Neurotoxicity In Rats Research Articles

Developmental neuro-toxicity evaluation of endocrine-disrupting chemical butylparaben

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

High affinity of β-amyloid proteins to cerebral capillaries: implications in chronic lead exposure-induced neurotoxicity in rats

Lead (Pb) is a known environmental risk factor in the etiology of Alzheimer’s disease (AD). The existing reports suggest that Pb exposure increases beta-amyloid (Aβ) levels in brain tissues and cerebrospinal fluid (CSF) and facilitates the formation of amyloid plaques, which is a pathological hallmark for AD. Pb exposure has long been associated with cerebral vasculature injury. Yet it remained unclear if Pb exposure caused excessive Ab buildup in cerebral vasculature, which may damage the blood–brain barrier and cause abnormal Ab accumulation. This study was designed to investigate the impact of chronic Pb exposure on Aβ accumulation in cerebral capillary and the expression of low-density lipoprotein receptor protein-1 (LRP1), a critical Aβ transporter, in brain capillary and parenchyma. Sprague–Dawley rats received daily oral gavage at doses of 0, 14 (low-dose), and 27 (high-dose) mg Pb/kg as Pb acetate, 5 d/wk, for 4 or 8 wks. At the end of Pb exposure, a solution containing Aβ40 was infused into the brain via the cannulated internal carotid artery. Data by ELISA showed a strikingly high affinity of Ab to cerebral vasculature, which was approximately 7–14 times higher than that to the parenchymal fractions collected from control brains. Pb exposure further aggravated the Aβ accumulation in cerebral vasculature in a dose-dependent manner. Western blot analyses revealed that Pb exposure decreased LRP1 expression in cortical capillaries and hippocampal parenchyma. Immunohistochemistry (IHC) studies further revealed a disrupted distribution of LRP1 alongside hippocampal vasculature accompanied with a decreased expression in hippocampal neurons by Pb exposure. Taken together, the current study demonstrated that the cerebral vasculature naturally possessed a high affinity to Aβ present in circulating blood. Pb exposure significantly increased Aβ accumulation in cerebral vasculature; such an increased Aβ accumulation was due partly to the diminished expression of LRP1 in response to Pb in tested brain regions. Perceivably, Pb-facilitated Ab aggravation in cerebral vasculature may contribute to Pb-associated amyloid alterations.

Neonatal sevoflurane exposure induces long-term changes in dendritic morphology in juvenile rats and mice.

General anesthetics are potent neurotoxins when given during early development, causing apoptotic deletion of substantial number of neurons and persistent neurocognitive and behavioral deficits in animals and humans. The period of intense synaptogenesis coincides with the peak of susceptibility to deleterious effects of anesthetics, a phenomenon particularly pronounced in vulnerable brain regions such as subiculum. With steadily accumulating evidence confirming that clinical doses and durations of anesthetics may permanently alter the physiological trajectory of brain development, we set out to investigate the long-term consequences on dendritic morphology of subicular pyramidal neurons and expression on genes regulating the complex neural processes such as neuronal connectivity, learning, and memory. Using a well-established model of anesthetic neurotoxicity in rats and mice neonatally exposed to sevoflurane, a volatile general anesthetic commonly used in pediatric anesthesia, we report that a single 6 h of continuous anesthesia administered at postnatal day (PND) 7 resulted in lasting dysregulation in subicular mRNA levels of cAMP responsive element modulator (Crem), cAMP responsive element-binding protein 1 (Creb1), and Protein phosphatase 3 catalytic subunit alpha, a subunit of calcineurin (Ppp3ca) (calcineurin) when examined during juvenile period at PND28. Given the critical role of these genes in synaptic development and neuronal plasticity, we deployed a set of histological measurements to investigate the implications of anesthesia-induced dysregulation of gene expression on morphology and complexity of surviving subicular pyramidal neurons. Our results indicate that neonatal exposure to sevoflurane induced lasting rearrangement of subicular dendrites, resulting in higher orders of complexity and increased branching with no significant effects on the soma of pyramidal neurons. Correspondingly, changes in dendritic complexity were paralleled by the increased spine density on apical dendrites, further highlighting the scope of anesthesia-induced dysregulation of synaptic development. We conclude that neonatal sevoflurane induced persistent genetic and morphological dysregulation in juvenile rodents, which could indicate heightened susceptibility toward cognitive and behavioral disorders we are beginning to recognize as sequelae of early-in-life anesthesia.

