Behavioral changes and hyperglycemia in NODEF mice following bisphenol S exposure are affected by diets.

Bisphenol S (BPS), an analogue of the controversial bisphenol A (BPA) that is found in epoxy resins and plastics, is a potential endocrine-disrupting chemical that can mimic endogenous hormone signaling. However, little is known about the behavioral or immunologic effects of BPS. The purpose of this study was to examine the impact of diets in BPS-treated mice in relation to hyperglycemia, development of type 1 diabetes, immunomodulation, and behavioral changes. Adult male and female nonobese diabetic excluded flora (NODEF) mice were exposed to environmentally relevant doses of BPS (VH, 30, or 300 µg/kg BW) and fed either a soy-based diet, a phytoestrogen-free diet, or a Western diet. NODEF male mice fed a soy-based diet exhibited a decreased curiosity/desire to explore, and possibly increased anxiety-like behavior and decreased short-term memory when exposed to BPS (300 µg/kg BW). In addition, these mice had significant increases in non-fasting blood glucose levels along with increased insulin sensitivity, impaired glucose tolerance, resistance to fasting and proinflammation. Although BPS had little effect on the glucose parameters in NODEF male mice fed a Western diet, there were decreases in %CD24+CD5+ and %B220+CD40L-cell populations and increases in distance traveled during the novel object test, suggesting hyperactivity. NODEF females fed a phytoestrogen-free diet exhibited slight decreases in time spent immobile during the tail suspension test in both the 30 and 300 µg/kg BW dose groups along with increases in %CD4+CD8+ and %Mac3+CD45R+ cell populations, signifying increased hyperactivity and anxiety-like behavior. In conclusion, BPS-exposed NODEF mice exhibited sex and diet-related changes in hyperglycemia, behaviors and immune endpoints.

In vivo evaluation of effects of histamine H3 receptor antagonists on methamphetamine-induced hyperlocomotion in mice.

A single administration with METH (3 mg/kg) induced a hyperlocomotion in male ICR mice. Pretreatment of mice with pitolisant, a histamine H3 receptor antagonist (5 and 10 mg/kg), for 30 min showed a significant reduction of the hyperlocomotion induced by METH, as compared with vehicle (saline)-pretreated subjects. Pretreatment of mice with the histamine H3 receptor antagonists JNJ-10181457 (5 and 10 mg/kg) or conessine (20 mg/kg), also showed similar inhibitory effects on METH-induced hyperlocomotion, similar to pitolisant. No significant change in locomotion was observed in mice pretreated with pitolisant, JNJ-10181457, or conessine alone. The pitolisant (10 mg/kg) action on METH-induced hyperlocomotion was completely abolished by the histamine H1 receptor antagonist pyrilamine (10 mg/kg), but not by the peripherally acting histamine H1 receptor antagonist fexofenadine (20 mg/kg), the brain-penetrating histamine H2 receptor antagonist zolantidine (10 mg/kg), or the brain-penetrating histamine H4 receptor antagonist JNJ-7777120 (40 mg/kg). Pretreatment with a histamine H3 receptor agonist immepip (10 mg/kg) augmented METH--induced behavior, including hyperlocomotion and stereotyped biting, and combined pretreatment with pitolisant (10 mg/kg) significantly attenuated stereotyped biting. These observations suggest that pretreatment with histamine H3 receptor antagonists attenuate METH-induced hyperlocomotion via releasing histamine after blocking H3 receptors, which then bind to the post-synaptic histamine receptor H1 (but not H2 or H4). It is likely that activation of brain histamine systems may be a good strategy for the development of agents, which treat METH abuse and dependence.

Selective enhancement of NMDA receptor-mediated locomotor hyperactivity by male sex hormones in mice.

RATIONALE: Altered glutamate NMDA receptor function is implicated in schizophrenia, and gender differences have been demonstrated in this illness. OBJECTIVES: This study aimed to investigate the interaction of gonadal hormones with NMDA receptor-mediated locomotor hyperactivity and PPI disruption in mice. RESULTS: The effect of 0.25 mg/kg of MK-801 on locomotor activity was greater in male mice than in female mice. Gonadectomy (by surgical castration) significantly reduced MK-801-induced hyperlocomotion in male mice, but no effect of gonadectomy was seen in female mice or on amphetamine-induced locomotor hyperactivity. The effect of MK-801 on prepulse inhibition of startle (PPI) was similar in intact and castrated male mice and in ovariectomized (OVX) female mice. In contrast, there was no effect of MK-801 on PPI in intact female mice. Forebrain NMDA receptor density, as measured with [3H]MK-801 autoradiography, was significantly higher in male than in female mice but was not significantly altered by either castration or OVX. CONCLUSIONS: These results suggest that male sex hormones enhance the effect of NMDA receptor blockade on psychosis-like behaviour. This interaction was not seen in female mice and was independent of NMDA receptor density in the forebrain. Male sex hormones may be involved in psychosis by an interaction with NMDA receptor hypofunction.

