The antioxidant and neuroprotective effects of the Psychotria camptopus Verd. Hook. (Rubiaceae) stem bark methanol extract contributes to its antiepileptogenic activity against pentylenetetrazol kindling in male Wistar rats

A substantial number of epileptic patients are resistant to the current medication thus necessitating the search for alternative therapies for intractable forms of the disease. Previous studies demonstrated the acute anticonvulsant properties of the methanol extract of the stem bark of Psychotria camptopus (MEPC) in rats. This study investigated the effects of MEPC on pentylenetetrazole-kindled Wistar rats. Kindling was induced by intraperitoneal injection of pentylenetetrazole (37.5 mg/kg) on every alternate day, 1 h after each daily oral pretreatment of rats (8?≤?n?≤?10) with MEPC (40, 80 and 120 mg/kg), vehicle or diazepam (3 mg/kg) for 43 days. The kindling development was monitored based on seizure episodes and severity. Rats’ brains were collected on day 43 for the determination of oxidative stress parameters. The histomorphological features and neuronal cell viability of the prefrontal cortex (PFC) and hippocampus were also assessed using H&E and Cresyl violet stains. Chronic administration of pentylenetetrazole time-dependently decreased the latency to myoclonic and generalized seizures, and increased seizure scores and the number of kindled rats. MEPC and diazepam significantly increased the latencies to myoclonic jerks and generalized tonic-clonic seizures. These substances also reduced seizure score and the number of rats with PTZ-kindling. MEPC improved glutathione status and decreased lipid peroxidation in the brains of kindled rats. MEPC also exhibited neuroprotection against pentylenetetrazole-induced hippocampal and PFC neuronal damages. These results suggest that P. camptopus has antiepileptogenic activity, which might be related to the augmentation of antioxidant and neuroprotective defense mechanisms, and further confirm its usefulness in the management of epilepsy.

     

D-ribose-L-cysteine enhances memory task,attenuates oxidative stress and acetyl-cholinesterase activity in scopolamine amnesic mice

d -Ribose-l -cysteine (DRLC) is an analogue of cysteine that has been shown to boost cellular antioxidant capacity by enhancing intracellular biosynthesis of glutathione (GSH). Deficiency of GSH has been implicated in the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disorder associated with loss of memory. Thus, the use of antioxidants to prevent or retard the progression of memory deteriorations in persons with AD has been the focus of intense investigations. This study was carried out to evaluate the effects of DRLC on memory and scopolamine-induced amnesia, acetyl-cholinesterase activity, and oxidative stress in mice. Male Swiss mice were given oral administration of saline (10 ml/kg), DRLC (25, 50, and 100 mg/kg) or donepezil (1 mg/kg) 30 min before testing for memory performance using Y-maze and object recognition models. Another set of mice were also pretreated orally with saline, DRLC (25, 50, and 100 mg/kg) or donepezil (1 mg/kg) but in combination with scopolamine (3 mg/kg, i.p.) daily for 7 days. Thirty minutes after treatment on Day 7, memory function was then evaluated. The brain levels of acetyl-cholinesterase and oxidative stress parameters were assayed. DRLC significantly (p < .05) enhanced memory performance and attenuated scopolamine-induced amnesia. Increased acetyl-cholinesterase activity and oxidative stress, as shown by decreased antioxidant substrates (glutathione and catalase) and elevated malondialdehyde contents in mice with scopolamine amnesia were also attenuated by DRLC. Our findings suggest that inhibition of oxidative stress and acetyl-cholinesterase activity might contribute to the potential benefit of DRLC in persons with amnesia.     

Morin hydrate attenuates chronic stress-induced memory impairment and degeneration of hippocampal subfields in mice: The role of oxidative,nitrergic and neuroinflammatory pathways

Metabolic Brain Disease - Morin hydrate (MH) is the major flavonoid constituent of Morus alba acclaimed to have antioxidant, anti-inflammatory, anti-stress and neuroprotective properties. However,...     

