The effect of acute aripiprazole treatment on chemically and electrically induced seizures in mice: The role of nitric oxide

The potential role of nitric oxide in the anticonvulsant effects of betulin in pentylenetetrazole (PTZ)-induced seizures in mice

Epilepsy poses a significant challenge, especially for drug-resistant cases, necessitating novel treatment avenues. This study explores the potential interplay between nitric oxide (NO) and the anticonvulsant effects of betulin, a triterpene with promising neuroprotective properties. While betulin exhibits anticonvulsant effects, the specific involvement of NO remains inadequately understood, constituting a pivotal gap in current knowledge. One hundred NMRI mice were randomly assigned to diverse treatment groups, with seizures induced by pentylenetetrazol (PTZ). Parameters such as seizure threshold, nitrite levels, total antioxidant capacity (TAC), malondialdehyde (MDA) levels, and iNOS/nNOS gene expressions were assessed. Betulin significantly increased seizure thresholds and mitigated PTZ-induced NO levels. These findings suggest a potential modulation of NO-related pathways, emphasizing betulin's anti-inflammatory and antioxidant attributes. The study sheds light on betulin's multifaceted impact on oxidative stress, NO regulation, and iNOS/nNOS gene expressions. The ability of betulin to suppress iNOS/nNOS gene expressions, leading to reduce NO production, underscores its potential as an anticonvulsant.

Blood-based oxidation markers in medicated and unmedicated schizophrenia patients: A meta-analysis

Increased reactive species due to the effect of antipsychotics on oxidative stress may be involved in the development of schizophrenia. However, antipsychotics may have different direct antioxidant effects due to their chemical structures. The present meta-analysis aimed to investigate whether the cause increased oxidant status in schizophrenia patients is due to the illness or induction by antipsychotics. Studies published from 1964 to 2021 were selected from Pubmed and Scopus databases. Data were analysed using Comprehensive Meta-Analysis version 2. Effect sizes were calculated and compared between unmedicated and medicated patients and healthy controls. Heterogeneity and publication bias were assessed. Subgroup analyses were conducted on drug-free and drug-naïve patients, and patients treated with atypical and typical antipsychotics. We found that medicated patients had significantly higher malondialdehyde (MDA), thiobarbituric acid reactive substances (TBARS) and total oxidant status (TOS). Meanwhile, significantly increased plasma/serum MDA and nitric oxide (NO) were observed in unmedicated patients only. Higher lipid peroxidation in the drug-naïve group may be associated schizophrenia. However, both atypical and typical antipsychotics may worsen lipid peroxidation. Antipsychotic discontinuation in the drug-free group led to significantly increased plasma/serum NO, with larger effect size than the atypical antipsychotic group. In conclusion, medicated schizophrenia patients were more suffered from increased oxidative stress. Therefore, future study may focus on the mechanism of action of specific antipsychotic on oxidative stress.

Involvement of H2 S, NO and BDNF-TrkB signalling pathway in the protective effects of simvastatin against pentylenetetrazole-induced kindling and cognitive impairments in mice

Cognitive dysfunction was observed in pentylenetetrazole (PTZ)-kindled mice. The potential effectiveness of simvastatin (SIM) on PTZ-induced kindling and cognitive impairments in mice was evaluated. The influence of SIM on hydrogen sulphide (H2 S), nitric oxide (NO), reactive aldehydes and brain-derived neurotrophic factor/tyrosine receptor kinase B (BDNF-TrkB) signalling was also investigated. Kindling and cognitive impairments in mice were induced by 12 ip injections of PTZ (35 mg/kg) once every alternate day. The levels of reactive aldehydes and nitrite were increased while H2 S was decreased in PTZ-treated mice. These results were accompanied by a reduction in the gene expression of aldehyde dehydrogenase 2, cystathionine β-synthase, BDNF and TrkB. In PTZ-kindled mice, a rise in brain inducible nitric oxide synthase protein expression associated with histopathological changes was observed. SIM administration (1, 5 and 10 mg/kg, daily orally) along with alternate day of PTZ (35 mg/kg) resulted in a decrease in PTZ-induced kindling with a dose-dependent improvement in cognitive function. SIM (10 mg/kg) prevented, to variable extent, the disturbances associated with PTZ-kindled mice with cortical, cerebellar and hippocampal structural improvement. These results suggested that SIM triggers multiple mechanisms that improve cognitive function in PTZ-kindled mice through modulation of oxidative stress, H2 S, NO and BDNF-TrkB signalling pathway.

