Tetrapleura tetraptera fruit extracts ameliorate pentylenetetrazol-induced seizures as well as ensuing cognitive deficit and oxidative stress

Kindling is an experimental-induced seizure consistent with epilepsy disease, a chronic neurological disorder characterised by spontaneous and repeated seizures. This disease is associated with oxidative stress, and most therapeutic strategies against epilepsy aim at improving the antioxidant defence mechanism in the brain. However, prolonged usage and associated adverse side effects limit antiepileptics, warranting natural antioxidant patronage. The present study investigated the behavioural and antioxidant actions of Tetrapleura tetraptera fruit extracts (TT) against pentylenetetrazol (PTZ)-kindling rats. Twenty-five male Wistar rats (150-180 g) were assigned into five groups (1-5, n = 5): Control (normal saline, 5 ml/kg body weight, b.w.), PTZ-only (40 mg/kg/b.w. i.p.), and groups 3-5 administered PTZ (40 mg/kg/b.w. i.p.) after, respectively, receiving oral TT (500 mg/kg/b.w.), TT flavonoid (fTT, 50 mg/kg/b.w.), and sodium valproate (SV, 15 mg/kg/b.w.). All administrations were carried out 48 hourly for 21 days. In the end, buried food, novel object recognition (NOR), Y-maze, elevated plus maze (EPM), and beam walk tests were done, and the rats were sacrificed. Whole brains were processed for antioxidant assays. The results showed a high (p <.05) seizure score and buried food test latency, preference for the familiar object in the NOR test, aversion to open-arm and reduced grooming in the EPM, reduced beam walk latency, elevated brain malondialdehyde (MDA), and decreased superoxide dismutase (SOD) in the PTZ group. The TT, fTT, and SV suppressed seizure, decreased buried food latency, `preference for the novel object and open-arm, increased grooming, decreased brain MDA, and elevated SOD. In conclusion, TT extracts protected against PTZ-induced cognitive deficits and brain oxidative stress, with results similar to those of the standard anticonvulsant drug, SV.

Rauvolfia vomitoria phenol extract relieves pentylenetetrazol-induced seizures in Swiss mice and protects some temporal lobe structures

BACKGROUND

Rauvolfia vomitoria (R. vomitoria) is a plant of economic importance due to its diverse ethnomedicinal properties, including the anticonvulsant effect. In this study, we studied the antiseizure and neuroprotective potentials of R. vomitoria extracts against pentylenetetrazol (PTZ)-induced kindling.

METHODS

Twenty-five adult Swiss mice (25-30 g) were assigned to five groups (n = 5): control group, PTZ treatment group, and PTZ treatment after receiving oral R. vomitoria crude extract (100 mg/kg), R. vomitoria phenol extract (50 mg/kg) or sodium valproate (15 mg/kg) every 48 h for 28 days. Seizure scores, cognitive behavioral tests including novel object test, Y-maze test, and the elevated plus maze test, as well as brain neurochemicals and histomorphology studies, were performed.

RESULTS

Compared with the control group, the PTZ group showed comparable body weight and durations in closed and open arms (P > 0.05), but preference for familiar objects, significant (P < 0.05) spontaneous alternation, increased monoamine oxidase activity and nitric oxide level, and Nissl chromatolysis in the temporal lobe structures including the cortex, hippocampus, and amygdala. R. vomitoria phenol extract pretreatment significantly (P < 0.05) reduced seizures, prevented adverse cognitive behaviors, decreased the nitric oxide level, and reduced the temporal lobe Nissl chromatolysis compared with the R. vomitoria crude extract pretreatment group and the sodium valproate pretreatment groups.

CONCLUSIONS

Thus, R. vomitoria phenol extract showed promising results against seizures and potential for general brain protection, suggesting that the anticonvulsant property of R. vomitoria may be attributed to its phenol constituent. More studies are needed to delineate the mechanisms of its action.

D-Ribose-LCysteine attenuates manganese-induced cognitive and motor deficit, oxidative damage, and reactive microglia activation

Due to overexposure, manganese (Mn) accumulation in the brain can trigger the inhibition of glutathione synthesis and lead to increased generation of reactive oxygen species (ROS) and oxidative stress. D-Ribose-L-Cysteine (RibCys) has been demonstrated to effectively support glutathione synthesis to scavenge ROS and protect cells from oxidative damage. In the present study, we examined the effects of RibCys on weight changes, cognitive and motor associated activities, oxidative stress markers, striatal and cortical histology, and microglia activation following Mn exposure. Rats were exposed to either saline, Mn or/and RibCys for two weeks. The Mn exposed rats received RibCys either as pre-, co-, or post-treatments. Mn caused a significant decrease in weight, memory and motor activities, increased lactate dehydrogenase level, overexpression of IBA1 reflecting microglia activation, and distortion of the neuronal cytoarchitecture of the striatum and motor cortex, respectively. Interventions with RibCys mitigated Mn-induced neurotoxic events. Our novel study demonstrates that RibCys effectively ameliorates the neurotoxicity following Mn treatment and maybe a therapeutic strategy against the neurological consequences of Mn overexposurec.

