Potentiation of the antidepressant-like effect of mirtazapine by low doses of risperidone in the forced swimming test in mice

Effect of 5-HT6 Receptor Ligands Combined with Haloperidol or Risperidone on Antidepressant-/Anxiolytic-Like Behavior and BDNF Regulation in Hippocampus and Prefrontal Cortex of Rats

BACKGROUND

The presence of depressive and anxiety symptoms in patients with schizophrenia may have an important impact on treatment and compliance. Hence, interventions addressing such comorbidity in schizophrenia should be explored. One target may be a serotonergic 5-HT₆ receptor (5-HT₆R) since its ligands displayed antidepressant- and anxiolytic-like activities in preclinical experiments.

METHODS

Acute and chronic (21 days) administration of haloperidol or risperidone in combination with a selective 5-HT₆R agonist (WAY-181187) or antagonist (SB-742457) to rats was performed for detecting antidepressant- and anxiolytic-like behaviors. In addition, the level of brain-derived neurotrophic factor (BDNF) protein and its gene expression in hippocampus and prefrontal cortex were determined.

RESULTS

Both single and chronic administration of WAY-181187 with haloperidol produced antidepressant- and anxiolytic-like activities. SB-742457 did not provide full benefits in terms of improvement of haloperidol-induced adverse mood effects. However, the administration of SB-742457 with risperidone triggered its anxiolytic-like activity. Both 5-HT₆R ligands evoked no changes in haloperidol-induced effects on BDNF level. WAY-181187 induced repression of the BDNF gene while SB-742457 increased its expression in both structures. 5-HT₆R ligands, when combined with risperidone, did not change BDNF protein level and increased gene expression in the hippocampus, while they elevated BDNF level and potentiated gene expression in the prefrontal cortex.

CONCLUSION

The combined administration of WAY-181187 and haloperidol provided the greatest benefits, which were manifested by antidepressant-like effects and suppression of the anxiogenic-like properties. The combined administration of risperidone with both agonist and antagonist resulted only in an anxiolytic-like effect. It seems that the anxiolytic-like effects induced by haloperidol or risperidone with the addition of 5-HT₆R ligands are task-specific. The data on BDNF protein and gene expression did not fully correspond with the behavioral outcomes, and thus it appears that other factors/mechanisms are involved in the observed antidepressant- and/or anxiolytic-like effects.

Mirtazapine attenuates anxiety- and depression-like behaviors in rats during cocaine withdrawal

BACKGROUND

Anxiety and depression, key symptoms of the cocaine withdrawal syndrome in human addicts, are considered the main factors that precipitate relapse in chronic cocaine addiction. Preclinical studies have found that rodents exposed to different withdrawal periods show an increase in anxiety and depressive-like behavior. Mirtazapine - a tetracyclic medication - is used primarily to treat depression and, sometimes, anxiety. It has also successfully improved withdrawal symptoms in drug-dependent patients.

AIM

This study sought to determine whether chronic dosing of mirtazapine during cocaine withdrawal reduced depression- and anxiety-like behaviors that characterize cocaine withdrawal in animals.

METHODS

Cocaine pre-treated Wistar rats were subjected to a 60-day cocaine withdrawal period during which depression- and anxiety-like behaviors were evaluated in open field tests (OFT), the elevated plus-maze (EPM), the light-dark box test (LDT), the forced swimming test (FST) and spontaneous locomotor activity (SLA).

RESULTS

We found that chronic dosing with different doses of mirtazapine (30 and 60 mg/kg) decreased depression- and anxiety-like behaviors induced by different doses of cocaine (10, 20 and 40 mg/kg) during the 60-day cocaine withdrawal.

INTERPRETATION

Our results suggest that the pharmacological effect of mirtazapine on its target sites of action (α₂-adrenergic and 5-HT_2A and 5-HT₃ receptors) within the brain may improve depression- and anxiety-like behaviors for long periods.

CONCLUSION

Therefore, the findings support the use of mirtazapine as a potentially effective therapy to reduce anxiety and depressive-like behavior during cocaine withdrawal.