Permeation of Polymethoxyflavones into the Mouse Brain and Their Effect on MK-801-Induced Locomotive Hyperactivity.

Accumulating data have indicated that citrus polymethoxyflavones (PMFs) have the ability to affect brain function. In the present study, we showed that 3,5,6,7,8,3',4'-heptamethoxy- flavone (HMF) given intraperitoneally to mice was immediately detected in the brain and that the permeability of the brain tissues to it was significantly higher than that of other citrus PMFs (nobiletin, tangeretin, and natsudaidain). The permeation of these PMFs into the brain well correlated with their abilities to suppress MK-801-induced locomotive hyperactivity, suggesting that HMF had the ability to act directly in the brain. We also obtained data suggesting that the suppressive effect of HMF on MK-801-induced locomotive hyperactivity was mediated by phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) in the hippocampus.

Omega-3 fatty acids and mood stabilizers alter behavioral and oxidative stress parameters in animals subjected to fenproporex administration.

Studies have shown that oxidative stress is involved in the pathophysiology of bipolar disorder (BD). It is suggested that omega-3 (ω3) fatty acids are fundamental to maintaining the functional integrity of the central nervous system. The animal model used in this study displayed fenproporex-induced hyperactivity, a symptom similar to manic BD. Our results showed that the administration of fenproporex, in the prevent treatment protocol, increased lipid peroxidation in the prefrontal cortex (143%), hippocampus (58%) and striatum (181%), and ω3 fatty acids alone prevented this change in the prefrontal cortex and hippocampus, whereas the co-administration of ω3 fatty acids with VPA prevented the lipoperoxidation in all analyzed brain areas, and the co-administration of ω3 fatty acids with Li prevented this increase only in the prefrontal cortex and striatum. Moreover, superoxide dismutase (SOD) activity was decreased in the striatum (54%) in the prevention treatment, and the administration of ω3 fatty acids alone or in combination with Li and VPA partially prevented this inhibition. On the other hand, in the reversal treatment protocol, the administration of fenproporex increased carbonyl content in the prefrontal cortex (25%), hippocampus (114%) and striatum (91%), and in prefrontal coxter the administration of ω3 fatty acids alone or in combination with Li and VPA reversed this change, whereas in the hippocampus and striatum only ω3 fatty acids alone or in combination with VPA reversed this effect. Additionally, the administration of fenproporex resulted in a marked increase of TBARS in the hippocampus and striatum, and ω3 fatty acids alone or in combination with Li and VPA reversed this change. Finally, fenproporex administration decreased SOD activity in the prefrontal cortex (85%), hippocampus (52%) and striatum (76%), and the ω3 fatty acids in combination with VPA reversed this change in the prefrontal cortex and striatum, while the co-administration of ω3 fatty acids with Li reversed this inhibition in the hippocampus and striatum. In conclusion, our results support other studies showing the importance of ω3 fatty acids in the brain and the potential for these fatty acids to aid in the treatment of BD.

N,N-dimethylglycine differentially modulates psychotomimetic and antidepressant-like effects of ketamine in mice.

Ketamine, a dissociative anesthetic, produces rapid and sustained antidepressant effects at subanesthtic doses. However, it still inevitably induces psychotomimetic side effects. N,N-dimethylglycine (DMG) is a derivative of the amino acid glycine and is used as a dietary supplement. Recently, DMG has been found acting at glycine binding site of the N-methyl-d-aspartate receptor (NMDAR). As blockade of NMDARs is one of the main mechanisms responsible for the action of ketamine on central nervous system, DMG might modulate the behavioral responses to ketamine. The present study determined the effects of DMG on the ketamine-induced psychotomimetic, anesthetic and antidepressant-like effects in mice. DMG pretreatment reversed the ketamine-induced locomotor hyperactivity and impairment in the rotarod performance, novel location and novel object recognition tests, and prepulse inhibition. In addition, DMG alone exhibited antidepressant-like effects in the forced swim test and produced additive effects when combined with ketamine. However, DMG did not affect ketamine-induced anesthesia. These results reveal that DMG could antagonize ketamine's psychotomimetic effects, yet produce additive antidepressant-like effects with ketamine, suggesting that DMG might have antipsychotic potential and be suitable as an add-on therapy to ketamine for patients with treatment-resistant depression.

