YKP1447, A Novel Potential Atypical Antipsychotic Agent

Preliminary assessment of proanthocyanidin isolates of Vitis vinifera seed on the central nervous system of male Albino mice

This study evaluated the potential neurobehavioral effects of proanthocyanidin-rich-fraction (PRF) obtained from Vitis vinifera seed in male Albino mice. Adult (2½- to 3-month old) male Albino mice were treated with PRF (200, 100, 50 mg/kg) and subjected to diverse behavioral models specially designed for the assessment of central nervous system-acting agents. One-shot intraperitoneal (i.p) injection of PRF (200 and 100 mg/kg) decreased the rectal temperature, exploratory activities (locomotion, rearing, and grooming), anxiety-like responses (% open-arm time, open-arm entries but decreased the total number of enclosed arm times). However, acute i.p administration of PRF decreased the total score of apomorphine-induced stereotyped behaviors, latency to hexobarbitone-induced sleep, and increased the total sleep duration. Moreover, indices of convulsion (tonic flexion, extension, clonic convulsion, stupor, and recovery time) were decreased in the PRF treatment groups, especially the PRF (50 mg/kg)-treated mice. Based on these present findings, it could therefore be inferred that systemic administration of PRF of V. vinifera seed origin induces diverse modification on the behaviors of the treated mice stemming from anxiolytic, anticonvulsant, sedative, and decrease in core temperature.

Spontaneous head twitches in aged rats: behavioral and molecular study

RATIONALE

We have discovered that rats at the age of 18 months begin to twitch their heads spontaneously (spontaneous head twitching, SHT). To date, no one has described this phenomenon.

OBJECTIVES

The purpose of this study was to characterize SHT pharmacologically and to assess some possible mechanisms underlying SHT.

METHODS

Wistar male rats were used in the study. Animals at the age of 18 months were qualified as HSHT (SHT ≥ 7/10 min observations) or LSHT (SHT < 7/10 min observations). Quantitative real-time PCR with TaqMan low-density array (TLDA) approach was adopted to assess the mRNA expression of selected genes in rat's hippocampus.

RESULTS

HSHT rats did not differ from LSHT rats in terms of survival time, general health and behavior, water intake, and spontaneous locomotor activity. 2,5-dimethoxy-4-iodoamphetamine (DOI) at a dose of 2.5 mg/kg increased the SHT in HSHT and LSHT rats, while ketanserin dose-dependently abolished the SHT in the HSHT rats. The SHT was reduced or abolished by olanzapine, clozapine, risperidone, and pimavanserin. All these drugs have strong 5-HT2A receptor-inhibiting properties. Haloperidol and amisulpride, as antipsychotic drugs with a mostly dopaminergic mechanism of action, did not influence SHT. Similarly, escitalopram did not affect SHT. An in-depth gene expression analysis did not reveal significant differences between the HSHT and the LSHT rats.

CONCLUSIONS

SHT appears in some aging rats (about 50%) and is permanent over time and specific to individuals. The 5-HT2A receptor strongly controls SHT. HSHT animals can be a useful animal model for studying 5-HT2A receptor ligands.

Effect of ketamine administration, alone and in combination with E-6837, on climbing behavior

Some types of schizophrenia have been associated with repetitive movements lacking specific purpose, also known as stereotyped behavior. Dopamine agonists (D2) and noncompetitive N-methyl-D-aspartate receptor antagonists (e.g. ketamine) have been administered in rodent models to induce stereotyped behavior that resembles some motor symptoms of schizophrenia. Recently, a relationship has been found between 5-HT6 receptors (5-HT6Rs) and dopaminergic activity. The present study evaluates the effect of ketamine (5 and 10 mg/kg), alone and in combination with the 5-HT6R agonist E-6837, on the climbing behavior of male mice. Ketamine was administered with an acute (1 day) and subchronic (5 day) scheme. Later, these doses and schemes were combined with an acute scheme of E-6837 (5 and 10 mg/kg). With both the acute and the subchronic schemes, ketamine increased climbing behavior at a dose of 10 mg/kg, and this effect was reversed by E-6837 (at 5 and 10 mg/kg). The present results suggest that there is an interaction between N-methyl-D-aspartate and 5-HT6 receptors in the regulation of climbing behavior. Further research is necessary to provide more evidence on this interaction.