Pharmacological interaction between NSAIDS with clomipramine and risperidone in mice visceral pain

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess as primary action mechanism the inhibition of cyclooxygenases (COX-1, COX-2, and COX-3), thus producing a decreasing prostaglandin synthesis. This study was designed to evaluate whether the antinociception induced by NSAIDs could be modulated by clomipramine or risperidone using a chemical model of inflammatory acute visceral pain, the abdominal acetic acid induced a writhing test in mice. Dose-response curves, intraperitoneal, or intrathecal for the antinociceptive activity displayed by ketoprofen, piroxicam, nimesulide, parecoxib, and paracetamol were analyzed in order to obtain the ED₅₀ of each drug. Pretreatment of mice with either clomipramine or risperidone, increased antinociceptive potency of ketoprofen, piroxicam, nimesulide, parecoxib, and paracetamol, expressed by a decrease in the values of antinociceptive ED_50. The results that were obtained are in line with those where the inhibition of COXs provides a justification for most of the pharmacological actions. Nevertheless, several findings suggest other molecular mechanisms, among which may be mentioned, L-selecting shedding; inhibition of i-NOS; inhibition of NF-Kappa B; suppression metaloproteinasas; inhibition of ß2 integrin activation; activation of α₂ -adrenoceptor; increase of IL-1ß; upregulation IL-6. In conclusion, the data generated in this study demonstrated that risperidone and clomipramine, separately, increase antinociceptive potency of NSAIDs in a chemical model of inflammatory acute visceral tonic pain.

Depressive-like effect of prenatal exposure to DDT involves global DNA hypomethylation and impairment of GPER1/ESR1 protein levels but not ESR2 and AHR/ARNT signaling

Several lines of evidence suggest that exposures to Endocrine Disrupting Chemicals (EDCs) such as pesticides increase the risks of neuropsychiatric disorders. Despite extended residual persistence of dichlorodiphenyltrichloroethane (DDT) in the environment, the mechanisms of perinatal actions of DDT that could account for adult-onset of depression are largely unknown. This study demonstrated the isomer-specific induction of depressive-like behavior and impairment of Htr1a/serotonin signaling in one-month-old mice that were prenatally exposed to DDT. The effects were reversed by the antidepressant citalopram as evidenced in the forced swimming (FST) and tail suspension (TST) tests in the male and female mice. Prenatally administered DDT accumulated in mouse brain as determined with gas chromatography and tandem mass spectrometry, led to global DNA hypomethylation, and altered the levels of methylated DNA in specific genes. The induction of depressive-like behavior and impairment of Htr1a/serotonin signaling were accompanied by p,p'-DDT-specific decrease in the levels of estrogen receptors i.e. ESR1 and/or GPER1 depending on sex. In contrast, o,p'-DDT did not induce depressive-like effects and exhibited quite distinct pattern of biochemical alterations that was related to aryl hydrocarbon receptor (AHR), its nuclear translocator ARNT, and ESR2. Exposure to o,p'-DDT increased AHR expression in male and female brains, and reduced expression levels of ARNT and ESR2 in the female brains. The evolution of p,p'-DDT-induced depressive-like behavior was preceded by attenuation of Htr1a and Gper1/GPER1 expression as observed in the 7-day-old mouse pups. Because p,p'-DDT caused sex- and age-independent attenuation of GPER1, we suggest that impairment of GPER1 signaling plays a key role in the propagation of DDT-induced depressive-like symptoms.

Celecoxib and omega-3 fatty acids alone and in combination with risperidone affect the behavior and brain biochemistry in amphetamine-induced model of schizophrenia

The implications of oxidative stress and neuro-inflammation in the pathogenesis of schizophrenia have been elucidated. Despite their effectiveness against positive symptoms of schizophrenia, antipsychotics have limited effectiveness against negative and cognitive symptoms and are associated with remarkable adverse effects. The use of celecoxib or omega-3 in schizophrenia may have beneficial effects. This study aimed to evaluate the possible efficacies of celecoxib, omega-3 or the combination of celecoxib+risperidone and omega-3+ risperidone compared to risperidone on the behavior and brain biochemistry in rats. In the present study, an amphetamine-induced model of schizophrenia in adult male rats was used to evaluate the effects of celecoxib, omega-3, celecoxib+risperidone and omega-3+ risperidone on the behavior of animals and on brain lipid peroxidation or tumor necrosis factor-alpha. In the water maze task, celecoxib, omega-3, celecoxib+risperidone, omega-3+ risperidone significantly decreased the latency time compared to amphetamine-treated group. Celecoxib, omega-3, celecoxib+risperidone, omega-3+risperidone also significantly reversed the decreased spontaneous alternation induced by amphetamine in the Y-maze task. In the social interaction task, groups treated with celecoxib, omega-3, celecoxib+risperidone, omega-3+ risperidone spent less time to recognize foreign animals than animals in the amphetamine-treated group. Increased brain MDA and TNF-α levels due to amphetamine were significantly reduced in groups treated with celecoxib+risperidone or omega-3+ risperidone. The present findings showed that celecoxib or omega-3 can attenuate amphetamine- induced behavioral impairment and these effects may be associated with their ability to decrease lipid peroxidation and cytokine release. Celecoxib or omega-3 may be promising candidates as adjuvant therapy for schizophrenia.