The "induced hyperactivity" test for the de-risking of potential off-target activity of antihypertensive drugs.

INTRODUCTION: Compound X is a new proprietary antihypertensive agent that induces its pharmacodynamic effect at an approximate plasma Cmax.u of 0.6nmol/L (rat hypertension model). However, Compound X also shows potent off-target activity at PDE-10a (IC50~12nmol/L). Since PDE-10a is expressed predominantly in brain (striatum) and inhibition/knockout of PDE-10a have been reported to result in anti-psychotic effects, we have established the "induced hyperactivity" test for CNS de-risking of Compound X. METHODS: Male Wistar rats treated orally with vehicle or Compound X (single dose; 1-3-10mg/kg) were assessed for exploratory locomotor activity following induction of hyperactivity by d-amphetamine (2mg/kg) or the NMDA antagonist MK-801 (0.2mg/kg). The assay was validated with anti-psychotic drugs (haloperidol, clozapine). RESULTS: Induced hyperactivity was not antagonized by Compound X at doses relevant for its primary pharmacodynamic activity (0.1-0.3mg/kg, rat). Although sufficient plasma concentrations were reached with Compound X (Cmax.u up to ~8nmol/L at 10mg/kg) to show its PDE-10a activity, its low brain penetration (~10%) likely precluded any meaningful PDE-10a inhibition. In comparison, other blood pressure lowering agents such as prazosin (alpha-1 adrenoceptor antagonist) and isradipine (L-Type Ca(2+) channel blocker), but not the NO-donor ISDN, tended to attenuate induced hyperactivity in rats at high doses. CONCLUSION: The relevance of a potent in-vitro off-target hit (PDE-10a inhibition) by Compound X was attenuated by a robust in-vivo assay (rat induced hyperactivity test), hence lowering the potential liability profile of Compound X. Finally, this piece of investigative safety pharmacology work enabled early de-risking of Compound X based on its primary pharmacodynamic activity in a relevant rat model.

Further Advances in Optimizing (2-Phenylcyclopropyl)methylamines as Novel Serotonin 2C Agonists: Effects on Hyperlocomotion, Prepulse Inhibition, and Cognition Models.

A series of novel compounds with two halogen substituents have been designed and synthesized to further optimize the 2-phenylcyclopropylmethylamine scaffold in the quest for drug-like 5-HT2C agonists. Compound (+)-22a was identified as a potent 5-HT2C receptor agonist, with good selectivity against the 5-HT2B and the 5-HT2A receptors. ADMET assays showed that compound (+)-22a possessed desirable properties in terms of its microsomal stability, and CYP and hERG inhibition, along with an excellent brain penetration profile. Evaluation of (+)-22a in animal models of schizophrenia-related behaviors revealed that it had a desirable activity profile, as it reduced d-amphetamine-stimulated hyperlocomotion in the open field test, it restored d-amphetamine-disrupted prepulse inhibition, it induced cognitive improvements in the novel object recognition memory test in NR1-KD animals, and it produced very little catalepsy relative to haloperidol. These data support the further development of (+)-22a as a drug candidate for the treatment of schizophrenia.

Design and Synthesis of Mannich bases as Benzimidazole Derivatives as Analgesic Agents.

Mannich bases were selected for 2D QSAR study to derive meaningful relationship between the structural features and analgesic activity. Using the knowledge of important features a novel series was designed to obtain improved analgesic activity. A series of novel Mannich bases 1-(N-substituted amino)methyl]-2-substituted benzimidazole derivatives were synthesized and were screened for analgesic activity. Some of these compounds showed promising analgesic activity when compared with the standard drug diclofenac sodium.

The safety of high-dose buprenorphine administered subcutaneously in cats.

