Effect of thioperamide on modified forced swimming test-induced oxidative stress in mice

Discovery of Novel Steroid-Based Histamine H3 Receptor Antagonists/Inverse Agonists

Steroid-based histamine H3 receptor antagonists (d-homoazasteroids) were designed by combining distinct structural elements of HTS hit molecules. They were characterized, and several of them displayed remarkably high affinity for H3 receptors with antagonist/inverse agonist features. Especially, the 17a-aza-d-homolactam chemotype demonstrated excellent H3R activity together with significant in vivo H3 antagonism. Optimization of the chemotype was initiated with special emphasis on the elimination of the hERG and muscarinic affinity. Additionally, ligand-based SAR considerations and molecular docking studies were performed to predict binding modes of the molecules. The most promising compounds (XXI, XXVIII, and XX) showed practically no muscarinic and hERG affinity. They showed antagonist/inverse agonist property in the in vitro functional tests that was apparent in the rat in vivo dipsogenia test. They were considerably stable in human and rat liver microsomes and provided significant in vivo potency in the place recognition and novel object recognition cognitive paradigms.

Antidepressant properties of voluntary exercise mediated by gut microbiota

Although regular exercise has been reported to prevent depression, it has not been clarified whether the gut microbiota is involved in the factors that prevent depression through exercise. We investigated the effects of voluntary exercise on the gut microbiota and the prevention of depression-like behaviors using mice. C57BL/6 J male mice were subjected to 10 weeks of sedentary control or wheel running, then they were subjected to social defeat stress (SDS). Exercise attenuated that sucrose drinking was decreased by SDS treatment. Exercise increased the expression of Bdnf and decreased expression of Zo-1 and Claudin5 in the brain. Fecal Turicibacter, Allobaculum, and Clostridium sensu stricto, and propionate in the cecum were decreased by the exercise. Voluntary exercise-induced antidepressant properties might be partially caused by suppression of serotonin uptake into gut microbiota and increase the permeability of the blood-brain barrier via reduced propionate production.

Effects of low-dose/high-dose-rate X-irradiation on oxidative stress in organs following forced swim test and its combined effects on alcohol-induced liver damage in mice

The liver's susceptibility to oxidative stress after a combination of forced swim test (FST) and low-dose-rate γ-irradiation has been observed. Therefore, this study aims to clarify the effects of low-dose (0.1 and 0.5 Gy)/high-dose-rate (1.2 Gy/min) irradiation on combined oxidative stressors-liver damage associated with FST and alcohol administration. In addition, the effects of similar irradiation on FST-induced immobility, which induces psychomotor retardation, and antioxidative effects on the brain, lungs, liver and kidneys were investigated, and the results were compared with those of a similar previous study that utilized low-dose-rate irradiation. Low-dose/high-dose-rate (especially 0.5 Gy) irradiation temporarily worsened liver antioxidant function and hepatic function with FST- and alcohol administration-related oxidative damage; however, the damages improved soon after. In addition, the increase in total glutathione content in the liver contributed to the early improvement of hepatic functions. However, pre-irradiation did not suppress immobility during the FST. The results also suggested that the effects of low-dose/high-dose-rate irradiation on the antioxidant functions of each organ after the FST were different from those of low-dose/low-dose-rate irradiation. Overall, this study provides further insights into the effects of low-dose irradiation on exposure to a combination of different oxidative stressors. It will also contribute to the elucidation of dose rate effects on oxidative stress in the low-dose irradiation range.

Antidepressant and antioxidant effects of transcranial irradiation with 830-nm low-power laser in an animal model of depression

The present study aimed at investigating the antidepressant and antioxidant actions of near-infrared (NIR) laser at a wavelength of 830 nm and power of 100 mW which applied transcranially on an animal model of depression induced by repeated doses of reserpine (0.2 mg/kg). Thirty male Wistar adult rats were divided into three groups: rat model of depression; rat model of depression irradiated with laser for 14 days after induction of depression; and the control group that was given the drug vehicle and sham-exposed to the laser. Forced swimming test (FST) was used to verify the induction of animal model of depression and to screen the effect of antidepressant effect of low-level laser at the end of the experiment. Monoamine level, oxidative stress markers, and activities of acetylcholinesterase (AchE) and monoamine oxidase (MAO) were determined in the cortex and hippocampus of the rat brain. Reserpine resulted in depletion of monoamines and elevation in the oxidative stress markers and change in the enzymatic activities measured in both brain areas. Laser irradiation has an inhibitory action on the monoamine oxidase (MAO) in the cortex and hippocampus leading to elevation of the monoamine levels and attenuation of the oxidative stress in the studied areas. FST has emphasized the antidepressant effect of the utilized laser irradiation parameters on the behavioral level. The present findings provide evidence for the antidepressant and antioxidant actions of NIR low-power laser in the rat model of depression. Accordingly, low-laser irradiation may be presented as a potential candidate modality for depression treatment.