Effect of risperidone on the fluoxetine-induced changes in extracellular dopamine, serotonin and noradrenaline in the rat frontal cortex

BACKGROUND

Several clinical reports have documented a beneficial effect of the addition of a low dose of risperidone to the ongoing treatment with antidepressants, in particular selective serotonin reuptake inhibitors, in the treatment of drug resistant depression. The aim of our study was to understand the mechanism of the clinical efficacy of a combination of fluoxetine (FLU) and risperidone (RIS) in drug-resistant depression. We studied the effect of FLU and RIS, given separately or jointly on the extracellular levels of dopamine (DA), serotonin (5-HT) and noradrenaline (NA) in the rat frontal cortex.

METHODS

Animals were given single intraperitoneal injections of RIS at a doses of 0.1 or 1 mg/kg and FLU at a dose of 10 mg/kg. The release of DA, 5-HT and NA in the rat frontal cortex was investigated using microdialysis in freely moving animals. The extracellular level of DA, 5-HT and NA was assayed by HPLC with coulochemical detection.

RESULTS

RIS (0.1 and 1 mg/kg) and FLU (10 mg/kg) increased the extracellular level of cortical DA, 5-HT and NA. Co-treatment of both drugs was more effective in increasing DA release than administration of each of the drugs alone at doses of RIS 1 mg/kg and FLU 10 mg/kg. Co-treatment of FLU and RIS 0.1 mg/kg was more potent than FLU alone, while the effect of joint injection of FLU and RIS 1 mg/kg was stronger than RIS 1 mg/kg alone on 5-HT release. The combination of FLU with both doses of RIS was not effective in increasing NA release as compared to drugs given alone.

CONCLUSIONS

Our data indicate that the effect of the combined administration of RIS and FLU on DA and 5-HT release in the rat frontal cortex may be of crucial importance to the pharmacotherapy of drug resistant depression.

The role of alpha-1 and alpha-2 adrenoceptors in restraint stress-induced liver injury in mice

Acute stress affects cellular integrity in many tissues including the liver, but its underlying mechanism is still unclear. The aim of the present study was to investigate the potential involvement of catecholamines and adrenoceptors in the regulation of acute restraint stress-induced liver injury. Restraint was achieved by placing mice in restraint tubes. Mice were treated with either an α-l antagonist, prazosin, an α-2 antagonist, yohimbine, a β-l antagonist, betaxolol, a β-2 antagonist, ICI 118551, or a central and peripheral catecholamine depleting agent, reserpine, and followed by restraint stress. Assessment of liver injury (serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) , hepatic total GSH, GSSG and GSH/GSSG ratio) , histopathology and of apoptosis, by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay and western blotting, was performed. Three hours of restraint stress resulted in liver injury, as indexed by elevated serum transaminase levels, decreased hepatic total GSH levels and GSH/GSSG ratio, increased hepatic GSSG levels as well as enhanced hepatocytes apoptosis. Either reserpine or prazosin or yohimbine was found to attenuate liver injury. Furthermore, prazosin and yohimbine protected against restraint-induced hepatocytes apoptosis through attenuating the activation of caspases-9 and -3 and reducing the Bax/Bcl-2 ratio. These results suggest that α-1 and α-2 adrenoceptors mediate restraint-induced liver oxidative injury through caspase-9 and Bcl-2 family of apoptotic regulatory proteins.

Effects of co-administration of fluoxetine and risperidone on properties of peritoneal and pleural macrophages in rats subjected to the forced swimming test

BACKGROUND

Literature data show that administration of atypical antipsychotic drug, risperidone (RIS), enhances antidepressive action of fluoxetine (FLU). As antidepressive treatments also regulate immune functions, we examined whether combined administration of FLU and RIS to rats subsequently subjected to a forced swimming test (FST) modifies parameters of macrophage activity that are directly related to their immunomodulatory functions, i.e., arginase (ARG) activity and nitric oxide (NO) synthesis.

METHODS

Antidepressive action of the drugs was assessed with FST. Peritoneal and pleural cells were eluted and selected parameters of immunoreactivity were assessed colorimetrically.

RESULTS

We found that the concomitant administration of FLU (10 mg/kg) and RIS (0.1 mg/kg) produced antidepressive-like effects in the FST,whereas the drugs were ineffective if administered separately. Stress related to the FST affected immune cell redistribution and changed some of the metabolic and immunomodulatory properties of macrophages. FLU administered to rats at a suboptimal dose for antidepressive action potently influenced macrophage immunomodulatory properties and redirected their activity toward anti-inflammatory M2 functional phenotype, as manifested by changes in the ARG/NO ratio. These effects resulted from a direct cellular influence of the drug, as well as its action via neuroendocrine pathways, as evidenced in peritoneal and pleural cells. Addition of RIS did not augment immunomodulatory action of FLU, though the combination showed antidepressant-like activity in the FST.