The safety of a proprietary formulation of buprenorphine hydrochloride administered subcutaneously (SC) to young cats was investigated in a blinded, randomized study. Four cohorts of eight cats aged approximately 4 months were administered saline, 0.24, 0.72 or 1.20 mg/kg/day buprenorphine SC for nine consecutive days, representing 0×, 1×, 3× and 5× of the intended dose. Cats were monitored daily for evidence of clinical reactions, food and water intake and adverse events (AEs). Physical examinations, clinical pathology, vital signs and electrocardiograms (ECGs) were evaluated at protocol-specified time points. Complete necropsy and histopathologic examinations were performed following humane euthanasia. Four buprenorphine-treated cats experienced AEs during the study, two unrelated and two related to study drug administration. The two cats with AEs considered related to drug administration had clinical signs of hyperactivity, difficulty in handling, disorientation, agitation and dilated pupils in one 0.24 mg/kg/day cat and one 0.72 mg/kg/day cat. All of these clinical signs were observed simultaneously. There were no drug-related effects on survival, injection response, injection site inspections, body weight, food or water consumption, bleeding time, urinalysis, respiration rate, heart rate, ECGs, blood pressures, body temperatures, macroscopic examinations or organ weights. Once daily buprenorphine s.c. injections at doses of 0.24, 0.72 and 1.20 mg/kg/day for 9 consecutive days were well tolerated in young domestic cats.

L-tetrahydropalmatine inhibits methamphetamine-induced locomotor activity via regulation of 5-HT neuronal activity and dopamine D3 receptor expression.

Methamphetamine (METH) is a psychomotor stimulant that produces hyperlocomotion in rodents. l-tetrahydropalmatine (l-THP) is an active ingredient found in Corydalis ternata which has been used as a traditional herbal preparation in Asian countries for centuries, however, the effect of l-THP on METH-induced phenotypes largely unknown. In this study, to evaluate the effect of l-THP on METH-induced psychotropic effects, rats were pretreated with l-THP (10 and 15 mg/kg) before acute METH injection, following which the total distance the rats moved in an hour was measured. To clarify a possible mechanism underlying the effect of l-THP on METH-induced behavioral changes, dopamine receptor mRNA expression levels in the striatum of the rats was measured following the locomotor activity study. In addition, the effect of l-THP (10 and 15 mg/kg) on serotonergic (5-HTergic) neuronal pathway activation was studied by measurement of 5-HT (80 µg/10µl/mouse)-induced head twitch response (HTR) in mice. l-THP administration significantly inhibited both hyperlocomotion in rats and HTR in mice. l-THP inhibited climbing behavior-induced by dopaminergic (DAergic) neuronal activation in mice. Furthermore, l-THP attenuated the decrease in dopamine D3 receptor mRNA expression levels in the striatum of the rats induced by METH. These results suggest that l-THP can ameliorate behavioral phenotype induced by METH through regulation of 5-HT neuronal activity and dopamine D3 receptor expression.

N-acetylcysteine prevents increased amphetamine sensitivity in social isolation-reared mice.

Treating individuals at risk to develop schizophrenia may be strategic to delay or prevent transition to psychosis. We verified the effects of N-acetylcysteine (NAC) in a neurodevelopmental model of schizophrenia. C57 mice were reared in isolation or social groups and treated with NAC from postnatal day 42-70; the locomotor response to amphetamine was assessed at postnatal day 81. NAC treatment in isolated mice prevented the hypersensitivity to amphetamine, suggesting neuroprotection relevant to striatal dopamine. Considering its safety and tolerability profile, complementary studies are warranted to further evaluate the usefulness of NAC to prevent conversion to schizophrenia in at-risk individuals.

Omega-3 fatty acids alter behavioral and oxidative stress parameters in animals subjected to fenproporex administration.

