Is Forced Swimming Immobility a Good Endpoint for Modeling Negative Symptoms of Schizophrenia? - Study of Sub-Anesthetic Ketamine Repeated Administration Effects

ABSTRACT Immobility time in the forced swimming has been described as analogous to emotional blunting or apathy and has been used for characterizing schizophrenia animal models. Several clinical studies support the use of NMDA receptor antagonists to model schizophrenia in rodents. Some works describe the effects of ketamine on immobility behavior but there is variability in the experimental design used leading to controversial results. In this study, we evaluated the effects of repeated administration of ketamine sub-anesthetic doses in forced swimming, locomotion in response to novelty and novel object recognition, aiming a broader evaluation of the usefulness of this experimental approach for modeling schizophrenia in mice. Ketamine (30 mg/kg/day i.p. for 14 days) induced a not persistent decrease in immobility time, detected 24h but not 72h after treatment. This same administration protocol induced a deficit in novel object recognition. No change was observed in mice locomotion. Our results confirm that repeated administration of sub-anesthetic doses of ketamine is useful in modeling schizophrenia-related behavioral changes in mice. However, the immobility time during forced swimming does not seem to be a good endpoint to evaluate the modeling of negative symptoms in NMDAR antagonist animal models of schizophrenia.

Is Forced Swimming Immobility a Good Endpoint for Modeling Negative Symptoms of Schizophrenia? - Study of Sub-Anesthetic Ketamine Repeated Administration Effects.

Immobility time in the forced swimming has been described as analogous to emotional blunting or apathy and has been used for characterizing schizophrenia animal models. Several clinical studies support the use of NMDA receptor antagonists to model schizophrenia in rodents. Some works describe the effects of ketamine on immobility behavior but there is variability in the experimental design used leading to controversial results. In this study, we evaluated the effects of repeated administration of ketamine sub-anesthetic doses in forced swimming, locomotion in response to novelty and novel object recognition, aiming a broader evaluation of the usefulness of this experimental approach for modeling schizophrenia in mice. Ketamine (30 mg/kg/day i.p. for 14 days) induced a not persistent decrease in immobility time, detected 24h but not 72h after treatment. This same administration protocol induced a deficit in novel object recognition. No change was observed in mice locomotion. Our results confirm that repeated administration of sub-anesthetic doses of ketamine is useful in modeling schizophrenia-related behavioral changes in mice. However, the immobility time during forced swimming does not seem to be a good endpoint to evaluate the modeling of negative symptoms in NMDAR antagonist animal models of schizophrenia.

Uliginosin B, a natural phloroglucinol derivative with antidepressant-like activity, increases Na+,K+-ATPase activity in mice cerebral cortex

ABSTRACT Uliginosin B, a phloroglucinol isolated from Hypericum polyanthemum Klotzsch ex Reichardt, Hypericaceae, has antidepressant-like effect in the forced swimming test in rodents and inhibits monoamines neuronal reuptake without binding to their neuronal carriers. Studies showed the involvement of Na+,K+-ATPase brain activity in depressive disorders, as well as the dependence of neuronal monoamine transport from Na+ gradient generated by Na+,K+-ATPase. This study aimed at evaluating the effect of uliginosin B on Na+,K+-ATPase activity in mice cerebral cortex and hippocampus (1 and 3 h after the last administration) as well as the influence of veratrine, a Na+ channel opener, on the antidepressant-like effect of uliginosin B. Mice were treated (p.o.) with uliginosin B single (10 mg/kg) or repeated doses (10 mg/kg/day, 3 days). Acute administration reduced the immobility in the forced swimming test and tail suspension test and increased Na+,K+-ATPase activity in cerebral cortex 1 h after treating, whereas the repeated treatment induced the antidepressant-like effect and increased the Na+,K+-ATPase activity at both times evaluated. None treatment affected the hippocampus enzyme activity. Veratrine pretreatment prevented uliginosin B antidepressant-like effect in the forced swimming test, suggesting the involvement of Na+ balance regulation on this effect. Altogether, these data indicate that uliginosin B reduces the monoamine uptake by altering Na+ gradient.

LASSBio-579, a prototype antipsychotic drug, and clozapine are effective in novel object recognition task, a recognition memory model.

Previous studies on the N-phenylpiperazine derivative LASSBio-579 have suggested that LASSBio-579 has an atypical antipsychotic profile. It binds to D2, D4 and 5-HT1A receptors and is effective in animal models of schizophrenia symptoms (prepulse inhibition disruption, apomorphine-induced climbing and amphetamine-induced stereotypy). In the current study, we evaluated the effect of LASSBio-579, clozapine (atypical antipsychotic) and haloperidol (typical antipsychotic) in the novel object recognition task, a recognition memory model with translational value. Haloperidol (0.01 mg/kg, orally) impaired the ability of the animals (CF1 mice) to recognize the novel object on short-term and long-term memory tasks, whereas LASSBio-579 (5 mg/kg, orally) and clozapine (1 mg/kg, orally) did not. In another set of experiments, animals previously treated with ketamine (10 mg/kg, intraperitoneally) or vehicle (saline 1 ml/100 g, intraperitoneally) received LASSBio-579, clozapine or haloperidol at different time-points: 1 h before training (encoding/consolidation); immediately after training (consolidation); or 1 h before long-term memory testing (retrieval). LASSBio-579 and clozapine protected against the long-term memory impairment induced by ketamine when administered at the stages of encoding, consolidation and retrieval of memory. These findings point to the potential of LASSBio-579 for treating cognitive symptoms of schizophrenia and other disorders.

