Agmatine protection against chlorpromazine-induced forebrain cortex injury in rats

Neuroprotection by agmatine: Possible involvement of the gut microbiome?

Agmatine, an endogenous polyamine derived from L-arginine, elicits tremendous multimodal neuromodulant properties. Alterations in agmatinergic signalling are closely linked to the pathogeneses of several brain disorders. Importantly, exogenous agmatine has been shown to act as a potent neuroprotectant in varied pathologies, including brain ageing and associated comorbidities. The antioxidant, anxiolytic, analgesic, antidepressant and memory-enhancing activities of agmatine may derive from its ability to regulate several cellular pathways; including cell metabolism, survival and differentiation, nitric oxide signalling, protein translation, oxidative homeostasis and neurotransmitter signalling. This review briefly discusses mammalian metabolism of agmatine and then proceeds to summarize our current understanding of neuromodulation and neuroprotection mediated by agmatine. Further, the emerging exciting bidirectional links between agmatine and the resident gut microbiome and their implications for brain pathophysiology and ageing are also discussed.

Ultrasound-assisted synthesis of graphene@MXene hybrid: A novel and promising material for electrochemical sensing

To date, multiple graphene@MXene hybrids have been reported via various synthesis approaches, but almost all the graphene@MXene hybrids inevitably used the reduced graphene oxide that prepared by chemical oxidation/reduction method, which generally involved the complex and dangerous operation procedure, and the highly toxic chemical reagent. How to prepare graphene@MXene hybrid through a simple, safe and eco-friendly synthetic route is highly desired. Compared with traditional synthesis technology, ultrasound synthesis strategy displays the merits of simplicity, low cost and environment protection. Herein, MXene (Ti₃C₂T_x) nanoflakes coupled with graphene nanosheets (graphene@MXene) were prepared in N-methylpyrrolidone (NMP) by simple ultrasound-assisted liquid-phase exfoliation method for the first time. Besides, the effect of types of solvent with different viscocity, sonication temperature and sonication duration time on the property of graphene@MXene hybrids were systematacially investigated. It is found the liquid-phase exfoliated graphene owned excellent electron transfer ability and the MXene (Ti₃C₂T_x) nanoflakes possessed outstanding adsorption property, the as-synthesized graphene@MXene hybrid exhibited significant signal synergistic enhancement effect toward the oxidation of hazardous veterinary drug residue compound (chlorpromazine) and food additives (rhodamine B). Based on this, a novel and sensitive electrochemical sensor was fabricated, the linear detection ranges were 5 nM to 0.5 μM for chlorpromazine with sensitivity of 1090 µA μM^-1 cm^-2, and 10 nM to 2.5 μM for rhodamine B with sensitivity of 440 and 102.14 µA μM^-1 cm^-2. Besides, the detection limits were evaluated to be as low as 1.25 nM and 2.45 nM for chlorpromazine and rhodamine B, respectively.

Quetiapine Ameliorates MIA-Induced Impairment of Sensorimotor Gating: Focus on Neuron-Microglia Communication and the Inflammatory Response in the Frontal Cortex of Adult Offspring of Wistar Rats

The maternal immune activation produced by the systemic administration of lipopolysaccharide (LPS) in rats provides valuable insights into the basis of behavioural schizophrenia-like disturbances and biochemical changes in the brains of the offspring, such as microglial activation. Regarding therapy, antipsychotics continually constitute the cornerstone of schizophrenia treatment. To their various efficacy and side effects, as well as not fully recognised mechanisms of action, further characteristics have been suggested, including an anti-inflammatory action via the impact on neuron–microglia axes responsible for inhibition of microglial activation. Therefore, in the present study, we sought to determine whether chronic treatment with chlorpromazine, quetiapine or aripiprazole could influence schizophrenia-like behavioural disturbances at the level of sensorimotor gating in male offspring prenatally exposed to LPS. Simultaneously, we wanted to explore if the chosen antipsychotics display a positive impact on the neuroimmunological parameters in the brains of these adult animals with a special focus on the ligand-receptor axes controlling neuron–microglia communication as well as pro- and anti-inflammatory factors related to the microglial activity. The results of our research revealed the beneficial effect of quetiapine on deficits in sensorimotor gating observed in prenatally LPS-exposed offspring. In terms of axes controlling neuron–microglia communication and markers of microglial reactivity, we observed a subtle impact of quetiapine on hippocampal Cx3cl1 and Cx3cr1 levels, as well as cortical Cd68 expression. Hence, further research is required to fully define and explain the involvement of quetiapine and other antipsychotics in Cx3cl1-Cx3cr1 and/or Cd200-Cd200r axes modulation and inflammatory processes in the LPS-based model of schizophrenia-like disturbances.

