Polyelectrolyte-Graphene Oxide Multilayer Composites for Array of Microchambers which are Mechanically Robust and Responsive to NIR Light.

Development of composite polymer/graphene oxide (GO) materials attracts significant attention due to their unique properties. In this work, highly ordered arrays of hollow microchambers made of composite polyelectrolyte/GO multilayers (PEGOMs) are successfully fabricated via layer-by-layer assembly on sacrificial or sustainable templates having imprinted patterns of microwells on their surface. Mechanical and optical properties of PEGOMs are studied by nanoindentation and near-infrared (NIR) absorption spectroscopy. Incorporation of three GO layers in between the polyelectrolyte multilayer stacks increases Young's modulus and critical stress of the microchambers by a factor of 5.6 and 2.6, respectively. Optical density of this PEGOM film is found to decrease gradually from 0.14 at λ = 800 nm to 0.06 at λ = 1500 nm. Remote opening of PEGOM microchambers with NIR laser beam is also demonstrated. One of the possible applications of the developed structures includes micropackaging and delivery systems in biological tissues with remote triggering.

Atypical antipsychotic profile of flunarizine in animal models.

RATIONALE: Flunarizine is known as a calcium channel blocker commonly used in many countries to treat migraine and vertigo. Parkinsonism has been described as one of its side-effects in the elderly, which is in agreement with its recently characterized moderate D2 receptor antagonism. OBJECTIVES: To perform a pre-clinical evaluation of flunarizine as a potential antipsychotic. METHODS: We evaluated the action of orally administered flunarizine in mice against hyperlocomotion induced by amphetamine and dizocilpine (MK-801) as pharmacological models of schizophrenia, induction of catalepsy as a measure for extrapyramidal symptoms and impairment induced by dizocilpine on the delayed alternation task for working memory. RESULTS: Flunarizine robustly inhibited hyperlocomotion induced by both amphetamine and dizocilpine at doses that do not reduce spontaneous locomotion (3-30 mg/kg). Mild catalepsy was observed at 30 mg/kg, being more pronounced at 50 mg/kg and 100 mg/kg. Flunarizine (30 mg/kg) improved dizocilpine-induced impairment on the delayed alternation test. CONCLUSIONS: These results suggest a profile comparable to atypical antipsychotics. The low cost, good tolerability and long half-life (over 2 weeks) of flunarizine are possible advantages for its use as an atypical antipsychotic. These results warrant clinical trials with flunarizine for the treatment of schizophrenia.

Chronic treatment with caffeine blunts the hyperlocomotor but not cognitive effects of the N-methyl-D-aspartate receptor antagonist MK-801 in mice.

RATIONALE: Administration of N-methyl- d-aspartate (NMDA) receptor antagonists produce hyperlocomotion and cognitive deficits in rodents. Activation of NMDA receptors promotes adenosine release, and adenosine agonists prevent central effects of NMDA receptor antagonists. We hypothesized that if NMDA receptor antagonists require adenosine to produce behavioral effects, mice tolerant to the adenosine receptor antagonist caffeine would have a diminished response to NMDA receptor antagonists. OBJECTIVES: To evaluate MK-801-induced hyperlocomotion and cognitive deficits after chronic caffeine treatment in mice. METHODS: Locomotor activity was analyzed in a computerized system, spontaneous alternation was assessed in the Y-maze and long-term memory was assessed with the inhibitory avoidance task in mice. RESULTS: Mice chronically treated with caffeine in drinking solution (1 mg/ml for 7 days) presented normal habituation and substantial tolerance to acute caffeine (30 mg/kg, i.p.) locomotor effects. MK-801 (0.25 mg/kg, i.p.) produced pronounced hyperlocomotion in water-treated mice, but this effect was abolished in caffeine-drinking mice. Chronic caffeine treatment had no influence on either normal or MK-801-induced deficits in spontaneous alternation and inhibitory avoidance tasks. CONCLUSION: Hyperlocomotion induced by MK-801 may be mediated by reduced adenosinergic activity. These results also suggest that locomotor and cognitive effects of MK-801 can be dissociated and are distinctly modulated. Finally, these findings agree with the adenosine hypofunction model of schizophrenia, since NMDA receptor antagonists are a pharmacological model for this disorder.

