In Vivo Brain Oxidative Stress Model Induced by Microinjection of Sodium Nitroprusside in Mice

Beyond animal models: revolutionizing neurodegenerative disease modeling using 3D in vitro organoids, microfluidic chips, and bioprinting

Neurodegenerative diseases (NDs) are characterized by uncontrolled loss of neuronal cells leading to a progressive deterioration of brain functions. The transition rate of numerous neuroprotective drugs against Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease, leading to FDA approval, is only 8-14% in the last two decades. Thus, in spite of encouraging preclinical results, these drugs have failed in human clinical trials, demonstrating that traditional cell cultures and animal models cannot accurately replicate human pathophysiology. Hence, in vitro three-dimensional (3D) models have been developed to bridge the gap between human and animal studies. Such technological advancements in 3D culture systems, such as human-induced pluripotent stem cell (iPSC)-derived cells/organoids, organ-on-a-chip technique, and 3D bioprinting, have aided our understanding of the pathophysiology and underlying mechanisms of human NDs. Despite these recent advances, we still lack a 3D model that recapitulates all the key aspects of NDs, thus making it difficult to study the ND's etiology in-depth. Hence in this review, we propose developing a combinatorial approach that allows the integration of patient-derived iPSCs/organoids with 3D bioprinting and organ-on-a-chip technique as it would encompass the neuronal cells along with their niche. Such a 3D combinatorial approach would characterize pathological processes thoroughly, making them better suited for high-throughput drug screening and developing effective novel therapeutics targeting NDs.

A novel hypothesis on metal dyshomeostasis and mitochondrial dysfunction in amyotrophic lateral sclerosis: Potential pathogenetic mechanism and therapeutic implications

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motor dysfunctions resulting from the loss of upper (UMNs) and lower (LMNs) motor neurons. While ALS symptoms are coincidental with pathological changes in LMNs and UMNs, the causal relationship between the two is unclear. For example, research on the extra-motor symptoms associated with this condition suggests that an imbalance of metals, including copper, zinc, iron, and manganese, is initially induced in the sensory ganglia due to a malfunction of metal binding proteins and transporters. It is proposed that the resultant metal dyshomeostasis may promote mitochondrial dysfunction in the satellite glial cells of these sensory ganglia, causing sensory neuron disturbances and sensory symptoms. Sensory neuron hyperactivation can result in LMN impairments, while metal dyshomeostasis in spinal cord and brain stem parenchyma induces mitochondrial dysfunction in LMNs and UMNs. These events could prompt intracellular calcium dyshomeostasis, pathological TDP-43 formation, and reactive microglia with neuroinflammation, which in turn activate the apoptosis signaling pathways within the LMNs and UMNs. Our model suggests that the degeneration of LMNs and UMNs is incidental to the metal-induced changes in the spinal cord and brain stem. Over time psychiatric symptoms may appear as the metal dyshomeostasis and mitochondrial dysfunction affect other brain regions, including the reticular formation, hippocampus, and prefrontal cortex. It is proposed that metal dyshomeostasis in combination with mitochondrial dysfunction could be the underlying mechanism responsible for the initiation and progression of the pathological changes associated with both the motor and extra-motor symptoms of ALS.

An electrochemical investigation into the effects of local and systemic administrations of sodium nitroprusside in brain extracellular fluid of mice

Sodium nitroprusside (SNP) is a nitric oxide (NO)-donor drug used clinically to treat severe hypertension, however, there are limitations associated with its mechanism of action that prevent widespread adoption. In particular, its impact on cerebral hemodynamics is controversial and direct evidence on its effects are lacking. Electrochemical methods provide an attractive option to undertake real time neurochemical measurements in situ using selective microsensors. Herein, we report the novel application of an existing platinum (Pt)-Nafion® sensor to measure the release of NO from SNP under in vitro and in vivo conditions. Initially, the temporal release of NO was measured and the effect of the reducing agent, ascorbic acid (AA), was elucidated in vitro. A combined microdialysis/NO sensor construct was implanted into the striatum of anaesthetised mice and the local perfusion of 10 mM SNP with/without AA resulted in increased NO concentration detected using the Pt-Nafion® sensor. Subsequently, the NO sensor, coupled with carbon paste electrodes (CPEs) for the electrochemical measurement of O₂, were applied to investigate SNP effects in freely moving mice. A complex mechanism of action was identified that infers NO inhibition and biphasic O₂ dynamics. The preliminary findings within support a strong cerebrovascular effect of systemic SNP administration that warrants careful consideration for clinical use.