Evaluation of Neurotoxicity With Human Pluripotent Stem Cell–Derived Cerebral Organoids

The recent development of human cerebral organoids provides an invaluable in vitro model of human brain development to assess the toxicity of natural or man-made toxic substances. By recapitulating key aspects of early human neurodevelopment, investigators can evaluate with this three-dimensional (3D) model the effect of certain compounds on the formation of neuronal networks and their electrophysiological properties with more physiological relevance than neurons grown in monolayers and in cultures composed of a unique cell type. This promising potential has contributed to the development of a large number of diverse protocols to generate human cerebral organoids, making interlaboratory comparisons of results difficult. Based on a previously published protocol to generate human cortical organoids (herein called cerebral organoids), we detail several approaches to evaluate the effect of chemicals on neurogenesis, apoptosis, and neuronal function when exogenously applied to cultured specimens. Here, we take as an example 4-aminopyridine, a potassium channel blocker that modulates the activity of neurons and neurogenesis, and describe a simple and cost-effective way to test the impact of this agent on cerebral organoids derived from human induced pluripotent stem cells. We also provide tested protocols to evaluate neurogenesis in cerebral organoids with ethynyl deoxyuridine labeling and neuronal activity with live calcium imaging and microelectrode arrays. Together, these protocols should facilitate the implementation of cerebral organoid technologies in laboratories wishing to evaluate the effects of specific compounds or conditions on the development and function of human neurons with only basic cell culture equipment. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Generation of human cerebral organoids from pluripotent stem cells Support Protocol 1: Human pluripotent stem cell culture Basic Protocol 2: Evaluation of neurogenesis in cerebral organoids with ethynyl deoxyuridine labeling Basic Protocol 3: Calcium imaging in cerebral organoids Basic Protocol 4: Electrophysiological evaluation of cerebral organoids with microelectrode arrays Support Protocol 2: Immunostaining of cerebral organoids.

Combining tissue clearing and Fluoro-Jade C labeling for neurotoxicity assessments.

Tissue clearing refers to laboratory methods that make tissue transparent by chemical means. This approach allows the labeling, visualization, and analysis of specific targets without cutting the tissue into sections, thereby maintaining three-dimensional architecture. More than two dozen tissue-clearing methods have been developed by different research teams to date. While tissue clearing has been successfully applied in several studies concerning basic science or diseases, little is known about the utilization of tissue clearing for neurotoxicity evaluation. In this study, several tissue-clearing methods were combined with Fluoro-Jade C (FJ-C), a standard marker of neurodegeneration. The results suggest that some but not all tissue-clearing media are compatible with the FJ-C fluorophore. By utilizing a neurotoxicity animal model, the results further suggest that FJ-C labeling can be combined with tissue clearing for neurotoxicity assessments. This approach has the potential to be expanded further by combining multicolor labeling of molecular targets involved in the development and/or mechanisms of neurotoxicity and neurodegeneration.

Vasicinone, a pyrroloquinazoline alkaloid from Adhatoda vasica Nees enhances memory and cognition by inhibiting cholinesterases in Alzheimer's disease

