Kolaviron was protective against sodium azide (NaN3) induced oxidative stress in the prefrontal cortex

Kolaviron neuroprotective effect against okadaic acid-provoked cognitive impairment

Alzheimer's disease (AD) is acknowledged as the main causative factor of dementia that affects millions of people around the world and is increasing at increasing pace. Okadaic acid (OA) is a toxic compound with ability to inhibit protein phosphatases and to induce tau protein hyperphosphorylation and Alzheimer's-like phenotype. Kolaviron (KV) is a bioflavonoid derived from Garcinia kola seeds with anti-antioxidative and anti-inflammation properties. The main goal of this study was to assess whether kolaviron can exert neuroprotective effect against okadaic acid-induced cognitive deficit. Rats had an intracerebroventricular (ICV) injection of OA and pretreated with KV at 50 or 100 mg/kg and examined for cognition besides histological and biochemical factors. OA group treated with KV at 100 mg/kg had less memory deficit in passive avoidance and novel object discrimination (NOD) tasks besides lower hippocampal levels of caspases 1 and 3, tumor necrosis factor α (TNFα) and interleukin 6 (IL-6) as inflammatory factors, reactive oxygen species (ROS), protein carbonyl, malondialdehyde (MDA), and phosphorylated tau (p-tau) and higher level of acetylcholinesterase (AChE) activity, mitochondrial integrity index, superoxide dismutase (SOD), and glutathione (GSH). Moreover, KV pretreatment at 100 mg/kg attenuated hippocampal CA1 neuronal loss and glial fibrillary acidic protein (GFAP) reactivity as a factor of astrogliosis. In summary, KV was able to attenuate cognitive fall subsequent to ICV OA which is partly mediated through its neuroprotective potential linked to mitigation of tau hyperphosphorylation, apoptosis, pyroptosis, neuroinflammation, and oxidative stress and also improvement of mitochondrial health.

Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

Comparative Biochemical Profiling of Aluminum Chloride and Sodium Azide Induced Neuroinflammation and Cardiometabolic Disturbance

Comorbidities in human beings signify the numerous risk factors that increase the incidences of neuro- and cardio-metabolic disorders. Experimental models depicting comorbidities are important to explore the molecular pathophysiology that can help suggest appropriate treatment strategies. Tissue-accumulating potential and pathological effects of aluminium chloride (AlCl₃)and sodium azide (NaN₃) are well recognized. Hence, in the current work, we have for the first time aimed to investigate the unexplored potential of graded dose effects of AlCl₃ and NaN₃ in inducing early inflammation and cardiometabolic toxicity via comparative biochemical analysis of AlCl₃ and/or NaN₃. Rats were allocated into seven groups (n = 6). Group 1 was normal control. Remaining groups were given graded doses of AlCl₃ and/or NaN₃, as LD-AlCl₃ (AlCl₃ 40 mg), MD-AlCl₃ (AlCl₃ 45 mg), and HD-AlCl₃ (AlCl₃ 50 mg) representing low dose, medium dose, and high dose of AlCl₃, respectively, and the remaining as LD-NaN₃ (NaN₃ 13 mg), MD-NaN₃ (NaN₃ 15 mg), and HD-NaN₃ (NaN₃ 17 mg) representing low dose, medium dose, and high dose of NaN₃, respectively. Serum levels of glucose, insulin, lipid profile, inflammatory mediators like IL-6 and oxidative stress marker, and malondialdehyde (MDA) were analyzed. Likewise, subacute toxicity parameters were analyzed. Immunohistochemistry (IHC) and histopathology (H&E/Masson's trichrome staining) of brain, heart, and pancreatic tissues were done. ECG pattern of all groups was observed. HD-AlCl₃ was associated with elevated levels of inflammatory biomarkers, MDA, and glycemic and lipid profiles, whereas it decreased the insulin levels. HD-NaN₃ also showed the similar effects of aggravated inflammatory biomarkers, impaired glycemic and lipid profiles, but depicted the maximum mortality rate as compared to HD-AlCl₃. IHC showed prominent amyloid plaques and neurofibrillary tangle formation with MD-AlCl₃ and HD-AlCl₃ as compared to NaN₃-treated groups. Likewise, in brain tissues, vacuolation of white matter, vascular congestion, and hemorrhage were seen in HD-AlCl₃ treated group, while HD-NaN₃ induced death in animals. AlCl₃ exposure resulted in an inverted QRS complex, while exposure to NaN₃ showed ST depression but with increased mortality. AlCl₃ has better controlled results as compared to NaN₃ for induction of comorbid experimental animal model depicting early neuroinflammation and cardiometabolic disruption. These determined efforts facilitate the researchers for the development of clinically effective treatment strategies using such experimental models.

