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

Tardive dyskinesia (TD) is a side effect associated with the long-term use of certain antipsychotics. Considering the modulatory role of the endocannabinoid system upon dopaminergic neurotransmission, the present study tested the hypothesis that increasing endocannabinoid (anandamide and 2-arachidonoylglycerol) levels attenuates haloperidol-induced TD (vacuous chewing movements, VCMs) in male Wistar rats. The animals received administration of chronic haloperidol (38 mg/kg; 29 days) followed by acute FAAH (URB597, 0.1-0.5 mg/kg) or MAGL (JZL184, 1-10 mg/kg) inhibitors before VCM quantification. The underlying mechanisms were evaluated by pre-treatments with a CB₁ receptor antagonist (AM251, 1 mg/kg) or a TRPV₁ channel blocker (SB366791, 1 mg/kg). Moreover, CB₁ receptor expression was evaluated in the striatum of high-VCM animals. As expected, haloperidol induced VCMs only in a subset of rats. Either FAAH or MAGL inhibition reduced VCMs. These effects were prevented by CB₁ receptor antagonism, but not by TRPV1 blockage. Remarkably, CB₁ receptor expression was increased high-VCM rats, with a positive correlation between the levels of CB₁ expression and the number of VCMs. In conclusion, increasing endocannabinoid levels results in CB₁ receptor-mediated protection against haloperidol-induced TD in rats. The increased CB₁ receptor expression after chronic haloperidol treatment suggests a counter-regulatory protective mechanism.

Naringin Ameliorates Haloperidol-Induced Neurotoxicity and Orofacial Dyskinesia in a Rat Model of Human Tardive Dyskinesia

Animal models of haloperidol (HAL)-induced neurotoxicity and orofacial dyskinesia (OD) have long been used to study human tardive dyskinesia (TD). Similar to patients with TD, these models show strong pathophysiological characteristics such as striatal oxidative stress and neural cytoarchitecture alteration. Naringin (NAR), a bioflavonoid commonly found in citrus fruits, has potent antioxidative, anti-inflammatory, antiapoptotic, and neuroprotective properties. The present study evaluated the potential protective effects of NAR against HAL-induced OD in rats and the neuroprotective mechanisms underlying these effects. HAL treatment (1 mg/kg i.p. for 21 successive days) induced OD development, characterized by increased vacuous chewing movement (VCM) and tongue protrusion (TP), which were recorded on the 7th, 14th, and 21st day of drug treatment. NAR (30, 100, and 300 mg/kg) was administered orally 60 min before HAL injection for 21 successive days. On the 21st day, after behavioral testing, the rats were sacrificed, and the nitrosative and oxidative status, antioxidation power, neurotransmitter levels, neuroinflammation, and apoptotic markers in the striatum were measured. HAL induced OD development, with significant increases in the frequency of VCM and TP. NAR treatment (100 and 300 mg/kg) prevented HAL-induced OD significantly. Additionally, NAR treatment reduced the HAL-induced nitric oxide and lipid peroxide production, increased the antioxidation power and neurotransmitter levels in the striatum, and significantly reduced the levels of neuroinflammatory and apoptotic markers. Our results first demonstrate the neuroprotective effects of NAR against HAL-induced OD, suggesting that NAR may help in delaying or treating human TD in clinical settings.

Antioxidant effects of rice bran oil mitigate repeated haloperidol-induced tardive dyskinesia in male rats

Tardive dyskinesia (TD) is associated with the use of antipsychotic drugs such as D2 antagonist haloperidol (HP). The chronic use of HP is involved in the causation of free radicals and/or oxidative stress. In view of the nootropic, anti-anxiety, anti-inflammatory-like effects of rice bran oil (RBO) in a variety of investigations, we assessed the protective properties of RBO on HP-induced TD and neurochemical alteration. Rats treated with HP orally at a dose of 0.2 mg/kg/day for a period of 5 weeks developed VCMs which increased progressively as the treatment continued for 5 weeks. Co-administration of RBO by oral tubes at a dose of 0.4 ml/day prevented the induction of HP-induced VCMs. Repeated administration of HP increases the turnover of dopamine metabolism in the striatum. Conversely animals treated with HP + RBO decrease the metabolism of DA than water + HP treated animals. Striatal, malondieldehyde (MDA), hydrogen peroxide (H₂O₂) and antioxidant enzyme superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were also determined. It is suggested that beneficial role of RBO in attenuation of HP-induced TD. The results therefore recommended that supplementation of RBO may be useful in the HP-induced TD. The findings have also potential implication in the treatment of schizophrenia and motor disorders.

Co-treatment with imipramine averted haloperidol-instigated tardive dyskinesia: Association with serotonin in brain regions

Outcome of imipramine (IMI) treatment was scrutinized on progression of haloperidol instigated tardive dyskinesia (TD). 0.2 mg/kg/rat dosage of haloperidol provided orally to rats for 2 weeks enhanced vacuous chewing movements that escalated when the process proceeded for 5 weeks. Following 2 weeks co-injection 5 mg/kg dosage of IMI was diminished haloperidol-instigated VCMs and fully averted following five weeks. The potency of 8-OH-DPAT-instigated locomotor activity exhibited higher in saline+haloperidol treated rats while not observed in IMI+ haloperidol treated rats. 8-OH-DPAT-instigated low 5-hydroxytryptamine (5-HT; serotonin) metabolism was higher in saline+ haloperidol treated rats when compare to IMI+ haloperidol treated rats in both regions of brain (striatum and midbrain). It is recommended that IMI possibly competent in averting TD, in cases receiving treatment to antipsychotics.