Quantitative in vivo measurement of central benzodiazepine receptors in the brain of cats by use of positron-emission tomography and [11C]flumazenil.
OBJECTIVE
To map central benzodiazepine receptors (BZRs) in the brain of cats by use of positron-emission tomography (PET) and [11C]flumazenil.


METHODS
6 male cats that weighed between 2.0 and 3.6 kg.


METHODS
Brain images obtained by PET evaluation of [11C]flumazenil were superimposed on T2-weighted magnetic-resonance imaging (MRI) scans of the same cats. Detailed anatomic regions, such as the cerebral cortex, striatum, thalamus, midbrain, and cerebellum, on the PET images were evident by PET-MRI registration. Regional binding of [11C]flumazenil to BZRs was quantitatively measured by use of a model with 2 tissue compartments and 4 variables.


RESULTS
The highest value for distribution volume was observed in the cerebral cortex, and the lowest value was found in the midbrain of cats.


CONCLUSIONS
Binding of [11C]flumazenil to BZRs in the brain of cats can be quantitatively measured by use of PET with the aid of PET-MRI registration. It is difficult to diagnose changes in these neuroreceptors within the field of current veterinary science. In the future, PET should prove useful for investigating and diagnosing brain disorders in animals in clinical settings.
Shimada
Yuhei
Y
Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1 Naka-cho, Itabashi-ku, Tokyo 172-0022, Japan.
Kiyosawa
Motohiro
M
Nariai
Tadashi
T
Oda
Keiichi
K
Toyama
Hinako
H
Ono
Kenichirou
K
Senda
Michio
M
Ishiwata
Kiichi
K
D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002250:Carbon Radioisotopes; D002415:Cats / Q000378:metabolism*; D005442:Flumazenil / Q000378:metabolism*; D018757:GABA Modulators / Q000378:metabolism*; D008297:Male; D011963:Receptors, GABA-A / Q000032:analysis / Q000378:metabolism*; D014055:Tomography, Emission-Computed / Q000379:methods*
D002250:Carbon Radioisotopes; D018757:GABA Modulators; D011963:Receptors, GABA-A; D005442:Flumazenil