A novel tauopathy model mimicking molecular and spatial aspects of human tau pathology.

Creating a mouse model that recapitulates human tau pathology is essential for developing strategies to intervene in tau-induced neurodegeneration. However, mimicking the pathological features seen in human pathology often involves a trade-off with artificial effects such as unexpected gene insertion and neurotoxicity from the expression system. To overcome these issues, we developed the rTKhomo mouse model by combining a transgenic CaMKII-tTA system with a P301L mutated 1N4R human tau knock-in at the Rosa26 locus with a C57BL/6J background. This model closely mimics human tau pathology, particularly in the hippocampal CA1 region, showing age-dependent tau accumulation, neuronal loss and neuroinflammation. Notably, whole-brain 3D staining and light-sheet microscopy revealed a spatial gradient of tau deposition from the entorhinal cortex to the hippocampus, similar to the spatial distribution of Braak neurofibrillary tangle staging. Furthermore, [18F]PM-PBB3 positron emission tomography imaging enabled the quantification and live monitoring of tau deposition. The rTKhomo mouse model shows potential as a promising next-generation preclinical tool for exploring the mechanisms of tauopathy and for developing interventions targeting the spatial progression of tau pathology.

Chemogenetic activation of mammalian brain neurons expressing insect Ionotropic Receptors by systemic ligand precursor administration.

Chemogenetic approaches employing ligand-gated ion channels are advantageous regarding manipulation of target neuronal population functions independently of endogenous second messenger pathways. Among them, Ionotropic Receptor (IR)-mediated neuronal activation (IRNA) allows stimulation of mammalian neurons that heterologously express members of the insect chemosensory IR repertoire in response to their cognate ligands. In the original protocol, phenylacetic acid, a ligand of the IR84a/IR8a complex, was locally injected into a brain region due to its low permeability of the blood-brain barrier. To circumvent this invasive injection, we sought to develop a strategy of peripheral administration with a precursor of phenylacetic acid, phenylacetic acid methyl ester, which is efficiently transferred into the brain and converted to the mature ligand by endogenous esterase activities. This strategy was validated by electrophysiological, biochemical, brain-imaging, and behavioral analyses, demonstrating high utility of systemic IRNA technology in the remote activation of target neurons in the brain.

Metallic radionuclide-labeled tetrameric 2,6-diisopropylphenyl azides for cancer treatment.

This study proposes a new method for radionuclide therapy that involves the use of oligomeric 2,6-diisopropylphenyl azides and a chelator to form stable complexes with metallic radionuclides. The technique works by taking advantage of the endogenous acrolein produced by cancer cells. The azides react with the acrolein to give a diazo derivative that immediately attaches to the nearest organelle, effectively anchoring the radionuclide within the tumor. Preliminary in vivo experiments were conducted on a human lung carcinoma xenograft model, demonstrating the feasibility of this approach for cancer treatment.

Simultaneous visualization of multiple radionuclides in vivo.

The insufficient energy and spatial resolutions of radionuclide imaging with conventional scintillation detectors restrict the visualization of multiple radionuclides and of microstructures in tissue. Here we report the development and performance of an imaging system equipped with a cadmium telluride diode detector that achieves an energy resolution of 1.7% at 140 keV and a spatial resolution of 250 µm. The combination of high-resolution spectra fitted to an X-ray analysis model of the emission lines of the radionuclides in a chosen energy band allowed us to accurately determine individual radiation activities from three radionuclides to simultaneously visualize thyroid tissue (via intravenously administered iodine-125), mandibular lymph nodes (via the intramuscular injection of indium-111) and parotid lymph nodes (via a subcutaneous injection of technetium-99m) in mice. Multi-radionuclide imaging may find advantageous applications in biomedical imaging.

Neural correlates of beneficial effects of young plasma treatment in aged mice: PET-SPM analyses and neuro-behavioural/molecular biological studies.