A Simple Ex Vivo Semiquantitative Fluorescent Imaging Utilizing Planar Laser Scanner: Detection of Reactive Oxygen Species Generation in Mouse Brain and Kidney

Objective:

Oxidative stress plays an important role in the onset of many neuronal and peripheral disorders. We examined the feasibility of obtaining semiquantitative fluorescent images of reactive oxygen species (ROS) generation in mouse brain and kidney utilizing a planar laser scanner and dihydroethidium (DHE).

Methods:

To investigate ROS generation in brain, sodium nitroprusside was injected into the striatum. Dihydroethidium was injected into the tail vein. After DHE injection, tissue slices were analyzed utilizing a planar laser scanner. For kidney study, cis-diamminedichloroplatinum [II] (cisplatin) was intraperitoneally administrated into mice.

Results:

Clear and semiquantitative fluorescent images of ROS generation in the mouse brain and kidney were obtained. Furthermore, the fluorescence intensity was stable and not affected by fading. Sodium nitroprusside induced approximately 6 times the fluorescence accumulation in the brain. Cisplatin caused renal injury in all mice, and in comparison with control mice, more than 10 times fluorescence accumulation was observed in the renal medulla with tubular necrosis and vacuolization.

Conclusions:

We successfully obtained ex vivo semiquantitative fluorescent images of ROS generation utilizing a planar laser scanner and DHE. This simple method is useful for ROS detection in several ROS-related animal models and would be applicable to a variety of biochemical processes.

Effects of sodium nitroprusside on mouse erythrocyte catalase activity and malondialdehyde status

There is controversy about the anti- or pro-oxidative effects of the nitric oxide (NO)-donor sodium nitroprusside (SNP). Hence, the activity of the antioxidant enzyme catalase (CAT) and the status of malondialdehyde (MDA) were investigated after a 2.5 mg/kg dose of SNP had been i.p. administered to different and comparable groups of mice (n = 48). The drug was administered at two different circadian times (1 and 13 h after light onset [HALO]). There were, irrespectively of sampling time, no significant differences in the means of CAT activity and MDA status between control and SNP-treated groups, no matter the treatment time. However, CAT activity was significantly (Student's t-test, p < 0.001) increased 1 h following SNP administration at 1 HALO, whereas the significant (p < 0.001) increase in the enzyme activity was found only 3 h after injection at 13 HALO. The drug dosing either at 1 or 13 HALO resulted in no significant differences of MDA status between control and treated groups regardless to the sampling time. Two-way analysis of variance (ANOVA) detected a significant (F0.05(7,88)= 5.3; p < 0.0006) interaction between sampling time and treatment in mice injected at 1 HALO, suggesting the influence of treatment on sampling-time-related changes in CAT activity. However, ANOVA validated no interaction between the two factors in mice treated at 13 HALO, illustrating that the sampling-time differences in enzyme activity were greater. Furthermore, two-way ANOVA revealed no interaction in the variation of MDA status in animals treated either at 1 or 13 HALO. This study indicates that SNP significantly affected the anti-oxidant system.

