Submissive behavior in mice as a test for antidepressant drug activity

Previously, with the administration of antidepressant drugs, it has been demonstrated that the rat model of clinical depression, known as the reduction of submissive behavior model (RSBM), has considerable validity. The present study is an attempt to extend the model to mice. Several antidepressant drugs as well as a number of non-antidepressant agents were administered to mice that had been identified as submissive in a behavioral testing situation. Imipramine, desipramine, amoxapine and fluoxetine, representing three different classes of antidepressant drugs, were each able to increase competitive behavior in submissive mice and to decrease the dominance level between dominant and submissive mice in the behavioral tests. The stimulant amphetamine also reduced submissive behavior while yohimbine (also a stimulant), and the antianxiety agent diazepam had no such effect. The neuroleptic drug thiothixen had antidepressant-like effect on submissive C57BL/6J mice behavior. We conclude that like the rat model of depression from which it was developed, the mouse model responds to various antidepressants as predicted and thus may serve as a potential model of clinical depression.

Effects of antipsychotic treatment on polysomnographic measures in schizophrenia: a replication and extension

OBJECTIVE

The authors sought to replicate and extend previous observations of improvement in some EEG sleep measures during the course of antipsychotic treatment in schizophrenia patients.

METHOD

Fourteen medication-free patients with schizophrenia underwent 2 nights of sleep EEG monitoring before and after 3-4 weeks of treatment with clinically determined doses of haloperidol or thiothixene.

RESULTS

Measures of sleep continuity improved consistently. REM latency increased, although five of 14 patients continued to exhibit short REM latencies (less than 60 minutes). Stage 3 sleep increased during neuroleptic treatment, while stage 4 sleep did not change.

CONCLUSIONS

These data demonstrate partial improvement of some but not all EEG sleep measures in schizophrenic patients through the course of neuroleptic treatment. They suggest that shortened REM latency and disturbed sleep continuity might represent reversible state abnormalities, while reduced slow-wave sleep may represent a more persistent trait abnormality in schizophrenia.

Suppression of natural killer cell activity in mouse spleen lymphocytes by several dopamine receptor antagonists

The effects of dopaminergic receptor inhibitors such as thiothixine (D1/D2), fluphenazine (D1/D2), trifluoperazine (D1/D2), pimozide (D2), flupenthixol (D1/D2), (+/-)-SKF 83566 (D1), and spiperone (D2) on splenic natural killer (NK) cell cytotoxic activities were assessed in vitro using mouse spleen lymphocytes or enriched NK cells. Both the activities of the splenic NK cell cytotoxicity and the effector-target cell conjugation were suppressed by thiothixine, fluphenazine, and trifluoperazine at concentrations from 2.64 to 14.78 microM. In addition, the augmentation of the cytolytic activity of NK cells induced by interferon-alpha or interleukin-2 was antagonized by pretreatment with these neuroleptic compounds. However, neither the splenic NK cell cytotoxicity nor the effector-target cell conjugation were affected by treatment with other neuroleptic compounds such as pimozide, flupenthixol, (+/-)-SKF 83566, and spiperone. Thus, it appears that neuroleptic compounds such as thiothixine, fluphenazine, and trifluoperazine may act through the mechanisms other than a dopaminergic pathway to affect the NK cell-target cell interaction.

Neuroleptic medications inhibit complex I of the electron transport chain

Neuroleptic medications are prescribed to millions of patients, but their use is limited by potentially irreversible extrapyramidal side effects. Haloperidol shows striking structural similarities to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which produces parkinsonism apparently through inhibition of NADH:ubiquinone oxidoreductase (complex I) of the mitochondrial electron transport chain. We now report that haloperidol, chlorpromazine, and thiothixene inhibit complex I in vitro in rat brain mitochondria. Clozapine, an atypical antipsychotic reported to have little or no extrapyramidal toxicity, also inhibits complex I, but at a significantly higher concentration. Neuroleptic treated patients have significant depression of platelet complex I activity similar to that seen in idiopathic Parkinson's disease. Complex I inhibition may be associated with the extrapyramidal side effects of these drugs.