Discovery of Potential, Dual-Active Histamine H3 Receptor Ligands with Combined Antioxidant Properties

In an attempt to find new dual acting histamine H₃ receptor (H₃R) ligands, we designed a series of compounds, structurally based on previously described in our group, a highly active and selective human histamine H₃ receptor (hH₃R) ligand KSK63. As a result, 15 obtained compounds show moderate hH₃R affinity, the best being the compound 17 (hH₃R K_i = 518 nM). Docking to the histamine H₃R homology model revealed two possible binding modes, with key interactions retained in both cases. In an attempt to find possible dual acting ligands, selected compounds were tested for antioxidant properties. Compound 16 (hH₃R K_i = 592 nM) showed the strongest antioxidant properties at the concentration of 10⁻⁴ mol/L. It significantly reduced the amount of free radicals presenting 50–60% of ascorbic acid activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, as well as showed antioxidative properties in the ferric reducing antioxidant power (FRAP) assay. Despite the yet unknown antioxidation mechanism and moderate hH₃R affinity, 16 (QD13) constitutes a starting point for the search of potential dual acting H₃R ligands-promising tools for the treatment of neurological disorders associated with increased neuronal oxidative stress.

S-allyl Cysteine, a Garlic Compound, Produces an Antidepressant-Like Effect and Exhibits Antioxidant Properties in Mice

Depression is a psychiatric disorder, and oxidative stress is a significant mechanism of damage in this mood disorder. It is characterized by an enhancement of oxidative stress markers and low concentrations of endogenous antioxidants, or antioxidants enzymes. This suggests that antioxidants could have an antidepressant effect. S-allyl cysteine (SAC) is a compound with antioxidant action or free radical scavenger capacity. The purpose of the current research was to evaluate the antidepressant-like effect as well as the antioxidant role of SAC on a preclinical test, using the Porsolt forced swim test (FST). SAC (30, 70, 120, or 250 mg/kg, ip) was administered to male BALB/c mice daily for 17 days, followed by the FST at day 18. Oxidative stress markers (reactive oxygen species, superoxide production, lipid peroxidation, and antioxidant enzymes activities) were analyzed in the midbrain, prefrontal cortex, and hippocampus. SAC (120 mg/kg) attenuated the immobility scores (44%) in the FST, and protection was unrelated to changes in locomotor activity. This antidepressant-like effect was related to decreased oxidative stress, as indicated by lipid peroxidation and manganese-superoxide dismutase (Mn-SOD) activity in the hippocampus. SAC exerts an antidepressant-like effect that correlated, in part, with preventing oxidative damage in hippocampus.

X-Irradiation at 0.5 Gy after the forced swim test reduces forced swimming-induced immobility in mice

The forced swim test (FST) is a screening model for antidepressant activity; it causes immobility and induces oxidative stress. We previously reported that radon inhalation has antidepressant-like effects in mice potentially through the activation of antioxidative functions upon radon inhalation. This study aimed to investigate the effect of prior and post low-dose X-irradiation (0.1, 0.5, 1.0 and 2.0 Gy) on FST-induced immobility and oxidative stress in the mouse brain, and the differences, if any, between the two. Mice received X-irradiation before or after the FST repeatedly for 5 days. In the post-FST-irradiated group, an additional FST was conducted 4 h after the last irradiation. Consequently, animals receiving prior X-irradiation (0.1 Gy) had better mobility outcomes than sham-irradiated mice; however, their levels of lipid peroxide (LPO), an oxidative stress marker, remained unchanged. However, animals that received post-FST X-irradiation (0.5 Gy) had better mobility outcomes and their LPO levels were significantly lower than those of the sham-irradiated mice. The present results indicate that 0.5 Gy X-irradiation after FST inhibits FST-induced immobility and oxidative stress in mice.