PURPOSE: To investigate the in vivo neurofunctional changes and therapeutic effects of young blood plasma (YBP) in aged mice, as well as the molecular mechanisms underlying the therapeutic effects of YBP ex vivo and in vitro. METHODS: Aged C57/BL6 mice received systemic administrations of phosphate-buffered saline (PBS) or YBP twice a week, for 4 weeks. In vivo 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) under conscious state and cognitive behavioural tests were performed after 4-week treatment. In addition, an in vitro senescent model was established, and the expressions of key cognition-associated proteins and/or the alterations of key neuronal pathways were analysed in both brain tissues and cultured cells. RESULTS: Aged mice treated with YBP demonstrated higher glucose metabolism in the right hippocampus and bilateral somatosensory cortices, and lower glucose metabolism in the right bed nucleus of stria terminalis and left cerebellum. YBP treatment exerted beneficial effects on the spatial and long-term social recognition memory, and significantly increased the expressions of several cognition-related proteins and altered the key neuronal signalling pathways in the hippocampus and somatosensory cortex. Further in vitro studies suggested that YBP but not aged blood plasma significantly upregulated the expressions of several cognition-associated proteins. CONCLUSION: Our results highlight the role of the hippocampus and somatosensory cortex in YBP-induced beneficial effects on recognition memory in aged mice. 18F-FDG PET imaging under conscious state provides a new avenue for exploring the mechanisms underlying YBP treatment against age-related cognitive decline.

PET imaging of neural activity, ß-amyloid, and tau in normal brain aging.

Normal brain aging is commonly associated with neural activity alteration, ß-amyloid (Aß) deposition, and tau aggregation, driving a progressive cognitive decline in normal elderly individuals. Positron emission tomography (PET) with radiotracers targeting these age-related changes has been increasingly employed to clarify the sequence of their occurrence and the evolution of clinically cognitive deficits. Herein, we reviewed recent literature on PET-based imaging of normal human brain aging in terms of neural activity, Aß, and tau. Neural hypoactivity reflected by decreased glucose utilization with PET imaging has been predominately reported in the frontal, cingulate, and temporal lobes of the normal aging brain. Aß PET imaging uncovers the pathophysiological association of Aß deposition with cognitive aging, as well as the potential mechanisms. Tau-associated cognitive changes in normal aging are likely independent of but facilitated by Aß as indicated by tau and Aß PET imaging. Future longitudinal studies using multi-radiotracer PET imaging combined with other neuroimaging modalities, such as magnetic resonance imaging (MRI) morphometry, functional MRI, and magnetoencephalography, are essential to elucidate the neuropathological underpinnings and interactions in normal brain aging.

Enhanced Retrieval of Taste Associative Memory by Chemogenetic Activation of Locus Coeruleus Norepinephrine Neurons.

The ability of animals to retrieve memories stored in response to the environment is essential for behavioral adaptation. Norepinephrine (NE)-containing neurons in the brain play a key role in the modulation of synaptic plasticity underlying various processes of memory formation. However, the role of the central NE system in memory retrieval remains unclear. Here, we developed a novel chemogenetic activation strategy exploiting insect olfactory ionotropic receptors (IRs), termed "IR-mediated neuronal activation," and used it for selective stimulation of NE neurons in the locus coeruleus (LC). Drosophila melanogaster IR84a and IR8a subunits were expressed in LC NE neurons in transgenic mice. Application of phenylacetic acid (a specific ligand for the IR84a/IR8a complex) at appropriate doses induced excitatory responses of NE neurons expressing the receptors in both slice preparations and in vivo electrophysiological conditions, resulting in a marked increase of NE release in the LC nerve terminal regions (male and female). Ligand-induced activation of LC NE neurons enhanced the retrieval process of conditioned taste aversion without affecting taste sensitivity, general arousal state, and locomotor activity. This enhancing effect on taste memory retrieval was mediated, in part, through α1- and ß-adrenergic receptors in the basolateral nucleus of the amygdala (BLA; male). Pharmacological inhibition of LC NE neurons confirmed the facilitative role of these neurons in memory retrieval via adrenergic receptors in the BLA (male). Our findings indicate that the LC NE system, through projections to the BLA, controls the retrieval process of taste associative memory.SIGNIFICANCE STATEMENT Norepinephrine (NE)-containing neurons in the brain play a key role in the modulation of synaptic plasticity underlying various processes of memory formation, but the role of the NE system in memory retrieval remains unclear. We developed a chemogenetic activation system based on insect olfactory ionotropic receptors and used it for selective stimulation of NE neurons in the locus coeruleus (LC) in transgenic mice. Ligand-induced activation of LC NE neurons enhanced the retrieval of conditioned taste aversion, which was mediated, in part, through adrenoceptors in the basolateral amygdala. Pharmacological blockade of LC activity confirmed the facilitative role of these neurons in memory retrieval. Our findings indicate that the LC-amygdala pathway plays an important role in the recall of taste associative memory.