BackgroundAlzheimer's disease (AD) is a neurodegenerative disease with cognitive and memory decline. Due to the lack of effective treatment for AD, there is an interest in finding novel compounds to treat AD. The leaves of Adhatoda vasica Nees (AV) exhibited anti-AD effects and known to be rich in pyrroloquinazoline alkaloids. However, the role of pyrroloquinazoline alkaloids as an anti-AD was not explored. Therefore, the present study aimed to isolate active pyrroloquinazoline alkaloids through bioactivity guided fractionation from AV to explore their anti-AD effect. MethodColumn chromatography of dichloromethane (DCM) fraction of methanolic extract was used to isolate the alkaloids from AV. The isolated compounds were characterized by TLC, HPLC, ATR, HRMS, and NMR techniques. In-silico, studies were performed to investigate the interaction of the isolated compounds with cholinesterase enzymes (AChE and BuChE). Further, in-vitro assays were carried out to evaluate the AChE, BuChE, and Aβ inhibition properties. Propidium iodide displacement assay was performed to know the selectivity of isolated compounds at AChE PAS site. Furthermore, in-vivo studies were performed to evaluate memory and cognitive improvement against scopolamine-induced amnesia and Aβ induced neurotoxicity in rats. ResultsA couple of leads were identified through bioactivity guided fractionation, such as vasicinone (VAS) and vasicine (VA) were responsible for the cholinesterase inhibition in DCM fraction. In-silico studies identified that both compounds exhibited stable interactions at AChE and BuChE active sites. VAS and VA inhibited the AChE, BuChE, and Aβ aggregation in-vitro studies and effectively displaced the propidium iodide at AChE PAS site. Further, in-vivo studies showed that administration of VAS and VA significantly improved the memory and cognitive dysfunction in scopolamine and Aβ induced cognitive and memory impairments in rats. Besides, both VAS and VA recovered the hippocampal cell density in AD rats. Moreover, VAS and VA did not show any sign of toxicity. ConclusionsThe present study revealed that VAS acts as potent anti-AD agent from Adhatoda vasica Nees and it showed similar potency profile to VA against memory and cognitive impairment in AD. Both compounds VAS and VA possess strong potential in the preclinical development as natural drugs for anti-AD.

RETRACTION NOTICE: Molecular mechanism of electroacupuncture treatment on oxaliplatin-induced peripheral neurotoxicity in rats

RETRACTION NOTICE: Molecular mechanism of electroacupuncture treatment on oxaliplatin-induced peripheral neurotoxicity in rats

Apigenin Attenuates Hippocampal Microglial Activation and Restores Cognitive Function in Methotrexate-Treated Rats: Targeting the miR-15a/ROCK-1/ERK1/2 Pathway

Microglial activation underpins the methotrexate (MTX)-induced neurotoxicity; however, the precise mechanism remains unclear. This study appraised the potential impact of apigenin (Api), a neuroprotective flavonoid, in MTX-induced neurotoxicity in rats in terms of microglial activation through targeting the miR-15a/Rho-associated protein kinase-1 (ROCK-1)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Male Sprague Dawley rats were randomly divided into 4 groups: Normal control (saline i.p. daily and i.v. on days 8 and 15); Api control (20 mg/kg, p.o.) daily for 30 days; MTX-alone (75 mg/kg, i.v.) on days 8 and 15, then four i.p. injections of leucovorin (LCV): 6 mg/kg after 18 h, then three doses (3 mg/kg) every 8 h post-MTX; and Api co-treated (20 mg/kg/day, p.o.) throughout the model for 30 days, with administration of MTX and LCV as in group 3. MTX administration elevated hippocampal ionized calcium-binding adaptor protein-1 (Iba-1) immunostaining, indicating microglial activation. This was accompanied by neuroinflammation, oxidative stress, and enhanced apoptosis manifested by elevated hippocampal interleukin-1β, malondialdehyde, and caspase-3, and decreased reduced glutathione levels. Concurrently, abated miR-15a expression, overexpression of its target ROCK-1, diminished downstream ERK1/2 and cAMP response element-binding protein (CREB) phosphorylation, and decreased hippocampal brain-derived neurotrophic factor (BDNF) levels were observed. Api mitigated the MTX-induced neurotoxicity by reversing the biochemical, histopathological, and behavioral derangements tested by novel object recognition and Morris water maze tests. Conclusively, Api lessens MTX-induced neuroinflammation, oxidative stress, and apoptosis and boosts cognitive function through inhibiting microglial activation via modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway.Graphical Graphical abstract showing the effects of methotrexate and apigenin co-treatment in MTX-induced neurotoxicity model.On the left, methotrexate (MTX) administration to rats resulted in hippocampal miR-15a downregulation, which triggered an enhanced expression of its target ROCK-1, consequently inhibiting the downstream ERK1/2/CREB/BDNF pathway, instigating a state of microglial activation, neuroinflammation, oxidative stress, and apoptosis. On the other hand, apigenin (Api) co-treatment restored miR-15a, inhibited ROCK-1 expression, and activated the ERK1/2/CREB/BDNF pathway, leading to diminished hippocampal microglial activation, neuroinflammation, and apoptosis, and restoration of the redox balance, along with improvement in memory and cognitive function of the MTX-treated rats.