Correction to: Morin hydrate attenuates chronic stress-induced memory impairment and degeneration of hippocampal subfields in mice: The role of oxidative,nitrergic and neuroinflammatory pathways

Metabolic Brain Disease -     

Methyl jasmonate ameliorates rotenone-induced motor deficits in rats through its neuroprotective activity and increased expression of tyrosine hydroxylase immunopositive cells

Decreased tyrosine hydroxylase (TH) activity, due to degeneration of dopaminergic neurons contributes to the low dopamine content and the motor deficits that characterized Parkinson’s disease (PD). This study examines the effect of methyl jasmonate (MJ), a neuroprotective bioactive compound isolated from jasminum grandiflorum, on motor functions, immunopositive cells of TH, dendritic neurons and dopamine contents in rotenone (Rot)-treated rats. Rats pretreated daily with MJ (100 mg/kg, i.p) for 21 days also received Rot (2.5 mg/kg, i.p.) 30 min after each pretreatment for every 48 h for 21 days. Motor functions were assessed on day 22. The specific brain regions of the rats were processed for determination of dopamine contents, immunopositive cells of TH, neuronal cell morphology and dendritic aborizations. Rot impaired locomotion and rearing behavior, and decreased dopamine content in the striatum, prefrontal cortex and midbrain. It further reduced the expression of TH in the substantia nigra and striatum relative to vehicle-control (p?<?0.05). Histopathologic studies revealed that Rot-treated rats had degenerated neurons with pyknotic nuclei and loss of nigrostriatal neuronal cells. Rot also altered the nigrostriatal dendritic neuronal networks, decreased the dendritic length and spine density. However, pretreatment with MJ improved motor deficits, increased TH activity and dopamine contents in the specific brain regions of Rot-treated rats. MJ also attenuated the cyto-architectural distortions, loss of neuronal cells and dendritic aborizations of the striatum of Rot-treated rats. These findings suggest that MJ may reverse the motor deficits associated with PD by modifying the key pathological abnormalities involved in the disease progression.

     

Neuroprotective effects of the ethanol stem bark extracts of Terminalia ivorensis in ketamine-induced schizophrenia-like behaviors and oxidative damage in mice

Context: Schizophrenia is a heterogenous neurological disorder, which has been hypothetically linked to oxidative imbalance and associated behavioral perturbations. Preliminary evidence from animal models predictive of human psychosis suggests that Terminalia ivorensis A. Chev. (Combretaceae) has antipsychotic-like activity in mice.

Objective: This study investigates the neuroprotective property of the ethanol stem bark extracts of T. ivorensis (EETI) in reversal treatment of ketamine-induced schizophrenia-like behaviors and oxidative alteration in adult male Swiss albino mice.

Materials and methods: Animals were divided into six treatment groups (n?=?5). Animals received distilled water or ketamine (20?mg/kg) once daily intraperitoneally (i.p.) for 14 days, and from the 8th to the 14th day, they were treated with EETI (125, 250 or 500?mg/kg), risperidone (RIS) or vehicle orally once daily. Behaviors related to positive (locomotor activity) and cognitive (Y maze) symptoms of schizophrenia were assessed. Glutathione (GSH) levels, superoxide dismutase (SOD) and catalase (CAT) activities, including malondialdehyde (MDA) concentration were measured in mice whole brains.

Result: The LD₅₀ of EETI was 2236.06?mg/kg, p.o. body weight. EETI (125, 250 or 500?mg/kg, p.o.) demonstrated significant (p?<?0.05) inhibition of ketamine-induced hyperlocomotion and cognitive dysfunction. The extract decreased MDA concentration (39.0, 62.6 and 67.5%) in a dose-dependent manner. Moreover, EETI significantly (p?<?0.05) reversed the depletion of GSH, and increased activities of SOD and CAT in brain tissues.

Discussion and conclusion: These findings suggest that EETI probably exert its antipsychotic-like activity, via a neuroprotective compensatory mechanism of action, and as such, could be relevant in the management of schizophrenia.     

Jobelyn® ameliorates neurological deficits in rats with ischemic stroke through inhibition of release of pro-inflammatory cytokines and NF-κB signaling pathway