Effect of lacosamide on ethanol induced conditioned place preference and withdrawal associated behavior in mice: Possible contribution of hippocampal CRMP-2

BACKGROUND

Excessive consumption of ethanol is known to activate the mTORC1 pathway and to enhance the Collapsin Response Mediator Protein-2 (CRMP-2) levels in the limbic region of brain. The latter helps in forming microtubule assembly that is linked to drug taking or addiction-like behavior in rodents. Therefore, in this study, we investigated the effect of lacosamide, an antiepileptic drug and a known CRMP-2 inhibitor, which binds to CRMP-2 and inhibits the formation of microtubule assembly, on ethanol-induced conditioned place preference (CPP) in mice.

METHODS

The behavior of mice following ethanol addiction and withdrawal was assessed by performing different behavioral paradigms. Mice underwent ethanol-induced CPP training with alternate dose of ethanol (2 g/kg, po) and saline (10 ml/kg, po). The effect of lacosamide on the expression of ethanol-induced CPP and on ethanol withdrawal associated anxiety and depression-like behavior was evaluated. The effect of drug on locomotor activity was also assessed and hippocampal CRMP-2 levels were measured.

RESULTS

Ethanol-induced CPP was associated with enhanced CRMP-2 levels in the hippocampus. Lacosamide significantly reduced the expression of ethanol-induced CPP and alleviated the levels of hippocampal CRMP-2 but aggravated withdrawal-associated anxiety and depression in mice.

CONCLUSION

The present study demonstrated the beneficial effect of lacosamide in attenuation of expression of ethanol induced conditioned place preference via reduction of hippocampal CRMP-2 level. These findings suggest that lacosamide may be investigated further for ethanol addiction but not for managing withdrawal.

Neuroprotective activity of tetramethylpyrazine against 3-nitropropionic acid induced Huntington's disease-like symptoms in rats

Huntington's disease (HD) is an autosomal neurodegenerative disease characterized by chorea, dystonia, motor ataxia, cognitive decline and psychiatric disorders with gradual loss of nerve cells and has no existing cure for the disease. In the present study, a mitochondrial toxin, 3-nitropropionic acid (3-NP) is used to induce HD like symptoms in rats. Tetramethylpyrazine is one of the active ingredients of Chuan Xiong which was reported to have neurotrophic and neuroprotective activities. The present study was designed to evaluate the role of TMP on 3-NP induced behavioral, biochemical, neurochemical, and histological alterations in the different regions of the brain. Animals were pretreated with normal saline/TMP for 7 days. From 8th day, the treatment groups were co-administered with 3-NP (10 mg/kg, i.p) and continued to the 21st day of the treatment protocol. At the end of the study, we found that the TMP improved all the behavioral performances of 3-NP induced neurotoxic rats, significantly. Further, oxidative stress parameters (lipid peroxidation, reduced glutathione, catalase, and superoxide dismutase), succinate dehydrogenase enzyme, and neurochemical (GABA and glutamate) estimations were done in the brain homogenate. In our study, the treatment with TMP ameliorated the 3-NP induced alterations, in the biochemical and neurochemical parameter in the brain homogenate, dose-dependently. The protective role of TMP further confirmed by measuring the lesion area with the 2,3,5-triphenyltetrazolium chloride staining of the brain slices and histopathological alteration in the hippocampus (CA1 and CA3) and striatal regions of the brain. Hence, the present findings suggest that the protective role of TMP against 3-NP induced behavioral, biochemical, neurochemical, and histological alterations in rats.

A voltammetric and mathematical analysis of histaminergic modulation of serotonin in the mouse hypothalamus