Biphasic dose-dependent effects of dopamine and involvement of dopamine autoreceptors on intra-ocular pressure in the rabbit

1. This work was conducted to provide new data concerning the possible dose-dependent activity of dopamine (DA) after ocular instillation. Experiments were done in rabbits with normal intraocular pressure (IOP), or after transitory induced ocular hypertension in water-loaded animals. 2. In ocular normotensive animals, a biphasic dose-dependent activity is observed, with no significant effect for 0.001% and 0.003% DA, a decrease in IOP after 0.005% and 0.01% DA instillation, then an important increase in IOP at concentrations from 0.05% onwards. 3. During transitory ocular hypertension, this phenomenon was confirmed, with a marked ocular hypotensive activity for 0.01% DA, no effect after 0.005% DA, then an important ocular hypertension with 0.05% and 0.5% DA as compared to the control group (0.9% NaCl). 4. An immediate and similar ocular hypertensive effect with DA could be reproduced by a subsequent instillation at high concentration (1%), while the hypotensive activity induced at low concentration (0.01%) is followed by a long-lasting refractory period (about 18 h). 5. Such a dose-dependent biphasic effect was also observed with N-methyl-dopamine (NMDA) after ocular instillation. The effects of instilled dopaminergic compounds were tested and ocular hypotensive activities of the S(-)enantiomer of the DA analogues 3-(3-hydroxyphenyl)-N-propylpiperidine (3-PPP), and of thiothixene (TIX) were also demonstrated. 6. The possible relationships to DA1 and DA2 receptors of the dual effect is discussed.

Investigation of striatal dopamine D2 receptor acquisition following prenatal neuroleptic exposure

To test the hypothesis that neuroleptic blockade impairs the development of striatal dopamine D2 receptors, pregnant rats were given haloperidol, thiothixene, or trifluoperazine for gestational days 15-18 (short-term exposure) or days 5-20 (long-term exposure). All of the drugs were demonstrated to cross the placenta and enter the fetal brains equally well. Striatal dopamine D2 receptors of the pups were assayed on postnatal day 14. Neither receptor density nor receptor affinity was altered significantly by the short- or long-term prenatal neuroleptic treatment.

Effects of antidepressants on histamine H2 receptors in rat isolated uterus

The antagonist effect of various antidepressants, both tricyclic and non-tricyclic, and of thiothixene on the histamine H2 receptors has been studied in the rat isolated uterus. All the drugs studied inhibit the effect of histamine, acting as competitive antagonists. Trimipramine and mianserin were the antidepressants which showed the highest activity, superior to cimetidine, whereas nomifensine, viloxazine, trazodone and maprotiline were those which showed the lowest antihistamine H2 activity. These results suggest that there is an interaction between antidepressants and histamine H2 receptors in rat isolated uterus similar to the interaction existing between antidepressants and histamine H2 receptors in brain and other tissues.

Drug interactions on spontaneous locomotor activity in rats. Neuroleptics and amphetamine-induced hyperactivity

The locomotor activity of female rats was recorded during 10-min sessions in a circular open-field apparatus after the administration of vehicle or drug. Dose-response curves were obtained for seven neuroleptic drugs both alone (spontaneous activity) and in combination with 1.0 mg/kg of d-amphetamine. Haloperidol, pimozide, loxapine, thiothixene, molindone and chlorpromazine all produced graded decreases in spontaneous locomotor activity. Haloperidol, pimozide, loxapine, thiothixene and molindone also produced graded reversals of the hyperactivity produced by d-amphetamine, while chlorpromazine did not. Clozapine neither altered spontaneous activity nor reversed the hyperactivity produced by d-amphetamine. The data indicate that measures of locomotor activity provide important additional information about the actions of neuroleptics and do not necessarily mirror the actions of these drugs on other measures of performance such as lever-pressing for brain stimulation.

