Dual 5-HT and 5-HT Receptor Inverse Agonist That Affords In Vivo Antipsychotic Efficacy with Minimal hERG Inhibition for the Treatment of Dementia-Related Psychosis.

Psychosis is a distressing symptom commonly occurring in people with dementia. To treat Parkinson's disease psychosis, pimavanserin (), a 5-HT receptor inverse agonist having minimal 5-HT receptor affinity and no dopamine D receptor affinity, was approved in the United States, but not for dementia-related psychosis due to limited efficacy issues. Herein, we report on the identification of a potent and dual 5-HT and 5-HT receptor inverse agonist having minimal hERG inhibition, after having demonstrated the involvement of both 5-HT and 5-HT receptors to deliver antipsychotic efficacy in an MK-801-induced locomotor model and having conducted 5-HT and 5-HT occupancy studies including a surrogate method.

Relationship between receptor occupancy and the antinociceptive effect of mu opioid receptor agonists in male rats.

The analgesic mechanisms of mu opioid receptor (MOR) agonists, including receptor occupancy at the site of action, are not completely understood. The aims of the present study were to evaluate: (i) receptor occupancy in the rat brain after administration of MOR agonists; (ii) the relationship between occupancy and the antinociceptive effect. Morphine (2 or 4 mg/kg) or oxycodone (1 or 3 mg/kg) was subcutaneously administered to rats.

Imaging of drug and metabolite distribution by MS: case studies.

Analysis of drug and metabolite distribution is essential for understanding of the mechanisms underlying the pharmacological or toxicological effects. MS imaging (MSI) can visualize the distribution of drugs or biological molecules in tissue sections without radiolabeling, and distinguish between the distribution of a drug and that of its metabolites in tissue sections. Therefore, it is expected to be a potent imaging technique for drug distribution studies.

Imaging of reactive oxygen species using [(3)H]hydromethidine in mice with cisplatin-induced nephrotoxicity.

Background: Reactive oxygen species (ROS) have been implicated in cisplatin-induced nephrotoxicity. The aim of this study was to investigate the potential of using [(3)H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([(3)H]hydromethidine) for ex vivo imaging of regional ROS overproduction in mouse kidney induced by cisplatin.

Methods: Male C57BL/6 J mice were intraperitoneally administered with a single dose of cisplatin (30 mg/kg).

Imaging of reactive oxygen species in focal ischemic mouse brain using a radical trapping tracer [(3)H]hydromethidine.

Background: Reactive oxygen species (ROS) have been implicated in the pathophysiology of the brain after ischemic stroke. In this study, we investigate the generation of brain ROS after transient focal ischemia in mice using a radical trapping radiotracer, [(3)H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([(3)H]hydromethidine), which we recently reported as a ROS imaging probe. We also examined the effect of dimethylthiourea (DMTU), a hydroxyl radical scavenger, on brain ROS generation and infarct volume after transient focal ischemia in mice.

Using Improved Serial Blood Sampling Method of Mice to Study Pharmacokinetics and Drug-Drug Interaction.

In pharmacokinetic evaluation of mice, using serial sampling methods rather than a terminal blood sampling method could reduce the number of animals needed and lead to more reliable data by excluding individual differences. In addition, using serial sampling methods can be valuable for evaluation of the drug-drug interaction (DDI) potential of drug candidates. In this study, we established an improved method for serially sampling the blood from one mouse by only one incision of the lateral tail vein, and investigated whether our method could be adapted to pharmacokinetic and DDI studies.

Using improved serial blood sampling method of mice to study pharmacokinetics and drug-drug interaction.

In pharmacokinetic evaluation of mice, using serial sampling methods rather than a terminal blood sampling method could reduce the number of animals needed and lead to more reliable data by excluding individual differences. In addition, using serial sampling methods can be valuable for evaluation of the drug-drug interaction (DDI) potential of drug candidates. In this study, we established an improved method for serially sampling the blood from one mouse by only one incision of the lateral tail vein, and investigated whether our method could be adapted to pharmacokinetic and DDI studies.

