[11C]-DASB microPET imaging in the aged rat: Frontal and meso-thalamic increases in serotonin transporter binding

Whereas molecular imaging studies in the aging human brain have predominantly demonstrated reductions in serotonin transporter (5-HTT) availability, the majority of the rodent studies, using autoradiographic methods, report increases in neural 5-HTT levels with age. To our knowledge, however, no previous rodent studies have assessed this topic in vivo, and therefore it remains unclear whether this discrepancy arises from methodological or inter-species differences. We performed an [(11)C]-DASB microPET study to evaluate the effects of aging on 5-HTT availability in the rat brain. To generate binding potential estimates, quantitative tracer kinetic modeling was applied using the simplified r…

Diastereomeric Differentiation in the Quenching of Excited States by Hydrogen Donors

In vivo biodistribution of amino-functionalized ceria nanoparticles in rats using positron emission tomography.

A variety of nanoparticles have been proposed for several biomedical applications. To gauge the therapeutic potential of these nanoparticles, in vivo biodistribution is essential and mandatory. In the present study, ceria nanoparticles (5 nm average particle size) were labeled with F-18 to study their in vivo biodistribution in rats by positron emission tomography (PET). The F-18 isotope was anchored by reaction of N-succinimidyl 4-[F-18]fluorobenzoate (F-18-SFB) with a modified nanoparticle surface obtained by silylation with 3-aminopropylsilyl. Radiolabeled ceria nanoparticles accumulated mainly in lungs, spleen, and liver. Metabolic products of the radiolabeled nanoparticulate material w…

THE EFFECTS OF AGING ON DOPAMINERGIC NEUROTRANSMISSION A microPET STUDY OF [11C]-raclopride BINDING IN THE AGED RODENT BRAIN

Rodent models are frequently used in aging re search to investigate biochemical age effects and aid in the development of therapies for pathological and non pathological age related degenerative processes In order to validate the use of animal models in aging research and pave the way for longitudinal intervention based animal studies, the consistency of cerebral aging processes across species needs to be evaluated The dopaminergic system seems particularly susceptible to the aging process, and one of the most consistent findings in human brain aging research is a decline in striatal D2-like receptor (D2R) availability, quantifiable by positron emission tomography (PET) imaging In this stud…

Erythrocytes labeled with [18F]SFB as an alternative to radioactive CO for quantification of blood volume with PET

Inhaled radioactive CO is currently the tracer of choice for blood volume quantification by positron emission tomography (PET). This measurement is of great interest for several clinical and research applications. However, owing to the short half-life of the radiolabeled CO, it can only be used in centers equipped with a cyclotron. In the present work, we propose an alternative method to label the red blood cells with [(18) F] in order to obtain blood volume measurements by PET. The use of the radioactive synthon [(18) F] N-succinimidyl 4-[(18) F]fluorobenzoate ([(18) F]SFB) was evaluated for erythrocyte labeling and PET blood volume imaging. The images provided by [(18) F]SFB labeled eryth…

In vivo molecular imaging of the GABA/benzodiazepine receptor complex in the aged rat brain

The GABA-ergic system, known to regulate neural tissue genesis during cortical development, has been postulated to play a role in cerebral aging processes. Using in vivo molecular imaging and voxel-wise quantification, we aimed to assess the effects of aging on the benzodiazepine (BDZ) recognition site of the GABA A receptor. To visualize BDZ site availability, [C-11]-flumazenil microPET acquisitions were conducted in young and old rats. The data were analyzed and region of interest analyses were applied to validate the voxel-wise approach. We observed decreased [C-11]-flumazenil binding in the aged rat brains in comparison with the young control group. More specifically, clusters of reduce…