Molecular mechanisms involved in the prevention and reversal of ketamine-induced schizophrenia-like behavior by rutin: the role of glutamic acid decarboxylase isoform-67, cholinergic, Nox-2-oxidative stress pathways in mice

Mounting evidences have shown that nicotinamide adenine dinucleotide phosphate oxidase-2 (Nox-2) pathway modifies glutamic-acid decarboxylase-67 (GAD₆₇) (GABAergic enzyme) and cholinergic systems via oxidative-nitrergic mechanisms in schizophrenia pathology. Rutin, a neuroactive antioxidant compound, with proven neuroprotective property has been shown to reduce schizophrenic-like behavior in mice. This study sought to investigate the mechanisms of action of the psychopharmacological activity of rutin in the preventive and reversal effects of ketamine-induced schizophrenic-like behavior, oxidative-nitrergic stress, cholinergic and GABAergic derangements in mice. In the preventive treatment, male mice were given rutin (0.1, 0.2 and 0.4 mg/kg) or risperidone (0.5 mg/kg) orally for 14 days prior to ketamine (20 mg/kg, i.p.) treatment from the 8 to 14th day. However, in the reversal treatment, ketamine was given for 14 days prior to rutin and risperidone. Behavioral (open-field, social-interaction and Y-maze tests), biochemical (oxidative/nitrergic stress markers, acetylcholinesterase activity), immunohistochemical (GAD₆₇, Nox-2) and neuronal cell deaths in the striatum, prefrontal cortex, and hippocampus were evaluated. Ketamine-induced behavioral impairments were prevented and reversed by rutin. Exposure of mice to ketamine increased malondialdehyde, nitrite contents, acetylcholinesterase activity, neuronal cell death and Nox-2 expressions in the striatum, prefrontal cortex and hippocampus. Conversely, these derangements were prevented and reversed by rutin. The decreased glutathione levels due to ketamine were marked increased by rutin. Rutin only prevented ketamine-induced decrease in GAD₆₇ expression in the striatal-hippocampal region. Altogether, the study showed that the prevention and reversal treatments of mice with rutin attenuated ketamine-induced schizophrenic-like behaviors via reduction of Nox-2 expression, oxidative/nitrergic stresses, acetylcholinesterase activity, and increased GAD₆₇ enzyme.

D-Ribose-L-cysteine exhibits adaptogenic-like activity through inhibition of oxido-inflammatory responses and increased neuronal caspase-3 activity in mice exposed to unpredictable chronic mild stress

Adaptogens are substances that act nonspecifically to combat stress by regulating the key elements involved in stress-induced pathologies. D-Ribose-L-cysteine (DRLC), a potent glutathione (GSH) booster, has been recommended for relief of stress. Hence, we investigated its adaptogenic-like effect in mice subjugated to unpredictable chronic mild stress (UCMS). Thirty six male Swiss mice were assigned to 6 groups (n = 6): group 1 received saline (p.o, non-stress control), group 2 (stress-control) also had saline, groups 3 to 5 received DRLC (25, 50 and 100 mg/kg, p.o) whereas group 6 had ginseng (50 mg/kg, p.o). The animals in groups 2-6 were subjugated to UCMS 30 min later, daily for 21 days and afterwards, tested for memory and anxiety. Blood glucose, serum corticosterone concentrations and adrenal weight were determined. The brain tissues were processed for estimation of malondialdehyde (MDA), GSH, superoxide-dismutase (SOD), catalase, tumor necrosis factor-alpha (TNF-α), interleukin-6, acetyl-cholinesterase, and caspase-3 activities. The histomorphologic features and neuronal viability of the hippocampus, amygdala and prefrontal cortex were also determined. DRLC (25-100 mg/kg) reduces anxiety, memory deficit, adrenal gland enlargement, glucose, and corticosterone concentrations in UCMS-mice. The increased brain contents of MDA, TNF-α, interleukin-6, acetyl-cholinesterase and decreased antioxidant (GSH, SOD and catalase) status induced by UCMS were attenuated by DRLC. The DRLC increased caspase-3 activity and reduces histomorphological distortions of neuronal cells of the hippocampus, amygdala and prefrontal cortex of stressed-mice. These findings suggest that DRLC has adaptogenic-like effect which might be related to modulation of corticosterone-mediated oxido-inflammatory processes and altered caspase-3 activity.