In vivo imaging of reactive oxygen species in mouse brain by using [3H]hydromethidine as a potential radical trapping radiotracer.

To assess reactive oxygen species (ROS) production by detecting the fluorescent oxidation product, hydroethidine has been used extensively. The present study was undertaken to evaluate the potential of the hydroethidine derivative as a radiotracer to measure in vivo brain ROS production. [(3)H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([(3)H]Hydromethidine) was synthesized, and evaluated using in vitro radical-induced oxidization and in vivo brain ROS production model.

Quantification of small molecule drugs in biological tissue sections by imaging mass spectrometry using surrogate tissue-based calibration standards.

Quantitative analysis of administered drugs in biological tissues is essential for understanding the mechanisms underlying their efficacy or toxicity. Imaging mass spectrometry (IMS) may allow the quantification of targeted drugs in tissue sections along with the visualization of their spatial distribution. In this study, surrogate tissue-based calibration standards were prepared to quantify a small molecule drug (S-777469 or raclopride) in tissue sections of mice administered with the drug, followed by analysis with a linear ion trap mass spectrometer equipped with a matrix-assisted laser desorption/ionization (MALDI) source.

Quantitative imaging of a therapeutic peptide in biological tissue sections by MALDI MS.

Background: Therapeutic peptides and proteins are being increasingly explored as potential therapeutic agents for molecular-targeted therapy, and the requirement for quantitative bioanalytical tools for such molecules has been discussed.

Results: The distribution of octreotide, a synthetic octapeptide analog of somatostatin, in the liver and kidney of mice administered with the analog was clearly visualized by MALDI-Imaging MS (IMS). The developed MALDI-IMS analytical method successfully quantified the amount of octreotide on tissue sections (accuracy was 76-127%) and the 2,5-dihydroxybenzoic acid-based normalization method was effective.

Quantitative analysis of pharmaceutical drug distribution in multiple organs by imaging mass spectrometry.

Rationale: Recently, the requirement for a quantitative research method using imaging mass spectrometry (IMS) to be developed has been discussed. Specifically, the simultaneous quantification of a drug in multiple organs by using whole-body sections could be insightful for the pharmaceutical industry in the study of drug distribution.

Methods: Frozen whole-body sections were obtained from mice injected with raclopride, a dopamine D2 receptor selective antagonist, and coated with a matrix-assisted laser desorption/ionization (MALDI) matrix compound.

Tissue factor detection for selectively discriminating unstable plaques in an atherosclerotic rabbit model.

Unlabelled: Tissue factor (TF), a transmembrane glycoprotein that acts as an essential cofactor to factor VII/VIIa, initiates the exogenous blood coagulation cascade leading to thrombin generation and subsequent thrombus formation in vivo. TF expression is closely related to plaque vulnerability, and high TF expression is shown in macrophage-rich atheromatous lesions, making TF a potential target for detecting atheromatous lesions in vivo. Thus, we prepared (99m)Tc-labeled anti-TF-monoclonal antibody (TF-mAb) IgG as a molecular probe and evaluated its usefulness to achieve TF-specific imaging using myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits.

Imaging with radiolabelled anti-membrane type 1 matrix metalloproteinase (MT1-MMP) antibody: potentials for characterizing atherosclerotic plaques.

Purpose: Membrane type 1 matrix metalloproteinase (MT1-MMP) activates pro-MMP-2 and pro-MMP-13 to their active forms and plays important roles in the destabilization of atherosclerotic plaques. This study sought to determine the usefulness of (99m)Tc-labelled monoclonal antibody (mAb), recognizing MT1-MMP, for imaging atherosclerosis in a rabbit model (WHHLMI rabbits).

Methods: Anti-MT1-MMP monoclonal IgG(3) and negative control IgG(3) were radiolabelled with (99m)Tc after derivatization with 6-hydrazinonicotinic acid (HYNIC) to yield (99m)Tc-MT1-MMP mAb and (99m)Tc-IgG(3), respectively.