Dosing-time dependent effects of sodium nitroprusside on cerebral, renal, and hepatic catalase activity in mice

To investigate the time dependence of sodium nitroprusside- (NPS-) induced oxidative effects, the authors study the variation of the antioxidant enzyme CAT activity in various tissues after the administration of a single 2.5 mg/kg dose of SNP or sodium chloride (NaCl 0.9%). For each of the two dosing times (1 and 13 hours after light onset, HALO, which correspond to the beginning of diurnal rest span and of nocturnal activity span of mice, resp.), brain, kidney, and liver tissues were excised from animals at 0, 1, 3, 6, 9, 12, 24, and 36 h following the drug administration and CAT activity was assayed. The results suggest that SNP-induced stimulation of CAT activity is greater in all three tissues when the drug is administered at 1 HALO than at 13 HALO. Two-way ANOVA revealed that CAT activity significantly (P < 0.004) varied as a function of the sampling time but not of the treatment in all three tissues. Moreover, a statistically significant (P < 0.004) interaction between the organ sampling-time and the SNP treatment was revealed in kidney regardless of the dosing time, whereas a highly significant (P < 0.0002) interaction was validated in liver only in animals injected at 13 HALO.

In vivo imaging of reactive oxygen species in mouse brain by using [3H]hydromethidine as a potential radical trapping radiotracer

To assess reactive oxygen species (ROS) production by detecting the fluorescent oxidation product, hydroethidine has been used extensively. The present study was undertaken to evaluate the potential of the hydroethidine derivative as a radiotracer to measure in vivo brain ROS production. [(3)H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([(3)H]Hydromethidine) was synthesized, and evaluated using in vitro radical-induced oxidization and in vivo brain ROS production model. In vitro studies have indicated that [(3)H]Hydromethidine is converted to oxidized products by a superoxide radical (O(2)(•)-) and a hydroxyl radical (OH(•)-) but not hydrogen peroxide (H(2)O(2)). In vivo whole-body distribution study showed that [(3)H]Hydromethidine rapidly penetrated the brain and then was washed out in normal mice. Microinjection of sodium nitroprusside (SNP) into the brain was performed to produce ROS such as OH(•)- via Fenton reaction. A significant accumulation of radioactivity immediately after [(3)H]Hydromethidine injection was seen in the side of the brain treated with SNP (5 and 20 nmol) compared with that in the contralateral side. These results indicated that [(3)H]Hydromethidine freely penetrated into the brain where it was rapidly converted to oxidized forms, which were trapped there in response to the production of ROS. Thus, [(3)H]Hydromethidine should be useful as a radical trapping radiotracer in the brain.

Dosing-time dependent oxidative effects of sodium nitroprusside in brain, kidney, and liver of mice

The purpose of this study was to investigate if the oxidative effects of sodium nitroprusside (SNP) are dosing-time dependent. Therefore, the variation of malondialdehyde (MDA) status was assessed after a single i.p. administration of SNP (2.5mgkg(-1) b.w.) or vehicle (9‰ NaCl) to different and comparable groups of mice (n=48) at two different circadian times (1 and 13h after light onset [HALO]). Brain, kidney, and liver tissues were excised over 36h, and their MDA contents were estimated at 0, 1, 3, 6, 9, 12, 24, and 36h after SNP administration.

RESULTS

indicated mean MDA level was not significantly changed in each investigated tissue compared with the control. In contrast, the mean MDA value varied among organs and was comparable in brain and liver but lower than in kidney. The data show SNP significantly (P<0.05) increases MDA status in both tissues and exerts time-dependent oxidative effects with the greatest toxicity coinciding with the beginning of the diurnal rest span (local time: 08:00h, i.e., at 1 HALO). The obtained results reveal SNP-induced oxidative damage (evidenced by MDA accumulation) varies according to both the dosing-time and the target organ.

Downregulation of miRNA-134 protects neural cells against ischemic injury in N2A cells and mouse brain with ischemic stroke by targeting HSPA12B