A review on garcinia kola heckel: traditional uses, phytochemistry, pharmacological activities, and toxicology

PURPOSE

Garcinia kola is a medicinal plant commonly known as bitter kola. It is utilised in ethnomedicine for the treatment of diarrhoea, bronchitis, bacterial infection, cough, hepatitis, gonorrhoea, laryngitis, food poison, liver and gastric diseases.

OBJECTIVE

This study reviewed the phytochemistry, pharmacological activities, and ethnomedicinal potentials of G. kola.

MATERIALS AND METHODS

An extensive review was performed using electronic literature collated from ScienceDirect, Springer, Wiley, and PubMed databases.

RESULTS

Phytochemical analysis revealed the isolation of several chemical compounds including 9-octadecenoic acid, linoleic acid, 14-methylpentadecanoic acid, 1-butanol, hexadecanamide, I-4',II-4',I-5,II-5,I-7,II-7-hexahydroxy-I-3,II-8-biflavanone, lanost-7-en-3-one, kolaflavanone (8E)-4-geranyl-3,5-dihydroxybenzophenone, glutinol, Garcinia biflavonoid (GB-2a-II-4'-OMe), 9,19-cyclolanost-24-en-3-ol, 24-methylene, tirucallol, lupeol, β-amyrin, obtusifoliol and Kolaviron. Diverse pharmacological in-vivo and in vitro investigations revealed that G. kola has anti-inflammatory, antimalarial, hepatoprotective, cardioprotective, anti-asthmatic, neuroprotective, antioxidant, and antidiabetic activities.

CONCLUSION

The present study revealed that G. kola has preventive and therapeutic potentials against various diseases in both in vivo and in vitro studies and therefore can be utilised as a raw material in the pharmaceutical industries for the development of therapeutic products. However, there is a need for clinical trial experiments to validate and provide accurate and substantial information on the required safe dosage and efficacy for the treatment of several diseases.

Zinc and ascorbic acid treatment alleviates systemic inflammation and gastrointestinal and renal oxidative stress induced by sodium azide in rats

Background

Sodium azide (NaN3) is a chemical of rapidly increasing economic importance but with high toxic attributes. In this study, the effects of zinc (Zn) and ascorbic acid (AsA) supplementation on sodium azide (NaN3)-induced toxicity in the stomach, colon and kidneys were evaluated in Wistar rats. Twenty-eight rats were randomly allocated to four experimental groups as follows: group A (control) given distilled water only; group B (NaN3 only, 20 mg/kg); group C (NaN3 + zinc sulphate, ZnSO4 80 mg/kg); and group D (NaN3 + AsA 200 mg/kg).

Results

NaN3 was found to significantly (p < 0.05) induce increases in serum nitric oxide (NO), advanced oxidation protein products (AOPP), myeloperoxidase (MPO) and total protein levels, along with significant (p < 0.05) increase in gastric, colonic and renal malondialdehyde (MDA) and protein carbonyl (PCO) levels. In addition, NaN3 induced significant (p < 0.05) reduction in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities in the colon and kidneys. Treatment with Zn or AsA caused significant (p < 0.05) reduction in serum levels of oxidative and inflammatory markers, as well as tissue PCO and MDA levels. Moreover, co-treatment with Zn or AsA significantly (p < 0.05) restored colonic and renal levels of antioxidant enzymes, reduced glutathione and protein thiols.