Comparison of the effects of antipsychotic drugs on the schedule-controlled behavior of squirrel monkeys and pigeons

Lever pressing by squirrel monkeys and key pecking by pigeons were maintained under a multiple 3-min fixed-interval (FI), 30-response fixed-ratio (FR) schedule by the presentation of food. These responses, which differed under the two schedules, but were similar for both species, were used to compare the effects of antipsychotic compounds from different pharmacological classes. Except for differences in potency levels, the effects of intermediate doses of haloperidol and molindone were similar in monkeys and pigeons; these compounds decreased responding under the fixed-interval schedule at doses that did not affect fixed-ratio responding. Similar effects also occurred with chlorpromazine, promazine and thiothixene in pigeons. With monkeys, however, intermediate doses of promazine decreased fixed-ratio responding more than responding maintained under the fixed-interval schedule, while chlorpromazine and thiothixene produced similar effects on responding under both schedules. The effects of novel antipsychotic, clozapine, differed from those of the other agents in both monkeys and pigeons. With both species clozapine increased fixed interval responding at doses that did not affect responding under the fixed-ratio schedule. Doses required to reduce responding at least 50% were approximately 5 to 160 times greater for pigeons than for monkeys for all drugs except clozapine which was equipotent in both species. In monkeys the order of potency was haloperidol greater than molindone = thiothixene greater than chlorpromazine greater than clozapine greater than promazine, whereas in pigeons the order was haloperidol greater than thiothixene greater than clozapine greater than molindone greater than promazine greater than chlorpromazine.

Subjective response to antipsychotic drugs

Sixty-three newly admitted schizophrenic patients were given a test dose of thiothixene and their subjective response was recorded by a technician blind to clinical ratings. All patients were then treated wih thiothixene in an active milieu setting. Patients varied widely in their subjective responses. An initial dysphoric response was a powerful predictor of both immediate and eventual drug refusal. Before treatment, dysphoric responders tended to be less symptomatic and did significantly better on the Continuous Performance Test. Dysphoric responders experienced significantly more extrapyramidal symptoms following the test dose. Some dysphoric responders did have a good outcome when treated with very low doses. We recommend that patients with a history of dysphoric response be given a very low dose initially.

The effect of antipsychotic drugs on body weight: a retrospective review

Weight gain in schizophrenic patients during chemotherapy was first reported with chlorpromazine. Since then other antipsychotic drugs have exhibited this effect, while some have reduced weight. A retrospective review of 78 schizophrenic patients revealed that thiothixene, fluphenazine, haloperidol, and thioridazine produced a mean weight gain and loxapine a mean weight loss after 12 and 36 weeks of treatment. The ability of an effective antipsychotic drug, such as loxapine, to prevent weight gain or to produce weight loss offers a clinical advantage in the treatment of those schizophrenic patients where weight gain should be a problem.

Effect of melperone, two of its metabolites and thiothixene on central monoamine metabolism and prolactin levels in rodents

The effects of melperone and thiothixene on the concentrations of monoamine metabolites in brain and prolactin in the serum of rats and mice were determined. Both drugs increased brain concentrations of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in a dose-dependent manner. 5-Hydroxyindoleacetic acid (5-HIAA) was unaffected. The effect of thiothixene was longer lasting and about 5 times greater than that of melperone. Melperone, but not thiothixene, increased levels of 3-methoxy-4-hydroxyphenylethylene glycol (MOPEG). Several hours after administration of melperone, levels of HVA and MOPEG were diminished. Both drugs increased prolactin concentrations in rat serum. Thiothixene was about 10 times more potent than melperone. Of two urinary metabolites of melperone investigated, one caused the same qualitative effects on monoamine metabolism as melperone itself but with reduced potency. The other metabolite was ineffective.

Changes in psychopathology in relation to EEG variables and visual averaged evoked responses (V.AER) in schizophrenic patients treated with penfluridol or thiothixene

In a study of 28 schizophrenic in-patients treated with penfluridol or thiothixene, patients were followed with clinical ratings, EEG variables, the mean integrated amplitude (MIA) on both the left and right sides--both with filters with frequency ranges from 7.5 to 13.5 and 0.5 to 25 Hz--as well as its within-patient variance (WPV) on both sides and with both filters, and also with visual averaged evoked responses (V.AER). Moreover, determinations of plasma levels of the drugs were conducted in a search for possible objective measurements of the effects of the treatment, but also to try to find measurements that would make it possible to predict the outcome of treatment. MIA left/right and WPV left/right were found to be the most promising variables to follow the effect of treatment, which were correlated to factors 1 and 2 of the Mårten's S-scale. WPV left/right before treatment was correlated to changes in factor 4 of the S-scale during the trial.

