Modulation of MK-801-elicited mouse popping behavior by galantamine is complex and dose-dependent

Ketamine Inhalation Alters Behavior and Lower Urinary Tract Function in Mice

We aimed to evaluate behavioral and lower urinary tract changes in mice using a novel ketamine inhalation model mimicking human ketamine abusers and compare the results to those obtained using a ketamine intraperitoneal injection model. C57BL/6N mice were placed in a transparent acrylic observation cage connected to an ultrasonic nebulizer producing ketamine (KI) or saline (SI) fog. The mice were given KI or SI fog twice a week for three months. In another experiment arm, the mice were given intraperitoneal ketamine injections (KP) or saline injections (SP) twice a week for three months. The presence of urine ketamine (>100 ng/mL) was determined using a quick test kit. Locomotor activity was recorded by video using the open field test. Lower urinary tract function was assessed using urine spots, cystometry and histology. KI and KP mice crossed the center more frequently and traveled farther than SI and SP mice. Only KI mice, however, demonstrated popcorn-like jumping, and frequent center crossing. Detrusor overactivity, reduced cystometric bladder capacity, and denuded mucosa were observed in both KI and KP mice. Ketamine inhalation induces behavioral and lower urinary tract changes in mice that are comparable to intraperitoneal ketamine injections.

Citicoline (CDP-choline) add-on therapy to risperidone for treatment of negative symptoms in patients with stable schizophrenia: A double-blind, randomized placebo-controlled trial

OBJECTIVE

We aimed to evaluate the efficacy and tolerability of citicoline add-on therapy in treatment of negative symptoms in patients with stable schizophrenia.

METHODS

In a double-blind and placebo-controlled study, patients with stable schizophrenia (DSM-5) were randomized to receive either 2,500 mg/day citicoline or placebo in addition to risperidone for 8 weeks. The patients were assessed using the positive and negative syndrome scale (PANSS), the extrapyramidal symptom rating scale (ESRS), and Hamilton depression rating scale (HDRS). The primary outcome was the difference in PANSS negative subscale score reduction from baseline to week 8 between the citicoline and the placebo groups.

RESULTS

Sixty-six individuals (out of 73 enrolled) completed the trial. The citicoline group demonstrated significantly greater improvement in negative scores, F(1.840, 118.360) = 8.383, p = .001, as well as general psychopathology, F(1.219, 78.012) = 6.636, p = .008; change in general psychopathology did not remain significant after adjustment, and total PANSS scores, F(1.633, 104.487) = 15.400, p < .001, compared with the placebo. HDRS scores and its changes, ESRS score, and frequency of other side effects were not significantly different between the two groups.

CONCLUSIONS

Citicoline add-on therapy to risperidone can effectively improve the primary negative symptoms of patients with schizophrenia.

The interactive effects of ketamine and nicotine on human cerebral blood flow

AIM

The purpose of this study was to determine if acute nicotine attenuated ketamine-induced regional cerebral blood flow (rCBF).

METHOD

Following 2-4 h of nicotine abstinence, healthy chronic smokers participated in four sets of rCBF studies, H2(15)O positron emission tomography, during a simple sensory motor control task. The four drug conditions studied were placebo, ketamine alone, nicotine alone, and ketamine + nicotine.

RESULTS

Intravenous ketamine increased rCBF in frontal, orbital-frontal, and anterior cingulate areas. Nicotine alone induced marked rCBF elevations in the lateral occipital cortex and rCBF suppressions in the basal ganglia and anterior cingulate cortex. Nicotine added to ketamine attenuated the ketamine-induced elevated rCBF in the anterior cingulate cortex but caused a marked rCBF increase in the orbital frontal region.

CONCLUSION

This study illustrates the interactive effects of ketamine, an NMDA receptor antagonist, and nicotine in multiple brain regions. Nicotine substantially ameliorated the effects of ketamine on anterior cingulate rCBF and, when given alone, markedly suppressed anterior cingulate rCBF. The enhanced, synergistic orbitofrontal effects observed with ketamine and nicotine together suggest a marked increase in excitatory neurotransmission in a brain region often linked to psychosis, reward, and addictive behaviors.

NMDA receptor subunit expression in GABAergic interneurons in the prefrontal cortex: application of laser microdissection technique

The selective involvement of a subset of neurons in many psychiatric disorders, such as gamma-aminobutyric acid (GABA)-ergic interneurons in schizophrenia, creates a significant need for in-depth analysis of these cells. Here we introduce a combination of techniques to examine the relative gene expression of N-methyl-d-aspartic acid (NMDA) receptor subtypes in GABAergic interneurons from the rat prefrontal cortex. Neurons were identified by immunostaining, isolated by laser microdissection and RNA was prepared for reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR. These experimental procedures have been described individually; however, we found that this combination of techniques is powerful for the analysis of gene expression in individual identified neurons. This approach provides the means to analyze relevant molecular mechanisms that are involved in the neuropathological process of a devastating brain disorder.