A new mouse model of GLUT1 deficiency syndrome exhibits abnormal sleep-wake patterns and alterations of glucose kinetics in the brain.

Dysfunction of glucose transporter 1 (GLUT1) proteins causes infantile epilepsy, which is designated as a GLUT1 deficiency syndrome (GLUT1DS; OMIM #606777). Patients with GLUT1DS display varied clinical phenotypes, such as infantile seizures, ataxia, severe mental retardation with learning disabilities, delayed development, hypoglycorrhachia, and other varied symptoms. Glut1Rgsc200 mutant mice mutagenized with N-ethyl-N-nitrosourea (ENU) carry a missense mutation in the Glut1 gene that results in amino acid substitution at the 324th residue of the GLUT1 protein. In this study, these mutants exhibited various phenotypes, including embryonic lethality of homozygotes, a decreased cerebrospinal-fluid glucose value, deficits in contextual learning, a reduction in body size, seizure-like behavior and abnormal electroencephalogram (EEG) patterns. During EEG recording, the abnormality occurred spontaneously, whereas the seizure-like phenotypes were not observed at the same time. In sleep-wake analysis using EEG recording, heterozygotes exhibited a longer duration of wake times and shorter duration of non-rapid eye movement (NREM) sleep time. The shortened period of NREM sleep and prolonged duration of the wake period may resemble the sleep disturbances commonly observed in patients with GLUT1DS and other epilepsy disorders. Interestingly, an in vivo kinetic analysis of glucose utilization by positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose imaging revealed that glucose transportation was reduced, whereas hexokinase activity and glucose metabolism were enhanced. These results indicate that a Glut1Rgsc200 mutant is a useful tool for elucidating the molecular mechanisms of GLUT1DS.This article has an associated First Person interview with the joint first authors of the paper.

MHC matching improves engraftment of iPSC-derived neurons in non-human primates.

The banking of human leukocyte antigen (HLA)-homozygous-induced pluripotent stem cells (iPSCs) is considered a future clinical strategy for HLA-matched cell transplantation to reduce immunological graft rejection. Here we show the efficacy of major histocompatibility complex (MHC)-matched allogeneic neural cell grafting in the brain, which is considered a less immune-responsive tissue, using iPSCs derived from an MHC homozygous cynomolgus macaque. Positron emission tomography imaging reveals neuroinflammation associated with an immune response against MHC-mismatched grafted cells. Immunohistological analyses reveal that MHC-matching reduces the immune response by suppressing the accumulation of microglia (Iba-1+) and lymphocytes (CD45+) into the grafts. Consequently, MHC-matching increases the survival of grafted dopamine neurons (tyrosine hydroxylase: TH+). The effect of an immunosuppressant, Tacrolimus, is also confirmed in the same experimental setting. Our results demonstrate the rationale for MHC-matching in neural cell grafting to the brain and its feasibility in a clinical setting.Major histocompatibility complex (MHC) matching improves graft survival rates after organ transplantation. Here the authors show that in macaques, MHC-matched iPSC-derived neurons provide better engraftment in the brain, with a lower immune response and higher survival of the transplanted neurons.