Conclusions

This study shows that Zn or AsA supplementation alleviated  NaN3 toxicity by suppressing systemic inflammation and preventing oxidative damage in the stomach, colon and kidneys of rats.

Environmental toxicants, oxidative stress and health adversities: interventions of phytochemicals

OBJECTIVES

Oxidative stress is the most common factor mediating environmental chemical-induced health adversities. Recently, an exponential rise in the use of phytochemicals as an alternative therapeutics against oxidative stress-mediated diseases has been documented. Due to their free radical quenching property, plant-derived natural products have gained substantial attention as a therapeutic agent in environmental toxicology. The present review aimed to describe the therapeutic role of phytochemicals in mitigating environmental toxicant-mediated sub-cellular and organ toxicities via controlling cellular antioxidant response.

METHODS

The present review has covered the recently related studies, mainly focussing on the free radical scavenging role of phytochemicals in environmental toxicology.

KEY FINDINGS

In vitro and in vivo studies have reported that supplementation of antioxidant-rich compounds can ameliorate the toxicant-induced oxidative stress, thereby improving the health conditions. Improving the cellular antioxidant pool has been considered as a mode of action of phytochemicals. However, the other cellular targets of phytochemicals remain uncertain.

CONCLUSIONS

Knowing the therapeutic value of phytochemicals to mitigate the chemical-induced toxicity is an initial stage; mechanistic understanding needs to decipher for development as therapeutics. Moreover, examining the efficacy of phytochemicals against mixer toxicity and identifying the bioactive molecule are major challenges in the field.

Inhibitory potentials of Cymbopogon citratus oil against aluminium-induced behavioral deficits and neuropathology in rats

Cymbopogon citratus is a tropical phytomedicinal plant that is widely known for its hypoglycemic, hypolipidemic, anxiolytic, sedative, antioxidative and anti-inflammatory properties. In this study, we have examined the neuroprotective effects of the essential oil (ESO) of Cymbopogon citratus, following aluminum chloride (AlCl₃)-induced neurotoxicity within the cerebellum of Wistar rats. A total of 40 adult male Wistar rats were assigned into five groups and treated orally as follows: A–phosphate-buffered saline (1 ml daily for 15 days); B–ESO (50 mg/kg daily for 15 days); C–AlCl₃ (100 mg/kg daily for 15 days); D–AlCl₃ then ESO (100 mg/kg AlCl₃ daily for 15 days followed by 50 mg/kg ESO daily for subsequent 15 days); E–ESO then AlCl₃ (50 mg/kg ESO daily for 15 days followed by 100 mg/kg AlCl₃ daily for following 15 days). To address our questions, we observed the locomotion and exploratory behavior of the rats in the open field apparatus and subsequently evaluated cerebellar oxidative redox parameters, neural bioenergetics, acetylcholinesterase levels, transferrin receptor protein, and total protein profiles by biochemical assays. Furthermore, we investigated cerebellar histomorphology and Nissl profile by H&E and Cresyl violet Nissl staining procedures. ESO treatment markedly attenuated deficits in exploratory activities and rearing behavior following AlCl₃ toxicity, indicating its anxiolytic potentials. Additionally, AlCl₃ evokedincrease in malondialdehyde and nitric oxide levels, as well as repressed cerebellar catalase, glutathione peroxidase, and superoxide dismutase profiles were normalised to baseline levels by ESO treatment. Treatment with ESO, ergo, exhibits substantial neuroprotective and modulatory potentials in response to AlCl₃ toxicity.

The Protective Effect of Kolaviron on Molecular, Cellular, and Behavioral Characterization of Cerebellum in the Rat Model of Demyelinating Diseases

INTRODUCTION

This study aimed at assessing the protective mechanisms of Kolaviron (KV) on the cerebellum in a rat model of demyelination.