Neuroprotective Effects of Nano-Curcumin against Cypermethrin Associated Oxidative Stress and Up-Regulation of Apoptotic and Inflammatory Gene Expression in Rat Brains.

Cypermethrin (CPM) is the most toxic synthetic pyrethroid that has established neurotoxicity through oxidative stress and neurochemical agitation in experimental rats. The toxic effects are supposed to be mediated by modifying the sodium channels, reducing Na-K ATPase, acetylcholine esterase (AchE), and monoamine oxidase (MAO). The use of curcumin nanoparticles (NC) that have potent antioxidant, anti-inflammatory and antiapoptotic properties with improved bioavailability attenuates neurotoxicity in rat brains. To test this hypothesis, animals were divided into five groups, each having six animals. Group-I control received vehicle only, while Group-II was treated with 50 mg/kg CPM. Group-III and Group-IV received both CPM and NC 2.5 mg/kg and 5 mg/kg, respectively. Group-V received 5 mg of NC alone. The CPM and NC were given by oral route. Afterwards, brain antioxidant status was measured by assessing lipid peroxidation (LPO), 4-HNE, glutathione reduced (GSH), antioxidant enzyme catalase, and superoxide dismutase (SOD) along with neurotoxicity markers Na-K ATPase, AchE, and MAO. Inflammation and apoptosis indices were estimated by ELISA, qRT-PCR, and immunohistochemistry, while morphologic changes were examined by histopathology. Observations from the study confirmed CPM-induced neurotoxicity by altering Na-K ATPase, AchE, and MAO, and by decreasing the activity of antioxidant enzymes and GSH. Oxidative stress marker LPO and the level of inflammatory interleukins IL-6, IL-1β, and TNF-α were notably high, and elevated expressions of Bax, NF-kB, and caspase-3 and -9 were reported in CPM group. However, NC treatment against CPM offers protection by improving antioxidant status and lowering LPO, inflammation, and apoptosis. The neurotoxicity marker's enzyme successfully attenuated after NC treatment. Therefore, this study supports the administration of NC effectively ameliorated CPM-induced neurotoxicity in experimental rats.

Evaluation of BDE-47-induced neurodevelopmental toxicity in zebrafish embryos.

There are growing concerns about the neurodevelopmental toxicity of polybrominated diphenyl ethers (PBDEs), but the toxicological phenotypes and mechanisms are not well elucidated. Here, zebrafish (Danio rerio) were exposed to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) from 4 to 72 h post-fertilization (hpf). The results showed that BDE-47 stimulated the production of dopamine and 5-hydroxytryptamine, but inhibited expression of Nestin, GFAP, Gap43, and PSD95 in 24 hpf embryos. Importantly, we unraveled the inhibitory effects of BDE-47 on neural crest-derived melanocyte differentiation and melanin syntheses process, evidenced by disrupted expression of wnt1, wnt3, sox10, mitfa, tyrp1a, tyrp1b, tryp2, and oca2 gene in 72 hpf embryos and decreased tyrosinase activities in embryos at 48 and 72 hpf. The transcriptional activities of myosin VAa, kif5ba, rab27a, mlpha, and cdc42 genes, which are associated with intracellular transport process, were also disturbed during zebrafish development. Ultimately, these alterations led to fast spontaneous movement and melanin accumulation deficit in zebrafish embryos upon BDE-47 exposure. Our results provide an important extension for understanding the neurodevelopmental effects of PBDEs and facilitate the comprehensive evaluation of neurotoxicity in embryos.

Intraperitoneal pretreatment of ellagic acid and chrysin alleviate ifosfamide-induced neurotoxicity, but betanin induces death in male wistar rats.

