Unique Distribution of Aromatase in the Human Brain: In Vivo Studies With PET and [N-Methyl-11C]Vorozole

Journal Article · Fri Oct 01 00:00:00 EDT 2010 · Synapse

DOI:https://doi.org/10.1002/syn.20791· OSTI ID:1014325

Biegon, A; Biegon, A; Kim, S W; Alexoff, D; Millard, J; Carter, P; Hubbard, B; King, P; Logan, J; Muench, L; Pareto, D; Schlyer, D; Shea, C; Telang, F; Wang, G -J; Xu, Y; Fowler, J

Aromatase catalyzes the last step in estrogen biosynthesis. Brain aromatase is involved in diverse neurophysiological and behavioral functions including sexual behavior, aggression, cognition, and neuroprotection. Using positron emission tomography (PET) with the radiolabeled aromatase inhibitor [N-methyl-{sup 11}C]vorozole, we characterized the tracer distribution and kinetics in the living human brain. Six young, healthy subjects, three men and three women, were administered the radiotracer alone on two separate occasions. Women were scanned in distinct phases of the menstrual cycle. Specificity was confirmed by pretreatment with a pharmacological (2.5 mg) dose of the aromatase inhibitor letrozole. PET data were acquired over a 90-min period and regions of interest placed over selected brain regions. Brain and plasma time activity curves, corrected for metabolites, were used to derive kinetic parameters. Distribution volume (V{sub T}) values in both men and women followed the following rank order: thalamus > amygdala = preoptic area > medulla (inferior olive) > accumbens, pons, occipital and temporal cortex, putamen, cerebellum, and white matter. Pretreatment with letrozole reduced VT in all regions, though the size of the reduction was region-dependent, ranging from {approx}70% blocking in thalamus andpreoptic area to {approx}10% in cerebellum. The high levels of aromatase in thalamus and medulla (inferior olive) appear to be unique to humans. These studies set the stage for the noninvasive assessment of aromatase involvement in various physiological and pathological processes affecting the human brain.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 1014325
• Report Number(s): BNL-94364-2010-JA; R&D Project: MO-085; kp1602010; TRN: US1102724
• Journal Information: Synapse, Vol. 64, Issue 11; ISSN 0887-4476
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BIOSYNTHESIS
BRAIN
CEREBELLUM
DISTRIBUTION
ESTROGENS
IN VIVO
KINETICS
MENSTRUAL CYCLE
METABOLITES
PLASMA
POSITRONS
SPECIFICITY
THALAMUS
TOMOGRAPHY
estrogen
testosterone
androgens
steroidogenesis
imaging
PET