Effects of acute iron overload on Nrf2-related glutathione metabolism in rat brain

Iron (Fe) overload triggers free radical production and lipid peroxidation processes that may lead to cell death (ferroptosis). The hypothesis of this work was that acute Fe-dextran treatment triggers Nrf2-mediated antioxidant regulation in rat brain involving glutathione (GSH) metabolism. Over the initial 8 h after Fe-dextran administration (single dose of 500 mg Fe-dextran/kg), total Fe, malondialdehyde (MDA) content, glutathione peroxidase (GPx), GPx-Se dependent (GPx-Se) and glutathione S-transferases (GST) activities were increased in rat whole brain. The content of GSH and the activity of glutathione reductase (GR) showed decreases (p < 0.05) after 6 and 8 h post injection in cortex. A significant increase in nuclear Nrf2 protein levels over control values was achieved after 6 h of Fe-dextran administration, while no significant differences were observed in the cytosolic fraction. Nuclear Nrf2/cytosolic Nrf2 ratios showed enhancement (p < 0.05) after 6 h of Fe overload, suggesting a greater translocation of the factor to the nucleus. No significant differences were observed in the expression of Keap1 in nuclear or cytosolic extracts. It is concluded that acute Fe overload induces oxidative stress in rat brain with the concomitant lipid peroxidation increase and GSH depletion, leading to the elevation of Nrf2-controlled GPx, GPx-Se and GST protein expression as a protective adaptive response. Further studies are required to fully comprehend the complex network of interrelated processes keeping the balance of GSH functions as chelator, antioxidant and redox buffer in the understanding of the ferroptotic and hormetic mechanisms triggered by Fe overload in brain.

The effect of levomepromazine on the healthy and injured developing mouse brain - An in vitro and in vivo study

Levomepromazine (LMP) is a phenothiazine neuroleptic drug with strong analgesic and sedative properties that is increasingly used off-label in pediatrics and is being discussed as an adjunct therapy in neonatal intensive care. Basic research points towards neuroprotective potential of phenothiazines, but LMP's effect on the developing brain is currently unknown. The aim of the present study was to assess LMP as a pharmacologic strategy in established neonatal in vitro and in vivo models of the healthy and injured developing mouse brain. In vitro, HT-22 cells kept exposure-naïve or injured by glutamate were pre-treated with vehicle or increasing doses of LMP and cell viability was determined. In vivo, LMP's effects were first assessed in 5-day-old healthy, uninjured CD-1 mouse pups receiving a single intraperitoneal injection of vehicle or different dosages of LMP. In a second step, mouse pups were subjected to excitotoxic brain injury and subsequently treated with vehicle or LMP. Endpoints included somatometric data as well as histological and immunohistochemical analyses. In vitro, cell viability in exposure-naïve cells was significantly reduced by high doses of LMP, but remained unaffected in glutamate-injured cells. In vivo, no specific toxic effects of LMP were observed neither in healthy mouse pups nor in experimental animals subjected to excitotoxic injury, but body weight gain was significantly lower following higher-dose LMP treatment. Also, LMP failed to produce a neuroprotective effect in the injured developing brain. Additional studies are required prior to a routine clinical use of LMP in neonatal intensive care units.