Ifosfamide (IFO) is a widely used antineoplastic drug with broad-spectrum efficacy against various types of cancer. However, different toxicities associated with IFO has limited its use. This study was to establish the prophylactic effects of betanin, chrysin and ellagic acid against IFO-induced neurotoxicity in rats. Animals were randomly divided into eight groups, control, IFO, IFO + betanin, IFO + chrysin, IFO + ellagic acid, betanin, chrysin and ellagic acid groups. Betanin (50mg/kg, i.p.), chrysin (25mg/kg, i.p.) and ellagic acid (25mg/kg, i.p.) were administered to rats once daily for two consecutive days. IFO (500mg/kg, i.p.) was administered on third day. Results demonstrated that only ellagic acid markedly decreased the activity of acetylcholinesterase (AChE) and butrylcholinesterase (BChE) compared with IFO alone, while chrysin was only effective on BChE activity. Also, ellagic acid ameliorated IFO-induced lipid peroxidation and glutathione (GSH) depletion, while chrysin only decreased GSH depletion. Histopathological alteration in the IFO-induced brain tissues were decreased especially after administration of ellagic acid. Intraperitoneal pretreatment with betanin, followed by IFO resulted in death of all treated animals. In addition, all mitochondrial toxicity parameters induced by IFO in the rat brain tissue were ameliorated by ellagic acid, chrysin and even betanin. Taken together, our results demonstrated that especially ellagic acid and to some extent chrysin show a typical neuroprotective effect on IFO-induced acute neurotoxicity through mitochondrial protection and antioxidant properties. Also, the results of our studies showed that pretreatment with betanin followed by IFO was lethal.

Neuroprotective effect of quercetin and Zingiber officinale on sodium arsenate-induced neurotoxicity in rats.

The study was aimed at determining the ameliorative potential of quercetin and Zingiber officinale (ZO) against sodium arsenate-induced neurotoxicity in male Wistar rats. Thirty adult animals were randomly allocated to five groups (n=6). Group I served as control, groups II and IV were treated with ZO [300 mg/kg, PO (per os)/day], and group V animals were administered quercetin (50 mg/kg, PO/day) for 18 days. Groups III, IV, and V were injected with sodium arsenate (20 mg/kg, intraperitoneally/day) for 4 days starting from day 15. The administration of sodium arsenate resulted in a significant decrease in total antioxidant status, total thiols, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and aryl esterase in brain tissue of the animals compared with the control group. In addition, a significant increase was observed in malondialdehyde, advanced oxidation protein product and plasma nitric oxide levels, indicating oxidative stress-mediated neuronal damage. However, these arsenic-induced alterations were significantly reversed by quercetin or ZO in the treatment groups, indicating their ameliorative potential. These positive effects were further confirmed by histopathological examination of brain tissue revealing the suppression of severe neuronal injury, spongiosis and gliosis in the samples pretreated with quercetin and ZO. Our results suggest that inclusion of ZO and quercetin-rich foods in the diet can help in preventing the neurotoxic effects in areas with elevated levels of arsenic in food chain and ground water.

Vitamin D3 promotes oligodendrogenesis and modulates synucleinopathy in lead-induced nigral pars compacta neurotoxicity in rats.

Lead-induced neurotoxicity was marked with locomotor and Parkinsonian-like changes. Oligodendrocytes and synucleinopathy were signed to in the pathophysiology of some neurodegenerative diseases. Vitamin D3's (D3) role in substantia nigra pars compacta (SNpc) disorders is debated between neuroscientists. The aim of the study was to investigate lead-induced SNpc neurotoxic changes and explore the possible neuroprotective role of D3 and the possible involvement of oligodendrocytes and α-synuclein. This study included 40 adult Wistar rats assigned into four equal groups: control, lead (Pb) (in drinking water, 1,000 mg/L), Pb + D3 (D3 injection, 1,000 IU/kg IM; 3 days/week), and D3. After 8 weeks, the rats were sacrificed, and their midbrain underwent biochemical and immunoblotting analysis. Midbrain paraffin blocks were stained for histological and immunohistochemical assessment. Lead (Pb) had increased significantly (p < 0.05) nigral α-synuclein and caspase-11 by immunoblotting analysis. Histologically, it induced neurodegeneration in SNpc and significantly decreased neuronal cell density by cresyl violet staining. Pb also significantly reduced SNpc tyrosine hydroxylase immunoreaction, significantly elevated glial fibrillatory acid protein (GFAP) and α-synuclein immunoreaction associated with a mild but significant increase in caspase-3. In the Pb + D3 group, all the previous deleterious changes were significantly alleviated in addition to significant upregulation of anti-oligodendrocytes immunoexpression. Lead (Pb) may induce SNpc neurotoxicity presumably via activation of caspase-11 and α-synuclein. D3 may modulate this neurotoxicity probably through an oligodendrogenic effect.