Human iPS cell-derived dopaminergic neurons function in a primate Parkinson's disease model.

Induced pluripotent stem cells (iPS cells) are a promising source for a cell-based therapy to treat Parkinson's disease (PD), in which midbrain dopaminergic neurons progressively degenerate. However, long-term analysis of human iPS cell-derived dopaminergic neurons in primate PD models has never been performed to our knowledge. Here we show that human iPS cell-derived dopaminergic progenitor cells survived and functioned as midbrain dopaminergic neurons in a primate model of PD (Macaca fascicularis) treated with the neurotoxin MPTP. Score-based and video-recording analyses revealed an increase in spontaneous movement of the monkeys after transplantation. Histological studies showed that the mature dopaminergic neurons extended dense neurites into the host striatum; this effect was consistent regardless of whether the cells were derived from patients with PD or from healthy individuals. Cells sorted by the floor plate marker CORIN did not form any tumours in the brains for at least two years. Finally, magnetic resonance imaging and positron emission tomography were used to monitor the survival, expansion and function of the grafted cells as well as the immune response in the host brain. Thus, this preclinical study using a primate model indicates that human iPS cell-derived dopaminergic progenitors are clinically applicable for the treatment of patients with PD.

Serotonin rebalances cortical tuning and behavior linked to autism symptoms in 15q11-13 CNV mice.

Serotonin is a critical modulator of cortical function, and its metabolism is defective in autism spectrum disorder (ASD) brain. How serotonin metabolism regulates cortical physiology and contributes to the pathological and behavioral symptoms of ASD remains unknown. We show that normal serotonin levels are essential for the maintenance of neocortical excitation/inhibition balance, correct sensory stimulus tuning, and social behavior. Conversely, low serotonin levels in 15q dup mice (a model for ASD with the human 15q11-13 duplication) result in impairment of the same phenotypes. Restoration of normal serotonin levels in 15q dup mice revealed the reversibility of a subset of ASD-related symptoms in the adult. These findings suggest that serotonin may have therapeutic potential for discrete ASD symptoms.

Involvement of the Septo-Hippocampal Cholinergic Pathway in Association with Septal Acetylcholinesterase Upregulation in a Mouse Model of Tauopathy.

BACKGROUND: Cholinergic cell loss in the basal forebrain, the major source of hippocampal cholinergic projections, has been implicated in Alzheimer's disease. OBJECTIVE: To examine whether the septohippocampal pathway is involved in tauopathy model mice and to elucidate the tau-associated mechanism underlying cholinergic alteration. METHODS: Adult (6 to 8 months old) and old (16 to 18 months old) transgenic mice expressing wild-type human tau, Tg601, were examined using Ex vivo diffusion tensor magnetic resonance imaging (DTI) and 2-[18F]fluoro- 2-deoxy-D-glucose positron emission tomography (FDG-PET). Choline acetyltransferase (ChAT)-positive neurons in the medial septum (MS) were counted by stereological methods. Acetylcholinesterase (AChE) activity and AChE mRNA in 6 brain regions were measured. RESULTS: Ex vivo DTI revealed that the number of fractional anisotropy (FA) streamlines in the septohippocampal tract decreased with age in Tg601 mice. The FA value in the septum was lower in old Tg601 mice than in non-tg mice. A voxel-based statistical analysis of FDG-PET revealed the presence of low glucose uptake areas, involving the MS in adults, and spread over regions including the hippocampal dentate gyrus in old mice. In the MS, the number of choline acetyltransferase (ChAT)-positive neurons decreased in old Tg601 mice. AChE activity and AChE mRNA T transcripts were exclusively higher in the septum. CONCLUSION: The upregulation of AChE in the septum may result in the selective degeneration of the septohippocampal cholinergic pathway in the tauopathy mouse model.

