentially upregulate RagA and activate mTOR and p70S6K pathways in mice and neural stem cells.

CONCLUSIONS

This study for the first time demonstrated that LPS might induce depressive-like behaviors in mice via the upregulation of RagA and subsequent activation of mTOR/p70S6K pathway. Such information may highlight the RagA-mTOR-p70S6K signaling cascade as a novel therapeutic target for the development of new anti-depressant therapeutics.

Rb1, the Primary Active Ingredient in Panax ginseng C.A. Meyer, Exerts Antidepressant-Like Effects via the BDNF-Trkb-CREB Pathway

Panax ginseng C.A. Meyer (Araliaceae), a popular tonic and dietetic herbal medicine, has been traditionally prescribed in China and other countries to treat affective disorders. The medicinal parts of ginseng, the roots and flower buds, have become increasingly popular as dietary supplements due to the current holistic healthcare trend. We have investigated for the first time the antidepressive actions of the different medicinal parts, namely, the main roots, fibrous roots, and flower buds (in water extract and powder), of garden-cultivated ginseng through behavioral and drug-induced tests in mice. The water extracts, but not the powders of ginseng fibrous roots, flower buds, and main roots (1.5 g of crude drug per kilogram, p.o.), significantly reduced the immobility time in the forced swim test (FST) and tail suspension test (TST); moreover, the water extracts enhanced the 5-hydroxytryptophan (5-HTP)-induced head-twitch response and antagonized the action of reserpine in the mouse. We then explored the antidepressive mechanism of action of the ginsenoside Rb1 (Rb1) related to the brain-derived neurotrophic factor (BDNF) and its downstream proteins in mice exposed to chronic unpredictable mild stress (CUMS). Treatment with Rb1 (20 mg/kg, p.o.) for 21 days significantly attenuated the CUMS-induced decrease in the activities of BDNF, tropomyosin-related kinase B (TrkB), protein kinase B (AKT), extracellular regulatory protein kinase (ERK), and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) in the mouse hippocampal CA3 region and prefrontal cortex (PFC). Interestingly, treatment with the novel TrkB antagonist ANA-12 (0.5 mg/kg, i.p.) did not alter the level of BDNF but significantly blocked the antidepressive effects of Rb1 on proteins downstream of BDNF in CUMS-treated mice. These results suggest that BDNF–TrkB–CREB signaling may be involved in the antidepressive mechanism of the action of Rb1.

The Glucosinolates: A Sulphur Glucoside Family of Mustard Anti-Tumour and Antimicrobial Phytochemicals of Potential Therapeutic Application

This study reviewed aspects of the biology of two members of the glucosinolate family, namely sinigrin and glucoraphanin and their anti-tumour and antimicrobial properties. Sinigrin and glucoraphanin are converted by the β-sulphoglucosidase myrosinase or the gut microbiota into their bioactive forms, allyl isothiocyanate (AITC) and sulphoraphanin (SFN) which constitute part of a sophisticated defence system plants developed over several hundred million years of evolution to protect them from parasitic attack from aphids, ticks, bacteria or nematodes. Delivery of these components from consumption of cruciferous vegetables rich in the glucosinolates also delivers many other members of the glucosinolate family so the dietary AITCs and SFN do not act in isolation. In vitro experiments with purified AITC and SFN have demonstrated their therapeutic utility as antimicrobials against a range of clinically important bacteria and fungi. AITC and SFN are as potent as Vancomycin in the treatment of bacteria listed by the World Health Organisation as antibiotic-resistant “priority pathogens” and also act as anti-cancer agents through the induction of phase II antioxidant enzymes which inactivate potential carcinogens. Glucosinolates may be useful in the treatment of biofilms formed on medical implants and catheters by problematic pathogenic bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus and are potent antimicrobials against a range of clinically important bacteria and fungi. The glucosinolates have also been applied in the prevention of bacterial and fungal spoilage of food products in advanced atmospheric packaging technology which improves the shelf-life of these products.

Sulforaphane - role in aging and neurodegeneration

In the last several years, numerous molecules derived from plants and vegetables have been tested for their antioxidant, anti-inflammatory, and anti-aging properties. One of them is sulforaphane (SFN), an isothiocyanate present in cruciferous vegetables. SFN activates the antioxidant and anti-inflammatory responses by inducing Nrf2 pathway and inhibiting NF-κB. It also has an epigenetic effect by inhibiting HDAC and DNA methyltransferases and modifies mitochondrial dynamics. Moreover, SFN preserves proteome homeostasis (proteostasis) by activating the proteasome, which has been shown to lead to increased cellular lifespan and prevent neurodegeneration. In this review, we describe some of the molecular and physical characteristics of SFN, its mechanisms of action, and the effects that SFN treatment induces in order to discuss its relevance as a "miraculous" drug to prevent aging and neurodegeneration.

Effects of sulforaphane in the central nervous system

Sulforaphane (SFN) is an active component extracted from vegetables like cauliflower and broccoli. Activation of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling is a common mechanism for the anti-oxidative and anti-inflammatory activity of some herb-derived compounds, such as icariin and berberine. However, due to its peculiar ability in Nrf2 activation, SFN is recognized as an activator of Nrf2 and recommended as a supplementation for prevention and/or treatment of disorders like neoplasm and heart failure. In the central nervous system (CNS), the prophylactic and/or therapeutic effects of SFN have been revealed in recent years. For example, it has been reported to prevent the progression of Alzheimer's disease, Parkinson's disease, cerebral ischemia, Huntington's disease, multiple sclerosis, epilepsy, and psychiatric disorders via promotion of neurogenesis or inhibition of oxidative stress and neuroinflammation. SFN is also implicated in reversing cognition, learning, and memory impairment in rodents induced by scopolamine, lipopolysaccharide, okadaic acid, and diabetes. In models of neurotoxicity, SFN has been shown to suppress neurotoxicity induced by a wide range of toxic factors, such as hydrogen peroxide, prion protein, hyperammonemia, and methamphetamine. To date, no consolidated source of knowledge about the pharmacological effects of SFN in the CNS has been presented in the literature. In this review, we summarize and discuss the pharmacological effects of SFN as well as their possible mechanisms in prevention and/or therapy of disorders afflicting the CNS, aiming to get a further insight into how SFN affects the pathophysiological process of CNS disorders.

Actions of Brain-Derived Neurotrophin Factor in the Neurogenesis and Neuronal Function, and Its Involvement in the Pathophysiology of Brain Diseases

It is well known that brain-derived neurotrophic factor, BDNF, has an important role in a variety of neuronal aspects, such as differentiation, maturation, and synaptic function in the central nervous system (CNS). BDNF stimulates mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), phosphoinositide-3kinase (PI3K), and phospholipase C (PLC)-gamma pathways via activation of tropomyosin receptor kinase B (TrkB), a high affinity receptor for BDNF. Evidence has shown significant contributions of these signaling pathways in neurogenesis and synaptic plasticity in in vivo and in vitro experiments. Importantly, it has been demonstrated that dysfunction of the BDNF/TrkB system is involved in the onset of brain diseases, including neurodegenerative and psychiatric disorders. In this review, we discuss actions of BDNF and related signaling molecules on CNS neurons, and their contributions to the pathophysiology of brain diseases.