Sea urchin (Diadema savignyi) extract as a novel protective agent against cisplatin induced neurotoxicity in rats

Neurotoxicity is a severe side effect of platinum compounds used for cancer chemotherapy such as Cisplatin. This neurotoxicity leads to severe cognitive and nervous dysfunction, therefore, limiting the dose of Cisplatin and compromising the treatment protocol.The present study investigates the neuroprotective effect of Sea Urchins which is a marine animal known for its rich bioactive compounds. Male Sprague Dawley rats received Cisplatin (2 mg/kg body weight) for 4 weeks, two times per week, followed by Sea Urchin extracts (50 and 100 mg/kg body weight) twice weekly for 4 weeks.Results show that rats treated with Urchin’s extracts showed a significant improvement in the thermal (heat and cold) sensitivity compared to untreated rats. Liver enzymes Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) and Urea levels were also significantly decreased back to normal following treatment with sea urchin extracts. Brain tissue oxidative stress marker Nitric oxide (NO) and lipid peroxidation marker Malondialdehyde (MDA) increased significantly in the cisplatin-treated rats while the reduced glutathione levels (GSH) and catalase activity (CAT) showed a significant decrease. Treatment with sea Urchin extracts reversed these changes.Histological and immunohistochemical examination of the cerebral cortex reveled degenerative changes such as karyopyknosis and shrunken necrotic ghost like neurons in the cisplatin treated groups. There was also strong positive Glial fibrillary acidic protein (GFAP) reactivity and a negative B-cell leukemia/lymphoma 2 protein (Bcl2) reaction in most apparent neurons, indicating strong apoptotic changes. Treatment with Urchin extracts reversed these changes. Quantification of cerebral cortex neurons also revealed the strong effect of the extracts. Cisplatin treated groups showed 3708 cells/ mm3 compared to 8091 cells/mm3 in the normal rats. Extract treatment increased the neuronal numbers to almost normal levels. Quantification of the Immuno-histochemical expression of GFAP showed an increase by 10-folds after cisplatin administration. A remarkable decline from the cisplatin group was seen in the extract treated groups.In Conclusion, Sea Urchins extracts possess a strong neuroprotective activity and could provide a novel therapeutic method to prevent Cisplatin-induced neurotoxicity.

Protective effect of compatible herbs in Jin-Gu-Lian formula against Alangium chinense-induced neurotoxicity via oxidative stress, neurotransmitter metabolisms, and pharmacokinetics.

Background: A. chinense frequently used in Miao medicine to treat rheumatic diseases. However, as a famous toxic herb, Alangium chinense and its representative components exhibit ineluctable neurotoxicity, thus creating significant challenges for clinical application. The combined application with compatible herbs in Jin-Gu-Lian formula attenuates such neurotoxicity according to the compatible principle of traditional Chinese medicines. Purpose: We aimed to investigate the detoxification of the compatible herbs in Jin-Gu-Lian formula on A. chinense-induced neurotoxicity and investigate its mechanism. Methods: Neurobehavioral and pathohistological analysis were used to determine the neurotoxicity in rats administered with A. chinense extract (AC), extract of compatible herbs in Jin-Gu-Lian formula (CH) and combination of AC with CH for 14days. The mechanism underlying the reduction of toxicity by combination with CH was assessed by enzyme-linked immunosorbent assays, spectrophotometric assays, liquid chromatography tandem-mass spectrometry and real-time reverse transcription-quantitative polymerase chain reaction. Results: Compatible herbs attenuated the AC-induced neurotoxicity as evidenced by increased locomotor activity, enhanced grip strength, the decreased frequency of AC-induced morphological damage in neurons, as well as a reduction of neuron-specific enolase (NSE) and neurofilament light chain (NEFL) levels. The combination of AC and CH ameliorated AC-induced oxidative damage by modulating the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC). AC treatment significantly reduced the levels of monoamine and acetylcholine neurotransmitters in the brains of rats, including acetylcholine (Ach), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), norepinephrine (NE), and serotonin (5-HT). Combined AC and CH treatment regulated the abnormal concentrations and metabolisms of neurotransmitters. Pharmacokinetic studies showed that the co-administration of AC and CH significantly decreased plasma exposure levels of two main components of AC, as evidenced by the reduction of maximum plasma concentration (Cmax), area under the plasma concentration-time curve (AUC) compared to AC. In addition, the AC-induced downregulation in mRNA expression of cytochrome P450 enzymes was significantly reduced in response to combined AC and CH treatment. Conclusion: Compatible herbs in Jin-Gu-Lian formula alleviated the neurotoxicity induced by A. chinense by ameliorating oxidative damage, preventing abnormality of neurotransmitters and modulating pharmacokinetics.