Histamine and serotonin are neuromodulators which facilitate numerous, diverse neurological functions. Being co-localized in many brain regions, these two neurotransmitters are thought to modulate one another's chemistry and are often implicated in the etiology of disease. Thus, it is desirable to interpret the in vivo chemistry underlying neurotransmission of these two molecules to better define their roles in health and disease. In this work, we describe a voltammetric approach to monitoring serotonin and histamine simultaneously in real time. Via electrical stimulation of the axonal bundles in the medial forebrain bundle, histamine release was evoked in the mouse premammillary nucleus. We found that histamine release was accompanied by a rapid, potent inhibition of serotonin in a concentration-dependent manner. We developed mathematical models to capture the experimental time courses of histamine and serotonin, which necessitated incorporation of an inhibitory receptor on serotonin neurons. We employed pharmacological experiments to verify that this serotonin inhibition was mediated by H3 receptors. Our novel approach provides fundamental mechanistic insights that can be used to examine the full extent of interconnectivity between histamine and serotonin in the brain. Histamine and serotonin are co-implicated in many of the brain's functions. In this paper, we develop a novel voltammetric method for simultaneous real-time monitoring of histamine and serotonin in the mouse premammillary nucleus. Electrical stimulation of the medial forebrain bundle evokes histamine and inhibits serotonin release. We show voltammetrically, mathematically, and pharmacologically that this serotonin inhibition is H3 receptor mediated.

Comparative Evaluation of Partial α2 -Adrenoceptor Agonist and Pure α2 -Adrenoceptor Antagonist on the Behavioural Symptoms of Withdrawal after Chronic Alcohol Administration in Mice

As an addictive drug, alcohol produces withdrawal symptoms if discontinued abruptly after chronic use. Clonidine (CLN), a partial α2 -adrenergic agonist, and mirtazapine (MRT), an antagonist of α2 -adrenoceptor, both clinically aid alcohol withdrawal. Considering different mechanisms of action of the two drugs, this study was designed to see how far these two mechanistically different drugs differ in their ability to decrease the severity of ethanol withdrawal syndrome. The effect of CLN and MRT on ethanol withdrawal-induced anxiety, depression and memory impairment was analysed using EPM, FST and PAR tests, respectively. Animals received distilled water, ethanol and/or either of the drugs (CLN and MRT) in different doses. Relapse to alcohol use was analysed by CPP test. Animals received ethanol as a conditioning drug and distilled water, CLN or MRT as test drug. CLN and MRT both alleviated anxiety in a dose-dependent manner. MRT (4 mg/kg) was more effective than CLN (0.1 mg/kg) in ameliorating the anxiogenic effect of alcohol withdrawal. However, CLN treatment increased depression. It significantly decreased swimming time and increased immobility time, whereas MRT treatment decreased immobility time and increased climbing and swimming time during abstinence. The effect was dose dependent for both drugs. The results of PAR test show that CLN treatment worsens working memory. Significant increase in SDE and TSZ and decrease in SDL were observed in CLN-treated animals. MRT treatment, on the other hand, improved working memory at both doses. Further, both CLN and MRT alleviated craving. A significant decrease in time spent in the ethanol-paired chamber was seen. MRT treatment at both doses showed better effect than CLN in preventing the development of preference in CPP test. These findings indicate a potential therapeutic use and better profile of mirtazapine over clonidine in improving memory, as well as in alleviating depression, anxiety and craving associated with alcohol withdrawal.

Protective effects of Radix Pseudostellariae polysaccharides against exercise-induced oxidative stress in male rats

The main purpose of this study was to examine the effect of Radix Pseudostellariae polysaccharides (RPPs) against swimming exercise-induced oxidative stress in male rats. A total of 40 male Wistar rats were randomized into four groups: the control (C), low-dose RPP supplementation (LRS), medium-dose RPP supplementation (MRS) and high-dose RPP supplementation (HRS) groups. The control group received saline solution and the supplementation groups received different doses of RPPs (100, 200 and 400 mg/kg body weight, respectively). The animals were medicated orally and daily for 28 days. On day 28, the rats were made to swim until exhausted. The exhaustive swimming time and various biochemical parameters, including blood lactate, hemoglobin, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), were measured. The results showed that RPP supplementation elevates the exercise tolerance and decreases the blood lactate level of rats following exhaustive swimming exercise. RPP supplementation augments the levels of hemoglobin and anti-oxidant enzymes (CAT, SOD and GSH-Px), and effectively decreases the MDA content of the skeletal muscle of rats, which suggests that RPP supplementation has a protective effect against exercise-induced oxidative stress.