Aripiprazole prevents from development of vincristine-induced neuropathic nociception by limiting neural NOS overexpression and NF-kB hyperactivation

PURPOSE

Increased nitric oxide (NO) synthesis and NF-kB activation have been shown as critical players in the pathophysiology of vincristine-induced peripheral neuropathy. Consistently, neural nitric oxide synthase (nNOS) inhibitors alleviated the neuropathic pain. Previous studies demonstrated that aripiprazole is capable of modulating NO synthesis and also has been reported its modulatory effect on NF-kB activity.

METHODS

Aripiprazole was administered daily to the male Wistar rats at the same time with establishing neuropathic model by I.P. injection of vincristine every 2 days, over 2 weeks. Efficacy of aripiprazole in suppressing the development of neuropathy was evaluated by assessing changes in body weight, mechanical threshold, withdrawal latency, sciatic nerve conduction velocity (SNCV), and compound motor action potential (CMAP) characteristics. Expression of nNOS and NF-kB activation were evaluated by western blotting RESULTS: Rats receiving aripiprazole during neuropathy establishment period demonstrated a normal weight gain pattern, a significantly higher mechanical withdrawal threshold, and SNCV compared to vincristine-treated group. Furthermore, the amplitude and area of CMAP were significantly higher in aripiprazole group. Western blotting demonstrated a significantly reduced expression of nNOS and NF-kB activation in dorsal root ganglia of aripiprazole co-treated rats.

CONCLUSION

In conclusion, aripiprazole effectively prevents from vincristine-induced neuropathy by limiting nNOS overexpression and NF-kB hyperactivation.

Serotonin and sudden unexpected death in epilepsy

Epilepsy is a highly prevalent disease characterized by recurrent, spontaneous seizures. Approximately one-third of epilepsy patients will not achieve seizure freedom with medical management and become refractory to conventional treatments. These patients are at greatest risk for sudden unexpected death in epilepsy (SUDEP). The exact etiology of SUDEP is unknown, but a combination of respiratory, cardiac, neuronal electrographic dysfunction, and arousal impairment is thought to underlie SUDEP. Serotonin (5-HT) is involved in regulation of breathing, sleep/wake states, arousal, and seizure modulation and has been implicated in the pathophysiology of SUDEP. This review explores the current state of understanding of the relationship between 5-HT, epilepsy, and respiratory and autonomic control processes relevant to SUDEP in epilepsy patients and in animal models.

Anticonvulsant effect of minocycline on pentylenetetrazole-induced seizure in mice: involvement of nitric oxide and N-methyl-d-aspartate receptor

Anticonvulsant effects of minocycline have been explored recently. This study was designed to examine the anticonvulsant effect of acute administration of minocycline on pentylenetetrazole-induced seizures in mouse considering the possible role of the nitric oxide/N-methyl-d-aspartate (NMDA) pathway. We induced seizure using intravenous administration of pentylenetetrazole. Our results showed that acute administration of minocycline increased the seizure threshold. Furthermore, co-administration of subeffective doses of the nonselective nitric oxide synthase (NOS) inhibitor NG-l-arginine methyl ester (10 mg/kg) and the neuronal NOS inhibitor 7-nitroindazole (40 mg/kg) enhanced the anticonvulsant effect of subeffective doses of minocycline (40 mg/kg). We found that inducible NOS inhibitor aminoguanidine (100 mg/kg) had no effect on the antiseizure effect of minocycline. Moreover, l-arginine (60 mg/kg), as a NOS substrate, reduced the anticonvulsant effect of minocycline. We also demonstrated that pretreatment with the NMDA receptor antagonists ketamine (0.5 mg/kg) and MK-801 (0.05 mg/kg) increased the anticonvulsant effect of subeffective doses of minocycline. Results showed that minocycline significantly decreased the hippocampal nitrite level. Furthermore, co-administration of a neuronal NOS inhibitor like NMDA receptor antagonists augmented the effect of minocycline on the hippocampal nitrite level. In conclusion, we revealed that anticonvulsant effect of minocycline might be, at least in part, due to a decline in constitutive hippocampal nitric oxide activity as well as inhibition of NMDA receptors.