MicroRNAs (miRNAs) have emerged as a major regulator in neurological diseases, and understanding their molecular mechanism in modulating cerebral ischemic injury may provide potential therapeutic targets for ischemic stroke. However, as one of 19 differentially expressed miRNAs in mouse brain with middle cerebral artery occlusion (MCAO), the role of miR-134 in ischemic injury is not well understood. In this study, the miR-134 expression level was manipulated both in oxygen-glucose deprivation (OGD)-treated N2A neuroblastoma cells in vitro and mouse brain with MCAO-induced ischemic stroke in vivo, and its possible targets of heat shock protein A5 (HSPA5) and HSPA12B were determined by bioinformatics analysis and dual luciferase assay. The results showed that overexpression of miR-134 exacerbated cell death and apoptosis both in vitro and in vivo. Conversely, downregulating miR-134 levels reduced cell death and apoptosis. Furthermore, non-expression of miR-134 enhanced HSPA12B protein levels in OGD-treated N2A cells as well as in the ischemic region. It could attenuate brain infarction size and neural cell damage, and improve neurological outcomes in mice with ischemic stroke, whereas upregulation of miR-134 had the opposite effect. In addition, HSPA12B was validated to be a target of miR-134 and its short interfering RNAs (siRNAs) could block miR-134 inhibitor-induced neuroprotection in OGD-treated N2A cells. In conclusion, downregulation of miR-134 could induce neuroprotection against ischemic injury in vitro and in vivo by negatively upregulating HSPA12B protein expression.

Interaction of some commercial teas with some carbohydrate metabolizing enzymes linked with type-2 diabetes: a dietary intervention in the prevention of type-2 diabetes

This study is aimed at assessing the inhibitory effect of teas on key enzymes (α-amylase and α-glucosidase) linked with type-2 diabetes and their antioxidant properties. Four samples of three brands were used; infusions of green tea (GT), 2 brands of black tea (BT), and a formulated herbal preparation for diabetes (ADT) (white tea, Radix Puerariae, Radix ophiopogonis, hawthorn berry, Chinese yam, and fragrant Solomon seal rhizome) were prepared and subsequently analyzed for their total phenol, ascorbic acid contents, antioxidant properties (2,2-Azizobis (3-Ethylbenzo-Thiazoline~6-sulfonate) “ABTS” scavenging ability and ferric reducing antioxidant property), and inhibition of pancreatic-α-amylase and intestinal-α-glucosidase in vitro. The study revealed that GT had the highest total phenol content, ascorbic acid content, ABTS∗ scavenging ability, and ferric reducing ability. Furthermore, all the teas inhibited Fe²⁺ and sodium nitroprusside induced lipid peroxidation in pancreas, with GT having the highest inhibitory effect. Conversely, there was no significant difference (P > 0.05) in the inhibitory effects of the teas on α-amylase and α-glucosidase. The antidiabetic property of the teas could be attributed to their inhibitory effect on carbohydrate hydrolyzing enzymes implicated in diabetes and their antioxidant activities.

Potential protective effect of highly bioavailable curcumin on an oxidative stress model induced by microinjection of sodium nitroprusside in mice brain

The protective effects of conventional curcumin or highly bioavailable curcumin, Theracurmin^®, against oxidative stress is investigated using our in vivo oxidative stress model.

Protective effect of luteolin on an oxidative-stress model induced by microinjection of sodium nitroprusside in mice

Accumulating lines of evidence showed that luteolin, a polyphenolic compound, has potent neuroprotective effects. The purpose of this study was to examine whether luteolin can protect against sodium nitroprusside (SNP)-induced oxidative damage in mouse brain. Intrastriatal co-injection of luteolin (3 - 30 nmol) with SNP (10 nmol) dose-dependently protected against brain damage and motor dysfunction. Oral administrations of luteolin (600 - 1200 mg/kg) dose-dependently protected against brain damage and motor dysfunction induced by striatal injection of SNP. Furthermore, luteolin (30 - 100 μM) concentration dependently protected against Fe(2+)-induced lipid peroxidation in mouse brain homogenate. Luteolin (1 - 100 μg/ml) showed potent DPPH radical scavenging ability, when compared with ascorbic acid and glutathione. Finally, a ferrozine assay showed that luteolin (30 - 100 μg/ml) has Fe(2+)-chelating ability, but this was weaker than that of ethylenediaminetetraacetic acid. These results suggest that intrastriatal or oral administration of luteolin protected mice brain from SNP-induced oxidative damage by scavenging and chelating effects.