Antidepressant-like effect of a Ginkgo biloba extract (EGb761) in the mouse forced swimming test: role of oxidative stress

EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This extract is used clinically due to its neuroprotective effects, exerted probably via its potent antioxidant or free radical scavenger action. Previous studies suggest that oxidative stress, via free radical production, may play an important role in depression and animal models for depression-like behavior. Preclinical studies have suggested that antioxidants may have antidepressants properties. The aim of this study was to investigate the antidepressant-like of EGb761 due to its antioxidant role against oxidative stress induced in the forced swimming test, the most widely used preclinical model for assessing antidepressant-like behavior. Male BALB/c mice were pretreated with EGb761 (10mg/kg, ip) daily for 17 days followed by the forced swimming test and spontaneous locomotor activity. Animals were sacrificed to evaluate lipid peroxidation, different antioxidant enzyme activities, serotonin and dopamine content in midbrain, hippocampus and prefrontal cortex. EGb761 significantly decreased the immobility time (39%) in the forced swimming test. This antidepressant-like effect of EGb761 was associated with a reduction in lipid peroxidation and superoxide radical production (indicated by a downregulation of Mn-superoxide dismutase activity), both of which are indicators of oxidative stress. The protective effect of EGb761 is not related to excitatory or inhibitory effects in locomotor activity, and was also associated with the modulation of serotonergic and dopaminergic neurotransmission. It is suggested that EGb761 produces an antidepressant-like effect, and that an antioxidant effect against oxidative stress may be partly responsible for its observed neuroprotective effects.

Effect of thioperamide on oxidative stress markers in middle cerebral artery occlusion model of focal cerebral ischemia in rats

In view of the recent evidence for the involvement of histamine in cerebral ischemia, the present study evaluated the effect of thioperamide (THP), a selective histamine H3-receptor antagonist, on middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia in rats. The rats were subjected to 2 h of MCAO followed by 22 h reperfusion after which the grip strength, locomotor activity and spontaneous alternation performance were assessed. Animals were then killed and oxidative stress markers were estimated in the whole brain. An elevation of thiobarbituric acid reactive substance (TBARS) and a reduction in glutathione (GSH) and antioxidant enzymes, such as glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD), was observed following MCAO, the last two being statistically insignificant. Pretreatment with THP (5.5 mg/kg i.p. and 11 mg/kg i.p.) significantly reversed the MCAO-induced increase in TBARS, but could not reverse the other parameters. Paradoxically, it further reduced the levels of GPx, GR and SOD. No significant changes were observed in the catalase levels and in the grip strength and spontaneous alternation behavior of rats. Locomotor activity was reduced slightly, but reversed on pretreatment with THP. The dual effect of THP on oxidative stress requires further investigation and raises doubts on its possible use in cerebral ischemia.

Antipsychotic-like profile of thioperamide, a selective H3-receptor antagonist in mice

Experimental and clinical evidence points to a role of central histaminergic system in the pathogenesis of schizophrenia. The present study was designed to study the effect of histamine H(3)-receptor ligands on neuroleptic-induced catalepsy, apomorphine-induced climbing behavior and amphetamine-induced locomotor activities in mice. Catalepsy was induced by haloperidol (2 mg/kg p.o.), while apomorphine (1.5 mg/kg s.c.) and amphetamine (2 mg/kg s.c.) were used for studying climbing behavior and locomotor activities, respectively. (R)-alpha-methylhistamine (RAMH) (5 microg i.c.v.) and thioperamide (THP) (15 mg/kg i.p.), per se did not cause catalepsy. Administration of THP (3.75, 7.5 and 15 mg/kg i.p.) 1 h prior to haloperidol resulted in a dose-dependent increase in the catalepsy times (P < 0.05). However, pretreatment with RAMH significantly reversed such an effect of THP (15 mg/kg i.p.). RAMH per se showed significant reduction in locomotor time, distance traveled and average speed but THP (15 mg/kg i.p.) per se had no effect on these parameters. On amphetamine-induced hyperactivity, THP (3.75 and 7.5 mg/kg i.p.) reduced locomotor time, distance traveled and average speed (P < 0.05). Pretreatment with RAMH (5 microg i.c.v.) could partially reverse such effects of THP (3.75 mg/kg i.p.). Climbing behavior induced by apomorphine was reduced in animals treated with THP. Such an effect was, however, reversed in presence of RAMH. THP exhibited an antipsychotic-like profile by potentiating haloperidol-induced catalepsy, reducing amphetamine-induced hyperactivity and reducing apomorphine-induced climbing in mice. Such effects of THP were reversed by RAMH indicating the involvement of histamine H(3)-receptors. Findings suggest a potential for H(3)-receptor antagonists in improving the refractory cases of schizophrenia.