Aripiprazole prevents renal ischemia/reperfusion injury in rats, probably through nitric oxide involvement

Renal ischemia/reperfusion (I/R) injury is strongly related to morbidity and mortality. Oxidative stress, inflammation, and apoptosis play key roles in renal dysfunction following renal I/R. Aripiprazole is an atypical antipsychotic which used for the treatment of schizophrenia and bipolar disorder. Recent studies have reported aripiprazole as displaying certain anti-inflammatory effects. Regarding the underlying mechanisms of renal ischemia-reperfusion, therefore, nephroprotective effects might be predicted to be seen with aripiprazole. I/R injury was induced by bilateral clamping of the renal pedicles (45min) followed by reperfusion (24h). The mechanism of aripiprazole-mediated nephroprotection was explored by a combined use of aripiprazole and L-NAME (non-selective nitric oxide synthase inhibitor). Animals were given aripiprazole (2.5, 5, 10 and 20mg/kg) intraperitoneally, 30min before ischemia. L-NAME was administered before the aripiprazole injection. Serum creatinine and blood urea nitrogen were assessed after 24h of reperfusion. Serum levels of malondialdehyde (MDA), TNF-α and IL-1β were measured for rats treated with aripiprazole. The extent of necrosis was measured by the stereology method. Ischemia/reperfusion caused significant renal dysfunction and marked renal injury. Aripiprazole reduced creatinine and blood urea nitrogen. Serum levels of MDA, IL-1β and TNF-α were significantly lower in the aripiprazole group. Aripiprazole treatment also decreased the volume of kidney necrosis. The administration of L-NAME reversed the renoprotective effect of aripiprazole on BUN and creatinine, but enhanced the anti-necrotic effect of aripiprazole. The results show that a single dose of aripiprazole significantly improved renal function following ischemia/reperfusion injury - probably through the involvement of nitric oxide.

Retraction. Clc-2 knockout attenuated experimental temporal lobe epilepsy in mice by tonic inhibition mediated by GABAA receptors

Temporal lobe epilepsy (TLE), the most prevalent form of epilepsy, is often associated with drug-resistant seizures. In TLE, altered function of γ-aminobutyric acid (GABA)A receptors (GABAARs) results in potentiation of excitatory and/or failure of inhibitory neurotransmission, which contributes to seizure induction and propagation. Our previous study suggested that chloride channel-2 (Clc-2) contributed to chronically elevated tonic inhibition mediated by GABAARs in a rat model of TLE. In the present study, we used Clc-2 knockout mice to investigate further the role of Clc-2 and its interaction with tonic GABAergic inhibition in a model of TLE. The results revealed that knockout of Clc-2 decreased tonic seizure protection, latency of clonic seizure, seizure threshold and mortality protection in mice. Clc-2 knockout decreased the action potential (AP)peak and APthreshold, Clc-2 currents and GABAAR-mediated tonic inhibition in CA1 pyramidal neurons. Thus, the voltage-gated chloride channel Clc-2, which was functionally upregulated in CA1 pyramidal cells after seizures, may provide protection against TLE by its regulation of action potentials, Clc-2 currents and GABAARs in the CA1 region of the hippocampus.