[18F]FDG Uptake in the Aortic Wall Smooth Muscle of Atherosclerotic Plaques in the Simian Atherosclerosis Model.

Atherosclerosis is a self-sustaining inflammatory fibroproliferative disease that progresses in discrete stages and involves a number of cell types and effector molecules. Recently, [18F]fluoro-2-deoxy-D-glucose- ([18F]FDG-) positron emission tomography (PET) has been suggested as a tool to evaluate atherosclerotic plaques by detecting accumulated macrophages associated with inflammation progress. However, at the cellular level, it remains unknown whether only macrophages exhibit high uptake of [18F]FDG. To identify the cellular origin of [18F]FDG uptake in atherosclerotic plaques, we developed a simian atherosclerosis model and performed PET and ex vivo macro- and micro-autoradiography (ARG). Increased [18F]FDG uptake in the aortic wall was observed in high-cholesterol diet-treated monkeys and WHHL rabbits. Macro-ARG of [18F]FDG in aortic sections showed that [18F]FDG was accumulated in the media and intima in the simian model as similar to that in WHHL rabbits. Combined analysis of micro-ARG with immunohistochemistry in the simian atherosclerosis model revealed that most cellular [18F]FDG uptake observed in the media was derived not only from the infiltrated macrophages in atherosclerotic plaques but also from the smooth muscle cells (SMCs) of the aortic wall in atherosclerotic lesions.

Increase in [18F]-Fluoroacetate Uptake in Patients With Chronic Hemodynamic Cerebral Ischemia.

BACKGROUND AND PURPOSE: [18F]-fluoroacetate ((18)F-FACE) can be used for evaluating glial cell metabolism. Experimental studies have shown an increase in (18)F-FACE uptake in rodent models of cerebral ischemia. The aim of this study was to determine whether (18)F-FACE uptake is increased in the noninfarcted cerebral cortex in patients with hemodynamic ischemia owing to atherosclerotic internal carotid artery or middle cerebral artery disease. METHODS: We evaluated 9 symptomatic patients with unilateral atherosclerotic internal carotid artery or middle cerebral artery disease and no cortical infarction using positron emission tomography with (18)F-FACE and (15)O-gases. (18)F-FACE uptake during 40 to 60 minutes after injection was compared with the cerebral blood flow, cerebral metabolic rate of oxygen, oxygen extraction fraction, and cerebral blood volume in the middle cerebral artery distributions. RESULTS: Significant decreases of cerebral blood flow and cerebral metabolic rate of oxygen and increases of oxygen extraction fraction and cerebral blood volume were found in the hemisphere ipsilateral to the arterial lesion, and (18)F-FACE uptake in this region was greater than that in the contralateral hemisphere. The relative (18)F-FACE uptake (ipsilateral/contralateral ratio) was negatively correlated with cerebral blood flow or cerebral metabolic rate of oxygen values and was positively correlated with oxygen extraction fraction values. Multivariate analysis showed that the ipsilateral/contralateral (18)F-FACE uptake ratio was independently correlated with the cerebral blood flow (or oxygen extraction fraction) and cerebral metabolic rate of oxygen values. CONCLUSIONS: In patients with atherosclerotic internal carotid artery or middle cerebral artery disease, (18)F-FACE uptake is increased in the noninfarcted cerebral cortex with chronic hemodynamic ischemia characterized by misery perfusion with decreased oxygen metabolism. Increased (18)F-FACE uptake may indicate the cortical regions that are at particular risk for ischemic damage.

Effects of pitavastatin in Japanese patients with chronic heart failure: the Pitavastatin Heart Failure Study (PEARL Study).