Antidiabetic drug sitagliptin blocks cyclophosphamide cerebral neurotoxicity by activating Nrf2 and suppressing redox cycle imbalance, inflammatory iNOS/NO/NF-κB response and caspase-3/Bax activation in rats

Cyclophosphamide (CYP) is a classic DNA-interacting anticancer agent with broad application in chemotherapy. However, CYP cerebral neurotoxicity is a worrisome side effect for clinicians and patients. Strategies to mitigate the underlying oxidative inflammatory cascades and neuroapoptosis induced by CYP are urgently needed. Herein, we have repurposed an antidiabetic drug, sitagliptin (STG), for a possible abrogation of CYP-induced cerebral neurotoxicity in rats. Healthy rats were administered STG (20 mg/kg body weight) for 5 days prior to neurotoxicity induced by CYP (200 mg/kg body weight, ip) on day 5 only, and rats were sacrificed after 24 h post-CYP injection. CYP caused profound increases in the cerebral levels of nitric oxide (NO), acetylcholinesterase (AChE), malondialdehyde (MDA), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), nuclear factor-kappaB (NF-κB), inducible nitric oxide synthase (iNOS), caspase-3 and Bax protein compared to the control. Furthermore, CYP markedly depressed the activities of glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD), along with levels of reduced glutathione (GSH) and nuclear factor erythroid 2-related factor2 (Nrf2) compared to the control (p < 0.05). Interestingly, STG pretreatment inhibited the CYP-induced alterations in caspase-3, Bax, pro-inflammatory cytokines, NO, iNOS, AChE, NF-κB, and restored the cerebral antioxidant apparatus, including the Nrf2 and histopathological abrasions. Therefore, these findings show that STG could be repurposed to prevent CYP-induced cerebral toxicity in the brain.

Amelioration of AlCl3-induced Memory Loss in the Rats by an Aqueous Extract of Guduchi, a Medhya Rasayana

Background In ayurvedic practice, the Guduchi ( Tinospora cordifolia (Willd.) Miers) stem is used as a Medhya drug for its beneficial effects on memory improvement. Objectives The current study was planned to explore the Medhya properties of the Guduchi stem extract by observing its ameliorating effect on AlCl3-induced neurotoxicity in rats that acted as a chronic model of memory loss. Materials and Methods The aqueous extract of the Guduchi stem was prepared per the Ayurvedic Pharmacopoeia of India and administered to the AlCl3-treated Wistar rats for 42 days. The biochemical assessment of the brain tissues of the treated animals was done by the acetylcholinesterase (AChE) inhibition assay, protein expression, and oxidative stress assays, namely lipid peroxidation, reduced glutathione, superoxide dismutase, and catalase assay. The neurobehavioral assessment was done using the elevated plus maze (EPM) test. Results The EPM test revealed that treatment with Guduchi extract showed marked improvement of memory status in rats along with reduced oxidative stress, and a marked modulation of the AChE inhibition and expression of AChE tubulin proteins. Conclusion The results substantiate the Medhya properties of the Guduchi. Detailed investigations are required to be carried out to explore the precise mechanism of the neuroprotective action of the Guduchi stem extract against the AlCl3-induced neurotoxicity in rats.

Calpain-TRPC6 signaling pathway contributes to propofol-induced developmental neurotoxicity in rats