Synergistic interaction between diene valepotriates from Valeriana glechomifolia†Meyer (Valerianaceae) and classical antidepressants: an isobolographic analysis.

OBJECTIVES: Combinations of different classes of antidepressants (including herbal adjuvants) have been used as an alternative means of achieving better results in the treatment of depressed patients. However, studies characterizing the interactions between herbal adjuvants and antidepressants are lacking. This study is the first to investigate the interaction between diene valepotriates (VAL) from Valeriana glechomifolia, a species with antidepressant-like effects, and imipramine (IMI), desipramine (DESI) and bupropion (BUP). The interactions were assessed via isobolographic analyses, which represent a tool for evaluating interactions between drugs. METHODS: The interaction between VAL and each antidepressant was evaluated in mice given concurrent oral administration of each drug with fixed ED50 ratios and subjected to a forced swimming test (FST). Spontaneous locomotion was measured in the open field test. KEY FINDINGS: The drug combinations produced a dose-dependent anti-immobility effect in the FST without altering mouse locomotor activity. Isobolographic analysis revealed that VAL resulted in synergistic interactions in combination with each of the antidepressants tested. CONCLUSION: The synergistic interactions between VAL and IMI, DESI and BUP highlight the potential for VAL to serve as adjuvants to antidepressant drugs and suggest that VAL does not directly target the same sites on neuronal transporters as the antidepressants.

Biotransformation of LASSBio-579 and pharmacological evaluation of p-hydroxylated metabolite a N-phenylpiperazine antipsychotic lead compound.

Using a combination of docking and molecular dynamics simulations, we predicted that p-hydroxylation by CYP1A2 would be the main metabolic pathway for the 1-[1-(4-chlorophenyl)-1H-4pyrazolylmethyl] phenylhexahydropiperazine, LASSBio-579 (3). As the result of a screening process with strains of filamentous fungi, Cunninghamella echinulata ATCC 9244 was chosen to scale up the preparation of the p-hydroxylated metabolite (4). About 30 min after i.p. administration of (3) to rats was identified as the p-hydroxylated metabolite, confirming our in silico previsions. Chemical synthesis of the metabolite was performed and allowed its pharmacological evaluation in binding assays revealing its high affinity for D2 and D4 receptors, indicating that this metabolite should participate to the antipsychotic effect of (3) in vivo. Furthermore, we report here that both (3) and its p-hydroxylated metabolite (4) have a much lower affinity than clozapine for two receptors involved in adverse reactions. Voltammetric assays were useful to understand the redox profile of (3).

New insights into pharmacological profile of LASSBio-579, a multi-target N-phenylpiperazine derivative active on animal models of schizophrenia.

Previous behavioral and receptor binding studies on N-phenylpiperazine derivatives by our group indicated that LASSBio-579, LASSBio-580 and LASSBio-581 could be potential antipsychotic lead compounds. The present study identified LASSBio-579 as the most promising among the three compounds, since it was the only one that inhibited apomorphine-induced climbing (5 mg/kg p.o.) and apomorphine-induced hypothermia (15 mg/kg p.o.). Furthermore, LASSBio-579 (0.5 mg/kg p.o.) was effective in the ketamine-induced hyperlocomotion test and prevented the prepulse inhibition deficits induced by apomorphine, DOI and ketamine with different potencies (1 mg/kg, 0.5 mg/kg and 5 mg/kg p.o., respectively). LASSBio-579 also induced a motor impairment, catalepsy and a mild sedative effect but only at doses 3-120 times higher than those with antipsychotic-like effects. In addition, LASSBio-579 (0.5 and 1 mg/kg p.o.) reversed the catalepsy induced by WAY 100,635, corroborating its action on both dopaminergic and serotonergic neurotransmission and pointing to the contribution of 5-HT(1A) receptor activation to its pharmacological profile. Moreover, co-administration of sub-effective doses of LASSBio-579 with sub-effective doses of clozapine or haloperidol prevented the apomorphine-induced climbing without induction of catalepsy. In summary, our results characterize LASSBio-579 as a multi-target ligand active in pharmacological animal models of schizophrenia, confirming that this compound could be included in development programs aiming at a new drug for treating schizophrenia.

Antidepressant-like effect of Valeriana glechomifolia Meyer (Valerianaceae) in mice.