Cymbopogon citratus 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 2–5 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.

Repeated psychosocial stress causes glutamic acid decarboxylase isoform-67, oxidative-Nox-2 changes and neuroinflammation in mice: Prevention by treatment with a neuroactive flavonoid, morin

Psychosocial stress and biological predispositions are linked to mood and personality disorders related to psychiatric behaviors. Targeting neuroinflammation and oxidative stress has been recognized as a potential strategy for the prevention of psychosocial stress-induced psychiatric disorders. Morin, a bioactive compound isolated from mulberry leaf has been shown to produce antiamnesic, antipsychotic and anti-inflammatory effects relative to ginseng, a well-known adaptogen. Hence, the present study investigated the effect of morin on social-defeat stress (SDS)-induced behavioral, neurochemical, neuroimmune and neurooxidative changes in mice using intruder-resident paradigm. The intruder male mice were distributed into 6 groups (n = 10). Groups 1 (normal-control) and 2 (SDS-control) received normal saline, groups 3-5 had morin (25-100 mg/kg) while group 6 received ginseng (50 mg/kg) intraperitoneally daily for 14 days. Thirty minutes after treatment from days 7-14 onwards, mice in groups 2-6 were exposed to SDS for 10 min physical and psychological confrontations respectively with aggressive-resident mice. Neurobehavioral effects (locomotor activity, cognitive performance, anxiety- and depressive-like behavior) were assessed on day 14. Biomarkers of oxidative/nitrergic stress and neuroinflammation; acetylcholinesterase (AChE) and glutamic-acid decarboxylase-67 (GAD₆₇) were measured in the striatum, prefrontal-cortex and hippocampus. Behavioral deficits induced by SDS were attenuated by morin and ginseng. Both morin and ginseng decreasedmalondialdehyde, nitrite levels and increased glutathione concentrations in the brain regions. They also reduced inflammatory mediators (TNF-α, IL-6, COX-2 and NF-κB), AChE activity and Nox-2 expression in the specific brain regions. However, morin increased the levels of GAD₆₇ in the striatum, prefrontal-cortex and hippocampus in contrast to ginseng. Our results suggest that morin mitigates SDS-induced neurobehavioral deficits through enhancement of GAD₆₇, inhibition of AChE activity, oxidative stress, Nox-2 and neuroinflammatory pathways.

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.

D-Ribose-L-cysteine attenuates lipopolysaccharide-induced memory deficits through inhibition of oxidative stress, release of proinflammatory cytokines, and nuclear factor-kappa B expression in mice

D-Ribose-L-cysteine (DRLC), an analog of cysteine that boosts glutathione (GSH) content, has been reported to mitigate oxidative stress-mediated diseases. This study seeks to evaluate the effects of DRLC on memory deficits and the biochemical and histo-morphological changes induced by lipopolysaccharide (LPS) in mice. Male Swiss mice (n = 10) were pre-treated orally with three doses of DRLC (25 mg/kg, 50 mg/kg, and 100 mg/kg), donepezil (1 mg/kg), or vehicle (saline) for 30 min prior to the intraperitoneal injection of LPS (0.25 mg/kg) daily for 7 days. Memory functions were evaluated using the Y-maze, object recognition, and social recognition tests. The specific brain regions (prefrontal cortex and hippocampus) were evaluated to determine oxidative stress biomarkers (malondialdehyde, GSH, and catalase), acetyl-cholinesterase activity, proinflammatory cytokines (tumor necrosis factor-α and interleukin-6), expression of nuclear factor-kappa B (NF-κB), and neuronal cell morphology. DRLC (25-100 mg/kg) reversed the memory deficits in the LPS-treated mice (p < 0.05). The increased oxidative stress and proinflammatory cytokines in the brain regions of the LPS-treated mice were significantly (p < 0.05) reduced by DRLC. DRLC (50 mg/kg and 100 mg/kg) also reduced acetyl-cholinesterase activity and decreased NF-κB expression in the brains of LPS-treated mice. Finally, it attenuated the cytoarchitectural distortions and loss of neuronal cells of the prefrontal cortex and hippocampus that were induced by LPS in mice. The results of this study suggest that DRLC attenuates memory deficit induced by LPS in mice through mechanisms related to the inhibition of oxidative stress, release of proinflammatory cytokines, and expression of NF-κB in mice.