BACKGROUND: Recent clinical trials using rosuvastatin, a hydrophilic statin, did not show beneficial effects on cardiovascular events in patients with heart failure. We examined the cardioprotective effects of pitavastatin, a lipophilic statin, on Japanese patients with chronic heart failure (CHF). METHODS AND RESULTS: A total of 574 Japanese patients with CHF were randomly assigned to the pitavastatin group (n=288) or the control group (n=286). There was no significant difference between the 2 groups for the primary outcome, which was a composite of cardiac death and hospitalization for worsening HF (adjusted hazard ratio (aHR): 0.922, 95% confidence interval (CI): 0.632-1.345, P=0.672). A strongly significant statistical interaction between the effect of pitavastatin and left ventricular ejection fraction (LVEF) was found (P=0.004). In patients with LVEF ≥30%, a significant reduction in the primary outcome (aHR: 0.525, 95% CI: 0.308-0.896, P=0.018) was observed in the pitavastatin group. Pitavastatin did not show any effects on the primary outcome (aHR: 1.582, 95% CI: 0.890-2.813, P=0.118) in the subgroup of patients with LVEF <30%. CONCLUSIONS: Pitavastatin did not reduce cardiac death or hospitalization for worsening HF in Japanese patients with CHF. (UMIN-ID: UMINC000000428).

Imaging epigenetic regulation by histone deacetylases in the brain using PET/MRI with ¹8F-FAHA.

Epigenetic modifications mediated by histone deacetylases (HDACs) play important roles in the mechanisms of different neurologic diseases and HDAC inhibitors (HDACIs) have shown promise in therapy. However, pharmacodynamic profiles of many HDACIs in the brain remain largely unknown due to the lack of validated methods for noninvasive imaging of HDAC expression-activity. In this study, dynamic PET/CT imaging was performed in 4 rhesus macaques using [(18)F]FAHA, a novel HDAC substrate, and [(18)F]fluoroacetate, the major radio-metabolite of [(18)F]FAHA, and fused with corresponding MR images of the brain. Quantification of [(18)F]FAHA accumulation in the brain was performed using a customized dual-tracer pharmacokinetic model. Immunohistochemical analyses of brain tissue revealed the heterogeneity of expression of individual HDACs in different brain structures and cell types and confirmed that PET/CT/MRI with [(18)F]FAHA reflects the level of expression-activity of HDAC class IIa enzymes. Furthermore, PET/CT/MRI with [(18)F]FAHA enabled non-invasive, quantitative assessment of pharmacodynamics of HDAC inhibitor SAHA in the brain.

The action site of the synthetic kainoid (2S,3R,4R)-3-carboxymethyl-4-(4-methylphenylthio)pyrrolidine-2-carboxylic acid (PSPA-4), an analogue of Japanese mushroom poison acromelic acid, for allodynia (tactile pain).

We previously demonstrated that intrathecal (i.t.) administration of acromelic acid A (Acro-A) induced allodynia in mice and that simultaneous administration of (2S,3R,4R)-3-carboxymethyl-4-(phenylthio)pyrrolidine-2-carboxylic acid (PSPA-1), an Acro-A analogue, attenuated the Acro-A-induced allodynia. To clarify a mechanism of PSPA-1, we attached methyl radical to PSPA-1 and synthesized (2S,3R,4R)-3-carboxymethyl-4-(4-methylphenylthio) pyrrolidine-2-carboxylic acid (PSPA-4) and [(11)C]PSPA-4 for behavioral and autoradiography studies. Although PSPA-4 inhibited the Acro-A-induced allodynia in a dose-dependent manner from 1 to 10 fg/mouse, PSPA-4 itself induced allodynia at 10 to 100 pg/mouse. In vitro autoradiography, [(11)C]PSPA-4 was specifically bound to the rat brain and spinal cord, and the binding was significantly displaced by PSPA-1 and kainic acid, but not by AMPA and antagonists of NMDA, AMPA and kainate receptors. Conversely, [(3)H]kainate was specifically bound to the rat brain and the dorsal horn of spinal cord, and the binding was significantly displaced by PSPA-1 and PSPA-4. The PSPA-4-induced allodynia was blocked by the AMPA/kainate antagonist GYKI53655, but not by kainate antagonists NS102 and UBP296. PSPA-4 increased intracellular Ca(2+) concentration in 27.9% of cultured dorsal root ganglion neurons responding to glutamate, much higher than kainate in 10.9% of them. Taken together, these results suggest that PSPA-4 attenuated the Acro-A-induced allodynia at low doses and induced allodynia at high doses via a binding site different from known kainate antagonists. The development of a radio-labeled PSPA-4 will enable us to promote the understanding of the action mechanism not only of Acro-A, but also of pain transmission in the periphery and central nervous system.