The antidepressant-like effect of a supercritical CO2 (SCCO2) Valeriana glechomifolia extract enriched in valepotriates was investigated in a mice tail suspension test (TST) and forced swimming test (FST). The SCCO2 extract decreased mice immobility in the FST (0.5-20 mg/kg p.o.) and elicited a biphasic dose-response relationship in the TST (1-20 mg/kg p.o.) with no alterations in locomotor activity and motor coordination (assessed in the open-field and rota-rod tests, respectively). The anti-immobility effect of the SCCO2 extract (5 mg/kg, p.o.) was prevented by mice pre-treatment with yohimbine (1 mg/kg, i.p., an α2 adrenoceptor antagonist), SCH 23390 (15 µg/kg, s.c., D1 dopamine receptor antagonist) and sulpiride (50 mg/kg, i.p., D2 dopamine receptor antagonist). However, mice pre-treatments with prazosin (1 mg/kg, i.p., α1 adrenoceptor antagonist) and p-chlorophenilalanine methyl ester (4×100 mg/kg/day, i.p., a serotonin synthesis inhibitor) were not able to block the anti-immobility effect of the SCCO2 extract. Administration (p.o.) of the SCCO2 extract (0.25 mg/kg) and imipramine (10 mg/kg), desipramine (5 mg/kg) and bupropion (3 mg/kg) at sub-effective doses significantly reduced mice immobility time in the FST. These data provide the first evidence of the antidepressant-like activity of V. glechomifolia valepotriates, which is due to an interaction with dopaminergic and noradrenergic neurotransmission.

Toxicity and genotoxicity evaluation of Passiflora alata Curtis (Passifloraceae).

UNLABELLED: Passiflora alata is an official species of Brazilian Pharmacopoeia and its aerial parts are used as medicinal plant by local population as well as constitutes many phytomedicines commercialized in Brazil as sedative. AIMS OF STUDY: To evaluate the acute and sub-acute toxicity and genotoxicity of an aqueous spray-dried extract (PA) of Passiflora alata (2.6% flavonoids). MATERIALS AND METHODS: The acute and the sub-acute toxicity was evaluated in mice and rats, respectively. Behavioural, biochemical, hematological, histological and urine parameters were considered. Genotoxicity was assessed by using micronucleus test performed in peripheral blood and bone marrow cells and comet assay in peripheral blood leukocytes. RESULTS: Mice deaths were not observed up to 4800 mg/kg, p.o., single dose. Rats treated with aqueous extract at dose of 300 mg/kg, p.o., for 14 days did not present biochemical, hematological or histopathological significant alterations when compared to control group. However, these rats showed signs of irritability and did not show weight gain. In addition, mice acutely treated with extract 150, 300 and 600 mg/kg, p.o., presented DNA damage determined by comet assay in peripheral blood cells 3h after treatment. The effect of lower doses (12.5, 25 and 50mg/kg, p.o.) was evaluated at 3, 6 and 24h after treating. Only PA 50mg/kg (p.o.) induced significant damage at 3 and 6h. The maximum damage induction was observed at 6h. When the animals received PA 12.5, 25 or 50mg/kg/day during 3 days (i.e., 72h treatment) DNA damage (comet and micronucleus tests) increased significantly in a dose-dependent manner. CONCLUSION: In conclusion Passiflora alata presented genotoxic effect and deserves further toxicity evaluation in order to guarantee its safety for human use.

Serotonergic neurotransmission mediates hypothermia induced by the N-phenylpiperazine antipsychotic prototypes LASSBio-579 and LASSBio-581.

Previous studies have demonstrated that LASSBio-579 and LASSBio-581, two N-phenylpiperazine derivatives designed for the treatment of schizophrenia, are presynaptic dopamine D(2) receptor agonists that induce a hypothermic effect in mice that is not mediated by dopamine receptor activation. The aim of the present study was to investigate possible serotonergic mechanisms underlying hypothermia induced by LASSBio-579 and LASSBio-581 in CF1 mice. The reduction in core temperature was dose-dependent (15-60 mg/kg, i.p.) and occurred by the oral route (30 mg/kg). Pretreatment with haloperidol (4 mg/kg, i.p.) resulted in a synergistic hypothermic effect. Pretreatment with (+/-)DOI (0.25 mg/kg, i.p.), a serotonin 5-HT(2A/C) receptor agonist, reduced the hypothermic effect induced by LASSBio-579 and LASSBio-581 at 15 and 30 mg/kg, i.p. In contrast, (+/-)DOI enhanced the hypothermia induced by both compounds at 60 mg/kg, i.p. The serotonin 5-HT1A antagonist WAY 100635 (0.05 mg/kg, s.c.) abolished the hypothermia induced by LASSBio-579 and diminished the hypothermia induced by LASSBio-581. Pretreatment with LASSBio579 (30 and 60 mg/kg, i.p.) and LASSBio-581 (60 mg/kg, i.p.) reduced the number of head-twitches induced by (+/-)DOI (2.5 mg/kg, i.p.). The ear-scratch response induced by (+/-)DOI was inhibited by both LASSBio-579 and LASSBio-581 at 60 mg/kg, i.p. These results indicate that LASSBio-579 and LASSBio-581 have mechanisms of action through the serotonergic neurotransmitter system.