Studies have consistently reported the participation of oxidative stress in bipolar disorder (BD). Evidences indicate that omega-3 (ω3) fatty acids play several important roles in brain development and functioning. Moreover, preclinical and clinical evidence suggests roles for ω3 fatty acids in BD. Considering these evidences, the present study aimed to investigate the effects of ω3 fatty acids on locomotor behavior and oxidative stress parameters (TBARS and protein carbonyl content) in brain of rats subjected to an animal model of mania induced by fenproporex. The fenproporex treatment increased locomotor behavior in saline-treated rats under reversion and prevention model, and ω3 fatty acids prevented fenproporex-related hyperactivity. Moreover, fenproporex increased protein carbonyls in the prefrontal cortex and cerebral cortex, and the administration of ω3 fatty acids reversed this effect. Lipid peroxidation products also are increased in prefrontal cortex, striatum, hippocampus and cerebral after fenproporex administration, but ω3 fatty acids reversed this damage only in the hippocampus. On the other hand, in the prevention model, fenproporex increased carbonyl content only in the cerebral cortex, and administration of ω3 fatty acids prevented this damage. Additionally, the administration of fenproporex resulted in a marked increased of TBARS in the prefrontal cortex, hippocampus, striatum and cerebral cortex, and prevent this damage in the prefrontal cortex, hippocampus and striatum. In conclusion, we are able to demonstrate that fenproporex-induced hyperlocomotion and damage through oxidative stress were prevented by ω3 fatty acids. Thus, the ω3 fatty acids may be important adjuvant therapy of bipolar disorder.

Repeated asenapine treatment produces a sensitization effect in two preclinical tests of antipsychotic activity.

Among several commonly used atypical antipsychotic drugs, olanzapine and risperidone cause a sensitization effect in the conditioned avoidance response (CAR) and phencyclidine (PCP)-induced hyperlocomotion paradigms--two well established animal tests of antipsychotic drugs, whereas clozapine causes a tolerance effect. Asenapine is a novel antipsychotic drug recently approved for the treatment of schizophrenia and manic disorders. It shares several receptor binding sites and behavioral features with other atypical antipsychotic drugs. However, it is not clear what type of repeated effect (sensitization or tolerance) asenapine would induce, and whether such an effect is transferrable to other atypicals. In this study, male adult Sprague-Dawley rats were first repeatedly tested with asenapine (0.05, 0.10 or 0.20 mg/kg, sc) for avoidance response or PCP (3.20 mg/kg, sc)-induced hyperlocomotion daily for 5 consecutive days. After 2-3 days of retraining/drug-free recovery, they were then challenged with asenapine (0.10 mg/kg, sc), followed by olanzapine (0.50 mg/kg, sc) and clozapine (2.50 mg/kg, sc). During the 5-day drug test period (the induction phase), repeated asenapine treatment progressively increased its inhibition of avoidance response and PCP-induced hyperlocomotion in a dose-dependent fashion. On the asenapine and olanzapine challenge tests (the expression phase), rats previously treated with asenapine still showed significantly lower avoidance response and lower PCP-induced hyperlocomotion than those previously treated with vehicle. An increased reactivity to clozapine challenge in prior asenapine-treated rats was also found in the PCP-induced hyperlocomotion test. These findings suggest that asenapine is capable of inducing a sensitization effect and a cross-sensitization to olanzapine and clozapine (to a lesser extent). Because the behavioral profile of asenapine in both tests is similar to that of olanzapine, but different from that of clozapine, we suggest that asenapine resembles olanzapine to a greater extent than clozapine in its therapeutic and side effect profiles.

Electro-acupuncture stimulation improves spontaneous locomotor hyperactivity in MPTP intoxicated mice.

Bradykinesia is one of the major clinical symptoms of Parkinson`s disease (PD) for which treatment is sought. In most mouse models of PD, decreased locomotor activity can be reflected in an open field behavioral test. Therefore the open field test provides a useful tool to study the clinic symptoms of PD patients. Our previous work demonstrated that 100 Hz electro-acupuncture (EA) stimulation at ZUSANLI and SANYINJIAO protected the dopaminergic nigrostriatal system of C57BL/6 mice from MPTP toxicity, indicating that acupuncture might be an effective therapy for PD sufferers. In the present study, we investigated the effects of 100 Hz EA stimulation on the spontaneous locomotor activity in MPTP injured mice. Here we found that, in MPTP treated mice, the total movements significantly decreased and the movement time, velocity and distance dramatically increased, although the dopaminergic nigrostriatal system was devastated, revealed by immunohistochemistry and HPLC-ECD. After 12 sessions of 100 Hz EA stimulation, the total movements elevated and the movement time, velocity and distance decreased, in MPTP mice. 100 Hz EA increased striatal dopamine content in MPTP mice by 35.9%, but decreased its striatal dopamine turnover. We assumed that the injury of other regions in the brain, such as the A11 group in diencephalon, might be involved in the hypermotility in MPTP mice. The effects of 100 Hz EA on spontaneous locomotor activity in MPTP mice might not relate with the striatal dopamine, but with its neuroprotective and regulatory effects on motor circuits in the brain. Our study suggests that EA might be a promising treatment for neurological disorders including PD.