Antioxidant properties of the Lebanese plant Iris x germanica L. crude extracts and antagonism of chlorpromazine toxicity on Saccharomyces cerevisiae

Iris x germanica L., which belongs to the Iridaceae family, has been reported in the literature for its antioxidant properties in acellular chemical-antioxidant assays. Chlorpromazine (CPZ) is an antipsychotic drug known to cause adverse reactions in humans. Oxidative stress is among the main mechanisms by which CPZ exerts its toxicity in animal cell models as well as in the yeast Saccharomyces cerevisiae. In this study we investigated the protective effects of I. germanica L. crude extracts against CPZ toxicity. We demonstrated that methanolic extracts from rhizome (R-M), leaf (L-M) and flower (Fl-M) had potent antioxidant activity by scavenging the free radical DPPH, with half-maximal effective concentrations (EC₅₀) 193, 107, and 174 µg/mL, respectively. R-M, L-M and Fl-M at doses up to 1000 µg/mL, didn't affect yeast cell growth. In addition, we demonstrated for the first time that L-M at 1000 µg/mL and R-M at all tested doses counteracted CPZ toxicity, probably by promoting yeast cell antioxidant agents. The R-M capacity to counteract CPZ toxicity was lost in the yeast strain mutant in catalase-encoding gene (Cta1), while strains mutant in Sod2, Skn7 and Rap1 showed mild or full R-M-induced protective effect against CPZ toxicity. Our results demonstrated that I. germanica L. R-M extract counteracted CPZ toxicity in the yeast cell model. Further studies are planned to isolate the involved bioactive compounds and identify the involved genes and the antioxidant agents.

Neuroprotective effect of agmatine (decarboxylated l-arginine) against oxidative stress and neuroinflammation in rotenone model of Parkinson's disease

Parkinson's disease (PD) is the second most common age-related neurodegenerative disease after Alzheimer's disease, characterized by loss of dopaminergic neurons in substantia nigra pars compacta, accompanied by motor and nonmotor symptoms. The neuropathological hallmarks of PD are well reported, but the etiology of the disease is still undefined; several studies assume that oxidative stress, mitochondrial defects, and neuroinflammation play vital roles in the progress of the disease. The current study was established to investigate the neuroprotective effect of agmatine on a rotenone (ROT)-induced experimental model of PD. Adult male Sprague Dawley rats were subcutaneously injected with ROT at a dose of 2 mg/kg body weight for 35 days. Agmatine was injected intraperitoneally at 50 and 100 mg/kg body weight, 1 h prior to ROT administration. ROT-treated rats that received agmatine showed better performance on beam walking and an elevated number of rears within the cylinder test. In addition, agmatine reduced midbrain malondialdehyde as an indication of lipid peroxidation, pro-inflammatory cytokines including tumor necrosis factor alpha and interleukin-1β, and glial fibrillary acidic protein. Moreover, agmatine was responsible for preventing loss of tyrosine hydroxylase-positive neurons. In conclusion, our study showed that agmatine possesses a dose-dependent neuroprotective effect through its antioxidant and anti-inflammatory activities. These findings need further clinical investigations of agmatine as a promising neuroprotective agent for the future treatment of PD.

Effects of agmatine on chlorpromazine-induced neuronal injury in rat

This study was aimed to study the potentially beneficial effects of agmatine on oxidative/nitrosative stress development in the brain of Wistar rats during subacute chlorpromazine treatment. The animals were divided into control (0.9% saline), chlorpromazine (38.7 mg/kg b.w.), chlorpromazine+agmatine (agmatine 75 mg/kg b.w. immediately after chlorpromazine, 38.7 mg/kg b.w. i.p.) and agmatine (75 mg/kg b.w.) groups. All the tested substances were administered intraperitoneally for 15 consecutive days and the rats were sacrificed by decapitation on day 15. Subacute administration of chlorpromazine resulted in increased lipid peroxidation, nitric oxide concentration and superoxide anion production, while completely damaging the antioxidant defence system in the cerebral cortex, striatum, and hippocampus. However, the combined treatment with chlorpromazine and agmatine significantly attenuated the oxidative/nitrosative stress indices and restored the antioxidant capacity to the control values in all of the examined brain regions. Western blot analysis supported biochemical findings in all groups, but the most notable changes were found in the hippocampus. Our results suggest potentially beneficial effects of agmatine, which may be useful in the modified antioxidant approach in chlorpromazine-therapy.