Effects of the Essential Oil from Leaves of Alpinia zerumbet on Behavioral Alterations in Mice

In phytotherapy, the essential oil from the leaves of Alpinia zerumbet ( Alpinia speciosa K. Schum.) (EOAZ) is used for neuropsychiatric symptoms, such as depression, stress and anxiety, and chronic problems that are associated with reproductive hormone imbalances in women. The chemical composition of EOAZ was analyzed by GC/MS, and the EOAZ properties inducing behavioral alterations in mice were examined by behavioral observations (BO) and an elevated plus-maze task (EPM), widely used as a method for assessing anxiolytic-like behaviors. Five major compounds, p-cymene (28.0 ± 5.0%), 1,8-cineole (17.9 ± 4.2%), terpinen-4-ol (11.9 ± 6.3%), limonene (6.3 ± 2.2%), and camphor (5.2 ± 2.1%) were identified by retention indices, mass spectra and comparison with standards. Inhalational administration of EOAZ (8.7 ppm) induced unique jumping behaviors in mice. To further investigate the behavioral regulatory mechanisms of EOAZ, we administered an intraperitoneal injection of either 10 mg/kg 5-HTP or 10 mg/kg fluoxetine prior to the EOAZ inhalations. By 5-HTP or fluoxetine pretreatments, the jumping frequencies were significantly decreased. In EPM, EOAZ (0.087 and 8.7 ppm) obviously showed the anxiolytic-like activity in mice.

High-dose galantamine augmentation inferior to placebo on attention, inhibitory control and working memory performance in nonsmokers with schizophrenia

Dysfunction in the neuronal nicotinic acetylcholine receptor (nAChR) system has been implicated in the pathophysiology of schizophrenia, and it has been postulated that treatments that increase nAChR activity may improve symptoms of the disorder. We investigated the effects of the acetylcholinesterase inhibitor and allosteric nAChR modulator, galantamine, on cognitive performance and clinical symptoms when added to a stable antipsychotic medication regimen in nonsmoking outpatients with schizophrenia in a double-blind, placebo-controlled, parallel-group design. Participants were randomized to receive either galantamine (n=10) up to 32 mg/day or identical placebo (n=10) for 8 weeks and completed a cognitive battery at baseline and week 8 and clinical scales at baseline, week 4 and week 8. The primary outcome measure was attentional performance as measured by the d' measure in the Continuous Performance Test - Identical Pairs (CPT-IP) Version. Contrary to our hypothesis, galantamine treatment was associated with inferior performance on the CPT-IP, on the three-card Stroop task, and on the Letter-Number Span task without reordering. Galantamine had no effect on clinical symptoms. In summary, galantamine treatment, at a dose of 32 mg/day, was well tolerated but was not effective as an adjunctive treatment for cognitive deficits in stable nonsmokers with schizophrenia.

Effects of CDP-choline and the combination of CDP-choline and galantamine differ in an animal model of schizophrenia: development of a selective alpha7 nicotinic acetylcholine receptor agonist strategy

The regionally selective reduction of expression of the alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) in schizophrenia underlies impaired sensory inhibition, a possible endophenotype of the disorder. This ligand-gated ion channel receptor has been proposed as a pharmacotherapeutic target in schizophrenia. The current study examined the effect of CDP-choline alone and the combination of CDP-choline and galantamine, administered acutely and once-daily for five consecutive days, in an animal model of NMDA receptor hypofunction that is relevant to schizophrenia. The results support the allosteric modulatory influence of galantamine on CDP-choline; however, individual doses of CDP-choline and galantamine must be carefully titrated in order to achieve optimal levels of alpha7 nAChR "agonism" that may be necessary for the desired therapeutic effect.

Phencyclidine and dizocilpine induced behaviors reduced by N-acetylaspartylglutamate peptidase inhibition via metabotropic glutamate receptors

BACKGROUND

N-methyl-D-aspartate (NMDA) receptor open channel blockers phencyclidine (PCP) and dizocilpine (MK-801) elicit schizophrenia-like symptoms in humans and in animal models. Group II metabotropic glutamate receptor agonists reverse the behavioral effects of PCP and MK-801 in animal models. N-acetylaspartylglutamate (NAAG), the third most prevalent neurotransmitter in the mammalian nervous system, is a selective group II metabotropic glutamate receptor agonist. We previously reported that ZJ43, a potent inhibitor of the enzymes that inactivate synaptically released NAAG, reduced motor and stereotypic effects of PCP in the rat.

METHODS

To confirm the efficacy of NAAG peptidase inhibition in decreasing motor behaviors induced by PCP and MK-801, ZJ43 was tested in additional schizophrenia models.

RESULTS

ZJ43 reduced MK-801-induced motor activation in a mouse model that has been used to characterize the efficacy of a wide range of pharmacotherapies for this human disorder. In a second mouse strain, the peptidase inhibitor reduced PCP-induced stereotypic movements. ZJ43 also reduced PCP-induced negative symptoms in a resident-intruder assay. The group II metabotropic glutamate receptor antagonist, LY341495, blocked the effect of NAAG peptidase inhibition in these mouse models of positive and negative PCP- and MK-801-induced behaviors. Additionally, LY341495 alone increased some PCP-induced behaviors suggesting that normal levels of NAAG act to moderate the effect of PCP via a group II mGluR.