Bioactivity guided isolation of antipsychotic constituents from the leaves of Rauwolfia tetraphylla L.

This study was undertaken to ascertain the antipsychotic properties of Rauwolfia tetraphylla L. leaves and to isolate and characterize the antipsychotic constituents. Among the MeOH extract and some alkaloidal fractions at different pHs, the alkaloidal CHCl(3) fraction at pH-9 (2C) showed the highest antipsychotic activity against dopaminergic (DA-D(2)) and serotonergic (5-HT(2A)) receptors in-vitro and amphetamine induced hyperactive mouse model in-vivo. The activity guided isolation of CHCl(3) fraction (2C) afforded six indole alkaloids: 10-methoxytetrahydroalstonine (1), isoreserpiline (2), an isomeric mixture of 11-demethoxyreserpiline (3) and 10-demethoxyreserpiline (4), α-yohimbine (5) and reserpiline (6). Given orally, alkaloids 3-6 showed significant antipsychotic activity in a dose dependent manner. None of the extract, alkaloidal fractions or alkaloids showed any extra pyramidal symptoms at the tested doses. It was also observed that MeOH extract was behaving similar to other clinically used novel atypical antipsychotics in having 5-HT(2A) occupancy greater than the DA-D(2) receptor at the tested doses. Further toxicity and safety evaluation studies of MeOH extracts of R. tetraphylla leaves at different doses (10, 100, 300 and 2000 mg/kg) on female Swiss albino mice showed that MeOH extract is non toxic. The isolated alkaloids, 3-6 could serve as a promising lead structure for drug development of treating psychotic conditions in human.

Psychomotor stimulation by dopamine D1-like but not D2-like agonists in most mouse strains.

Many neurological and psychiatric disorders are treated with dopamine modulators. Studies in mice may reveal genetic factors underlying those disorders or responsiveness to various treatments, and species and strain differences both complicate the use of mice and provide valuable tools. We evaluated psychomotor effects of the dopamine D1-like agonist R-6-Br-APB and the dopamine D2-like agonist quinelorane using a locomotor activity procedure in 15 mouse strains (inbred 129S1/SvImJ, 129S6/SvEvTac, 129X1/SvJ, A/J, BALB/cByJ, BALB/cJ, C3H/HeJ, C57BL/6J, CAST/EiJ, DBA/2J, FVB/NJ, SJL/J, SPRET/EiJ, outbred Swiss Webster, and CD-1) and Sprague-Dawley rats, using groups of both females and males. Both D1 and D2 stimulation produced hyperactivity in the rats, and surprisingly, only two mouse strains were similar in that regard (C3H/HeJ, SPRET/EiJ). In contrast, the majority of mouse strains exhibited hyperactivity only with D1 stimulation, whereas D2 stimulation had no effect or decreased activity. BALB substrains, A/J and FVB/NJ mice showed only decreased activity after either D1 or D2 stimulation. CAST/EiJ mice exhibited hyperactivity exclusively with D2 stimulation. Sex differences were observed but no systematic trend emerged: For example, of the five strains in which a main factor of sex was identified for the stimulant effects of the D1 agonist, responsiveness was greatest in females in three of those strains and in males in two of those strains. These results should aid in the selection of mouse strains for future studies in which D1 or D2 responsiveness is a necessary consideration in the experimental design.

The amphetamine-chlordiazepoxide mixture, a pharmacological screen for mood stabilizers, does not enhance amphetamine-induced disruption of prepulse inhibition.