CONCLUSIONS

Our results suggest that when the drugs were administered together, FLU was potent enough to redirect macrophages toward M2 activity. It is also postulated that drug-induced changes in the immune system are not so closely related to antidepressant-like effects or might be secondary to those produced in the neuroendocrine system.

Intracellular pathways of antipsychotic combined therapies: implication for psychiatric disorders treatment

Dysfunctions in the interplay among multiple neurotransmitter systems have been implicated in the wide range of behavioral, emotional and cognitive symptoms displayed by major psychiatric disorders, such as schizophrenia, bipolar disorder or major depression. The complex clinical presentation of these pathologies often needs the use of multiple pharmacological treatments, in particular (1) when monotherapy provides insufficient improvement of the core symptoms; (2) when there are concurrent additional symptoms requiring more than one class of medication and (3) in order to improve tolerability, by using two compounds below their individual dose thresholds to limit side effects. To date, the choice of drug combinations is based on empirical paradigm guided by clinical response. Nonetheless, several preclinical studies have demonstrated that drugs commonly used to treat psychiatric disorders may impact common intracellular target molecules (e.g. Akt/GSK-3 pathway, MAP kinases pathway, postsynaptic density proteins). These findings support the hypothesis that convergence at crucial steps of transductional pathways could be responsible for synergistic effects obtained in clinical practice by the co-administration of those apparently heterogeneous pharmacological compounds. Here we review the most recent evidence on the molecular crossroads in antipsychotic combined therapies with antidepressants, mood stabilizers, and benzodiazepines, as well as with antipsychotics. We first discuss clinical clues and efficacy of such combinations. Then we focus on the pharmacodynamics and on the intracellular pathways underpinning the synergistic, or concurrent, effects of each therapeutic add-on strategy, as well as we also critically appraise how pharmacological research may provide new insights on the putative molecular mechanisms underlying major psychiatric disorders.

The administration of olanzapine and fluoxetine has synergistic effects on intracellular survival pathways in the rat brain

Recently, several studies have emerged suggesting a role of the intracellular survival pathways in the treatment of mood disorders. In addition, the beneficial effects of using a combination of antipsychotics and antidepressants have been shown. With this in mind, we evaluated the effects of the acute administration of fluoxetine (FLX), olanzapine (OLZ) and the combination of fluoxetine/olanzapine on the brain-derived-neurotrophic factor (BDNF), cAMP response element-binding (CREB), Protein Kinase B (PKB, Akt), B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated death promoter (BAD) in the rat brain. Adult Wistar rats received an acute injection of OLZ (3 or 6 mg/kg) and/or FLX (12.5 or 25 mg/kg), and were evaluated for Akt, BDNF, CREB, Bcl-2 and BAD protein levels in the prefrontal cortex, hippocampus and striatum. Our results showed that treatment with FLX and OLZ alone or in combination increased the Akt, CREB, BDNF, Bcl-2 and BAD levels in the prefrontal cortex, hippocampus and striatum. However, the combination of FLX and OLZ at high doses was associated with a greater increase in the levels of Akt in the prefrontal cortex, and did not have an effect on the levels of BAD in any of the brain areas that we evaluated. Finally, these findings further support the hypothesis that treatment with FLX and OLZ alone or in combination exert neuroprotective effects, and that intracellular survival pathways could be involved in the therapeutic effects of combining antipsychotic and antidepressant drugs in mood disorders.

Antidepressants differentially modify the extinction of an aversive memory task in female rats

Treatment of major depression, posttraumatic stress disorder and other psychopathologies with antidepressants can be associated with improvement of the cognitive deficits related to these disorders. Although the mechanisms of these effects are not completely elucidated, alterations in the extinction of aversive memories are believed to play a role in these psychopathologies. We have recently verified that female rats present low levels of extinction when submitted to the plus-maze discriminative avoidance task. In the present study, female rats were treated long term with clinically used antidepressants (fluoxetine, nortriptyline or mirtazapine) and subjected to the plus-maze discriminative avoidance task to evaluate learning, memory, extinction and anxiety-related behaviors as well as behavioral despair in the forced swimming test. All groups learned the task and exhibited retrieval. Chronic treatment with fluoxetine (but not with the other antidepressants tested) increased extinction of the discriminative task. In the forced swimming test, the animals treated with fluoxetine and mirtazapine showed decreased immobility duration. In conclusion, fluoxetine potentiated extinction, while both fluoxetine and mirtazapine were effective in ameliorating depressive-like behavior in the forced swimming test, suggesting a possible dissociation between the effects on mood and the extinction of aversive memories in female rats.