Agomelatine Protection in an LPS-Induced Psychosis-Relevant Behavior Model

BACKGROUND The aim of this study was to investigate the effect of agomelatine in a psychosis-relevant behavior model. MATERIAL AND METHODS We used 18 adult male Wistar rats in this study. Twelve rats given LPS for endotoxemia were randomly divided into 2 groups (n=6). Group I was treated with 1 mL/kg 0.9% NaCl i.p. and Group II was treated with 40 mg/kg agomelatine. Six normal rats served as the control group and were not given LPS for endotoxemia. Cylindrical steel cages containing vertical and horizontal metal bars with top cover were used. Rats were put in these cages for the purpose of orientation for 10 min. Apomorphine was given to rats removed from cages, and then they were immediately put back in the cages for the purpose of observing stereotyped conduct. Brain HVA levels and plasma TNF-a levels were evaluated in tissue homogenates using ELISA. The proportion of malondialdehyde (MDA) was measured in samples taken from plasma for detection of lipid peroxidation similar to thiobarbituric acid reactive substances. RESULTS LPS induced-plasma TNF-α, brain TNF-α, and plasma MDA levels were significantly lower in the LPS+agomelatine group compared to the LPS+saline group (p<0.05). HVA levels and stereotype scores were significantly lower in the LPS+agomelatine group compared to the LPS+saline group (p <0.001). CONCLUSIONS Agomelatine reduced TNF-α, HVA, MDA levels, and the stereotype score in relevant models of psychosis. Our results suggest that the anti-inflammatory effect of agomelatine involved oxidant cleansing properties and that its effects on the metabolism of dopamine can play an important role in the model of psychosis.

The Antipsychotic Effects of Omega-3 Fatty Acids in Rats

BACKGROUND

In humans, omega-3 fatty acids are necessary for cell membranes, brain function and nerve transmission continuation. When animals are exposed to a new environment-or as a result of an apomorphine application that creates an agonistic effect on D1 and D2 receptors-they display behavioral reactions like rearing and stereotypy. This study aims to reveal the possible antipsychotic and oxidative effects of omega-3 fatty acids by comparing with chlorpromazine, a conventional antipsychotic drug, through evaluating the novelty-induced rearing and apomorphine-induced stereotypic behaviors, as well as malondialdehyde and glutathione levels in rats.

METHODS

Twenty-eight, adult, male, Wistar rats were used in the study. Briefly, 4 groups of rats (n = 7) were administered docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) (300 mg/kg; DHA: 120 mg/kg + EPA: 180 mg/kg intraperitoneally [IP]), DHA + EPA (150 mg/kg; DHA: 60 mg/kg + EPA: 90 mg/kg IP), chlorpromazine (1 mg/kg, IP) and isotonic saline (1 mL/kg, IP). One hour later, apomorphine (2 mg/kg, subcutaneously) was administered to each rat. After the apomorphine administration, rats were observed for stereotypic behavior.

RESULTS

This study shows that omega-3 fatty acids, "similar to antipsychotics," reversed the psychotic like effects, increase of oxidants and decrease of antioxidants that are composed experimentally in rats.

CONCLUSIONS

The application of omega-3 fatty acids has antipsychotic effects and causes an oxidative imbalance. This study adds new evidence to the current literature regarding the possible antipsychotic effects of omega-3 fatty acids.

Low-grade chronic inflammation induces behavioral stereotypy in rats

Schizophrenia is known to be associated with metabolic disturbances including diabetes mellitus, obesity and cardiovascular diseases. A growing body of evidence has suggested abnormal cytokine levels in schizophrenia. In the present study, we explored the effects of low-grade chronic inflammation on behavioral stereotypy in a rat model of non-alcoholic fatty liver disease (NAFLD). In order to induce NAFLD, rats were fed with either water enriched with 30 % fructose or plain tap water for 8 weeks. Following feeding period, behavioral stereotypy was evaluated with apomorphine-induced stereotypy test. Also, levels of tumor necrosis factor alpha (TNF-α), interleukin 2 (IL-2) and nuclear factor kappa B (NF-κB) in the liver and brain tissues were assessed biochemically. Brain homovanilic acid (HVA) was measured to evaluate the dopamine turnover. NAFLD rats showed significantly higher stereotypy score compared to controls (p = 0.016). TNF-α, IL-2, and NF-κB levels were significantly increased in NAFLD rats compared to control group. Brain HVA levels were elevated in NAFLD rats as well (p = 0.008). Moreover, NAFLD group prompted a considerable increase in brain IL-2 immunoexpression (p = 0.005). In conclusion, the present study demonstrates that low-grade chronic inflammation such as NAFLD may enhance apomorphine-induced stereotypic behavior via increasing dopaminergic activity in rats.