Effects of low-dose D-serine on recognition and working memory in mice.

RATIONALE: D -Serine is an endogenous co-agonist of the N-methyl-D: -aspartate (NMDA) receptor and has been suggested to improve cognitive deficits in schizophrenia. OBJECTIVES: The present study investigates the effects of treatment with D -serine in mice on tasks that require recognition learning and working memory, two cognitive domains that are impaired in schizophrenia. METHODS: We studied the effects of various regimens of systemic administration of D -serine (50 mg/kg/day) on BALB/c mice performing object recognition, T-maze alternation, and open-field exploration tasks. For the object recognition task, we also contrasted the effects of D -serine and D -cycloserine and investigated whether D -serine could reverse alterations induced by subchronic injections of the NMDA antagonist MK-801. D -Serine levels after injections were measured by high-performance liquid chromatography. RESULTS: In the object recognition task, pre-training treatment with D -serine or D -cycloserine significantly enhanced recognition memory 24 h after training. A single administration of D -serine 30 min (but not 6 h) after training produced similar enhancement, suggesting an effect on memory consolidation. Daily treatment with D: -serine enhanced both object recognition and T-maze performance over multiple days and improved short-term memory in MK-801-treated mice. D -Serine treatment did not alter open-field exploration. Behavioral effects were accompanied by increased levels of D -serine in the hippocampus of treated animals. CONCLUSIONS: Our results show that treatment with D -serine can improve performance in tasks related to recognition learning and working memory, suggesting that this agent can be useful for the treatment of disorders involving declines in these cognitive domains.

Is flunarizine a long-acting oral atypical antipsychotic? A randomized clinical trial versus haloperidol for the treatment of schizophrenia.

BACKGROUND: Flunarizine is known as a nonspecific calcium channel blocker that has been used for decades for the treatment of migraine, vertigo, and cognitive deficits related to cerebrovascular disorders. Flunarizine also has dopamine D2 receptor blocking properties and was effective in animal models of predictive validity for antipsychotics. However, its clinical antipsychotic efficacy has never been investigated. OBJECTIVE: To evaluate the therapeutic efficacy and tolerability of flunarizine compared to haloperidol in outpatients with stable and chronic DSM-IV-defined schizophrenia and schizoaffective disorder. METHOD: Seventy patients from 2 centers were randomly assigned and participated in a double-blind, parallel-group, flexible-dose study comparing flunarizine (10-50 mg/day) and haloperidol (2.5-12.5 mg/day) for 12 weeks. Patients were assessed with the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions-Improvement (CGI-I) scale, the Extrapyramidal Symptom Rating Scale (ESRS), a battery for cognitive performance, and laboratory examinations. The study was conducted from September 2004 to May 2007. RESULTS: Mean doses at endpoint were 29.7 mg/day for flunarizine and 6.4 mg/day for haloperidol. Both groups showed significant symptom improvement during the study, with a reduction of 21% in the flunarizine group and 19% in the haloperidol group in PANSS total scores (p < .05). There were no significant differences in PANSS overall score and all subscales, CGI-I score, or cognitive performance. Dropout rates, ESRS scores, and prolactin levels were not different between groups, but significantly more patients reported emergence of akathisia in the haloperidol group (p = .04), and weight gain was significantly higher with flunarizine (1.2 kg) than with haloperidol (-0.8 kg) (p < .05). CONCLUSION: This is the first study evaluating the antipsychotic properties of flunarizine, which showed good efficacy and tolerability for the treatment of schizophrenia, with a possible atypical profile. Its unique pharmacokinetic profile as an oral drug with long half-life (2-7 weeks), low cost, and low induction of extrapyramidal symptoms warrants further investigation, particularly in psychiatric patients with low adherence to treatment.