Effect of psychotropic agents upon the blastogenic response of human t-lymphocytes

Antischizophrenic agents, phenothiazine and nonphenothiazine, inhibit the transformation of the T-lymphocyte in vitro. This inhibition occurs only in the early event and is neither competitive with dopamine, nor appears to involve Na+/K+ adenosine triphosphatase. RNA synthesis is more sensitive to the inhibitory effect than DNA or protein synthesis. This leads to the conclusion that chlorpromazine may act by inhibiting the synthesis of newly formed RNA, and subsequently, transformation, rather than by alteration of the cell membrane.

Action of the antipsychotic drugs thiotixene and thioridazine on isolated mitochondria

Thiotixene and thioridazine antipsychotic drugs produce a stimulation of mitochondrial respiration in state 3 and state 4 resulting in a complete respiratory control loss, only accompanied by slight alterations of oxidative phosphorylation. This effect may be of biological significance in the action mechanism of the drugs.

Hemodynamic effects of thiothixene and chlorpromazine in schizophrenic patients at rest and during exercise

The hemodynamic effects and plasma levels of noradrenaline were studied in schizophrenic patients at rest and during exercise after long-term treatment with chlorpromazine (150-600 mg daily) and thiothixene (60-80 mg daily). The results are compared with those from previous studies in untreated patients and patients receiving very large doses of chlorpromazine. The effects of thiothixene on the different hemodynamic variables were very moderate, and the observed differences between this group and the control group may be due to the different patient materials. In the two groups of patients receiving chlorpromazine, the heart rate at rest and durng exercise tended to be higher than in the control group. There was also a tendency towards a lower stroke volume after this drug and thiothixene during exercise. The noradrenaline levels in plasma were highest after the high dose of chlorpromazine both at rest and during exercise, while they were lower after the moderate chlorpromazine dose. After thiothixene, the values were between those of the group on the low chlorpromazine dose and those of the control group.

Blood platelet monoamine oxidase activity in anergic schizophrenics

Blood platelet monoamine oxidase (MAO) activity was evaluated in twenty-four anergic, schizophrenic outpatients during a double-blind study comparing a chlorpromazine-imipramine combination to thio-thixeneplacebo. Platelet MAO activity was determined on blood samples drawn after a two-week drug-free washout and once weekly over a four-week on-drug period. Schizophrenic patients could be classified according to their blood platelet MAO activity into either a low-MAO or a high-MAO group. In neither group of this population of schizophrenics did blood platelet MAO activity correlate with any of the primary or secondary symptoms of schizophrenia. Ten alcoholics and seven volunteer non-patients could similarly be divided into low- and high-MAO groups. Mean blood platelet MAO activity for these groups was not significantly different from the mean values of the low and high-MAO groups of the schizophrenics. These findings do not support published reports of low blood platelet activity as a genetic marker for schizophrenia. Discriminate function analysis of symptomatology ratings at baseline was used to characterize the low- and high-MAO schizophrenic patient groups. Individuals in the low-MAO group were distinguished by hyperactivity, anergia and sleep disturbance.

Some clinical and physiologic effects of a thioxanthene derivative, thiothixene (P-4657B), in 20 newly hospitalized male schizophrenics

This study was designed to evaluate some of the effects of a new thioxanthene, thiothixene (P-4657B), in 20 male schizophrenic patients recently admitted to Bellevue Hospital. The results of a dosage range trial indicated that at a dosage of approximately 50 mg per day, toxic and side effects as well as therapeutic effects were at their maximum. Parkinsonian reactions (in 17 of 20 patients) with restlessness and akathisia were the most prominent of these effects. Also, activation of psychopathology was observed in six of 20 subjects. Thiothixine did exhibit some antipsychotic activity, but it does not appear to be as valuable as it has been reported to be in chronic schizophrenic patients.