Evaluation of dopamine D2/D3 and serotonin 5-HT2A receptor occupancy for a novel antipsychotic, lurasidone, in conscious common marmosets using small-animal positron emission tomography.

RATIONALE: Lurasidone is a novel antipsychotic drug with potent binding affinity for dopamine D(2) and serotonin (5-hydroxytryptamine, 5-HT)(2A), 5-HT(7), and 5-HT(1A) receptors. Previous pharmacological studies have revealed that lurasidone exhibits a preferable profile (potent antipsychotic activity and lower incidence of catalepsy) to other antipsychotic drugs, although the contribution of receptor subtypes to this profile remains unclear. OBJECTIVES: To compare target engagements of lurasidone with those of an atypical antipsychotic, olanzapine, we performed evaluation of dopamine D(2)/D(3) and serotonin 5-HT(2A) receptor occupancy in vivo by positron emission tomography (PET) with conscious common marmosets. METHODS: We measured brain receptor occupancies in conscious common marmosets after oral administrations of lurasidone or olanzapine by PET with [(11)C]raclopride and [(11)C]R-(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine methanol (MDL 100907) for D(2)/D(3) and 5-HT(2A) receptors, respectively. RESULTS: Increases in brain D(2)/D(3) receptor occupancies of both lurasidone and olanzapine, which reached >80 % at maximum, were observed in the striatum with significant correlations to plasma drug levels. However, lurasidone showed lower 5-HT(2A) receptor occupancy in the frontal cortex within the same dose range, while olanzapine showed broadly comparable 5-HT(2A) and D(2)/D(3) receptor occupancies. CONCLUSIONS: Compared with olanzapine, lurasidone preferentially binds to D(2)/D(3) receptors rather than 5-HT(2A) receptors in common marmosets. These results suggest that the contribution of in vivo 5-HT(2A) receptor blocking activity to the pharmacological profile of lurasidone might differ from olanzapine in terms of the low risk of extrapyramidal syndrome and efficacy against negative symptoms.

The food reaching test: a sensitive test of behavioral improvements by deep brain stimulation in MPTP-treated monkey.

We modified an objective behavioral test, namely the food reaching test (FRT), for quantitative assessment of motor performance improved by deep brain stimulation (DBS) of the subthalamic nucleus (STN) in the Parkinsonian monkeys. The symptomatic features and their severity in 3 monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were evaluated with a subjective monkey Parkinson's disease rating scale (PDRS). We then performed STN-DBS with the minimum current intensity that stopped the tremor. The time required for the monkeys to pick up all 5 pieces of potato (FRT time) was measured as a major index to evaluate bradykinesia. The success rate was adopted as another index for assessing overall motor impairments. Although both FRT time and PDRS score were similarly improved by STN-DBS, change of FRT time appeared more sensitive than that of PDRS scores. FRT is an easily trained behavioral test with high objectivity and sensitivity that can be applied for assessing motor performance in MPTP-treated monkeys during experiments in a restrained condition such as functional imaging of the brain.