Protective role of endocannabinoid signaling in an animal model of haloperidol-induced tardive dyskinesia

G-Protein-Coupled Estrogen Receptor 1 (GPER1) Activation Mitigates Haloperidol-Induced Neurotoxicity in SHSY-5Y Cells and Improves Motor Functions in Adult Zebrafish

Haloperidol (Halo) is a typical antipsychotic medication used to treat schizophrenia, but its long-term treatment causes neurotoxicity, leading to irregular involuntary movements called Tardive Dyskinesia. Raloxifene (Ralo) and fulvestrant (Fulve) are G-protein-coupled estrogen receptor 1 (GPER1) activators and show similar pharmacological properties as identified in 17β-estradiol. It is reported to have anti-oxidant, anti-inflammatory, and anti-apoptotic properties against neurological disorders. Our study aimed to investigate the neuroprotective effect of ralo and fulve against halo-induced neurotoxicity in SHSY-5Y cells and adult zebrafish. In this study, SHSY-5Y cell lines were treated with ralo (0.01 µM), fulve (0.01 µM), G-15 (1 µM), and G-1 (2 µM) 1 h before halo (100 µM) exposure. Moreover, cell viability was analyzed using MTT assay; apoptosis was done using a confocal microscope, and molecular mechanism investigated through Western Blot and qRT-PCR analysis. For in-vivo study, zebrafish were divided into six groups (n = 12). Treatment with ralo and fulve significantly improved the viability of halo-exposed cells, while it was reduced by G15 treatment. Moreover, ralo and fulve substantially reversed ROS generation, and apoptosis by enhancing the qRT-PCR expression of Nrf2/HO-1/Bcl2 and reduced Bax expression in halo-treated cells. In addition, ralo and fulve treatment enhanced GPER1 expression in halo-treated cells, while G15 treatment reduced it. Furthermore, ralo and fulve injections improved total distance travelled, mean speed, and catalepsy-like behaviour, restoring antioxidant activity in halo-treated zebrafish. Findings suggest that ralo and fulve can activate GPER1/Nrf2/HO-1 signaling pathways and show neuroprotection against halo-induced neurotoxicity. It could be used in the management of neurological disorders.

Glycyrrhizic Acid Mitigates Haloperidol-Induced Neurotoxicity in SHSY-5Y Cells and Rats Via Activation of PI3k/Akt/Nrf2 Pathways

Antipsychotic medications are used to treat a psychological condition called 'Schizophrenia'. However, its long-term administration causes irregular involuntary motor movements, targeting the orofacial regions. Glycyrrhizic acid (GA) is a naturally occurring triterpene saponin glycoside obtained from the roots of the Glycyrrhiza glabra (liquorice) plant and well known for its antioxidant, antiapoptotic and neuroprotective abilities. The present study investigated the neuroprotective potential of GA against haloperidol (Halo) induced neurotoxicity in SHSY-5Y cells and Wistar rats. Schrodinger software was utilized to estimate the target binding affinity of GA with various targets. To assess cell viability, SHSY-5Y cells were pretreated with GA (25, 50, and 100 µM) 1 h before halo (100 µM) treatment. In an in-vivo study, Wistar rats were divided into five groups: control (saline), halo (1 mg/kg), GA (25 mg/kg), and GA (50 mg/kg). The GA was injected for 21 days, 1 h before halo. All behavior changes were recorded on the 14th and 21st days. Results indicate that pretreatment with GA improves cell viability and reduces ROS formation in halo-treated SHSY-5Y cells, showing its antioxidant ability. Furthermore, GA administration reduced vacuous chewing movements, tongue protrusion, facial jerking, and locomotor abnormalities in halo-treated rats. Moreover, GA treatment improves antioxidant levels, including GSH, and SOD, in halo-injected rats. Additionally, GA treatment upregulates the striatal expression of p-PI3k, p-Akt, and Nrf2 in rats injected with halo. Findings indicate that GA can be a therapeutic agent for tardive dyskinesia and other neurological disorders.