Development of a radiolabeled probe for detecting membrane type-1 matrix metalloproteinase on malignant tumors.

Membrane type-1 matrix metalloproteinase (MT1-MMP) expressed on the tumor cell surface activates pro-MMP-2 and pro-MMP-13 to exacerbate the malignancy, suggesting its suitability as a target molecule for diagnosis by in vivo molecular imaging. Thus, we prepared radiolabeled anti-MT1-MMP monoclonal antibody (mAb) as a novel radiolabeled probe for detecting MT1-MMP in vivo and evaluated its usefulness in breast tumor-bearing rodents. (99m)Tc-anti-MT1-MMP mAb was prepared using HYNIC as a bifunctional chelating agent and immunoreactivity was evaluated by flow cytometry.

Targeting of lectinlike oxidized low-density lipoprotein receptor 1 (LOX-1) with 99mTc-labeled anti-LOX-1 antibody: potential agent for imaging of vulnerable plaque.

Unlabelled: Lectinlike oxidized low-density lipoprotein (LDL) receptor 1 (LOX-1), a cell surface receptor for oxidized LDL, has been implicated in vascular cell dysfunction related to plaque instability, which could be a potential target for an atherosclerosis imaging tracer. In this study, we designed and prepared (99m)Tc-labeled anti-LOX-1 monoclonal IgG and investigated its usefulness as an atherosclerosis imaging agent.

Methods: Anti-LOX-1 monoclonal IgG and control mouse IgG2a were labeled with (99m)Tc after derivatization with 6-hydrazinonicotinic acid to yield (99m)Tc-LOX-1-mAb and (99m)Tc-IgG2a, respectively.

Prominent lectin-like oxidized low density lipoprotein (LDL) receptor-1 (LOX-1) expression in atherosclerotic lesions is associated with tissue factor expression and apoptosis in hypercholesterolemic rabbits.

Background: Despite increasing in vitro evidence that lectin-like oxidized low density lipoprotein (LDL) receptor-1 (LOX-1), a cell-surface receptor for oxidized LDL, is implicated in the atherogenesis and thrombus formation, its in vivo participation to the atherosclerotic plaque destabilization, rupture and thrombus formation remains unclear. Here, we compared the in vivo expression of LOX-1, with tissue factor (TF) expression and cell apoptosis, in atherosclerotic lesions of myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits.

Methods And Results: We prepared sixty series of cross sections in the aortic arch and the thoracic aorta from four WHHLMI rabbits.

Distribution profiles of membrane Type-1 matrix metalloproteinase (MT1-MMP), matrix metalloproteinase-2 (MMP-2) and cyclooxygenase-2 (COX-2) in rabbit atherosclerosis: comparison with plaque instability analysis.

Background: Despite increasing evidence that membrane type 1 matrix metalloproteinase (MT1-MMP), matrix metalloproteinase-2 (MMP-2), and cyclooxygenase-2 (COX-2) are involved in the pathogenesis of atherosclerosis, the possible links among these enzymes remain unclear. Accordingly, we investigated the distribution of MT1-MMP, MMP-2, and COX-2 immunohistologically in the atherosclerotic lesions of hypercholesterolemic (WHHLMI) rabbits.

Methods And Results: Distribution of MT1-MMP, MMP-2, and COX-2 was examined by immunohistochemical staining using sixty cross sections of the ascending-arch and thoracic aortas prepared from 4 WHHLMI rabbits.

99mTc-Annexin A5 for noninvasive characterization of atherosclerotic lesions: imaging and histological studies in myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits.

Purpose: Apoptosis is commonly observed in advanced atherosclerotic lesions. 99mTc-annexin A5 (99mTc-annexin V) has been proposed as a potential tracer for imaging apoptosis in atherosclerotic plaques. Accordingly, we determined the usefulness of 99mTc-annexin A5 as an atherosclerosis imaging tracer in a rabbit model (myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits; WHHLMI rabbits) of spontaneous atherosclerosis.