Antipsychotic-like effect of minocycline in a rat model

OBJECTIVES

Tetracycline antibiotic drug minocycline has strongly neuroprotective and anti-inflammatory effects. Minocycline has also remarkable brain tissue penetration, is clinically entirely tolerated and properly absorbed when taken orally. In our study, we class with the effects of minocycline and chlorpromazine, a conventional antipsychotic drug, by evaluating the novelty-induced rearing, apomorphine-induced stereotypic behavior, and brain MDA levels in rats.

MATERIALS AND METHODS

Four groups of rat (n = 7) were applied with minocycline (50 and 100 mg/kg, i.p.), chlorpromazine (1 mg/kg, i.p.), or isotonic saline (1 mL/kg, i.p.). One hour later, apomorphine (2 mg/kg, s.c.) was applied to each rat.

RESULT

Our results showed that both doses of minocycline significantly decreased the rearing behavior in rats, whereas the decrease with chlorpromazine was higher. Minocycline also decreased the stereotypy scores in a dose-dependent manner.

CONCLUSION

We concluded that minocycline has beneficial effects on rearing behavior and stereotypy, which are accepted to be indicators of antipsychotic effect. Taken together, minocycline, as an anti-oxidant and cytoprotective agent, can be useful in neuroprotection especially on early stages of psychosis or prepsychotic patients with insignificant symptoms. Minocycline is worthy of being investigated for its anti-psychotic effects as a primary or an adjunctive drug.

HDAC inhibitors restore the capacity of aged mice to respond to haloperidol through modulation of histone acetylation

Antipsychotic drugs are widely prescribed to elderly patients for the treatment of a variety of psychopathological conditions, including psychosis and the behavioral disturbances associated with dementia. However, clinical experience suggests that these drugs may be less efficacious in the elderly individuals than in the young. Recent studies suggest that aging may be associated with epigenetic changes and that valproic acid (VPA), a histone deacetylase inhibitor, may reverse such changes. However, it is not yet known whether HDAC inhibitors can modulate age-related epigenetic changes that may impact antipsychotic drug action. In this study, we analyzed conditioned avoidance response (CAR) and c-Fos expression patterns to elucidate the effect of HDAC inhibitors VPA and entinostat (MS-275) on behavioral and molecular markers of the effects of haloperidol (HAL) in aged mice. Our results showed that HAL administration failed to suppress the avoidance response during the CAR test, suggesting an age-related decrease in drug efficacy. In addition, HAL-induced c-Fos expression in the nucleus accumbens shell and prefrontal cortex was significantly lower in aged mice as compared with young mice. Pretreatment with VPA and MS-275 significantly improved HAL effects on the CAR test in aged mice. Also, VPA and MS-275 pretreatment restored HAL-induced increases in c-Fos expression in the nucleus accumbens shell and prefrontal cortex of aged mice to levels comparable with those observed in young mice. Lastly, but most importantly, increases in c-Fos expression and HAL efficacy in the CAR test of the HAL+VPA and HAL+MS-275 groups were correlated with elevated histone acetylation at the c-fos promoter region in aged mice. These findings suggest that pretreatment with VPA or MS-275 increases the behavioral and molecular effects of HAL in aged mice and that these effects occur via modulation of age-related histone hypoacetylation in the nucleus accumbens shell and prefrontal cortex.

Antipsychotic-like effect of trimetazidine in a rodent model

Trimetazidine (TMZ) has been used as an anti-ischemic agent for angina pectoris, chorioretinal disturbances, and vertigo. Also, it can induce extrapyramidal type adverse reaction such as parkinsonism, gait disorder, and tremor via blockade of D2 receptors. In the present study, we evaluated the effect of TMZ on novelty-induced rearing behavior and apomorphine-induced stereotypy behavior in male rats. Four groups of rat (n = 7) were administrated with TMZ (10 and 20 mg/kg, i.p.), chlorpromazine (1 mg/kg, i.p.), or isotonic saline. One hour later, apomorphine (2 mg/kg, s.c.) was administrated to each rat. Our results showed that both doses of TMZ significantly decreased the rearing behavior in rats, whereas the decrease with chlorpromazine was higher. TMZ also decreased the stereotypy scores in a dose-dependent manner. We concluded that TMZ has beneficial effects on rearing behavior and stereotypy, which are accepted to be indicators of antipsychotic effect. Taken together, with its antioxidative and cytoprotective properties, TMZ is worthy of being investigated for its anti-psychotic effects as a primary or an adjunctive drug.