Growing animal studies suggest a risk of neuronal damage following early childhood exposure to anesthesia and sedation drugs including propofol. Inhibition of transient receptor potential canonical 6 (TRPC6) degradation has been shown to protect neurons from neuronal damage induced by multiple brain injury models. Our aim was to investigate whether calpain-TRPC6 pathway is a target in propofol-induced neurotoxicity. Postnatal day (PND) 7 rats were exposed to five bolus injections of 25 mg/kg propofol or 10 % intralipid at hourly intervals. Neuronal injury was assessed by the expression pattern of TUNEL staining and cleaved–caspase-3. The Morris water maze test was used to evaluate learning and memory functions in later life. Pretreatments consisting of intracerebroventricular injections of a TRPC6 agonist, TRPC6 inhibitor, or calpain inhibitor were used to confirm the potential role of the calpain-TRPC6 pathway in propofol-induced neurotoxicity. Prolonged exposure to propofol induced neuronal injury, downregulation of TRPC6, and enhancement of calpain activity in the cerebral cortex up to 24 h after anesthesia. It also induced long-term behavioral disorders, manifesting as longer escape latency at PND40 and PND41 and as fewer platform-crossing times and less time spent in the target quadrant at PND42. These propofol-induced effects were attenuated by treatment with the TRPC6 agonist and exaggerated by the TRPC6 inhibitor. Pretreatment with the calpain inhibitor alleviated the propofol-induced TRPC6 downregulation and neuronal injury in the cerebral cortex. In conclusion, our data suggest that a calpain-TRPC6 signaling pathway contributes to propofol-induced acute cortical neuron injury and long-term behavioral disorders in rats.

Human Astrocyte Spheroids as Suitable In Vitro Screening Model to Evaluate Synthetic Cannabinoid MAM2201-Induced Effects on CNS.

There is growing concern about the consumption of synthetic cannabinoids (SCs), one of the largest groups of new psychoactive substances, its consequence on human health (general population and workers), and the continuous placing of new SCs on the market. Although drug-induced alterations in neuronal function remain an essential component for theories of drug addiction, accumulating evidence indicates the important role of activated astrocytes, whose essential and pleiotropic role in brain physiology and pathology is well recognized. The study aims to clarify the mechanisms of neurotoxicity induced by one of the most potent SCs, named MAM-2201 (a naphthoyl-indole derivative), by applying a novel three-dimensional (3D) cell culture model, mimicking the physiological and biochemical properties of brain tissues better than traditional two-dimensional in vitro systems. Specifically, human astrocyte spheroids, generated from the D384 astrocyte cell line, were treated with different MAM-2201 concentrations (1-30 µM) and exposure times (24-48 h). MAM-2201 affected, in a concentration- and time-dependent manner, the cell growth and viability, size and morphological structure, E-cadherin and extracellular matrix, CB1-receptors, glial fibrillary acidic protein, and caspase-3/7 activity. The findings demonstrate MAM-2201-induced cytotoxicity to astrocyte spheroids, and support the use of this human 3D cell-based model as species-specific in vitro tool suitable for the evaluation of neurotoxicity induced by other SCs.

Neuro-protective potentials of N-acetylcysteine and zinc against di(2-ethylhexyl)-phthalate-induced neuro-histopathology and dys-regulations of Dopamine and Glutamate in rat brain

This study examined neuro-protective potentials of N-acetyl-cysteine (NAC) and Zinc on expression levels of Dopamine and Glutamate in the Cerebrum, Hypothalami and Pituitary Glands in Di(2-ethylhexyl)-phthalate (DEHP)-induced neurotoxicity in rats. Thirty-six adult male Wistar rats were randomly divided into 6 groups (n = 6). Group 1 was control. Groups 2-6 received oral administrations of 100 mg/kg NAC, 0.5 mg/kg Zinc, 750 mg/kg DEHP, DEHP + NAC doses and DEHP + Zinc doses respectively for 21 days. Brain histology (Heamatoxyline and Eosine technique), histochemical and enzyme-linked-immunosorbent assays of Dopamine and Glutamate in homogenates of Cerebrum, Hypothalami and Pituitary Glands were evaluated. Data were statistically analyzed using One-way-ANOVA with Tukey-post-hoc test at p ≤ 0.05. Histo-pathological evaluations of Cerebrum, Hypothalami and Pituitary Glands showed gross histo-alterations and neurodegenerative changes (Group 4), mild histo- and neuro-degenerative changes (Groups 5 and 6) and normal histology (Group 1). Histochemical analyses showed higher Dopamine levels in Hypothalami (Group 5) and Pituitary Glands (Groups 5 and 6), compared with Group 4. Furthermore, results showed lower Glutamate levels in Cerebrum, Hypothalami and Pituitary Glands of Groups 5 and 6, compared with Group 4. Overall, NAC and Zinc conferred neuro-protection and histo-protection against DEHP-induced neuro-toxicity, neuro-histopathology, decreased Dopamine levels and increased Glutamate levels.