 |
| Chemical name: | [18F]Fluorobenzaldehyde-leptin | |
| Abbreviated name: | [18F]FBA-Leptin | |
| Synonym: | ||
| Agent category: | Polypeptide | |
| Target: | Leptin receptor | |
| Target category: | Receptor | |
| Method of detection: | PET | |
| Source of signal\contrast: | 18F | |
| Activation: | No | |
| Studies: |
| Click on gene for more information about leptin. |
[PubMed]
Leptin is secreted by white adipose tissue as a negative feedback response to maintain body weight by regulating appetite and fat metabolism (1). Leptin receptors (ObRs) are present in the brain (the choroid plexus and hypothalamus) and many peripheral tissues, such as the lungs, kidneys, adrenals, and lymph nodes (2, 3). There are at least six types of ObRs (a, b, c, d, e, and f). Administration of leptin is able to correct obesity in humans and in ob/ob obese mice that lack a functional leptin gene (ob) (4). However, a lack of responsiveness to leptin could lead to obesity. An ability to predict altered ObR biodistribution may provide imaging opportunities by the design of specific molecular imaging agents to target ObRs. Flavell et al. (5) introduced an aminooxy group at the C-terminus of leptin using expressed protein ligation technique for labeling with 4-[18F]fluorobenzaldehyde ([18F]FBA) to synthesize [18F]FBA-leptin to image ObRs.
[PubMed]
[18F]FBA was added to a solution of 30 nmol aminooxy-leptin in 100 mM anilinium acetate (5). The mixture was incubated for 15 min at 0°C. The resulting product, [18F]FBA-leptin, was purified with two spin columns. A decay-corrected yield of 25% based on [18F]FBA and a radiochemical purity of >95% were obtained. The specific activity of was 9.25–16.65 MBq/nmol (0.25–0.45 mCi/nmol) with a total synthesis time of 120 min. [18F]FBA-Leptin was stable in buffers and mouse serum after 1 h incubation.
[PubMed]
In vitro binding tests showed that binding of [18F]FBA-leptin to cells expressing ObRs was inhibited by 90% with 5 µM leptin (5).
[PubMed]
Flavell et al. (5) performed a preliminary study of positron emission tomography analysis in ob/ob mice after intravenous injection of 3.7 MBq (100 μCi) [18F]FBA-leptin. [18F]FBA-Leptin rapidly accumulated in the cortex of the kidneys. No blocking experiment was performed. The authors noted that further investigation of the biodistribution of [18F]FBA-leptin is being performed in various leptin-sensitive and leptin-resistant animal models.
GM072015, GM55843, GM07739
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