In rodents, administration of a mixture of the psychostimulant d-amphetamine and the benzodiazepine chlordiazepoxide results in supra-additive hyperlocomotion, a phenomenon used to identify mood stabilizers. In an attempt to determine whether the d-amphetamine/chlordiazepoxide assay could extend to other behaviors that are affected in mania, we evaluated the effects of the mixture on prepulse inhibition. In addition, we combined chlordiazepoxide with the selective dopamine reuptake inhibitor GBR 12909 or the noradrenergic stimulant (-) ephedrine, and tested these alternative mixtures in locomotor activity and prepulse inhibition tests. Chlordiazepoxide (3mg/kg) robustly potentiated amphetamine-induced hyperactivity, but did not change the amphetamine-induced disruption of prepulse inhibition. This indicates that the d-amphetamine-chlordiazepoxide-induced hyperlocomotion does not extend to other dopamine-driven behaviors. GBR 12909 (16mg/kg) and (-) ephedrine (50mg/kg) both enhanced locomotor activity and disrupted PPI, but combined treatment of either of these compounds with chlordiazepoxide had no significant additive effect on locomotor activity or prepulse inhibition. These findings suggest that the effect of the d-amphetamine/chlordiazepoxide mixture cannot be accounted for by the dopamine enhancing properties of amphetamine alone. Last, valproic acid (120-240mg/kg) did not reduce the GBR-induced hyperactivity. Therefore, further pharmacological evaluation of GBR 12909-induced hyperactivity is warranted to determine its pharmacological potential to model mania-like behavior. Based on the current results, it is concluded that the utility of the pharmacological d-amphetamine/chlordiazepoxide assay as a tool to study brain mechanisms relevant to mania is limited.

Preclinical profile of a novel metabotropic glutamate receptor 5 positive allosteric modulator.

Recent reports have indicated that patients with schizophrenia have a profound hypo-functionality of glutamatergic signaling pathways. Positive allosteric modulation of mGlu(5) receptor has been postulated to augment NMDA function and thereby alleviate the glutamatergic hypo-function observed in schizophrenic patients. Here we report the in vitro and in vivo characterization of CPPZ (1-(4-(2-chloro-4-fluorophenyl)piperazin-1-yl)-2-(pyridin-4-ylmethoxy)ethanone), a structurally novel positive allosteric modulator selective for mGlu(5) receptor. In HEK293 cells stably over-expressing human mGlu(5) receptor, CPPZ potentiates the intracellular calcium response elicited by a suboptimal concentration of the endogenous agonist glutamate. CPPZ does not have any intrinsic agonist activity and behaves functionally as a positive allosteric modulator. This is further supported by binding data, which demonstrate that CPPZ is able to displace the negative allosteric modulator MPEP but does not compete with the orthosteric ligand quisqualic acid. Instead, CPPZ enhances the binding of the orthosteric ligand. In native preparations, CPPZ potentiates calcium flux in rat cortical neurons stimulated with the group I agonist dihydroxyphenylglycine (DHPG). In addition, CPPZ modulates long-term potentiation in rat hippocampal slices, a process known to be NMDA dependent. In vivo, CPPZ reverses hyper locomotion triggered by the NMDA open channel blocker MK801 in CD1 mice. CPPZ was also able to reduce rat conditioned avoidance responding to electric shock. Both in vitro and in vivo data demonstrate that this novel compound acts as an mGlu(5) receptor positive allosteric modulator, which modulates NMDA dependent responses and suggests that the enhancement of mGlu(5) receptor activity may prove useful in the treatment of schizophrenia.

Effects of cannabidiol on amphetamine-induced oxidative stress generation in an animal model of mania.

Cannabidiol (CBD), a Cannabis sativa constituent, may present a pharmacological profile similar to mood stabilizing drugs, in addition to anti-oxidative and neuroprotective properties. The present study aims to directly investigate the effects of CBD in an animal model of mania induced by D-amphetamine (D-AMPH). In the first model (reversal treatment), rats received saline or D-AMPH (2 mg/kg) once daily intraperitoneal (i.p.) for 14 days, and from the 8th to the 14th day, they were treated with saline or CBD (15, 30 or 60 mg/kg) i.p. twice a day. In the second model (prevention treatment), rats were pretreated with saline or CBD (15, 30, or 60 mg/kg) regime i.p. twice a day, and from the 8th to the 14th day, they also received saline or D-AMPH i.p. once daily. In the hippocampus CBD (15 mg/kg) reversed the d-AMPH-induced damage and increased (30 mg/kg) brain-derived neurotrophic factor (BDNF) expression. In the second experiment, CBD (30 or 60 mg/kg) prevented the D-AMPH-induced formation of carbonyl group in the prefrontal cortex. In the hippocampus and striatum the D-AMPH-induced damage was prevented by CBD (15, 30 or 60 mg/kg). At both treatments CBD did not present any effect against d-AMPH-induced hyperactivity. In conclusion, we could not observe effects on locomotion, but CBD protect against d-AMPH-induced oxidative protein damage and increased BDNF levels in the reversal model and these effects vary depending on the brain regions evaluated and doses of CBD administered.