Cannabigerol Mitigates Haloperidol-Induced Vacuous Chewing Movements in Mice

Chronic use of typical antipsychotics can lead to varying motor effects depending on the timing of analysis. Acute treatment typically induces hypokinesia, resembling parkinsonism, while repeated use can result in tardive dyskinesia, a hyperkinetic syndrome marked by involuntary orofacial movements, such as vacuous chewing movements in mice. Tardive dyskinesia is particularly concerning due to its potential irreversibility and associated motor discomfort. One prevailing theory suggests that tardive dyskinesia arises from hypersensitivity of D2-type dopaminergic receptors caused by continuous blockade from typical antipsychotics like haloperidol. Additionally, increased inflammation, oxidative stress, and elevated FosB protein expression in the dorsolateral striatum are implicated in its pathophysiology. Current treatments for tardive dyskinesia often lack clear efficacy and may lead to significant side effects. Cannabigerol, a non-psychotomimetic cannabinoid with antioxidant and anti-inflammatory properties, has been investigated for its potential antidyskinetic effects. In this study, mice were treated with cannabigerol at doses of 3 and 10 mg/kg to evaluate its ability to prevent, ameliorate, or reverse haloperidol-induced vacuous chewing movements. Cannabigerol successfully reduced vacuous chewing movements without affecting normal motor activity, exacerbating haloperidol-induced hypokinesia, or inducing dyskinetic effects on its own. However, no significant reversal of the haloperidol-induced motor effects was observed under the current protocol. Furthermore, cannabigerol did not alter FosB expression or microglia morphology. These findings underscore the need for further research to explore cannabigerol's therapeutic potential and contribute to our understanding of its possible clinical applications in managing tardive dyskinesia.

Associations between polymorphisms in the cannabinoid receptor 1 gene, cognitive impairments and tardive dyskinesia in a Chinese population with schizophrenia

OBJECTIVE

Tardive dyskinesia (TD) is a medically induced movement disorder that occurs as a result of long-term use of antipsychotic medications, commonly seen in patients with schizophrenia (SCZ). The study aimed to investigate the relationship between single nucleotide polymorphisms (SNPs) of the CNR1 gene, TD and cognitive impairments in a Chinese population with SCZ.

METHODS

A total of 216 SCZ patients were recruited. The participants were divided into TD and without TD (WTD) groups using the Schooler-Kane International Diagnostic Criteria. The severity of TD was assessed using the Abnormal Involuntary Movement Scale (AIMS). Cognitive function was assessed using the Repeatable Battery for Assessment of Neuropsychological Status (RBANS) scale. Hardy-Weinberg equilibrium tests, chained disequilibrium analyses and haplotype analyses were performed using SHE-sis software. To explore the main effects of TD diagnosis, genotype and cognitive function, as well as interaction effects, analysis of covariance (ANCOVA) was employed.

RESULTS

The prevalence of TD was approximately 27.3%. Significant differences were observed in the rs806368 CT genotype and rs806370 TC genotype within the hypercongenic pattern between the male TD and WTD groups (OR = 2.508, 95% CI: 1.055-5.961, p = 0.037; OR = 2.552, 95% CI: 1.073-6.069, p = 0.034). Among TD patients, those carrying the rs806368 CC genotype exhibited higher limb trunk scores (p < 0.05). Moreover, there was a statistically significant difference in visuospatial/construction between the TD and WTD groups (p = 0.04), and a borderline significant difference in visuospatial/construction when considering the interaction between TD diagnosis and genotype at the rs806368 locus (p = 0.05).

CONCLUSION

CNR1 rs806368 and rs806370 polymorphisms may play a role in TD susceptibility. Additionally, CNR1 gene polymorphisms were associated with the severity of involuntary movements and cognitive impairments in TD patients.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

Genetic Factors Associated With Tardive Dyskinesia: From Pre-clinical Models to Clinical Studies

Tardive dyskinesia is a severe motor adverse event of antipsychotic medication, characterized by involuntary athetoid movements of the trunk, limbs, and/or orofacial areas. It affects two to ten patients under long-term administration of antipsychotics that do not subside for years even after the drug is stopped. Dopamine, serotonin, cannabinoid receptors, oxidative stress, plasticity factors, signaling cascades, as well as CYP isoenzymes and transporters have been associated with tardive dyskinesia (TD) occurrence in terms of genetic variability and metabolic capacity. Besides the factors related to the drug and the dose and patients’ clinical characteristics, a very crucial variable of TD development is individual susceptibility and genetic predisposition. This review summarizes the studies in experimental animal models and clinical studies focusing on the impact of genetic variations on TD occurrence. We identified eight genes emerging from preclinical findings that also reached statistical significance in at least one clinical study. The results of clinical studies are often conflicting and non-conclusive enough to support implementation in clinical practice.

Targeting Endocannabinoid System in Epilepsy: For Good or for Bad

Epilepsy is a neurological disorder with a high prevalence worldwide. Several studies carried out during the last decades indicate that the administration of cannabinoids as well as the activation of the endocannabinoid system (ECS) represent a therapeutic strategy to control epilepsy. However, there are controversial studies indicating that activation of ECS results in cell damage, inflammation and neurotoxicity, conditions that facilitate the seizure activity. The present review is focused to present findings supporting this issue. According to the current discrepancies, it is relevant to elucidate the different effects induced by the activation of ECS and determine the conditions under which it facilitates the seizure activity.