Advantages of the Alpha-lipoic Acid Association with Chlorpromazine in a Model of Schizophrenia Induced by Ketamine in Rats: Behavioral and Oxidative Stress evidences

Schizophrenia is a chronic mental disorder reported to compromise about 1% of the world's population. Although its pathophysiological process is not completely elucidated, evidence showing the presence of an oxidative imbalance has been increasingly highlighted in the literature. Thus, the use of antioxidant substances may be of importance for schizophrenia treatment. The objective of this study was to evaluate the behavioral and oxidative alterations by the combination of chlorpromazine (CP) and alpha-lipoic acid (ALA), a potent antioxidant, in the ketamine (KET) model of schizophrenia in rats. Male Wistar rats (200-300 g) were treated for 10 days with saline, CP or ALA alone or in combination with CP previous to KET and the behavioral (open field, Y-maze and PPI tests) and oxidative tests were performed on the last day of treatment. The results showed that KET induced hyperlocomotion, impaired working memory and decreased PPI. CP alone or in combination with ALA prevented KET-induced behavioral effects. In addition, the administration of KET decreased GSH and increased nitrite, lipid peroxidation and myeloperoxidase activity. CP alone or combined with ALA prevented the oxidative alterations induced by KET. In conclusion, the treatment with KET in rats induced behavioral impairments accompanied by hippocampal oxidative alterations, possibly related to NMDA receptors hypofunction. Besides that, CP alone or combined with ALA prevented these effects, showing a beneficial activity as antipsychotic agents.

Effects of agmatine on chlorpromazine toxicity in the liver of Wistar rats: the possible role of oxidant/antioxidant imbalance

Chlorpromazine (CPZ) is a member of a widely used class of antipsychotic agents. The metabolic pathways of CPZ toxicity were examined by monitoring oxidative/nitrosative stress markers. The aim of the study was to investigate the hypothesis that agmatine (AGM) prevents oxidative stress in the liver of Wistar rats 48 h after administration of CPZ. All tested compounds were administered intraperitoneally (i.p.) in one single dose. The animals were divided into control (C, 0.9% saline solution), CPZ (CPZ, 38.7 mg/kg b.w.), CPZ+AGM (AGM, 75 mg/kg b.w. immediately after CPZ, 38.7 mg/kg b.w. i.p.), and AGM (AGM, 75 mg/kg b.w.) groups. Rats were sacrificed by decapitation 48 h after treatment. The CPZ and CPZ+AGM treatments significantly increased thiobarbituric acid reactive substances (TBARS), the nitrite and nitrate (NO₂+NO₃) concentration, and superoxide anion (O₂^•-) production in rat liver homogenates compared with C values. CPZ injection decreased the capacity of the antioxidant defense system: superoxide dismutase (SOD) activity, catalase (CAT) activity, total glutathione (GSH) content, glutathione peroxidase (GPx) activity, and glutathione reductase (GR) activity compared with the values of the C group. However, treatment with AGM increased antioxidant capacity in the rat liver; it increased the CAT activity, GSH concentration, GPx activity, and GR activity compared with the values of the CPZ rats. Immunohistochemical staining of ED1 in rats showed an increase in the number of positive cells 48 h after acute CPZ administration compared with the C group. Our results showed that AGM has no protective effects on parameters of oxidative and/or nitrosative stress in the liver but that it absolutely protective effects on the antioxidant defense system and restores the antioxidant capacity in liver tissue after administration of CPZ.