CONCLUSIONS

These data support the proposal that NAAG peptidase inhibition and elevation of synaptic NAAG levels represent a new therapeutic approach to treating the positive and negative symptoms of schizophrenia that are modeled by open channel NMDA receptor antagonists.

Monoamine reuptake inhibition and nicotine receptor antagonism reduce amplitude and gating of auditory evoked potentials

BACKGROUND

Sensory encoding deficits have been extensively studied as endophenotypic markers of schizophrenia using auditory evoked potentials. In order to increase understanding of the neurochemical basis of such deficits, we utilized an animal model to test whether monoamine reuptake inhibition and nicotine receptor antagonism reduce the amplitude and gating of the P20 and N40 auditory components.

METHODS

C57BL/6J mice received 12 days of chronic vehicle, bupropion, haloperidol or bupropion plus haloperidol. Auditory evoked potentials were then recorded in alert mice to measure the amplitude and gating of evoked components during a paired click paradigm similar to tasks used to measure the P50 and N100 auditory potentials in schizophrenia. Evoked potentials were recorded prior to and following acute nicotine.

RESULTS

Bupropion reduced the amplitude and gating of the N40 evoked potential in mice, similar to the P50 and N100 endophenotypes associated with sensory encoding deficits in schizophrenia. This deficit was fully reversed only by the combination of haloperidol and nicotine, suggesting that dopamine reuptake inhibition and nicotine antagonism both contribute to the observed phenotype. Furthermore, nicotine increased P20 amplitude across all groups supporting a role for nicotine agonists in pre-attentive sensory encoding deficits.

CONCLUSIONS

We propose that the combination of monoamine inhibition and nicotine receptor antagonism may serve as a useful model for preclinical screening of pharmaceutical compounds aimed at treating sensory encoding deficits in schizophrenia.

Anabasine, a selective nicotinic acetylcholine receptor agonist, antagonizes MK-801-elicited mouse popping behavior, an animal model of schizophrenia

The expression of the alpha7-nicotinic acetylcholine receptor is diminished in selected brain areas of patients with schizophrenia. This diminished expression may account for the pathophysiological deficits of sensory inhibition and smooth pursuit eye movement performance in these patients. Furthermore, the deficits in sensory inhibition and smooth pursuit eye movement performance in schizophrenia appear to be inherited in an autosomal dominant fashion; thus, the "alpha7-nicotinic acetylcholine receptor-deficiency" may be a necessary condition for expression of schizophrenia. This deficit has encouraged speculation about the possible therapeutic benefit of selective alpha7-nicotinic acetylcholine receptor agonist interventions in this disorder. In view of this, we sought to examine the effect of anabasine, a selective alpha7-nicotinic acetylcholine receptor agonist, on popping behavior in mice elicited by MK-801. MK-801, a high affinity analogue of phencyclidine (PCP), is a noncompetitive N-methyl-D-aspartic acid (NMDA) receptor antagonist that binds to the hydrophobic domain of this ligand-gated channel. PCP is known to precipitate a schizophreniform psychosis in susceptible individuals, causing productive (e.g. hallucinations) deficit (e.g. affective blunting, amotivation, and social withdrawal), cognitive and motor symptoms similar to those seen in naturally-occurring schizophrenia. Behaviors elicited by MK-801 in mice reflect a pharmacologically-induced state of NMDA receptor hypofunction (NRH), which has been proposed to exist in schizophrenia. Compounds that attenuate MK-801-elicited behaviors, which are identified in this animal model, may have the potential to treat schizophrenia, including deficit and cognitive symptoms. In the current study, anabasine attenuated MK-801-elicited popping at a dose that did not cause clonic seizures. The development of alpha7-nicotinic acetylcholine receptor agonist interventions for schizophrenia must consider their potential liability to elicit seizure activity.

Therapeutic effects of herbal extracts and constituents in animal models of psychiatric disorders

A search for novel pharmacotherapy from medicinal plants for psychiatric illnesses has progressed significantly in the past decade. This is reflected in the large number of herbal preparations for which psychotherapeutic potential has been evaluated in a variety of animal models. The objective of this review is to provide an overview of herbal extracts and constituents that have significant therapeutic effects in animal models of psychiatric illnesses. Eighty five individual herbs reviewed were classified as anxiolytic, antidepressant, neuroleptic, antidementia, or anti-substance abuse herbs. The full scientific name of each herb, herbal part used, active constituent, extract, dose range and route, animal model, possible mechanisms of action, and pertinent references are presented via synoptic tables. The herbal mixtures were also mentioned. A considerable number of herbal constituents whose behavioral effects and pharmacological actions have been well characterized may be good candidates for further investigations that may ultimately result in clinical use. The investigation of a large portion of the herbal extracts and herbal mixtures is in its infancy. Herbal remedies that have demonstrable psychotherapeutic activities have provided a potential to psychiatric pharmaceuticals and deserve increased attention in future studies.