Nω-nitro-L-arginine, a nitric oxide synthase inhibitor, attenuates nickel-induced neurotoxicity

The various mediums of exposure to nickel (Ni) compounds have raised enormous public health concerns, as it has been illustrated to exert toxic effects in biological organs, including the brain. We have previously implicated the involvement of elevated nitric oxide (NO) in Ni-induced oxidative stress in the brain. Hence, the present study investigated the ameliorative potential of N^ω-nitro-L-arginine (L-NA), a NO synthase inhibitor, following Ni-induced neurotoxicity. Adult male rats were divided into four groups; control (normal saline), 10 mg/kg Ni chloride (NiCl₂) only, 1 mg/kg L-NA, or 2 mg/kg L-NA co-administered with NiCl₂. The administration was via daily intraperitoneal injections for three weeks. Neurobehavioural assessments performed thereafter ascertained short-term spatial memory and anxiety. Furthermore, histological evaluations of the cortex, hippocampus, and striatum were carried out using routine hematoxylin and eosin technique, while the phosphotungstic acid hematoxylin method was used to express the degree of astrogliosis. Biochemical analysis of NO levels was examined along with other oxidative stress markers (superoxide dismutase, catalase, glutathione, glutathione S transferase, glutathione peroxidase, myeloperoxidase, and lipid peroxidation). The results illustrated altered behavioral responses, a higher population of degenerating neurons, and astrocytes in the NiCl₂ group. There was also an elevation in the NO level and a corresponding reduction in antioxidant activities. However, these debilitating changes were ameliorated in the L-NA treated groups. These results demonstrate an association between alterations in NO synthesis pathway and Ni neurotoxicity, which may render neuronal cells susceptible to damage by oxidative stress. This may yet be another mechanism and useful therapeutic marker in deciphering Ni-induced neurotoxicity.

Pseudoginsenoside-F11 ameliorates okadiac acid-induced learning and memory impairment in rats via modulating protein phosphatase 2A

We have reported that pseudoginsenoside-F11 (PF11) can significantly improve the cognitive impairments in several Alzheimer's disease (AD) models, but the mechanism has not been fully elucidated. In the present study, the effects of PF11 on AD, in particular the underlying mechanisms related with protein phosphatase 2A (PP2A), were investigated in a rat model induced by okadaic acid (OA), a selective inhibitor of PP2A. The results showed that PF11 treatment dose-dependently improved the learning and memory impairments in OA-induced AD rats. PF11 could significantly inhibit OA-induced tau hyperphosphorylation, suppress the activation of glial cells, alleviate neuroinflammation, thus rescue the neuronal and synaptic damage. Further investigation revealed that PF11 could regulate the protein expression of methyl modifying enzymes (leucine carboxyl methyltransferase-1 and protein phosphatase methylesterase-1) in the brain, thus increase methyl-PP2A protein expression and indirectly increase the activity of PP2A. Molecular docking analysis, structural alignment and in vitro results showed that PF11 was similar in the shape and electrostatic field feature to a known activator of PP2A, and could directly bind and activate PP2A. In conclusion, the present data indicate that PF11 can ameliorate OA-induced learning and memory impairment in rats via modulating PP2A.

Neurotherapeutic and antioxidant response of D-ribose-L-Cysteine nutritional dietary supplements on Alzheimer-type hippocampal neurodegeneration induced by cuprizone in adult male wistar rat model

INTRODUCTION

Cuprizone is a neurotoxicant causing neurodegeneration through enzymes inhibition and oxidative stress. D-Ribose-L-Cysteine (DRLC) is a powerful antioxidant with neuroprotective properties. This study explored the antioxidant response of DRLC against cuprizone-induced behavioral alterations, biochemical imbalance and hippocampal neuronal damage in adult wistar rats.

MATERIALS AND METHODS

Thirty two (32) adult male wistar rats (150-200g) were divided into four groups (n = 8). Group A received normal saline only as placebo; Group B received 0.5% cuprizone diet only; Group C received a combination of 0.5% cuprizone diet and 100 mg/kg bw of DRLC and Group D received 100 mg/kg bw of DRLC only. The administration was done through oral gavage once daily for 45 days. After the last treatment, neurobehavioral tests (Morris Water Maze and Y maze) was conducted; animals sacrificed and brain harvested for histological analysis and biochemical estimations of levels of antioxidants, oxidative stress markers, neurotransmitters and enzyme activitties.

RESULTS

The results showed significant memory decline, hippocampal alterations, decrease levels of antioxidant markers, enzyme and neurotransmitters activities with concomitant increase in norepinephrine and oxidative stress markers in cuprizone induced rats relative to normal but was attenuated with DRLC administration.

CONCLUSION

Cuprizone causes cognitive impairment and neurodegeneration through oxidative stress; however, administration of DRLC ameliorated neuropathological alteration induced by cuprizone.

Reactive Gliosis Contributes to Nrf2-Dependent Neuroprotection by Pretreatment with Dimethyl Fumarate or Korean Red Ginseng Against Hypoxic-Ischemia: Focus on Hippocampal Injury

Recently, dimethyl fumarate (DMF) and Korean red ginseng (ginseng), based on their purported antioxidative and anti-inflammatory properties, have exhibited protective potential in various neurological conditions. Their effects on cerebral ischemia and underlying mechanisms remain inconclusive; however, increasing evidence indicates the involvement of the transcriptional factor Nrf2. This study evaluated the preventive effects of DMF and ginseng on hippocampal neuronal damage following hypoxia-ischemia (HI) and assessed the contributions of reactive gliosis and the Nrf2 pathway. Adult wild type (WT) and Nrf2-/- mice were pretreated with DMF or ginseng for 7 days prior to HI. At 24 h after HI, DMF or ginseng significantly reduced infarct volume (52.5 ± 12.3% and 47.8 ± 10.7%), brain edema (61.5 ± 17.4% and 39.3 ± 12.8%), and hippocampal CA1 neuronal degeneration, and induced expressions of Nrf2 target proteins in WT, but not Nrf2-/-, mice. Such hippocampal neuroprotective benefits were also observed at 6 h and 7 days after HI. The dynamic attenuation of reactive gliosis in microglia and astrocytes correlated well with this sustained neuroprotection in an Nrf2-dependent manner. In both early and late stages of HI, astrocytic dysfunctions in extracellular glutamate clearance and water transport, as indicated by glutamine synthetase and aquaporin 4, were also attenuated after HI in WT, but not Nrf2-/-, mice treated with DMF or ginseng. Together, DMF and ginseng confer robust and prolonged Nrf2-dependent neuroprotection against ischemic hippocampal damage. The salutary Nrf2-dependent attenuation of reactive gliosis may contribute to this neuroprotection, offering new insight into the cellular basis of an Nrf2-targeting strategy for stroke prevention or treatment.

Pretreatment with Korean red ginseng or dimethyl fumarate attenuates reactive gliosis and confers sustained neuroprotection against cerebral hypoxic-ischemic damage by an Nrf2-dependent mechanism

The transcriptional factor Nrf2, a master regulator of oxidative stress and inflammation that are tightly linked to the development and progression of cerebral ischemia pathology, plays a vital role in inducing the endogenous neuroprotective process. Here, hypoxic-ischemia (HI) was performed in adult Nrf2 knockout and wildtype mice that were orally pretreated either with standardized Korean red ginseng extract (Ginseng) or dimethyl fumarate (DMF), two candidate Nrf2 inducers, to determine whether the putative protection was through an Nrf2-dependent mechanism involving the attenuation of reactive gliosis. Results show that Nrf2 target cytoprotective genes were distinctly elevated following HI. Pretreatment with Ginseng or DMF elicited robust neuroprotection against the deterioration of acute cerebral ischemia damage in an Nrf2-dependent manner as revealed by the reductions of neurological deficits score, infarct volume and brain edema, as well as enhanced expression levels of Nrf2 target antioxidant proteins and anti-inflammation mediators. In both ischemic striatum and cortex, the dynamic pattern of attenuated reactive gliosis in astrocytes and microglia, including affected astrocytic dysfunction in glutamate metabolism and water homeostasis, correlated well with the Nrf2-dependent neuroprotection by Ginseng or DMF. Furthermore, such neuroprotective benefits extended to the late phase of ischemic brain damage after HI, as evidenced by improvements in neurobehavioral outcomes, infarct volume and brain edema. Overall, pretreatment with Ginseng or DMF identically attenuates reactive gliosis and confers long-lasting neuroprotective efficacy against ischemic brain damage through an Nrf2-dependent mechanism. This study also provides new insight into the profitable contribution of reactive gliosis in the Nrf2-dependent neuroprotection in acute brain injury.

Korean Red Ginseng Pretreatment Protects Against Long-Term Sensorimotor Deficits After Ischemic Stroke Likely Through Nrf2

Endogenous neuroprotective mechanisms by which the brain protects itself against noxious stimuli and recovers from ischemic damage are key targets of stroke research, ultimately facilitating functional recovery. Transcriptional factor Nrf2, enriched in astrocytes, is a master regulator of endogenous defense systems against oxidative stress and inflammation. Korean Red Ginseng (Ginseng), one most widely used herbal medicine, has exhibited promising potentials in neuroprotection. Our study aimed to determine whether the standardized Ginseng extract pretreatment could attenuate acute sensorimotor deficits and improve long-term functional recovery after ischemic stroke though Nrf2 pathway and whether reactive astrogliosis is associated with such effect. Adult Nrf2^−/− and matched wildtype control (WT) mice were pretreated with Ginseng orally for 7 days prior to permanent distal middle cerebral artery occlusion (pdMCAO). Using an optimized method that can accurately assess either severe or mild pdMCAO-induced sensorimotor deficits, neurobehavioral tests were performed over 28 days. The progression of lesion volume and the evolution of astrocytic and microglial activation were determined in the acute stage of ischemic stroke after pdMCAO (0–3 days). Nrf2-downstream target antioxidant genes expression levels was assessed by Western blot. We found that Ginseng pretreatment ameliorated acute sensorimotor deficits and promoted long-term functional recovery, prevented the acute enlargement of lesion volume (36.37 ± 7.45% on day 3), attenuated reactive astroglial progression but not microglia activation, and enhanced the induction of Nrf2-downstream target proteins after ischemic insult in WT mice, an effect which was lost in Nrf2 knockouts. The spatiotemporal pattern of reactive astrogliosis evaluation correlated well with acute ischemic damage progression in an Nrf2-dependent fashion during the acute phase of ischemia. In contrast, Nrf2 deficiency mice exhibited exacerbated ischemic condition compared to WT controls. Together, Ginseng pretreatment protects against acute sensorimotor deficits and promotes its long-term recovery after pdMCAO, at least partly, through Nrf2 activation, highlighting the potential efficacy of oral consumption of Ginseng for stroke preventative intervention in patients who are at great risk of recurrent stroke or transient ischemic attack. The attenuated reactive astrogliosis contributes to the Nrf2 pathway related neuroprotection against acute ischemic outcome and substantially long-term sensorimotor deficits in the context of ischemic stroke under pdMCAO.

Sub-acute nickel exposure impairs behavior, alters neuronal microarchitecture, and induces oxidative stress in rats' brain

Nickel (Ni) is a heavy metal with wide industrial uses. Environmental and occupational exposures to Ni are potential risk factors for neurological symptoms in humans. The present study investigated the behavior and histomorphological alterations in brain of rats sub-acutely exposed to nickel chloride (NiCl₂) and the possible involvement of oxidative stress. Rats were administered with 5, 10 or 20 mg/kg NiCl₂ via intraperitoneal injections for 21 days. Neurobehavioral assessment was performed using the Y-maze and open field test (OFT). Histomorphological analyses of brain tissues, as well as biochemical determination of oxidative stress levels were performed. Results showed that Ni treatments significantly reduced body weight and food intake. Cognitive and motor behaviors on the Y-maze and OFT, respectively, were compromised following Ni treatments. Administration of Ni affected neuronal morphology in the brain and significantly reduced percentage of intact neurons in both hippocampus and striatum. Additionally, markers of oxidative stress levels and nitric oxide (NO) levels were significantly altered following Ni treatments. These data suggest that compromised behavior and brain histomorphology following Ni exposures is associated with increase in oxidative stress.

Neuroprotective effect of Feronia limonia on ischemia reperfusion induced brain injury in rats

Objectives:

Brain stroke is a leading cause of death without effective treatment. Feronia limonia have potent antioxidant activity and can be proved as neuroprotective against ischemia-reperfusion induced brain injury.

Materials and Methods:

We studied the effect of methanolic extract of F. limonia fruit (250 mg/kg, 500 mg/kg body weight, p.o.) and Vitamin E as reference standard drug on 30 min induced ischemia, followed by reperfusion by testing the neurobehavioral tests such as neurodeficit score, rota rod test, hanging wire test, beam walk test and elevated plus maze. The biochemical parameters, which were measured in animals brain were catalase, superoxide dismutase (SOD), malondialdehyde and nitric oxide in control and treated rats.