METHODS

Twenty-eight male Wistar rats were used in the present study. They were randomly divided into 4 groups of 7 rats. Group A (control) received corn oil (0.5 mL/kg/d); group B received 0.2% Cuprizone (CPZ); group C was treated with 200 mg/kg/d of KV, and group D received 0.2% CPZ and 200 mg/kg/d KV for 6 weeks. CPZ powder was mixed with the regular diet while KV was dissolved in corn oil and administered orally. A behavioral test was conducted at the termination of the experiment. Thereafter, the animals were sacrificed and their brains were removed with the excision of the cerebellum. A part of the cerebelli underwent tissue processing with a series of 5 μm thick sections cut from paraffin blocks for histological and immunohistochemical assessment. Besides, the remaining cerebellar tissues were homogenized for the spectrophotometric assays of Oxidative Stress (OS) parameters.

RESULTS

The current research findings revealed minimal weight gain following CPZ treatment, but significant weight increase in KV-treated rats. CPZ treatment was associated with a reduction in the number of the line crossed, rearing frequency, rearing duration, center square entry, and center square duration; however, it increased the freezing time, i.e. significantly reversed in the KV-treated animals. Oxidative markers, such as Superoxide Dismutase (SOD) and GPx were reduced in CPZ-treated rats with elevated MDA levels. However, these data were significantly reversed by the co-administration of CPZ and KV. At the tissue level, the cerebellar cortex was characterized by poorly defined layers, cryptic granules, as well as chromatolysis and pyknotic Purkinje cells with the evidence of hypertrophic astrogliosis.

CONCLUSION

CPZ treatment significantly depressed locomotor and exploratory activities. Furthermore, it increased OS and cerebellar toxicity. However, KV intervention significantly enhanced behavioral functions and ameliorated CPZ-induced cerebellar degeneration. Moreover, it considerably regulated OS markers in the cerebellum of the rat model of demyelinating diseases.

Kolaviron protects against cognitive deficits and cortico-hippocampal perturbations associated with maternal deprivation in rats

Prolonged separation of pups from their mother in early postnatal period can interfere with normal growth and development, resulting in different behavioral changes similar to features of schizophrenia in man. This study explored the cytoprotective action of kolaviron, a biflavonoid, on the prefrontal cortex and hippocampus of maternally deprived Wistar rats. Eight months old female rats were time-mated, and after delivery their pups were randomly assigned into four groups; group A received 0.5 ml of normal saline, group B received kolaviron orally (200 mg/kg/bw) on postnatal days (PND) 21–35, group C were maternally deprived on PND 9 for 24 hours, while group D were also maternally deprived on PND 9 for 24 hours, and then received kolaviron orally (200 mg/kg/bw) on PND 21–35. Behavioral studies (open field test, Morris water test, and Y-maze test) were conducted after the experiment prior to sacrifice. Some of the rats were anesthetized with ketamine and perfusion-fixed with 0.1 M phosphate buffered saline and 4% paraformaldehyde, while others were sacrificed by cervical dislocation for enzyme studies. The hippocampus and prefrontal cortex were excised from the brain and processed for tissue histology, histochemistry, and enzymatic analysis. Results revealed behavioral deficits, oxidative stress, degenerative changes, and astrocytosis in the prefrontal cortex and hippocampus of maternally deprived rats, but intervention with kolaviron caused significant improvement in neurobehavior, morphology, and neurochemistry in these brain areas. We concluded that kolaviron could protect the brain against neurological consequences of nutritional and environmental insults arising from maternal separation in early postnatal period.

Moringa oleifera seed oil or virgin coconut oil supplementation abrogates cerebral neurotoxicity induced by antineoplastic agent methotrexate by suppression of oxidative stress and neuro-inflammation in rats

Methotrexate (MTX) is an effective antineoplastic drug associated with wide organ toxicity. Accumulating evidence implicates oxidative stress to be a leading underlying mechanism of MTX-induced neurotoxicity. The study explores antioxidant potential of virgin coconut oil (VCO) or Moringa oleifera seed oil (MOO) in MTX-induced oxidative stress-mediated cerebral neurotoxicity and inflammation in rats. Rats treated with VCO or MOO (5 ml/kg bw) for 17 days were administered MTX (20 mg/kg, intraperitoneally) on day 14 only. Cerebral activities of acetylcholinesterase, antioxidant enzymes, lipid peroxidation, reduced glutathione and nitric oxide levels as well as cytokines were evaluated. MTX-induced neurotoxic alterations were significantly abrogated by MOO and VCO supplementation via inhibition of cholinesterase, oxidative stress, and anti-inflammatory mechanisms. VCO and MOO showed comparable antioxidant potentials with the standards in DPPH and FRAP assays. VCO and MOO are promising natural oils for modulating MTX neurotoxicity in cancer patients. PRACTICAL APPLICATIONS: Methotrexate chemotherapy induces neurotoxicity in cancer patients, and this is a source of worry for clinicians. This study reports, for the first time, the beneficial health effects of functional food oils, Moringa oleifera seed oil, and virgin coconut oil against anticancer drug methotrexate-induced cerebral neurotoxicity. Supplementation of these natural oils may be beneficial in the prevention of cerebral neurotoxic side effect in cancer patients undergoing methotrexate chemotherapy.

Reversal of behavioral decline and neuropathology by a complex vitamin supplement involves modulation of key neurochemical stressors

Metal ions are crucial for normal neurochemical signaling and perturbations in their homeostasis have been associated with neurodegenerative processes. Hypothesizing that in vivo modulation of key neurochemical processes including metal ion regulation (by transferrin receptor-1: TfR-1) in cells can improve disease outcome, we investigated the efficacy of a complex vitamin supplement (CVS) containing B-vitamins and ascorbic acid in preventing/reversing behavioral decline and neuropathology in rats. Wistar rats (eight weeks-old) were assigned into five groups (n = 8), including controls and those administered CVS (400 mg/kg/day) for two weeks before or after AlCl₃ (100 mg/kg)-induced neurotoxicity. Following behavioral assessments, prefrontal cortex (PFC) and hippocampus were prepared for biochemical analyses, histology and histochemistry. CVS significantly reversed reduction of exploratory/working memory, frontal-dependent motor deficits, cognitive decline, memory dysfunction and anxiety. These correlated with CVS-dependent modulation of TfP-1 expression that were accompanied by significant reversal of neural oxidative stress in expressed superoxide dismutase, nitric oxide, catalase, glutathione peroxidase and malondialdehyde. Furthermore, CVS inhibited neural bioenergetics dysfunction, with increased labelling of glucokinase within PFC and hippocampus correlating with increased glucose-6-phosphate dehydrogenase and decreased lactate dehydrogenase expressions. These relates to inhibition of over-expressed acetylcholinesterase and increased total protein synthesis. Histological and Nissl staining of thin sections corroborated roles of CVS in reversing AlCl₃-induced neuropathology. Summarily, we showed the role of CVS in normalizing important neurochemical molecules linking concurrent progression of oxidative stress, bioenergetics deficits, synaptic dysfunction and cellular hypertrophy during neurodegeneration.

Neurotoxic Agent-Induced Injury in Neurodegenerative Disease Model: Focus on Involvement of Glutamate Receptors

Glutamate receptors play a crucial role in the central nervous system and are implicated in different brain disorders. They play a significant role in the pathogenesis of neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although many studies on NDDs have been conducted, their exact pathophysiological characteristics are still not fully understood. In in vivo and in vitro models of neurotoxic-induced NDDs, neurotoxic agents are used to induce several neuronal injuries for the purpose of correlating them with the pathological characteristics of NDDs. Moreover, therapeutic drugs might be discovered based on the studies employing these models. In NDD models, different neurotoxic agents, namely, kainic acid, domoic acid, glutamate, β-N-Methylamino-L-alanine, amyloid beta, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1-methyl-4-phenylpyridinium, rotenone, 3-Nitropropionic acid and methamphetamine can potently impair both ionotropic and metabotropic glutamate receptors, leading to the progression of toxicity. Many other neurotoxic agents mainly affect the functions of ionotropic glutamate receptors. We discuss particular neurotoxic agents that can act upon glutamate receptors so as to effectively mimic NDDs. The correlation of neurotoxic agent-induced disease characteristics with glutamate receptors would aid the discovery and development of therapeutic drugs for NDDs.

Kolaviron attenuated arsenic acid induced-cardiorenal dysfunction via regulation of ROS, C-reactive proteins (CRP), cardiac troponin I (CTnI) and BCL2

Arsenic acid is one of the abundant environmental pollutants present in soil, water and the air. Undoubtedly, it has found its way to the food chain in which humans and animals are the final targets thereby causing arrays of disease conditions including cardiovascular and renal dysfunction. Hence, the use of phytochemicals present in medicinal plants has gained global acceptance as chemotherapeutic agents that can prevent, ameliorate, reverse or treat diseases. From our study, arsenic acid intoxication led to significant increase in heart rate (HR), QRS, together with prolonged QT and QTc interval. However, Kolaviron (KV) at the dosage of 100 and 200 mg/kg body weight reversed the aforementioned electrocardiographic (ECG) changes. KV pre-treatment also ameliorated cardiorenal dysfunction via significant reduction in cardiac and renal markers of oxidative stress such as malondialdehyde, hydrogen peroxide generation, myeloperoxidase activity and nitric oxide contents. Immunohistochemistry revealed expressions of renal C-reactive proteins (CRP) and expressions of anti-apoptotic protein BCL2 in KV treated rats. Furthermore, cardiac troponin I (CTnI) expressions were lower in KV treated rats. Taken together, KV mitigated arsenic-acid induced cardiovascular dysfunction via up-regulation of antioxidant defense system and down-regulation of inflammatory and apoptotic signaling pathways.

Kolaviron Protects the Prefrontal Cortex and Hippocampus against Histomorphological and Neurobehavioural Changes in Cuprizone Model of Multiple Sclerosis

Background

This study explored the efficacy of kolaviron-a biflavonoid complex isolated from the seeds of Garcinia kola-in protecting against cuprizone (CPZ)-induced demyelination in both the prefrontal cortex and the hippocampus of Wistar rats.

Methodology

Thirty rats were treated to receive 0.5 mL phosphate-buffered saline (group A, control), 0.5 mL corn oil (group B), 0.2% CPZ (group C), for 6 weeks, 0.2% CPZ for 3 weeks and then 200 mg/kg of Kv for 3 weeks (group D), or 200 mg/kg of Kv for 3 weeks followed by 0.2% CPZ for 3 weeks (group E). Rats were assessed for exploratory functions and anxiety-like behaviour before being euthanised and perfused transcardially with 4% paraformaldehyde. Prefrontal and hippocampal thin sections were stained in hematoxylin and eosin and cresyl fast violet stains.

Results

CPZ-induced demyelination resulted in behavioural impairment as seen by reduced exploratory activities, rearing behaviour, stretch attend posture, center square entry, and anxiogenic characteristics. Degenerative changes including pyknosis, karyorrhexis, neuronal hypertrophy, and reduced Nissl integrity were also seen. Animals treated with Kv showed significant improvement in behavioural outcomes and a comparatively normal cytoarchitectural profile.

Conclusion

Kv provides protective roles against CPZ-induced neurotoxicity through prevention of ribosomal protein degradation.

Neuroscience in Nigeria: the past, the present and the future

The science of the brain and nervous system cuts across almost all aspects of human life and is one of the fastest growing scientific fields worldwide. This necessitates the demand for pragmatic investment by all nations to ensure improved education and quality of research in Neurosciences. Although obvious efforts are being made in advancing the field in developed societies, there is limited data addressing the state of neuroscience in sub-Saharan Africa. Here, we review the state of neuroscience development in Nigeria, Africa's most populous country and its largest economy, critically evaluating the history, the current situation and future projections. This review specifically addresses trends in clinical and basic neuroscience research and education. We conclude by highlighting potentially helpful strategies that will catalyse development in neuroscience education and research in Nigeria, among which are an increase in research funding, provision of tools and equipment for training and research, and upgrading of the infrastructure at hand.

Multidirectional inhibition of cortico-hippocampal neurodegeneration by kolaviron treatment in rats

Earliest signs of neurodegenerative cascades in the course of Alzheimer's disease (AD) are seen within the prefrontal cortex (PFC) and hippocampus, with pathological evidences in both cortical structures correlating with manifestation of behavioural and cognitive deficits. Despite the enormous problems associated with AD's clinical manifestations in sufferers, therapeutic advances for the disorder are still very limited. Therefore, this study examined cortico-hippocampal microstructures in models of AD, and evaluated the possible beneficial roles of kolaviron (Kv)-a biflavonoid complex in rats. Nine groups of rats were orally exposed to sodium azide (NaN₃) or aluminium chloride (AlCl₃) solely or in different combinations with Kv. Sequel to sacrifice and transcardial perfusion (using buffered saline then 4% paraformaldehyde), PFC and hippocampal tissues were harvested and processed for: spectrophotometric assays of oxidative stress and neuronal bioenergetics parameters, histological demonstration of cytoarchitecture and immunohistochemical evaluation of astrocytes and neuronal cytoskeleton. Results showed alterations in mitochondrial functions, which led to compromised neuronal antioxidant system, dysfunctional neural bioenergetics, hypertrophic astrogliosis, cytoskeletal dysregulation and neuronal death within the PFC and hippocampus. These degenerative events were associated with NaN₃ and AlCl₃ toxicity in rats. Furthermore, Kv inhibited cortico-hippocampal degeneration through multiple mechanisms that primarily involved halting of biochemical cascades that activate proteases which destroy molecules expedient for cell survival, and others that mediate a program of cell suicide in neuronal apoptosis. In conclusion, Kv showed important neuroprotective roles within cortico-hippocampal cells through multiple mechanisms, and particularly has prominent prophylactic activity than regenerative potentials.

Cerebellar Molecular and Cellular Characterization in Rat Models of Alzheimer's Disease: Neuroprotective Mechanisms of Garcinia Biflavonoid Complex

BACKGROUND

Recent evidences suggest that cerebellar degeneration may be associated with the development of Alzheimer's disease (AD). However, previous reports were mainly observational, lacking substantial characterization of cellular and molecular cerebellar features during AD progression.

PURPOSE

This study is aimed at characterizing the cerebellum in rat models of AD and assessing the corresponding neuroprotective mechanisms of Garcinia biflavonoid complex (GBc).

METHODS

Male Wistar rats were grouped and treated alone or in combination with PBS (ad libitum)/day, corn oil (CO; 2 mL/kgBw/day), GBc (200 mg/kgBw/day), sodium azide (NaN₃) (15 mg/kgBw/day) and aluminium chloride (AlCl₃) (100 mg/kgBw/day). Groups A and B received PBS and CO, respectively; C received GBc; D received NaN₃; E received AlCl₃; F received NaN₃ then GBc subsequently; G received AlCl₃ then GBc subsequently; H received NaN₃ and GBc simultaneously while I received AlCl₃ and GBc simultaneously. Following treatments, cerebellar cortices were processed for histology, immunohistochemistry and colorimetric assays.

RESULTS

Our data revealed that cryptic granule neurons and pyknotic Purkinje cell bodies (characterized by short dendritic/axonal processes) correspond to indistinctly demarcated cerebellar layers in rats treated with AlCl₃ and NaN₃. These correlates, with observed hypertrophic astrogliosis, increased the neurofilament deposition, depleted the antioxidant system-shown by expressed superoxide dismutase and glutathione peroxidase, and cerebellar glucose bioenergetics dysfunction-exhibited in assayed lactate dehydrogenase and glucose-6-phosphate dehydrogenase. We further showed that GBc reverses cerebellar degeneration through modulation of neurochemical signaling pathways and stressor molecules that underlie AD pathogenesis.

CONCLUSION

Cellular, molecular and metabolic neurodegeneration within the cerebellum is associated with AlCl₃ and NaN₃-induced AD while GBc significantly inhibits corresponding neurotoxicity and is more efficacious when pre-administered.

Ameliorative effect of kolaviron, a biflavonoid complex from Garcinia kola seeds against scopolamine-induced memory impairment in rats: role of antioxidant defense system

In Alzheimer's disease (AD) basal forebrain cholinergic neurons appear to be targeted primarily in early stages of the disease. Scopolamine (muscarinic receptor antagonist) has been used for decades to induce working and reference memory impairment in rodents. In this study, we evaluated the protective effect of kolaviron, a biflavonoid complex isolated from Garcinia kola seeds extract against scopolamine-induced memory impairment/oxidative stress. Rats were pretreated with kolaviron (25, 50 or 100 mg/kg p.o.) for 3 consecutive days, scopolamine (3 mg/kg, i.p.) was administered 1 h post-treatment on day 3. Five minutes post-scopolamine injection, memory function was assessed using the Y-maze or Morris water maze tests (MWM) in rats. The rats were sacrificed and brains isolated on the 8th day after the MWM test for estimation of acetylcholinesterase activity and nitrosative/oxidative stress status. Scopolamine injection induced deficit (P < 0.05) in percentage alternation behaviour in the Y-maze test indicating memory impairment which was ameliorated by kolaviron in a dose-dependent manner. Also, pre-training treatment with kolaviron significantly improved spatial learning evidenced in the session-dependent and more efficient localization of the hidden platform in the MWM test. Moreover, scopolamine injection induced significant increase in lipid peroxidation (prefrontal cortex), nitrite generation (striatum and hippocampus) and a decrease in glutathione (prefrontal cortex, striatum and hippocampus) and superoxide dismutase (striatum and hippocampus) level which was attenuated by kolaviron pre-treatment. These findings showed that kolaviron possesses cognition enhancing effect through enhancement of antioxidant defense and cholinergic systems.

Inhibition of neuroinflammation in BV2 microglia by the biflavonoid kolaviron is dependent on the Nrf2/ARE antioxidant protective mechanism

Kolaviron is a mixture of biflavonoids found in the nut of the West African edible seed Garcinia kola, and it has been reported to exhibit a wide range of pharmacological activities. In this study, we investigated the effects of kolaviron in neuroinflammation. The effects of kolaviron on the expression of nitric oxide/inducible nitric oxide synthase (iNOS), prostaglandin E2 (PGE2)/cyclooxygenase-2, cellular reactive oxygen species (ROS) and the pro-inflammatory cytokines were examined in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Molecular mechanisms of the effects of kolaviron on NF-κB and Nrf2/ARE signalling pathways were analysed by immunoblotting, binding assays and reporter assays. RNA interference was used to investigate the role of Nrf2 in the anti-inflammatory effect of kolaviron. Neuroprotective effect of kolaviron was assessed in a BV2 microglia/HT22 hippocampal neuron co-culture. Kolaviron inhibited the protein levels of NO/iNOS, PGE2/COX-2, cellular ROS and the pro-inflammatory cytokines (TNFα and IL-6) in LPS-stimulated microglia. Further mechanistic studies showed that kolaviron inhibited neuroinflammation by inhibiting IκB/NF-κB signalling pathway in LPS-activated BV2 microglia. Kolaviron produced antioxidant effect in BV2 microglia by increasing HO-1 via the Nrf2/antioxidant response element pathway. RNAi experiments revealed that Nrf2 is needed for the anti-inflammatory effects of kolaviron. Kolaviron protected HT22 neurons from neuroinflammation-induced toxicity. Kolaviron inhibits neuroinflammation through Nrf2-dependent mechanisms. This compound may therefore be beneficial in neuroinflammation-related neurodegenerative disorders.