The effects of Jobelyn® (JB) on neurological deficits and biochemical alterations associated with ischemic stroke induced by bilateral common carotid artery occlusion (BCCAO) in rats were investigated in this study. Male Wistar rats were divided into five groups (n?=?8): group 1 served as Sham control; group 2, which served as negative control received normal saline while groups 3–5 were given JB (25, 50 and 100?mg/kg, p.o) daily for 28 days. Then, rats in groups 2–5 were subjected to BCCAO for 30?min and reperfusion afterwards. Neurological deficits were assessed 3?h post-reperfusion using a 9-point neurological scoring scale. The levels of biomarkers of oxidative stress and pro-inflammatory cytokines (tumour necrotic factor-α and interleukin-6), expressions of immunopositive cells of nuclear factor-kappa B (NF-κB) and acetyl-cholinesterase (AChE) activity were determined in brain tissues. Histology of the striatum, prefrontal cortex (PFC) and hippocampus (CA1) was also evaluated. JB improved BCCAO-induced neurological deficits and attenuated increased oxidative stress and AChE activity in rats subjected to BCCAO (p?<?0.05). Increased brain levels of tumour necrotic factor-α and interleukin-6 as well as expressions of immunopositive cells of NF-κB were decreased by JB. JB reduced brain damage and also increased population of viable neurons in the striatum, PFC and hippocampus of ischemic stroke rats. These findings suggest that the positive effect of JB on neurological function in rats with ischemic stroke may be related to inhibition of oxidative stress, release of pro-inflammatory cytokines and expressions of immunopositive cells of NF-κB.     

Involvement of l-arginine-nitric oxide pathway in the antidepressant and memory promoting effects of morin in mice

l -Arginine-nitric oxide pathway has been reported to be involved in the mediation of the psychopharmacological effects of many psychotropic drugs. Previous studies have shown that morin, a psychotropic compound isolated from mulberry leaf produces functional psychopharmacological effects indicative of antidepressant, antipsychotic, anxiolytic and nootropic properties. However, the role of l -arginine-nitric oxide pathway in the psychotropic effects of morin has not been fully investigated, hence, the need for this study. Male Swiss mice were pretreated individually or in combination with nitric oxide precursor [l -arginine (750 mg/kg, i.p.)], competitive nonselective nitric oxide synthase (NOS) inhibitor [N(G)-nitro-l -arginine methyl ester (l -NAME, i.p) (50 mg/kg)] or selective neuronal NOS inhibitor [methylene blue (3.75 mg/kg, i.p)] prior to morin (100 mg/kg, i.p.) or saline (10 mL/kg, i.p.) treatment. Psychopharmacological activities were then evaluated 30 min later using open field, Y-maze, and forced swim tests. l -Arginine significantly reversed the effects of morin on locomotion, memory and depression in mice. The reduced motor activity and enhanced memory function produced by morin were significantly attenuated by methylene blue but augmented the antimobility activity of morin in the FST. Moreover, l -NAME potentiated the psychopharmacological effects of morin in the open field and forced swim tests but reduced its memory promoting effect. Meanwhile, morin supplementation reversed the effects of l -arginine on l -NAME-treated mice in all behavioral models. The results of this study suggest that l -arginine-nitric oxide pathway might play a role in the modulation of the antidepressant and memory promoting effects of morin in mice.     

Cymbogogoncitratus aqueous leaf extract attenuates neurobehavioral and biochemical changes induced by social defeat stress in mice

Objective Psychosocial stress has been implicated in the genesis of psychiatric disorders such as memory deficits, depression, anxiety and addiction. Aqueous leaf extract of Cymbopogon citratus (CYC) otherwise known as lemongrass tea has antidepressant, anxiolytic and anti-amnesic effects in rodents. This study was designed to evaluate if C. citratus could reverse the neurobehavioral and biochemical derangements induced by social defeat stress (SDS) in the resident/intruder paradigm. Methods Intruder male mice were divided into five groups (n = 7): group 1 received saline (10 mL/kg, p.o.; non-stress control), group 2 also received saline (10 mL/kg, p.o.; SDS control) while groups 3?5 had C. citratus (50, 100 and 200 mg/kg, p.o.) daily for 14 d. The SDS was carried out 30 min after each treatment from day 7 to day 14 by exposing each intruder mouse in groups 25 to a 10 min confrontation in the home cage of an aggressive resident counterpart. The neurobehavioral features (spontaneous motor activity-SMA, anxiety, memory, social avoidance and depression were then evaluated. The concentrations of nitrite, malondialdehyde and glutathione as well as acetylcholinesterase activity in the brain tissues were also determined. Results C. citratus (50, 100 and 200 mg/kg) attenuated hypolocomotion, heightened anxiety, depressive-like symptom, memory deficit and social avoidance induced by SDS. The altered levels of oxidative stress and acetyl-cholinesterase in SDS-mice were positively modulated by C. citratus. Conclusion The results of this study suggest that C. citratus might mitigate psychosocial stress-induced neurologic diseases in susceptible individuals.