123I-5-I-R91150, a new single-photon emission tomography ligand for 5-HT2A receptors: influence of age and gender in healthy subjects.
5-HT2A receptors have been implicated in the pathophysiology of mood disorders and in the therapeutic effect of the so-called atypical antipsychotics. Recently, a new radioiodinated ligand with high affinity and selectivity for serotonin 5-HT2A receptors, 123iodinated 4-amino-N-1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl] 5-iodo-2-methoxybenzamide (123I-5-I-R91150), has been developed and has been shown to be suitable for single-photon emission tomography (SPET) imaging. In this study the influence of age and gender on the ligand binding was investigated in normal volunteers. One hundred and fifty MBq of 123I-5-I-R91150 was administered to 26 normal volunteers (13 females and 13 males) with an age range of 23-60 years. SPET imaging was performed with a triple-headed gamma camera. For semi-quantitative analysis, ratios of ligand binding in different regions of interest to the binding in the cerebellum were calculated. Mean ratios of 1.7 were obtained. No gender difference was demonstrated. 5-HT2A binding was shown to decline with age. Over an age range of 40 years a reduction in ligand binding of 42% +/- 7% was found. These results are in agreement w in vitro and positron emission tomography findings of a decline in 5-HT2A receptor binding with age. The findings confirm the suitability of 123I-5-I-R91150 for SPET imaging of 5-HT2A receptors, and highlight the necessity for age-matched controls in clinical studies.
Baeken
C
C
Department of Psychiatry, Academic Hospital, Brussels, Belgium.
D'haenen
H
H
Flamen
P
P
Mertens
J
J
Terriere
D
D
Chavatte
K
K
Boumon
R
R
Bossuyt
A
A
D000328:Adult; D000375:Aging; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010880:Piperidines; D019275:Radiopharmaceuticals; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000378:metabolism*; D012737:Sex Factors; D015899:Tomography, Emission-Computed, Single-Photon
D007457:Iodine Radioisotopes; D010880:Piperidines; C105020:R 91150; D019275:Radiopharmaceuticals; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin