Evaluation of the Antipsychotic Potential of Panax quinquefolium in Ketamine Induced Experimental Psychosis Model in Mice

NMDA receptor modulation by Esculetin: Investigating behavioral, biochemical and neurochemical effects in schizophrenic mice model

Schizophrenia, a global mental health disorder affecting approximately 1 % of the population, is characterized by neurotransmitter dysregulation, particularly dopamine, serotonin, and glutamate. Current antipsychotic therapies, despite their efficacy, are accompanied by adverse effects, which has motivated researchers to investigate more secure substitutes. This study examines the potential antipsychotic effects of esculetin, a natural coumarin derivative recognized for its wide-ranging pharmacological activities (anti-inflammatory, antioxidant, anti-pathogenic, anticancer, and neuroprotective), in animal model of schizophrenia induced by ketamine. In order to induce disease, acute and chronic ketamine administration was performed on Swiss albino mice, supplemented with esculetin (as the test substance) and clozapine (as the reference standard). Behavioral studies and biochemical assays were performed to evaluate positive, negative, and cognitive symptoms of schizophrenia, as well as antioxidant and oxidant levels in various brain regions. Esculetin demonstrated significant improvements in behavioral symptoms, attenuated oxidative stress and neuroinflammation, and modulated neurotransmitter levels. Afterwards, ELISA was performed to evaluate levels of schizophrenia biomarkers AChE, BDNF. Moreover, proinflammatory cytokines (IL-6 and TNF-α) and NF-κB were also determined. Histopathological parameters of under study brain parts i.e., hippocampus, cortex and striata were also assessed. Esculetin and clozapine significantly (***p < 0.0001) altered ketamine induced behavioral symptoms and attenuated ketamine induced oxidative stress and neuroinflammation. Additionally, esculetin significantly (***p < 0.0001) altered neurotransmitter (dopamine, serotonin, glutamate) levels. ELISA analysis depicts ketamine reduced BDNF levels in hippocampus, cortex and striata while esculetin significantly (***p < 0.0001) increased BDNF levels in under study three parts of brain. Histopathological changes were seen in test groups. The findings of this study indicate that esculetin may have therapeutic potential in the treatment of schizophrenia induced by ketamine. As a result, esculetin may have the potential to be utilized as a treatment for schizophrenia.

Nano-hesperetin attenuates ketamine-induced schizophrenia-like symptoms in mice: participation of antioxidant parameters

RATIONALE

Antioxidant natural herb hesperetin (Hst) offers powerful medicinal properties. Despite having noticeable antioxidant properties, it has limited absorption, which is a major pharmacological obstacle.

OBJECTIVES

The goal of the current investigation was to determine if Hst and nano-Hst might protect mice against oxidative stress and schizophrenia (SCZ)-like behaviors brought on by ketamine (KET).

METHODS

Seven treatment groups (n=7) were created for the animals. For 10 days, they received distilled water or KET (10 mg/kg) intraperitoneally (i.p). From the 11th to the 40th day, they received daily oral administration of Hst and nano-Hst (10, 20 mg/kg) or vehicle. With the use of the forced swimming test (FST), open field test (OFT), and novel object recognition test (NORT), SCZ-like behaviors were evaluated. Malondialdehyde (MDA) and glutathione levels and antioxidant enzyme activities were assessed in the cerebral cortex.

RESULTS

Our findings displayed that behavioral disorders induced by KET would be improved by nano-Hst treated. MDA levels were much lower after treatment with nano-Hst, and brain antioxidant levels and activities were noticeably higher. The mice treated with nano-Hst had improved outcomes in the behavioral and biochemical tests when compared to the Hst group.

CONCLUSIONS

Our study's findings showed that nano-Hst had a stronger neuroprotective impact than Hst. In cerebral cortex tissues, nano-Hst treatment dramatically reduced KET-induced (SCZ)-like behavior and oxidative stress indicators. As a result, nano-Hst may have more therapeutic potential and may be effective in treating behavioral impairments and oxidative damage brought on by KET.

Ketamine induces schizophrenia-like condition in rats via amendment of neurotransmitters and behavior

Background

The pupae of mulberry silkworms, family Bombycidae, possess a great number of proteins that cover all of the necessary amino acids obligatory for well-being.

Objective

In this study, we aimed to evaluate the probable antipsychotic effect of pupae of mulberry silkworms in a rat model of schizophrenia prompted by ketamine on the cerebral cortex, hippocampus, and striatum, the brain areas involved in neuropsychiatric complaints.

Materials and methods

To this end, male albino rats were classified as follows: group 1 was the control group; group 2 animals were administered 135 mg/kg, p.o. silkworm pupae for 3 weeks; group 3 animals received vehicle for 3 weeks, and ketamine (30 mg/kg, i.p.) for the last 5 consecutive days of the experiment; and group 4 was the silkworm pupae and ketamine-treated group.

Results

The results revealed that treatment with silkworm pupae improved the exploration of schizophrenic rats in the novel object test and almost normalized their locomotor activity in the open field test. Additionally, silkworm pupae modulated the content of catecholamines and oxidative state in the cerebral cortex, hippocampus, and striatum of schizophrenic rats; however, the acetylcholine esterase activity was restored in the hippocampus only. Histopathological damages caused by ketamine are partially reduced by silkworm pupae.

Conclusion

Our data suggest that silkworm pupae, via neurobehavioral modulatory pathway, exhibit beneficial effects against psychomimetic influence of ketamine.

Niacin mitigates blood-brain barrier tight junctional proteins dysregulation and cerebral inflammation in ketamine rat model of psychosis: Role of GPR109A receptor

Dysregulated inflammatory responses and blood-brain barrier (BBB) dysfunction are recognized as central factors in the development of psychiatric disorders. The present study was designed to evaluate the effect of niacin on BBB integrity in ketamine-induced model of psychosis. Meanwhile, mepenzolate bromide (MPN), a GPR109A receptor blocker, was used to investigate the role of this receptor on the observed niacin's effect. Male Wistar rats received ketamine (30 mg/kg/day, i.p) for 5 consecutive days and then niacin (40 mg/kg/day, p.o), with or without MPN (5 mg/kg/day, i.p), was given for the subsequent 15 days. Three days before the end of experiment, rats were behaviorally tested using open field, novel object recognition, social interaction, and forced swimming tests. Niacin significantly ameliorated ketamine-induced behavioral deficits, amended gamma aminobutyric acid and glutamate concentration, decreased tumor necrosis factor-α and matrix metallopeptidase 9 levels, and increased netrin-1 contents in the hippocampus of rats. Niacin also augmented the hippocampal expression of ZO-1, occludin, and claudin-5 proteins, indicating the ability of niacin to restore the BBB integrity. Moreover, the histopathologic changes in hippocampal neurons were alleviated. Since all the beneficial effects of niacin in the present investigation were partially abolished by the co-administration of MPN; GPR109A receptor was proven to partially mediate the observed antipsychotic effects of niacin. These data revealed that GPR109A-mediated signaling pathways might represent potential targets for therapeutic interventions to prevent or slow the progression of psychosis.

Pretreatment with Carpolobia lutea ethanol extract prevents schizophrenia-like behavior in mice models of psychosis

ETHNOPHARMACOLOGICAL RELEVANCE

Carpolobia lutea decoction is widely used as a phytotherapeutic against central nervous system-related disorders including insomnia, migraine headache, and mental illness in West and Central Tropical Africa.

AIM

This study was designed to investigate the antipsychotic activity of Carpolobia lutea (EECL) in mice models of psychosis.

METHODS

Male Swiss mice (n = 5/group) were given EECL (100, 200, 400, and 800 mg/kg), haloperidol (1 mg/kg), clozapine (5 mg/kg) and vehicle (10 mL/kg) orally before amphetamine (5 mg/kg)-induced hyperlocomotion and stereotypy, apomorphine (2 mg/kg)-induced stereotypy, or ketamine (10, 30, and 100 mg/kg)-induced hyperlocomotion, enhancement of immobility and cognitive impairment.

RESULTS

EECL (200, 400, and 800 mg/kg) prevented amphetamine- and apomorphine-induced stereotypies, as well as reduced hyperlocomotion induced by amphetamine and ketamine, all of which are predictors of positive symptoms. Regardless of the dose administered, EECL prevented the index of negative symptoms induced by ketamine. Furthermore, higher doses of EECL (400 and 800 mg/kg) also prevented ketamine-induced cognitive impairment, a behavioral phenotype of cognitive symptoms.

CONCLUSION

Pretreatment with EECL demonstrated antipsychotic activity in mice, preventing amphetamine-, apomorphine-, and ketamine-induced schizophrenia-like symptoms, with 800 mg/kg being the most effective dose.

Antipsychotic-like effect of ethyl acetate fraction of Terminalia macroptera leaf in mice

Psychosis is a chronic neuropsychiatric disorder that affects millions of individuals worldwide and impairs the quality of life and productivity of the patients. Terminalia macroptera Guill & Perr. (Combrataceae) is a plant that is used in the management of anxiety related disorders. The present study investigates the antipsychotic effects of ethyl acetate fraction of T. macroptera (EFTM) leaf in ketamine-induced psychosis in mice. Acute toxicity of EFTM was determine using Lorke's method. Ketamine (25 mg/kg) was injected once daily for 7 consecutive days in Swiss albino mice to induce psychosis. The effect of the extracts (100, 200 and 400 mg/kg) was evaluated against psychotic-like behaviors induced by ketamine including locomotor activity and stereotypy in the open field test, immobility duration in the forced swim test, and memory impairment using the Y- maze test. The acute antipsychotic effect of EFTM was evaluated on apomorphine climbing test, while woodblock test was performed to assess its extrapyramidal side effects. The LD₅₀ was found to be 3807 mg/kg p.o. which is considered safe. EFTM (100, 200 and 400 mg/kg) exhibited significant antipsychotic effect by reducing ketamine-induced hyperactivity, immobility, and memory deficit in mice, EFTM also suppressed stereotypic climbing behavior due to apomorphine. Accordingly, the antipsychotic activity of EFTM was not associated with extrapyramidal side effects as evidenced by lack of catalepsy. The study revealed that EFTM ameliorated psychotic-like symptoms and is devoid of extrapyramidal side effects in mice, underscoring its antipsychotic-like effect.

Antimania-Like Effect of Panax ginseng Regulating the Glutamatergic Neurotransmission in REM-Sleep Deprivation Rats

Previous studies have shown the therapeutic properties of ginseng and ginsenosides on hyperactive and impulsive behaviors in several psychiatric diseases. Herein, we investigated the effect of Panax ginseng Meyer (PG) on hyperactive/impulsive behaviors in a manic-like animal model, sleep deprivation (SD) rats. Male rats were sleep-deprived for 48 h, and PG (200 mg/kg) was administered for 4 days, from 2 days prior to the start of SD to the end date of SD. The elevated plus maze (EPM) test showed that PG alleviated the increased frequency of entries into and spent time within open arms by SD. In order to investigate the molecular mechanism on this effect of PG, we assessed differentially expressed genes (DEGs) in the prefrontal cortex of PG-treated SD rats using RNA sequencing (RNA-seq) and performed gene-enrichment analysis for DEGs. The gene-enrichment analysis showed that PG most prominently affected the glutamatergic synapse pathway. Among the glutamatergic synapse pathway genes, particularly, PG enhanced the expressions of glutamate transporter Slc1a3 and Slc1a2 reduced in SD rats. Moreover, we found that PG could inhibit the SD-induced phosphorylation of the NR2A subunit of the NMDA receptor. These results suggested that PG might have a therapeutic effect against the manic-like behaviors, regulating the glutamatergic neurotransmission.

Chronic mild stress alters synaptic plasticity in the nucleus accumbens through GSK3β-dependent modulation of Kv4.2 channels

Although major depressive disorder (MDD) is highly prevalent, its pathophysiology is poorly understood. Recent evidence suggests that glycogen-synthase kinase 3β (GSK3β) plays a key role in memory formation, yet its role in mood regulation remains controversial. Here, we investigated whether GSK3β activity in the nucleus accumbens (NAc) is associated with depression-like behaviors and synaptic plasticity. We performed whole-cell patch-clamp recordings of medium spiny neurons (MSNs) in the NAc and determined the role of GSK3β in spike timing-dependent long-term potentiation (tLTP) in the chronic unpredictable mild stress (CUMS) mouse model of depression. To assess the specific role of GSK3β in tLTP, we used in vivo genetic silencing by an adeno-associated viral vector (AAV2) short hairpin RNA against GSK3β. In addition, we examined the role of the voltage-gated potassium Kv4.2 subunit, a molecular determinant of A-type K⁺ currents, as a potential downstream target of GSK3β. We found increased levels of active GSK3β and augmented tLTP in CUMS mice, a phenotype that was prevented by selective GSK3β knockdown. Furthermore, knockdown of GSK3β in the NAc ameliorated depressive-like behavior in CUMS mice. Electrophysiological, immunohistochemical, biochemical, and pharmacological experiments revealed that inhibition of the Kv4.2 channel through direct phosphorylation at Ser-616 mediated the GSK3β-dependent tLTP changes in CUMS mice. Our results identify GSK3β regulation of Kv4.2 channels as a molecular mechanism of MSN maladaptive plasticity underlying depression-like behaviors and suggest that the GSK3β-Kv4.2 axis may be an attractive therapeutic target for MDD.

Effect of Vaccinium macrocarpon on MK-801-induced psychosis in mice

OBJECTIVES

This study was aimed to investigate the effect of aqueous cranberry extract (ACE) on MK-801-induced psychosis in mice.

MATERIALS AND METHODS

MK-801-treated mice were administered ACE (1 and 2 g/kg, p.o.) for 14 days. Various behavioral parameters and neurochemical estimations such as dopamine (DA), 5-hydroxytryptamine (5-HT), norepinephrine (NE), gamma-aminobutyric acid (GABA), glutamate, and glycine as well as markers of oxidative stress such as nitrite levels were measured.

RESULTS

Psychosis-induced mice showed a significant elevation of immobility time in forced swim test, locomotor activity, and reduction in time of permanency in rota-rod test, escape latency time in Cook's pole test while treatment with ACE showed a significant alteration in above-mentioned behavioral parameters in MK-801-induced psychosis. Moreover, MK-801-induced psychosis in the mice showed a significant increase in DA, 5-HT, and NA levels and decrease in GABA, glutamate, and glycine levels in the brain. In contrast, treatment with ACE at both doses remarkably altered the neurochemical parameters. In addition, ACE-treated mice showed a substantial reduction in acetylcholinesterase, D-amino acid oxidase enzyme activity, and nitrite levels which were elevated by the administration of MK-801.

CONCLUSIONS

Treatment with ACE once for 14 days (1 and 2 g/kg) significantly ameliorated the behavioral symptoms in experimentally induced psychosis by virtue of neuromodulation and decreased oxidative stress.

Active ginseng components in cognitive impairment: Therapeutic potential and prospects for delivery and clinical study

Cognitive impairment is a state that affects thinking, communication, understanding, and memory, and is very common in various neurological disorders. Among many factors, age-related cognitive decline is an important area in mental health research. Research to find therapeutic medications or supplements to treat cognitive deficits and maintain cognitive health has been ongoing. Ginseng and its active components may have played a role in treating chronic disorders. Numerous preclinical studies have confirmed that ginseng and its active components such as ginsenosides, gintonin, and compound K are pharmacologically efficacious in different models of and are linked to cognitive impairment. Among their several roles, they act as an anti-neuroinflammatory and help fight against oxidative stress and modulate the cholinergic signal. These roles may be involved in enhancing cognition and attenuating impairment. There have been some clinical studies on the activity of ginseng in cognitive impairment, but many ginseng species and active compounds remain to be investigated. In addition, new formulations of active ginseng components such as nanoparticles and liposomes could be used for preclinical and clinical models of cognitive impairment. Here, we discuss the therapeutic potential of active ginseng components in cognitive impairment and their chemistry and pharmacokinetics and consider prospects for their delivery and clinical study with respect to cognitive impairment.

Effects of Panax ginseng C.A. Meyer extract on the offspring of adult mice with maternal immune activation

To understand maternal immune activation (MIA) during prenatal development, the synthetic double-stranded RNA polyriboinosinic-polyribocytidylic acid [poly(I:C)] has been widely used in animal models to induce behavioral deficits similar to those in schizophrenia and other psychotic disorders. Panax ginseng C.A. Meyer (PG) extract is widely used to treat various kinds of nervous system disorders in Asia particularly China and Korea. The present study aimed to examine the effects of PG extract on MIA offspring using behavioral activity tests and protein expression analyses. Pregnant mice were exposed to poly(I:C) (5 mg/kg) or vehicle treatment on gestation day 9, and the resulting MIA offspring were subjected to vehicle or PG (300 mg/kg) treatment. In the acoustic startle response test, MIA-induced sensorimotor gating deficit was ameliorated by PG. The majority of behavioral parameters measured in the social interaction (non-aggressive or/and aggressive pattern), open field (number/duration of behavior) and forced swimming test (immobility behavior) were significantly altered in the MIA offspring. Western blot and immunohistochemical analyses of the medial prefrontal cortex indicated that the expression levels of certain neurodevelopmental proteins, including dihydropyrimidinase-related 2, LIM and SH3 domain 1, neurofilament medium, and discs large homolog 4, were decreased in the untreated MIA offspring, whereas PG treatment improved behavioral impairments and increased neurodevelopmental protein expression in MIA offspring. These results suggested that PG may be useful in neurodevelopmental disorder therapy, including psychiatric disorders such as schizophrenia, owing to its antipsychotic effects.

Morin Attenuates Neurochemical Changes and Increased Oxidative/Nitrergic Stress in Brains of Mice Exposed to Ketamine: Prevention and Reversal of Schizophrenia-Like Symptoms

Previous studies have revealed that morin (MOR), a neuroactive bioflavonoid, with proven psychotropic and neuroprotective properties reduced schizophrenic-like behaviors in mice. This study further evaluated the ability of MOR to prevent and reverse ketamine-induced schizophrenic-like behaviors and the underlying neurochemical changes and increased oxidative/nitrergic stress in mice. In the preventive protocol, mice received intraperitoneal injection of MOR (100 mg/kg), reference antipsychotic drugs [haloperidol (1 mg/kg), risperidone (0.5 mg/kg)], or saline daily for 14 consecutive days prior to i.p. injection of ketamine (KET) (20 mg/kg/day) from the 8th to the 14th day. In the reversal protocol, the animals received KET or saline for 14 days prior to MOR, haloperidol, risperidone, or saline treatments. Schizophrenic-like behaviors: positive (open-field test), negative (social-interaction test) and cognitive (Y-maze test) symptoms were evaluated. Thereafter, the brain levels of dopamine, glutamate, 5-hydroxytryptamine and acetyl-cholinesterase, as well as biomarkers of oxidative/nitrergic stress were measured in the striatum, prefrontal-cortex (PFC) and hippocampus (HC). Morin prevented and reversed KET-induced hyperlocomotion, social and cognitive deficits. Also, MOR or risperidone attenuated altered dopaminergic, glutamatergic, 5-hydroxytryptaminergic and cholinergic neurotransmissions in brain region-dependent manner. The increased malondialdehyde and nitrite levels accompanied by decreased glutathione concentrations in the striatum, PFC and HC in KET-treated mice were significantly attenuated by MOR or risperidone. Taken together, these findings suggest that the anti-schizophrenic-like activity of MOR may be mediated via mechanisms related to attenuation of neurochemical changes and oxidative/nitrergic alterations in mice.

Probable mechanisms involved in the antipsychotic-like activity of morin in mice

Evidence derived from preliminary studies suggests that morin, a neuroactive flavonoid with proven antioxidant and antiinflammatory properties possess antipsychotic-like activity. The present study was designed to evaluate the probable mechanisms involve in the antipsychotic-like activity of morin in ketamine model of schizophrenia. The effects of morin, haloperidol and risperidone on neurobehavioral and anti-schizophrenia-like effects were evaluated in mice (n = 7) following intraperitoneal (i.p.) administration of morin (25-100 mg/kg), haloperidol (1 mg/kg) and risperidone (0.5 mg/kg) alone or in combination with ketamine (20 mg/kg, i.p.) for 10 days. Neurobehavioral and schizophrenia-like activities consisting of open-field (positive symptoms), Y-maze, novel-object recognition (cognitive symptoms), social interaction (negative symptoms) tests were assessed. Also, wood-block catalepsy and rota-rod tests were employed to evaluate extrapyramidal side effects of morin. Thereafter, brain levels of biomarkers of oxidative, nitrergic and acetylcholinesterase alterations as well as histomorphological changes in the striatum and prefrontal-cortex were determined. Administration of morin and risperidone alone but not haloperidol significantly (p > 0.05) prevented ketamine-induced hyperlocomotion, social withdrawal and cognitive impairments relative to controls, and were devoid of extrapyramidal side effects. Morin alone or in combination with ketamine significantly increased glutathione concentration, superoxide dismutase and catalase activities compared with saline- or ketamine-treated mice. Moreover, morin alone or in combination with ketamine also significantly decreased malondialdehyde, nitrite and acetylcholinesterase alterations in mice brains. Furthermore, morin prevented ketamine-induced brain neuronal alterations in the striatum and prefrontal-cortex. Together, our findings suggest that morin may demonstrate antipsychotic-like therapeutic effect via modulation of oxidative/nitrergic, cholinergic actions and neuroprotection.

Involvement of GABAergic, BDNF and Nox-2 mechanisms in the prevention and reversal of ketamine-induced schizophrenia-like behavior by morin in mice

GABAergic (Gamma-aminobutyric acid) and neurotrophic derangements have important implication in schizophrenia, a neuropsychiatric disease. Previous studies have shown that nicotinamide adenine dinucleotide phosphate oxidase (NADPH-oxidase) alters GABAergic and neurotrophic activities via inflammatory and oxidative pathways. Thus, it has been proposed that agents with anti-oxidant and anti-inflammatory properties might be beneficial for the treatment of the disease. Morin is neuroactive bioflavonoid compound, which has been reported to demonstrate antipsychotic and anti-oxidant/anti-inflammatory activities. In this study, we further evaluated its effects on the brain markers of GABAergic, neurotrophic and oxidative alterations in the preventive and reversal of schizophrenia-like behavior induced by ketamine (KET). In the prevention protocol, adult mice were treated intraperitoneally with morin (100 mg/kg/day), haloperidol (1 mg/kg/day), risperidone (0.5 mg/kg/day), or saline (10 mL/kg/day) for 14 consecutive days. In addition, the animals were administered KET (20 mg/kg/day) from the 8th to the 14th day. In the reversal protocol, the animals received KET or saline for 14 days. From 8th to 14th days mice were additionally treated with morin, haloperidol, risperidone or saline. Schizophrenic-like behaviors consisting of positive (stereotypy test), negative (behavioral despair in forced swim test) and cognitive (novel-object recognition test) symptoms were evaluated. Afterwards, brain levels of biomarkers of GABAergic (Glutamic acid decarboxylase-67, GAD₆₇), neurotrophic (Brain-derived neurotrophic factor, BDNF) and oxidative [NADPH-oxidase, superoxide dismutase, (SOD) and catalase (CAT)] alterations were determined in the striatum, prefrontal cortex (PFC) and hippocampus, respectively. Morin significantly (p < 0.05) prevented and reversed KET-induced increased stereotypy, behavioral despair and deficit in cognitive functions when compared with KET-treated mice respectively. Also, morin and risperidone but not haloperidol, significantly (p < 0.05) prevented and reversed the decreases in expressions of GAD₆₇ and BDNF immunoreactivity in the striatum, PFC and hippocampus caused by KET. Moreover, morin and risperidone significantly (p < 0.05) decreased regional brain expressions of NADPH-oxidase immunopositive cells and increased endogenous anti-oxidant enzymes (SOD and CAT) in the striatum, PFC and hippocampus relative to KET controls respectively. Taken together, these findings further suggest that the antipsychotic-like activity of morin may be mediated via mechanisms related to enhancement of GABAergic neurotransmission and neurotrophic factor, and suppression of NADPH-oxidase induced oxidative damage in mice.

Targeting oxidative stress, acetylcholinesterase, proinflammatory cytokine, dopamine and GABA by eucalyptus oil (Eucalyptus globulus) to alleviate ketamine-induced psychosis in rats

Essential oil of eucalyptus species is among the most common traded essential oils in the world. There is an increasing interest in the application of eucalyptus oil as a natural additive in food and pharmaceutical industry. The present study was undertaken to identify the phytoconstituents present in the essential oil of Eucalyptus globulus leaves (EO) and ascertain their protective effect against ketamine-induced psychosis in rats. GC-MS technique was used for analysis of phytoconstituents present in EO. Ketamine (50 mg/kg, i.p.) was used to induce psychosis in rats. Photoactometer, forced swim test and pole climb avoidance test were used to evaluate the protective effects of the EO (500, 1000 and 2000 mg/kg, p.o.) on acute and chronic administration. Bar test was used to test the side effect of EO. Biochemical and neurochemical estimations were carried out to explore the possible mechanism of action. GC-MS analysis of EO showed the presence of a number of biologically active compounds. EO at the dose of 500, 1000 and 2000 mg/kg, p.o. on acute and chronic administration, decreased locomotor activity, immobility duration and latency to climb the pole. EO was effective to facilitate the release of GABA, increase GSH levels, inhibit dopamine neurotransmission and decrease TNF-α levels as well as diminish AChE activity in different regions of the brain. EO at the dose of 500, 1000 mg/kg did not produce cataleptic behavior in rats. EO at the dose of 500, 1000 mg/kg produced protective effects against ketamine-induced psychosis and can be further explored clinically against neuropsychiatric disorders.

GABA-BZD Receptor Modulating Mechanism of Panax quinquefolius against 72-h Sleep Deprivation Induced Anxiety like Behavior: Possible Roles of Oxidative Stress, Mitochondrial Dysfunction and Neuroinflammation

Rationale:Panax quinquefolius (American Ginseng) is known for its therapeutic potential against various neurological disorders, but its plausible mechanism of action still remains undeciphered. GABA (Gamma Amino Butyric Acid) plays an important role in sleep wake cycle homeostasis. Thus, there exists rationale in exploring the GABA-ergic potential of Panax quinquefolius as neuroprotective strategy in sleep deprivation induced secondary neurological problems.

Objective: The present study was designed to explore the possible GABA-ergic mechanism in the neuro-protective effect of Panax quinquefolius against 72-h sleep deprivation induced anxiety like behavior, oxidative stress, mitochondrial dysfunction, HPA-axis activation and neuroinflammation.

Materials and Methods: Male laca mice were sleep deprived for 72-h by using Grid suspended over water method. Panax quinquefolius (American Ginseng 50, 100, and 200 mg/kg) was administered alone and in combination with GABA modulators (GABA Cl⁻ channel inhibitor, GABA-benzodiazepine receptor inhibitor and GABAA agonist) for 8 days, starting 5 days prior to 72-h sleep deprivation period. Various behavioral (locomotor activity, mirror chamber test), biochemical (lipid peroxidation, reduced glutathione, catalase, nitrite levels), mitochondrial complexes, neuroinflammation marker (Tumor Necrosis Factor, TNF-alpha), serum corticosterone, and histopathological sections of brains were assessed.

Results: Seventy two hours sleep deprivation significantly impaired locomotor activity, caused anxiety-like behavior, conditions of oxidative stress, alterations in mitochondrial enzyme complex activities, raised serum corticosterone levels, brain TNFα levels and led to neuroinflammation like signs in discrete brain areas as compared to naive group. Panax quinquefolius (100 and 200 mg/kg) treatment restored the behavioral, biochemical, mitochondrial, molecular and histopathological alterations. Pre-treatment of GABA Cl⁻ channel inhibitor as well as GABA-benzodiazepine receptor inhibitor, significantly reversed the protective effect of P. quinquefolius (100 mg/kg) in 72-h sleep deprived animals (P < 0.05). However, pretreatment with GABAA agonist, potentiated Panax quinquefolius's protective effect which was significant as compared to their effect per se (p < 0.05).

Conclusion: GABA-ergic mechanism could be involved in the neuroprotective effect of P.quinquefolius against sleep deprivation induced anxiety-like behavior, oxidative stress, mitochondrial dysfunction, HPA axis activation and neuroinflammation.

Antipsychotic activity of standardized Bacopa extract against ketamine-induced experimental psychosis in mice: Evidence for the involvement of dopaminergic, serotonergic, and cholinergic systems

CONTEXT

Schizophrenia is a chronic disabling psychiatric disorder affecting 1% of the population worldwide. Due to the adverse effects of available antipsychotic medications, recent investigations have focused on the search for well-tolerated, safe molecules from natural resources to control the severity and progression of schizophrenia.

OBJECTIVE

To screen the standardized extract of Bacopa monniera Linn. (Scrophulariaceae) (BM) for its antipsychotic potential in the ketamine-induced psychosis model with mice.

MATERIALS AND METHODS

Graded dose of BM (40, 80, and 120 mg/kg, p.o.) were given to the mice 1 h prior to ketamine administration and tested for positive symptoms and cognitive deficits. A chronic ketamine treatment regimen was used to study the effect of BM on negative symptoms such as immobility enhancement. Each mouse was used once for the behavioral studies.

RESULTS

BM reduced ketamine-induced hyperactivity with an EC50 value of 76.60 mg/kg. The 80 mg/kg dose was used for all other behavior analysis. Pretreatment with BM at 80 mg/kg showed two-fold increases in transfer latency time (TLT) in passive avoidance task. Chronic BM pretreatment (80 mg/kg p.o. daily × 10 d) ameliorated the ketamine-induced enhanced immobility effect by 21% in the forced swim test. BM treatment reversed ketamine-induced increase in monoamine oxidase activity in both cortex and striatum and normalized the acetylcholinesterase activity and the glutamate levels in the hippocampus.

DISCUSSION AND CONCLUSION

Overall our findings suggest that BM possesses antipsychotic properties which might be due to its modulatory action on dopamine, serotonin, and glutamate neurotransmission.

Assessment of possible immunotoxicity of the antipsychotic drug clozapine

OBJECTIVES

The immunomodulatory effects of clozapine (CLZ), antipsychotic drug, were investigated in vivo using female Balb/c mice. The main aim of this study was to evaluate the immunomodulatory effects of CLZ, antipsychotic drug, following daily intraperitoneal injection to female Balb/c mice over a period of 21 days.

METHODS

Mice were divided into five groups, eight animals per group. Group I, served as a control group, received only the vehicle. Groups II-V received a daily intraperitoneal dose of CLZ (1, 5, 10 and 20 mg/kg, respectively) over a period of 21 days.

KEY FINDINGS

CLZ has shown a significant decrease in the animal body weight, and it showed a significant decrease in the percentage of circulating neutrophils and lymphocytes while circulating monocytes were increased. The immunotoxicity has been also assessed by evaluating spleen cellularity, humoral immune response to a foreign antigen using sheep red blood cells and delayed-type hypersensitivity reaction. The results showed a marked suppression in these responses in CLZ-treated mice compared with the control group. Detectable changes have also been noticed in the histology of the footpad tissue and spleen.

CONCLUSIONS

Results showed significant immunomodulatory effects of CLZ when used in Balb/c mice.

Modulation of nitrergic signalling pathway by American ginseng attenuates chronic unpredictable stress-induced cognitive impairment, neuroinflammation, and biochemical alterations

Prolonged stress causes extensive loss of neurons leading to deficits in cognitive performance. Increasing evidence indicates that accumulation of intercellular messenger, nitric oxide (NO), plays a crucial role in the pathogenesis of memory disorders. American ginseng (AG) is known to show protection in different animal models of neurological diseases; however, its exact mechanism of action is not clearly understood. Therefore, the current study was designed to investigate the interaction of AG against chronic unpredictable stress (CUS)-associated behavioral and biochemical alterations and the probable role of nitrergic pathway in this effect. Male Laca mice were exposed to a series of stressors along with drug/vehicle treatment daily for 28 days. CUS paradigm caused significant impairment in both acquisition and retention memory as measured in Morris water maze and elevated plus maze task. This was coupled with alterations in oxidative stress markers, mitochondrial enzyme complex activities, pro-inflammatory cytokine (TNF-α), and acetylcholinesterase levels in the hippocampus as compared with naïve group. Besides, there was a marked increase in serum corticosterone levels. AG (100, 200 mg/kg; p.o.) treatment significantly improved cognitive impairment; reduced TNF-α, acetylcholinesterase, and corticosterone levels; and attenuated oxidative-nitrergic stress. Furthermore, pre-treatment of L-arginine (100 mg/kg; i.p.), a nitric oxide donor, with subeffective dose of AG (100 mg/kg; p.o.) reversed its protective effects. However, L-NAME (10 mg/kg, i.p.), a non-specific NO synthase inhibitor, potentiated the effects of AG. Our findings suggest that modulation of nitrergic signalling cascade is involved in the protective effects of AG against CUS-induced cognitive dysfunction, oxidative stress, and neuroinflammation.

Actoprotective effect of ginseng: improving mental and physical performance

Actoprotectors are preparations that increase the mental performance and enhance body stability against physical loads without increasing oxygen consumption. Actoprotectors are regarded as a subclass of adaptogens that hold a significant capacity to increase physical performance. The focus of this article is studying adaptogen herbs of genus Panax (P. ginseng in particular) and their capabilities as actoprotectors. Some animal experiments and human studies about actoprotective properties of genus Panax attest that P. ginseng (administered as an extract) significantly increased the physical and intellectual work capacities, and the data provided suggests that ginseng is a natural source of actoprotectors. Preparations of ginseng can be regarded as potential actoprotectors which give way to further research of its influence on physical and mental work capacity, endurance and restoration after exhaustive physical loads while compared with reference actoprotectors.

A comprehensive review of the therapeutic and pharmacological effects of ginseng and ginsenosides in central nervous system

Ginseng is one of the most widely used herbal medicines in human. Central nervous system (CNS) diseases are most widely investigated diseases among all others in respect to the ginseng’s therapeutic effects. These include Alzheimer’s disease, Parkinson’s disease, cerebral ischemia, depression, and many other neurological disorders including neurodevelopmental disorders. Not only the various types of diseases but also the diverse array of target pathways or molecules ginseng exerts its effect on. These range, for example, from neuroprotection to the regulation of synaptic plasticity and from regulation of neuroinflammatory processes to the regulation of neurotransmitter release, too many to mention. In general, ginseng and even a single compound of ginsenoside produce its effects on multiple sites of action, which make it an ideal candidate to develop multi-target drugs. This is most important in CNS diseases where multiple of etiological and pathological targets working together to regulate the final pathophysiology of diseases. In this review, we tried to provide comprehensive information on the pharmacological and therapeutic effects of ginseng and ginsenosides on neurodegenerative and other neurological diseases. Side by side comparison of the therapeutic effects in various neurological disorders may widen our understanding of the therapeutic potential of ginseng in CNS diseases and the possibility to develop not only symptomatic drugs but also disease modifying reagents based on ginseng.

Anxiolytic effects of Plumeria rubra var. acutifolia (Poiret) L. flower extracts in the elevated plus-maze model of anxiety in mice

Interest in alternative medicine and plant-derived medications that affect the "mind" is growing rapidly since last two decades. The aim of the present study was to investigate the effects of ethanolic extract of flower of Plumeria rubra (PR) along with its fractions in the elevated plus-maze (EPM) model of anxiety. The P. rubra extract or its fractions was administered orally to male Swiss mice, at graded doses, 1h prior to behavioural assessment. The PR extract at the dose of 100mg/kg p.o., significantly increased the time spent in the open arms of the EPM. Further, the anxiolytic properties of hexane, chloroform and butanolic soluble and insoluble fractions at one-fifth of the original dose were also observed in the EPM task. Out of which butanol insoluble fraction showed significant anxiolytic activity comparable to standard anxiolytic drug, diazepam. Further, pretreatment with crude ethanolic extract and butane insoluble fraction showed no significant effects in the horizontal activity, total distance travelled and stereotypy count in the animal activity monitor and had no motor in-coordination side effects in the rotarod test in mice. These observations suggest that the flower extract of P. rubra and its insoluble butanolic fraction might possess significant anxiolytic potential to be pursued further for drug development process.

Neurochemical and molecular characterization of ketamine-induced experimental psychosis model in mice

Ketamine, an NMDA receptor antagonist has been shown to induce aberrant behaviour phenotypes in rodents, some of which are known to simulate the behaviour abnormalities observed in patients suffering from schizophrenia. Thus, developing ketamine-induced animal models became an important tool of choice to study the mechanistic details of some critical symptoms associated with schizophrenia. In this study, our goal was to characterize and correlate the ketamine-induced changes in the behavioural phenotypes to the changes in neurochemical and molecular profile(s) in the brain tissues implicated in the pathophysiology of schizophrenia. We studied the effects of ketamine in mice using 'acute' and 'chronic' treatment regimens along with the 'drug withdrawal' effects on their biochemical and molecular parameters in the pre-frontal cortex, hippocampus, and striatum. Our results demonstrated that the acute and chronic ketamine administration, differentially and site specifically, modulated the levels of acetylcholine, dopamine, serotonin and noradrenaline. In addition, the chronic ketamine doses dramatically suppressed the levels of glycine among some of the amino acids examined and induced alternations in gene expression of the key neurotransmitter receptor systems, including some members of the dopamine and the serotonin receptor families. The acute and chronic ketamine treatment induced "signature" neurochemical and gene-expression patterns that are implicated in the pathophysiology of schizophrenia. Our analyses tend to support the "chronic ketamine" mice model for experimental psychosis as a tool for deeper investigation of the mechanistic paradigm associated with the schizophrenia spectrum disorder and for screening next-generation antipsychotic drugs.