Results:

The methanolic extract of F. limonia fruit (250 mg/kg, 500 mg/kg body weight, p.o.) treated groups showed a statistically significant improvement in the neurobehavioral parameters such as motor performance (neurological status, significant increase in grasping ability, forelimb strength improvement in balance and co-ordination). The biochemical parameters in the brains of rats showed a significant reduction in the total nitrite (P < 0.01) and lipid peroxidation (P < 0.01), also a significant enhanced activity of enzymatic antioxidants such as catalase (P < 0.01) and SOD (P < 0.05).

Conclusion:

These observations suggest the neuroprotective and antioxidant activity of F. limonia and Vitamin E on ischemia reperfusion induced brain injury and may require further evaluation.

Chronic nicotine administration does not alter cognitive or mood associated behavioural parameters

Nicotine, the major specific alkaloid in tobacco smoke, exhibits widespread pharmacological effects and may contribute to deterioration in behaviour. The present study thus examined the effects of its chronic administration on some cognitive and mood associated behaviours. Adult rats weighing between 150 and 200g were randomly divided into 4 groups each of 5 females and 5 males. Three groups were administered graded doses of nicotine at 0.25, 2 and 4mg/kg body weight via subcutaneous injections. One group served as control and received normal saline (vehicle for nicotine). Behavioural tests were performed using the Y-maze, elevated-plus maze (EPM) and tail suspension tests (TST) at various time points. Nicotine produced no significant effect in spontaneous alternation on Y-maze, nor on six parameters scored on EPM (open arm entries, time spent in open arms, time per open arm entries, open/closed arm quotient, closed arm entries, and total arm entries), and also no significant effect on immobility time in TST. This lack of effects was observed to be independent of sex and dose administered. The study shows that nicotine does not produce long-term changes in some cognitive and mood associated behaviours, thus suggesting it could be well tolerated even following chronic administration.

The effect of silybin on passive avoidance learning and pathological changes in hippocampal CA1 and DG regions in male Wistar rats offspring

Silybin, an extract from seeds of milk thistle (Silybum marianum), is known to have hepato-protective, anticarcinogenic, and estrogenic effects. Given that estrogen effects on memory have been reported, silybin may cause structural changes in the hippocampal CA1 and dentate gyrus (DG) neurons and as a result it may enhance learning and memory. Wistar rats were provided with silybin (from day 7 of gestational age up to 4 weeks after birth) with 2 dosages of 18 mg/kg in the experimental group 1 (Exp1) and 9 mg/kg in the experimental group 2 (Exp2). Offspring memory retention was compared by duration of step-through latency in passive avoidance apparatus. Furthermore, histological changes were investigated in experimental groups and control group (CG). Both the experimental groups showed significantly longer step-through latency than CG (p < 0.001 for Exp1 and p < 0.01 for Exp2). The average number of pyramidal cells in hippocampal CA1 and granular cells in hippocampal DG was remarkably higher in Exp1 and Exp2 compared with CG. The difference was significant between Exp1 and Exp2 for pyramidal cells (p < 0.05) but not for granular cells. Silybin administration during pregnancy resulted in histological changes in hippocampus and better memory function. These data may lay the ground work using silybin in memory impairment diseases.

Memory improvement in ibotenic acid induced model rats by extracts of Scutellaria baicalensis

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis Georgi (Labiatae) extracts have been used as traditional Korean medicine, to treat cerebral ischemia in addition to bacterial infection and inflammatory diseases.

AIM OF THE STUDY

The improvement effect on learning and memory by the administration of Scutellaria baicalensis extracts was evaluated and the underlying mechanisms were investigated.

MATERIALS AND METHODS

Memory behavior was tested by the passive avoidance test and Y-maze test. We also investigated the cells expressing neuronal markers related to memory processes by immunofluorescence staining analysis in memory deficient animal model (Ibo model) rats and in hippocampal progenitor cells.

RESULTS

We found neuronal cells immunoreactive to choline acetyltransferase (ChAT), a marker for cholinergic neurons were increased in the hippocampus, while cells producing GABA and glutamate were not after 30 mg/kg Scutellaria baicalensis administration. Futhermore, Scutellaria baicalensis extracts enhanced the survival of a hippocampal progenitor cell line, HiB5 and its differentiation to ChAT immunoreactive cells. The increased expression of memory related neurotransmitter, NMDA receptor and a reduction of activated microglia in the hippocampus were also observed in the Ibo model when administrated Scutellaria baicalensis extracts.

CONCLUSIONS

These results imply that Scutellaria baicalensis has significant neuroprotective effects in the Ibo model.